Engine Heeltoe Explains Tuning

A Bit About Ethanol Fuels; Is E85 or Flex Fuel Right for My Hi-Power Hondacar?

I had a friend who used to have a saying that alcohol was the lubrication for the ball-bearings of life. It was a fun phrase for a couple of 20-somethings who knew so little about the real challenges of life that this thinking might have set them back a few brain cells unnecessarily. Irony especially being that alcohol often leads to more life-friction than less, and it should come as no surprise that the very same buddy found himself abstaining indefinitely years later. Besides, ball-bearings are fairly frictionless without much lube at all, aren’t they?

If booze isn’t the life-motivator it is promised to be, converting to alcohol-enhanced automotive fuel by contrast can be a great way to motivate your car! We’ve been getting asked a lot of questions about E85 conversions, so we’ve made this post to give us a convenient place for our customers to get some answers.

Before learning about enhanced fuel, though, something important should be said about how engines make power:

How does the engine make power? It’s in the AIR.

To make power, engines pump air in, inject a little fuel at the right time, light the mix on fire. KEY: AIR is the primary limiting factor in making power. The oxygen found in the air is one of the most magical substances on Earth. If you mix just the right amount of hydrocarbons in and you have yourself a really volatile mix. Therefore, larger engines make more power; they pump more air. Likewise, boost adds more power; the pressure crams more air in. Adding air makes more power provided the right amount of fuel is added, too.

So, in case the point isn’t made clearly enough: If you aren’t having a plan to add more oxygen to the engine, adding more fuel of any kind is going to be of limited benefit.

There are exceptions to this broad sweeping statement. Increasing compression and advancing timing will create conditions that can produce more power without adding oxygen. It’s just that the biggest benefits to fuel changes are going to come with boost or nitrous.

What is ethanol?

Ethanol is alcohol, made from sugars. Like all alcohol, it burns when you add oxygen and an ignition source. Since it can be made from corn, and ‘Merica has lots of corn, we make ethanol from corn. Since ethanol is made from plants it has been a welcome renewable addition to our favorite supply of liquified dinosaurs to make fuel. The government loves it. Our gas has about 10% ethