Archive for the 'Gas Mileage' Category

Jul 30 2008

CRX D15Z1 (Civic VX) Fuel Economy Swap Guide

Since I knew what a Civic VX and d15z1 was I’ve always wanted to toss one of the swaps in my car. I never really had any money and was trying to look out for some sort of local deal, but in the end I’d saved up some money and figured I’d just go for a JDM swap. It’d come with all the sensors and wire harness and a bunch of junk I figured I’d end up spending for anyway, so I went ahead on bought the damn thing from a Canadian importer for $520 USD, shipping included.

Thing came in about 3 days (all the way across the continent and to my door), and I was ready to get started. I knew all the basics and honestly didn’t even look at anything online before starting the swap. Just figured I’d go ahead and do it and see what came up. Anyway, I intend this page to be a guide for those looking at the swap that can already do stuff like undo bolts and then put them back where they came from. This was my first engine swap, and it went fine, so I’m not going to bother with how to swap the engine as much as I’m going to discuss the specifics of this swap.

Why did I do it?

The short of it is that I wanted better fuel economy, and I knew this was going to be the most efficient engine I could get. The d15z1 has both vtec-e and lean burn, and is smashing good with my HF transmission.

Also, as you can see from this image, my gas mileage has sucked recently due to a doomed CX head swap. It was really sucking, and the car had horrible power to booth. Nowadays, I’m up in the 60s, with hoop dreams of fuel economy up in the 70s. Right now I’m just sitting on the 3rd tank, and I’m hoping to keep it up above 60 mpg consistently, though the numbers seem a little wonky just halfway through this tank…but that’s not important.

Anyway, the d15z1 swap was pretty cheap, maintained stock power, and promised much better fuel economy, so I went for it. I would’ve gone for an even smaller engine if I could get one, but it’s not exactly easy to find a working insight swap just laying around.

What did I have done beforehand?

Previous DPFI -> MPFI and and OBD0 -> OBD1 swaps left me in a decent position to get this done without having to rewire everything myself.

I did the obd1 rewiring myself, but in hindsight, having bought a conversion harness probably would’ve been a good idea. It’s not that it was hard to just chop my old plugs off, but it’s kind of messy now.

Also, when I did the dizzy swap I went with obd0 plugs since I got a dizzy with no plugs, and even though rewiring the dizzy was really easy, i would’ve saved 30 minutes if I’d thought ahead and used the obd1 plugs from the git go.

So, moral of this story (and more things you’ll learn later): think ahead!

What didn’t I have done beforehand (or what should you know)?

The fuel line on the VX is weird. You can see it in the picture, but it’s got to run around the EGR, neither my stock DX nor the replacement CX fuel line I’d been running would fit properly for the new, egr enabled engine.

I spliced to lines together to get it up and running at first, but I ended up spending 80 bucks for the damn thing from majestic honda, so try and find one in advance, but be warned that they’re hard to find.

The EGR Control Box is really just a bunch of crap, and is kind of hard to find. Since it’s on the firewall of the car it won’t come with the engine, and there aren’t many running around. Try to get one from someone who has swapped out a vx engine, I ended up spending 50 bucks on one cuz I needed it fast. Here’s what it looks like and the parts diagram:

ECU pins are a pain, and you’re going to need more for the VX swap. I only needed a few, but I bought some VX plugs anyway for about 10 bucks shipped. I had to wait a few days to finish my ecu wiring, so I’d wish I’d done it in advance.

The driver side engine mount that connects to the block is different from the EG civics to the EF civics, so you’ll need to swap it out. I forgot to do it until the engine was in there, and then I couldn’t get the crank pulley bolt off (easy solution, drove to my old shop and did it there), but you’ll need to remember that and know that you’ll need to notch the timing belt cover a bit for the new (old) mount. It’s hard to see in the picture, but you’ll see what I mean when you do it yourself.

Don’t forget how annoying the shift linkage pin can be. To tell you the truth, I just dropped the linkage with the engine and didn’t mess with the pin. After my last experiences with that, I figured this way was easier.

Don’t forget to be prepared to buy a new o2 sensor. They break easily. I got mine here and had good luck without paying 3-400 from honda (wasn’t cheap though).

JDM Engine Note: As you can see, the JDM catalytic converter has a second o2 sensor on it down near the bottom. You don’t need to worry about that but to leave it in or plug it so you’re not leaking exhaust.

Anyway, on to the swap!

So, how do I stick a d15z1 in my CRX?

Don’t forget this, first of all:

Pulling the engine

It’s seemingly simple! Just don’t let me forget anything! (NOTE: I’m not going to number the steps, that seems a little too arbitrary since I don’t plan on making them uniform difficulty or importance).

Safety, as always, is a priority. If you’re going to be doing this kind of work, make sure you have a proper jack, proper stands, and know where to jack up the car safely.

Anyway, the first step to anything like this is to disconnect your battery. With that out of the way, I just started stripping stuff off. Intake, wires, all sorts of stuff. I just disconnected everything I could besides the mounts.

Once I had a bunch of random junk off, I drained all the fluids and removed the coolant hoses from the engine.

I decided to remove the A/C at the same time I did the swap (I know, I know, it was leaking anyway and I just didn’t care), so I had to pull that out. Normally you’d need to empty the system, so you’d have to take it to a shop and have them do it. Shouldn’t cost too much, really. The a/c hoses normally require some big wrenches, but since I don’t own them I just used two vice grips and the came apart fine.

After pulling the a/c compressor and the hoses, I realized I needed to get rid of the stuff in the bumper and in front of the radiator. I pulled the bumper and removed everything off the front (with the intention of sliding the engine under, anyway), and pulled both the radiator and the a/c junk. Under the dash there is a clamp and some bolts, which allows you to pull out the a/c stuff, remove it from the case, and toss the case back in.

On the radiator I got rid of the stuff you see in red. The one fan is for the a/c and the hoses are a/c or automatic transmission related.

Next up is the axles. Took off the shock forks and then I undid the lca using the stick-a-1/2″-pry-bar-between-the-lca-and-the-knuckle-while-lifting-the-knuckle-then-lowering-it-down-and-jumping-on-the-studs-until-it-popped-method. I’ve always done it this way, and there may be a better way, but I like this. From there I just pulled back the axles and hoped they wouldn’t get in the way.

So, by this time you should have everything nominal removed besides the mounts, however, life will be easier if you remove the alternator and a/c compressor. It’ll prolly be easier without the intake or exhaust manifolds as well. Before I removed the engine I pretty much had it stripped down to a long block.

No, for the actual removal I had everything off the front of the car I could get off, including the front crossmember. Before actually dropping the engine, I lowered the car as close as I could to the ground the slipped a jack under there. I removed the transmission mount first, gave it some support with the jack, did the driveside mount, and lowered the engine completely. I did this alone and it wasn’t too hard, so *shrug*

Then I jacked the car up as high as I could and slipped the engine out under the front of the car.

Sticking the new engine back in

Hopefully I didn’t forget anything about pulling the engine, because we’re about to put the new engine back in.

The first thing to figure out is how you’re going to move the engine around. This image is not a joke, it worked for me:

There’s not much I can say here but do everything in reverse. I put the new engine in with all the manifolds and alternator on, so it was a bit tighter of a fit. Either way, be sure to put the driver side mount on the engine first and cut the timing belt cover to fit.

Once the engine is in, before you start hooking stuff up, make sure to put new fluids in the engine and the transmission, don’t want to forget that. From there I hooked up the cooling system and left off the radiator cap so I wouldn’t forget that either.

Anyway, after all the basic stuff is done, you start to get into a few annoying things. On the back of the DX block was the coolant temp sensor, in the shape of two single male/female prong plugs. I had to chop them off and solder on the z1 plug so that I could hook it up on the thermostat. I’m told the sensor isn’t polar, so it doesn’t matter how you solder up the plugs.

Also, on the back of the JDM intake manifold there is no spot for the purge solenoid, so you need to tap into some manifold vacuum and put that in and tie wrap it to something.

Hopefully you have the distributor wired up, but if not, follow these diagrams to switch around your wiring to get on the obd1 vtec distributor. Similarly, if you don’t have obd0 to obd1 ecu wiring then you’re gonna need to figure that out. I can’t give you much help there, but either buy a harness or just chop plugs and wire. Here are some pinouts, have fun.

Here’s where it gets to start customized. You’ll need to follow this to wire up your o2 sensor. I ran both the power and the ground straight back to the ecu just to be sure. I’ll talk about troubleshooting the o2 sensor here in a bit. The o2 sensor plug has 7 wires, and looks exactly like an obd1 distributor plug, in case you’re trying to find it.

The next thing you need to do is wire up stuff like the egr, egr control solenoid, vtec pressure switch, and vtec pressure sensor. That’s pretty damn easy, just follow these diagrams.

Other than that and the purge control solenoid, I don’t know what else is custom about this swap. Just make sure everything is together, all your fluids are in, and you don’t have wires flailing around. Go ahead and start it up! You should be done.

If not, I’ll have some o2 sensor troubleshooting (code 41).

O2 sensor troubleshooting

The internet way to fix such an issue is to check your wiring until you’re confounding about the solution and then to buy a new sensor. The real way is to follow these instructions I’ve taken from the 92-95 civic manual. You’ll need a digital multimeter, but it’s well worth it, I should say.


Well, my engine swap is done and good and hopefully yours will be done as well. I think this chart speaks for itself (7-18-08 being the first fill after the swap):

The first spike into the 50s you see is after my auto to manual swap, the following dip is after my misguided head swap, and the current spike into the 60s is the d15z1 goodness at work. If you’ve done or plan on doing this swap, drop a comment.

Also, if you have any questions or things I left out, just leave it in the comments and I’ll fix it up.

21 responses so far

Jul 11 2008

DIY PCV Catch Can

Published by Benjamin Jones under Gas Mileage

Part of having your engine perform well is having it in the very cleanest of shapes it can be in. The engine does some of this work itself by using it’s positive crankcase ventilation system, but this system simply throws the gunk throught the intake to be burnt. What is preferable, especially on a high performance engine, is to have said junk trapped before it can reach the intake manifold. This is done by adding a PCV catch can in line with the system to collect the oil on its way to the intake.

Purpose: To prevent gunk from being cycled back through the engine. After it’s caught you can just toss it with your old oil to be recycled.

Time: 12 minutes

- Knife
- Pliers
- 14mm Wrench

-Air Compressor Filter (11.49 at Home Depot)
-Two Fittings (1.17 each at Home Depot)

Look at your parts.

De-package them.

Get them put together, I used a 14mm, tightened like hell, only screwed in that far. Take out the filter from the middle! I forgot at first, which is why it isn’t out in the picture:

Locate your PCV line. You can determine it cuz it’ll only flow one way, should be into the manifold. Note that I also aligned the filter with this flow, it has a little arrow on the side to indicate the flow direction.

Cut a hole in the line and stick it in, I added some extra line just to move it to the side.

Take a look at in in use after just a few hundred miles:

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Jul 11 2008

Choosing Your Route for Maximum Fuel Economy

Good fuel economy isn’t all about driving an efficient car or modifying your car. One of the biggest limiting factors is your commute. The length of your commute isn’t something you can do much about, but there is almost always more than one way to get somewhere, as long as you’re willing to spend the time and effort to do it. This article will examine what makes a good route and how you can use different environmental factors to your benefit.

Before I get into techniques to save gas with your automobiles, it’s important to mention that if your commute is short and your climate is hospitable you have the perfect opportunity to get in shape. Your bike (or perhaps your legs) will become your best friends; saving you money and keeping your body in good health at the same time, what could be better? Besides people power, public transportation is a wonderful way to go, and will only get better as more people choose to ride. The park and ride is an especially attractive way to go when you’re commuting into a congested and polluted city.

That said, even the most diligent public transportation users or peddlers will need to drive every once in a while, whether it be to work, school, or out on the town. The first consideration is how many places you need to go. If it’s more than one plan your trip so that you’re looping around rather then zigzagging back and forth. For such trips you will not perform them enough to do a detailed analysis so you should abide by a few simple rules for best results (on average):
- Take the shortest path through all stops
- Avoid areas with heavy traffic (especially those that noticeably affect your driving patterns)
- Try to avoid roads with lots of stop signs and lights
Of course these things must all be balanced, but for most trips there are obvious options such as cruising down the interstate versus going through town.

Now, for those trips that are repeated with great frequency a bit of investigation is in order. By investigation I mean using your instantaneous fuel economy display to log your segment mileage over the course of several days so that you can compare different routes to see if there is on that gives consistently better mileage. However, be warned that you may chose a longer route with better mileage but still be burning more fuel! This is one of the reasons instant feedback is so important. If your vehicle was manufactured in 1996 or later check out or look online for a used model for sale. If your car is older but fuel injected email me and I will see what I can do to help you out with instrumentation (I have had great success with a device called the superMID in my 1991 CRX).

I’ll assume that most people are not instrumented yet and describe a few common scenarios and how they affect fuel economy:

1. Highway – In most cases highway driving will give you the best fuel economy you’ll see. There are some truly amazing fuel economy drivers that do much better around town than on the highway, but for most of us (myself included) the highway is a good place to be. But don’t forget: slow down! I drive 55 on the highway; that 10 MPH may seem like a lot but it does not extend the trip time very much and boosts gas mileage tremendously. Because aerodynamic drag increases greatly with speed, short of serious modifications to the car, slowing down will give you the biggest gain on the highway.

2. Around Town – This is the killer for most people. Frequent starts and stops, especially when coupled with a heavy foot, destroy gas mileage. Avoid heavy traffic, speeds that do not allow you to use your highest gear, and areas that do not lend themselves to safe coasting practices. Even if it extends your trip slightly the highway is preferable to 25 MPH speed limits and frequent, unexpected stops. However, if you have to drive through town try to stay in the highest gear possible. Your best instantaneous fuel economy will be achieved at the slowest speed you can go in the highest gear possible. When in a 30 MPH zone I regularly achieve 80+ MPG instantaneous readings because my engine is only turning over at 1,000 RPM.

3. Hills – It may seem counterintuitive, but hills can be a fuel economy driver’s best friends. Sure, you’ll get bad mileage up the hill, but as much as you go up you will eventually go down, and on the downhill engine off coasting will seriously increase your trip’s fuel economy. Some of the best fuel economy drivers live in hilly areas that allow them to have their engines on for only 50-60% of their commute, which allows them to achieve phenomenal mileage on their stock vehicles. When considering a hilly route it is best to plan stops that will be at the tops of hills so that you can coast while going up a hill and use less gas to get up to speed as you go down the other side. This may be hard to do but even a few stops can make a huge difference. Also, hills allow you to practice a technique called “driving with load.” DWLing means slowing down up the hill and regaining speed on the other side. This gives the engine a break when it’s working its hardest both as it struggles up his and as it struggles to regain speed.

4. Lights – In many places lights are timed in order to allow drivers who maintain the speed limit to pass through with limited obstruction. If you live in an area with timed light do your best to figure out the timing pattern and adjust your speeds in order to minimize stops. If a light is red it still might change based on the timing, so if you know it well enough you can plan your coast to coincide with the change of the light and the anticipated pace of traffic. When you do get caught in a red light, don’t take off, start up slowly and shift low in the RPM range. Chances are you will get caught by another soon enough and you will have wished you wasted less gas getting up to speed. Also, by accelerating slowly you leave space in front of you where you can coast while coming up to another stop. If you are right on someone’s bumper you have to yield to their reactions to upcoming lights. Another thing is that when stopping you should use engine braking as much as possible. When engine braking you are burning no gasoline and also reducing wear on your brakes.

So generally, to wrap it up, instantaneous information is necessary for a detailed analysis, but in the meantime anyone can improve their commute by taking advantage of existing circumstances or finding another route that is more exploitable. If the interstate you drive down has a side road with lower speed limits, take that, not only will you have a more relaxing drive but the lower speeds will improve your fuel economy. If you launch from the light to get up to speed just to hit the brakes for the next light, start up a little slower, shift lower, and coast to the next light. It’s all about attitude, once you stop rushing through things you won’t feel as rushed to get them done.

A friend, who I consider a good fuel economy driver, took the time to write up a few details of his commute and technique for the site. Please check it out here. Thanks alot, Phil.

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Jul 11 2008

Introducing A fuel economy forum for everyone

Every so often I get questions and comments from kind crxMPG browsers and wish I had a better place for them to interact and to learn more than I can offer about fuel economy. Luckily, a friend, Darin, and I have just set up our own forum over at Please stop on by to ask questions and learn even more about fuel economy!

So what is ecomodding
Ecomodding is, quite simply, changing your car, or your habits, in order to get better fuel economy, save some money, and save the environment. We ecomodders, like cars, whether it’s driving or just tinkering. Some of us (like myself) also love discussing cycling, public transportation, and other things related to the greater transportation experience.

The main thing to remember when coming to ecomodder is that we believe strongly in accurate testing and the fact that there is no silver bullet that will lead to increased fuel economy. However, a lot of little things can add up to a big increase.

So stop on by, looking forward to seeing you!

One response so far

Jul 11 2008

EcoDriving for Beginners: How to Get Great Gas Mileage

In response to the recent hype surrounding hypermiling, I have been meaning to write this article for a little while. Finally I have been able to get around to it. Even if it is not in need of immediate revision, I intend it to always be an open project, so feel free to email me about it anytime.

So, what is hypermiling?
Hypermiling is a term that has been around for a while, I’m not sure how long, but it is generally though to have either come from or been popularized by Wayne Gerdes of On, the site that I frequent, a hypermiler is someone who acheives 20% above the combined EPA rating for their car.

How does one hypermile their car?
Well, it’s really not all that difficult. The range of hypermiling techniques are quite wide, from easy to very difficult. I’m hoping to address them all, but with the emphasis on the safest and easiest. I will also concentrate on some general tips to help people save gas. Hypermiling your car isn’t always the best way to reduce consumption!

Why should I do it?
There are many reasons that hypermilers do their thing: fun, challenge, environmentalism, and thrift. Depending on the type you are, you will find yourself gravitating to certain groups of techniques. I myself am an environmentalist, so you will see that showing up, be warned!

I will organize this as best as I can, but it may get a little confusing. Please bear with me and feel free to email if you find something amiss.

Section 1: Drive Less
I put this section first because it is the best way to reduce your gas consumption. If this isn’t an option, skip on down, but I think it’s well worth a look for everyone.

1 – Live closer to work
Living near your job will not only reduce your gas consumption, but will reduce stress, be safer, and give you more free time. If you’re spending 10 hours a week commuting, consider a change.

2 – Carpool
Carpooling will not only reduce consumption, but will reduce vehicle wear and tear, saving you a lot of money overall. Carpooling reduces road congestion, and really isn’t all that bad. Make a friend at work and commute together, it’ll be nice not to have to drive all the time!

3 – Bike
If you live close to work, biking can create entire days when you don’t even turn on your car. Even if you don’t live close to work, chances are that you live close to something you do. For those short trips to the bank, the post office, etc., consider getting on the old bike and getting a workout. You’ll enjoy yourself more and won’t be using any gas! Also, keep in mind that short trips are the hardest on your gas mileage. Eliminating all those below-average, around-town trips will boost your mileage without even touching your car.

4 – Combine short trips
You’ve probably heard this a million times, combining trips will save you gas, simple as that.

Section 2: Change your vehicle
Regardless of how you drive or how much you drive, getting a more economical vehicle will help. Check out the 100 Greenest Cars at Yahoo!

1 – Buy a smaller car
This is usually the cheapest and easiest thing. Think about how much size you really need and how often you actually fill your car to capacity. So what if it’s a little squished in the back when you have to haul extra people? That’s never hurt anyone in the past. Moving to a smaller vehicle will save you money in just the vehicle cost, let alone the fuel savings. Just make sure your smaller car isn’t a sports car!

2 – Buy a hybrid
They’re all the rage right now, and for good reason. Honda and Toyota hybrids can regularly dominate their non-hybrid competition. For a bit more money, you get all the comfort of a bigger car and all the economy of a smaller car. Hybrids are generally some of the best cars on the market for pollution and reliability. Don’t let the skeptics get you down about battery replacements and pollution, these claims are greatly over blown.

3 – Buy a motorcycle
Though a motorcycle would be difficult to use as a sole means of transportation, small motorcycles such as the Kawasaki Ninja 250 can be had for about 2000 dollars and will return fuel economy great than 75 MPG and great performance. If you do go this route, don’t forget your gear and your safety course!

4 – Buy a scooter
Just like number 3, but even better mileage! If you live in the city, this is the perfect solution for a lot of people. Honda currently makes the best scooters out there, and a Honda Metropolitan will return over 100MPG. Just don’t buy a 2-stroke and remember the gear and the safety course!

Section 3: Change your driving habits
This is the most important thing you can do when working with an existing vehicle. There are a ton of strategies, but I will try to simplify them to serve as an introduction.

1 – Get instrumentation
The most important thing you can do is get some instant feedback so that you know what’s going on with you car. If you are driving an OBD2 vehicle (1996 and up), go to and pick yourself up a Scanguage II. You can also find them on ebay for a little cheaper, but they are indispensable. For older, fuel injected cars, check out the SuperMID. It is more limited in terms of compatibility, but very worth it if you are compatible.

2 – Slow down!
Air resistance increases exponentially with speed, so slow down! The difference between 55 and 75 is astronomical.

3 – Plan your route
One of the easiest things to do is choose a better route to work. In many cases, you may find that you use less gas but get lower mileage, or go further but use less gas, depending on which route you pick. This is why tip 1 of this section is important. Check out this article for more information.

4 – Stop idling
When you idle, you are getting 0 MPG. Idling the car in the cold does not help warm it up, it actually takes longer. Just drive gently after starting up.

5 – Avoid rapid acceleration and hard braking
These sort of actions waste gas. Instead of braking hard, coast from as distance. Use your brakes as sparingly as possible. Also, be aware the slamming the gas will only dump more fuel on than is necessary. Conservative acceleration will generally return the best fuel economy.

6 – Anticipate changes in traffic
If you know that a light is going to become read or turn green, slow down in advance and give it time to do so rather than gunning the gas up to the stop. In heavy traffic give yourself a bit of space before starting up, try to keep moving slowing rather than alternating between fast speeds and stops. This is one of the best tips for driving, as it will prevent you from making many unnecessary stops.

7 – EOC (Engine Off Coast)
Engine off coasting is the way to go to increase fuel economy to astronomical amounts. This is very difficult and can be unsafe, so be very careful when using it. Also be aware that long EOCs can reduce catalytic converter heat and increase emissions (though the time period or relative emissions increases are unknown.
Before EOCing, you need to be aware of how your car will preform under the circumstances. The basic drill is to put the car in neutral, turn the engine off, and turn the key back to run (to give you the use of the speedometer as well as the ability to turn the wheel). EOCing will cause you to lose both power steering and power brakes. You will have a limited power brake reserve, but this depends on each car.
For your first EOC, find a deserted road with a long open stretch and then key off, turn to run, and begin coasting. While coasting, test your steering and your brakes. If they do not feel comfortable, don’t EOC! You don’t want to risk anyone’s life in this pursuit. If steering is okay and the brakes work well, you are ready to EOC in normal driving. Just remember to be very alert and not to EOC in environments likely to have unexpected occurrences. Stay safe!

8 – Draft
On the highway you will notice that SUVs are basically moving walls, pushing all the air out of the way. If you get in behind one, air drag will be cut astronomically. Now, don’t get too close, try to leave 100 feet, or else the trucker will become angry and neither of you will be safe. Even at 100 feet drafting has benefits.

9 – Pulse and Glide
P&G is an interesting technique, taken from the hybrid drivers, which involves alternating EOC and acceleration. P&G is most effectively done at slower speeds, where air drag is not as much of an issue. To P&G you pick a target speed (say 40) and accelerate past it (to 50) and EOC until your speed drops (to 30), you then start up again and accelerate back to the upper target. Rinse and repeat for awesome mileage. Note: This is best done when no one is around and is very annoying to keep up!

10 – Driving with load
In hilly terrain, it can kill FE to be constantly gunning it up hills. DWL involves picking a fixed throttle and slowing down up hills and gaining speed down. Rather than holding speed, you are holding the pedal. This is a very affective way to deal with hills, though you often will need to bend the rules to not slow down traffic too much.

11 – Reduce engine loads
High fans, loud stereos, A/C, and heat add load to the engine and reduce fuel economy. It is much better to roll down your windows than to turn on A/C in almost any circumstance, so keep this in mind. A/C can reduce fuel economy 5-30%.

12 – Turn of 4WD
If you can, turn it off when it is not necessary, it increases driveline losses.

Section 4: Modify your vehicle
Vehicle modifications are some of the most difficult and hardest to quantify changes you can make. Some of them are great, others might seem like more effort than they are worth, and some will be just too hard to do. Pick and choose.

1 – Swap the engine
This depends greatly on your mechanical ability. If you can do it, pick out an engine, and throw it in. This is akin to getting a new car and can give you huge boosts in mileage. I won’t go in depth, however, because I’ll assume that if you know how to do it you can pick out an engine. Perhaps in a later article I will detail the options for Hondas. (Feel free to bug me if you want it done.)

2 – Swap the transmission
Very similar to the above. An auto to manual, like I did, will realize the biggest change. I picked up about 50% on my mileage with this swap. Figure out the gearing on various transmissions and see what suits your needs. You can also swap gears around from within transmission, but then it just gets more complicated! Check out this link for more.

3 – Increase tire pressure
This is one of the easiest ways to increase mileage. I currently have my 44 max psi tired inflated to 50 psi. This doesn’t mean that you should do it, but it has been done by many people. When overinflating, inflate a bit at a time to test handling and feel before you settle somewhere comfortable. Be prepared for a bit rougher of a ride, but you will see the fuel economy increase!

4 – Warm air intake
The WAI will not work for everyone, but it is worth noting because it is a very good mod for Saturn owners. For whatever reason, Saturns really respond to warm air intakes, so take advantage of it of you can. A WAI is generally constructed by extending the stock intake to suck air from closer to the exhaust manifold (where air is warmer). Once again, experiment before you finalize anything.

5 – Block your grill
The air drag caused by the radiator is rather large, so grab that corrugated plastic and block your grill. Be careful to make your first block easily removable and watch the temperature gauge to make sure you don’t overheat. It’s important to find a balance between cooling and aerodynamics, even a partial block will help.

6 – Rear wheel well covers
These snazzy looking covers will help smooth airflow across the car by closing the rear wheel wells. These are affective, though not mind-blowingly so. A must do for anyone with a lot of highway driving or someone interested in aero mods.

7 – Undertray
Covering the entire bottom of the car with corrugated plastic will reduce air drag caused by the roughest surface on most cars. This mod is difficult mainly because you have to get under the car and work on your back securing everything. If you do this, make sure to leave easy access to oil and anything else you might need to get at normally.

8 – Take off the alternator belt
This is a pretty hardcore thing to do, but pays large dividends. By removing the alternator belt you disable the alternator and remove all electrical load from the engine. This means that you will be running down the battery constantly, so to do this you need to minimize electrical loads and run a battery charger at home to keep the battery topped off. There is also the possibility of running a solar car battery charger, though I haven’t heard of anyone experimenting with this yet. Make sure to only remove the belt in case you need to reattach it at some point to deal with rain or darkness!

9 – Replace your radiator fan
If your fan is belt-driven or otherwise inefficient, pick up a new, electric fan to help reduce engine load. This is an especially good modification for those with belt-driven fans, and can save quite a few horsepower.

10 – Remove power steering
For many smaller cars, powering steering is more of a luxury than a necessity. My CRX does not have it and I’ve always been glad of that fact, it makes me feel more connected to the road to have manual steering. That being said, for cars with power steering there are often ways to disable it or to convert the car to manual steering. Also, electric power steering has become an option in recent years. Power steering is just another one of those little things that will rob you of a few HP here and there.

11 – Boattail
This is further down because it is difficult to do, even if it is good for a lot of improvement. A boattail reduces drag caused by turbulence at the rear of the car, which accounts for a large amount of a car’s aero drag. Check out Basjoos’ car in the gallery for some interesting ideas.

12 – Low rolling resistance tires
Much like increasing the tire pressure, LRR tires reduce rolling resistance by using a harder rubber material. They are more expensive and harder to find, but keep them in mind next time you’re shopping for a car.

Good luck and happy hypermiling! Don’t forget to make suggestions.

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Jul 11 2008

A New Spin on Old Fuel Economy Advice

This is taken from a thread on gassavers that can be found here. I’ve edited it to my liking, but feel free to check out the original as well. Red will be my/original edits and dark green will be examples and links to further reading on the subject. Feel free to email me with any suggestions or additions.

Original documents can be found at these two sites:


Normal people in normal cars can achieve gains in fuel economy. This is not rocket science or some miraculous product. It is a change in thinking that requires a change in behavior behind the wheel. With many cars today coming with a mpg gauge (see attached list) you can see how these changes are working in real time. For all cars after 1996 a scangauge can be used for getting an accurate reading. Best of all these solutions are free or part of normal maintenance. There are websites popping up with hundreds of members providing ideas and feedback as well in forums. Tracking your mpg is the fastest start to having it improve. Mileage logs are available online at

Drive Sensibly
Aggressive driving (speeding, rapid acceleration and braking) wastes gas. It can lower your gas mileage by 33% at highway speeds and by 5% around town. Sensible driving is also safer for you and others, so you may save more than gas money.

Hypermiler’s: Take driving sensible to the next level, some techniques used are driving without using brakes, coasting in neutral, avoiding jack rabbit starts or using quick starts to get to cruising speed and always traveling in the slow lane.

Check out this page for a general summary of commmon hypermiler driving techniques.

Fuel Economy Benefit: 5-33%
Equivalent Gasoline Savings: $0.15-$0.96/gallon

Observe the Speed Limit
While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph.
As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas.

Observing the speed limit is also safer.

Hypermiler’s: Are usually the slowest cars on the road doing the speed limit. Generally known for trying to limit maximum speed to 50 or 55 MPH, hypermilers often drive below the speed limit, especially during a coast.

Fuel Economy Benefit: 7-23%Equivalent Gasoline Savings: $0.20-$0.67/gallon

Remove Excess Weight
Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your MPG by up to 2%. The reduction is based on the percentage of extra weight relative to the vehicle’s weight and affects smaller vehicles more than larger ones. Golf clubs, business materials are just some of the items that add up quickly.

Hypermiler’s: May elect to remove spare tire (instead carrying fix a flat, plug kit), jack, some of the extra seating, as well as changing body panels, such as hoods to a lighter materials.

Fuel Economy Benefit: 1-2%/100 lbsEquivalent Gasoline Savings: $0.03-$0.06/gallon

Avoid Excessive Idling
Idling gets 0 miles per gallon. Cars with larger engines typically waste more gas at idle than do cars with smaller engines.

Hypermiler’s: Turn off the engine any chance they get, especially during coasting. DO NOT idle your car to warm it up, consider purchasing a block heater.

Use Cruise Control
Using cruise control on the highway helps you maintain a constant speed and, in most cases, will save gas.

Hypermiler’s: Use a combination of cruise control and pulse and glide to achieve constant speeds. In hilly areas cruise control is often blamed for using excess fuel.

Check out this page for some ideas on how to deal with hills and flats besides the stedy cruise.

Use Overdrive Gears
When you use overdrive gearing, your car’s engine speed goes down. This saves gas and reduces engine wear.

Keep Your Engine Properly Tuned
Fixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4 percent, though results vary based on the kind of repair and how well it is done.

Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by as much as 40 percent.

Hypermiler’s: May use different ECU’s or other modifications to air flow, timing or other systems for their particular vehicles.

Fuel Economy Benefit: 4%
Equivalent Gasoline Savings: $0.12/gallon

Check & Replace Air Filters Regularly
Replacing a clogged air filter can improve your car’s gas mileage by as much as 10 percent. Your car’s air filter keeps impurities from damaging the inside of your engine. Not only will replacing a dirty air filter save gas, it will protect your engine.

Hypermiler’s: Sometimes make changes to the air intakes which induce warm air into the system, this causes the car’s computer to run a leaner mixture. The opposite effect of a cold air intake. For many this works and for many others it does not. Individual testing with instantaneous feedback is necessary.

Fuel Economy Benefit: up to 10%
Equivalent Gasoline Savings: up to $0.29/gallon

Keep Tires Properly Inflated
You can improve your gas mileage by around 3.3% by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.4 percent for every 1 psi drop in pressure of all four tires. Properly inflated tires are safer and last longer. Regularly scheduled tire rotations can be beneficial as well.

Hypermiler’s: Set their tire pressures to what the sidewall pressure is on the tire, in some cases above that.

Fuel Economy Benefit: up to 3%
Equivalent Gasoline Savings: up to $0.09/gallon

Use the Recommended Grade of Motor Oil
You can improve your gas mileage by 1-2 percent by using the manufacturer’s recommended grade of motor oil. For example, using 10W-30 motor oil in an engine designed to use 5W-30 can lower your gas mileage by 1-2 percent. Using 5W-30 in an engine designed for 5W-20 can lower your gas mileage by 1-1.5 percent. Also, look for motor oil that says “Energy Conserving” on the API performance symbol to be sure it contains friction-reducing additives.

Hypermiler’s: Use of high quality 0W20 is common, though not always practiced. I won’t say uch else because I’m not an oil expert, but I think you should be wary of oil additives promising big fuel economy benefits.

Fuel Economy Benefit: 1-2%
Equivalent Gasoline Savings: $0.03-$0.06/gallon

Note: Cost savings are based on an assumed fuel price of $2.91/gallon.
Estimates for fuel savings from sensible driving are based on studies and literature reviews performed by Energy and Environmental Analysis, Inc., Washington, DC. Estimates for the effect of speed on MPG are based on a study by West, B.H., R.N. McGill, J.W. Hodgson, S.S. Sluder, and D.E. Smith, Development and Verification of Light-Duty Modal Emissions and Fuel Consumption Values for Traffic Models, Oak Ridge National Laboratory, Oak Ridge, Tennessee, March 1999.
Contact me with questions or comments!

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Jul 11 2008

Acceleration and Fuel Economy Tested

One thing that has been floating around the heads of many users at for a long time is which method of acceleration proves most effective for fuel economy. It would seem logical that the slow and steady would prevail, but there is also the argument that a quick sprint to cruising speed is best because it gives more high FE cruising time. Even though the acceleration would use more gas it would be balanced by the better FE from cruising or engine off coasting. I chose tonight, the last night I would have my car before heading off to Dartmouth College, to test this idea.

Before getting into the results the test route and procedure needs to be exhausted in order to understand what was actually going on. After warming up the car on the test route I got down to business. There were two theories at test here and I will now describe how each of them was applied in my testing:

  1. Slow and Steady – For this I used my regular acceleration patterns. I gave very light throttle, shifted into 2nd at 1500 RPM, 3rd at 1500 RPM, 4th at 1250 RPM, and 5th at 1250 RPM. From this point I accelerated in 5th (beginning at 1000 RPM) up to 40 MPH until I hit on of the designated engine off coast (EOC) points. If I was not at a stop and simply pulse and glide (P&G) coasting I would bump in 5th and get back up to speed in the highest gear possible at a slow pace.
  2. Jack Rabbit – Because extra throttle doesn’t do much at the low RPMS I usually accelerate at I took first gear to 2500 RPM, second to 2000 RPM, and 3rd to 2000 RPM. At this point I shifted straight into 5th as I was already going the mandated 40 MPH for the test. I gave the car 50-60% throttle during these periods of acceleration.

Here’s an edited version of the course I tested this on. It made for a total of 4.79 KM from start to finish. Each number on the map will correspond to a note discussing driving tactic or course layout:

**NOTE: Traffic was not an issue at this test was conducted at midnight on empty roads** On that note, here is a point by point description of the trip:

  1. Start point, stop sign. Accelerate to 40 MPH
  2. EOC to point 3.
  3. Traffic light but I stopped each time to keep it consistent. Accelerate to 40 MPH.
  4. EOC to point 5.
  5. Stop sign, accelerate to 40 MPH.
  6. P&G to 30 MPH.
  7. Bump start and acclerate to 40 MPH.
  8. EOC to point 9.
  9. After taking curve at 25 MPH bump start and accelerate to 30 MPH.
  10. EOC to point 11.
  11. Bump on for ~100 yard then EOC to Stop/Start.

Each of the EOCs was begun at the top of a hill or to a stop (the only flat EOC was to the stop). It was odd that each leg of the trip had a hill right in the middle, but that’s how the cookie crumbles I guess.


Ah, the fun stuff, finally! I won’t say I was surprised terribly, but a little bit. The difference isn’t much, but heck, it’s consistent.

Slow and Steady Results

Test Number 1 2 3
Time 6:28 6:23 6:32
Engine On % 53 51 51
Engine On FE 34.41 MPG 32.31 MPG 32.47 MPG
Fuel Used .228 L .236 L .234 L
Segment FE 65.53 MPG 63.30 MPG 64.12 MPG

Jack Rabbit Results

Test Number 1 2 3
Time 6:16 6:24 6:27
Engine On % 50 49 49
Engine On FE 33.06 MPG 32.22 MPG 32.49 MPG
Fuel Used .226 L .226 L .225 L
Segment FE 66.29 MPG 66.41 MPG 66.54 MPG

There is certainly no big gap between these two sets of results, but I believe they are consistent enough to draw a conclusion. The average of all the slow and steady results was 64.32 MPG while jack rabbit acceleration yielded an average of 66.42 MPG for a difference of 3.3%!

I attribute this difference to the increased amount of EOC available with the jack rabbit acceleration. I believe that if there were more distance on each leg the difference would be even greater, but that test will have to wait for another time!

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Jul 11 2008

Basic Fuel Economy Driving Techniques and Instrumentation

There’s been a lot of talk about how important instantaneous feedback is in achieving high fuel economy, but what role does it really play and how can it be most effectively used? Hopefully we can get into that a little bit here. Firstly you should not that this article will be focused mainly on using the SuperMID since I don’t have and can’t use a Scangauge. If your car is 1996+ you can check out there Scangauge at their homepage, Regardless of the device this article will be written in order to discuss how it is used to help you get better fuel economy.

Take a look at this little diagram that I made of the main screen of my MID:

Instantaneous FE – This tells you the fuel economy you are getting at the very moment and has little bars that fill up the top-middle such that more bars equal greater fuel use and so on. This is highly variable but you will use this feature when featuring the gas, driving with load, and a whole host of other things that are based mainly around a target fuel economy.
Average Speed – This gives you the average speed for the trip, pretty straightforward. You’ll notice, however, that if you’re repeating a specific trip a slower average speed will generally correspond to a higher trip fuel economy.
Injector Pulse Width – Raw data about how long the injectors are open for. This is a good indication of load in my experience as it takes the speed component out of the FE equation and tells you directly how much gas is going in there.
Distance – Records how far you’ve traveled since resetting the section you’re viewing.
Fuel Used – Records how much fuel you’ve used since resetting the section you’re viewing.
Percent Distance with Engine On – This is one of the neater features of the MID. Because it was originally designed for use with the Toyota Prius to allow FE readings higher than the stock computer could record it was also programmed with a function that records what percentage of the distance traveled is done so with the engine on. In the case of the Prius this would be a ratio between the combustion engine and electric motor, but for us it is a great measure of the use of engine off coasting and engine braking. It records any amount of distance traveled without the injectors opening as time with the engine off, and is a very helpful tool to compare engine off coasting’s effect on fuel economy.
Engine On FE – This is another Prius feature that is very interesting to compare engine efficiency with efficiency of driving technique. You can see that the engine on fuel economy is lower than the trip fuel economy (the difference translated to about 3 MPG) so that even on this very short trip where I didn’t do very much engine off coasting I have reaped the benefits!
Trip FE – Trip FE is either the most important or second most important function of the superMID. Trip FE will allow you to pick routes to work/school, help you figure out if your driving skills are improving, challenge you to do better on every drive, and let you test modifications you’ve done to the car. Most of the rest of this article will be based around the use of trip FE.
Last KM FE – The last KM FE is just that, the FE that you’ve managed over the last KM of distance. This section evens out some of the spikes of the instantaneous FE and alerts you to the fact that you might be getting bad FE due to a slight grade or unnecessary throttle pressure. It’s also rewarding to see it pegged at 99.99 KM/L after a > 1KM engine off coast.

SuperMID Daily Driving Tips&Tricks

  1. Begin with the most fuel efficient route – Why spends weeks fine tuning your trip to work when in the end you could’ve been getting better mileage on some other route? Before you spend all your time trying to max out a certain route experiment with others to help you find out which one is really best. Don’t go be straight trip FE, use the total fuel used section to see where you’re actually using the least. Make sure that you give each route a fair shake and try to collect data from days with similar weather patterns. Also, be aware of the hypermiling potential that one route might have over another; if one has a steep hill with a gradual downslope and the other has a gradual hill with a steep downslope you are more likely to succeed with the first option. You will spend less time going up the hill and more time coasting your way down. For more information on route selection check out this article.
  2. Set goals – Before the discussion on actual driving tips, you need to remember to set goals, both for tanks and individual trips. The most important thing about goals is breaking them, because every time you smack through a milestone you will be motivated to set another one and break that one too. Start of realistically though. If you’ve been getting 35 MPG say you want to hit a 40 MPG tank and 50 MPG segment, not too far out of the realm of possibility but certainly beyond what you’ve been getting.

    Another important method of goal setting is to make each particular milestone in your drive a goal in itself. For example, when I drove to school I would do whatever I could to get to 30 MPG before leaving the developement. This was rather difficult as there were many stops and it needed to be done on a completely cold engine, so the challenge was ever present. However, I knew that if I could accomplish this I was set up for a good day in terms of fuel economy. I would also set goals for FE when entering the highway, leaving, and passing other certain major changes in the trip. In this way I could tell whether or not I was on course for my overall goal and could thusly adjust my driving habits.

  3. Feather the gas – This technique is extremely important if you want to squeeze ever last bit of gas mileage out of your car. Generally when you drive you’re giving more throttle than you need to to maintain speed or you’re constantly and very slightly accelerating. With the superMID you can vary your throttle pressure until you’re at your very lightest point while maintaining speed and you’ll actually see the increase in fuel economy. Even with this knowledge now I cannot properly feather without the MID, it’s just crucial to be able to see the slight differences in pressure and road grade that you would never notice without instantaneous feedback. The MID challenges you to milk ever last MPG from your drive, even when you’re just cruising.
  4. Slow down – Speed kills! Aerodynamic drag increases greatly with speed, not to mention engine RPM and load. If you can manage it go 55 on the highway or avoid the main highway altogether. You’ll see a huge savings from 65 to 55 MPH, especially if you have short gearing that leaves you cruising at upwards of 2500 RPM.
  5. Engine Off Coast – Engine off coasting is just what it sounds like. When you come to a stop or a span where you can coast without losing speed you shut the engine down. To do so flip the key to I and allow a few seconds before switching back to II. This will disable power steering (if you have it) and your power brakes will only have enough charge for a few stops. Make sure to practice EOCing in an area where you can safely test you car’s reaction to this technique. If you’re EOCing to a stop simply stop and when you’re ready to go key back on. If the EOCing is part of a coast simply key back on when you’re ready to restart or bump start by letting the clutch out while in gear to restart the engine.
  6. Pulse and Glide – Perhaps the most intriguing and beneficial of all the FE driving techniques, P&G involves two basic steps. The first is a moderate throttle pulse to a target speed and the second is an engine off coast back down to the lower target speed. The idea behind this technique is that normal internal combustion engines are inefficient during normal cruising but more efficient at moderate throttle. When that moderate throttle is couple to the infinite FE of EOCing you will end up with a higher average FE than if you simply cruised at a steady pace. This is most easily accomplished at low speeds because there is less aerodynamic drag than would be present at higher speeds. So with a low speed P&G you can really increase the distance of your glide. Of course all the same issues apply with P&G that do with EOC, so practice in a safe area and make sure to measure your non-P&G FE first so that you can compare and refine your technique.
  7. Drive with Load – When DWLing you do your best to maintain fuel economy when encountering hills or small inclines. In normal driving you would attempt to hold 45 MPH by increasing throttle pressure, but when DWLing you pick a target fuel economy level and allow yourself to lose speed while going uphill in order to not lose fuel economy. You may then pick up speed on the downhill where you can speed up quickly and without greatly damaging fuel economy. DWL will greatly aid fuel economy but depending on the speed and size of the hill there is a limit to its benefits. If you’re in a trafficless area and willing you can bleed off as much speed as you want, but while in traffic you have to consider potential safety issues during DWL.
  8. Parking Tactics – Always park in the highest spot you can find. If your driveway at home has a slope, use it. Roll out into the road before starting and try to use some of that momentum to begin your drive. In parking lots back it in when you park. Reverse is a killer but using it on a warm engine is better than having to reverse out of a spot on a cold engine. If possible find a gap where you can pull straight through and be facing forward in the space so that you do not need to reverse at all. When entering a parking lot scout it out immediately and try to find a spot in a location that you can coast to without using any extra gas. If you can shut off the engine entering the lot and coast into your space you’ll have saved a lot of gas that would normally go to first or second gear navigation.
  9. Braking (or lack thereof) – Using the brakes is an awful waste of momentum, try to avoid it at all costs. Anticipate traffic flow and coast to a stop rather than following traffic and braking with it. If you coast early many times traffic will pick up by the time you reach the clog and you will not need to brake at all. Take curves as quickly as possible while maintaining safety. If possible coast to the turn so that you do not need to brake at all. When approaching lights coast first, engine brake second, and then brake as a last resort. If you time things just right you can make most lights and turns without using the brakes at all.

Well, now that that’s over with, I should describe some of the other functions of the superMID. As you may have noticed in my picture there is an “A” by the engine on percentage. This corresponds to a trip stored within the superMID, there is A, B, Start, Tank, and Lap. A and B are just arbitrary storage containers, Start records everything since the beginning of the use of the MID (unless it is reset), and Tank records your statistics for the tank. The Lap function stores 20 different laps and is very helpful for testing as you only need to push one button to switch to a new lap. It also allows you to compare the current lap FE to the last lap without switching menus.

Now that you know the tips, tricks, and function of the superMID, go out and get yourself one! If you’re seriously interested contact me and I will put you in touch with Yoshi, the maker.

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Jul 10 2008

DIY CRX LED Dome Light

The power in your car is not free, it comes from the alternator and is a product of the huge amount of drag that this electrical generator puts on your car’s engine. I chose to begin my (unfinished) quest for LED lighting by converting my dome light to LEDs. It make be a modest start but it looks great and I’ve recieved many comments on it, even from some outside of the car enthusiast world. It seems much harder than it is, so don’t be intimidated if you’ve never done anything of the sort before.

Purpose: To cut down electrical loads on the charging system.

Time: 1 hour

- Soldering Iron
- Knife

- LEDs (I used 15 10,000 MCD ultra brights)
- Resistors (100 ohm for this project)
- Some perf board (4 bucks at radio shack)

This is my awful demonstration of how the circuit should go. The resistor is crucial! I blew up one of these LEDs once and a flying chunk but a nick in my living room wall.

Grab your dome light outta the car. Mine was already out for randomness’s sake. Make yourself a little drawing to see how big the perf board should be cut.

Smash it into shape.

Start sticking the LEDs in. You want to line things up so that you’ll be able to tie all the negative sides together to go to the ground and the positives together in bunches of three so that each three can go to a resistor.

Look at it and be like, that’s hella sloppy. I just tied the four on the one end together and called it a day, in the end I soldered that straight onto the lead in the dome light housing.

All in!

Soldered completely.

Test wiring, notice the resistors are in also, don’t forget these!

All done but not mounted!

Mounted up on the car. I had to cut the board a bit to get the screw in there. Night pictures ought to be done but you can’t really see anything, just trust me and get it done! You can also use amber LEDs if you are into that look.

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Jul 10 2008

DIY Spark Plug Indexing

Doing a tune up? Replacing spark plugs? Just wanting to check things out? While you’re at it consider indexing your spark plugs. This is one of the few ignition modifications that can make a very small difference in engine performance. As said by the folks at Advance Auto Parts: “Real-world power gains vary. Some engines or combinations respond differently than others. In fact, all engines will pick up power, but some gains will be more dramatic than others.In the end, it can’t hurt to index the spark plugs. This can contribute to superior engine efficiency and improved economy.” So, no promises, but it can’t hurt!

Purpose: Indexing the plugs allows the flame to spread more uniformly through the combustion chambers in the individual cylinders. I am certainly not about to claim a plethora of scientific knowledge on the subject but I’ve seen many dyno charts supporting the theory and have thus accepted the idea that it’ll help. It’s really not too much extra effort on top of replacing the plugs, so what the heck.

Time: 20 minutes

- Socket Wrench
- Spark Plug Socket
- Extension


1. Go to the parts store and buy yourself some new spark plugs, preferably Denso U-Grooves or NGK V-Powers (basically the same). They’re the recommended stock replacement and generally used plugs; cheap and effective. Again, I do not profess to be a spark plug wizard.
2. Pop them out and take a look at how they get their name.

3. Mark with a marker the on the white part where the opening on the plug is. This will allow you to see where the opening it when the plug is in the head getting adjusted.

5. Go out to the car, yank your plug wires and then your old plugs.

6. Stick a new plug in and tighten it down and see where the opening is. On most cars you’ll want the opening facing the exhaust, but it’s different for everybody.
7. If it lines up perfectly stock, you’re lucky, if not, grab a copper indexing washer and throw it on the bottom of the plug and see how it works. There are different sizes of washers and all that to try and get the indexing right, so just mess around until you get it.

See if you can see how it’s lined up:

8. Once they are all indexed, slap everything together and be happy.

There are two methods of indexing, one is to buy lots of plugs and attempt to get lucky, the other is to use washers, take your pick. I chose to use washers rather than to try my luck. Less wasted gas driving to the store.

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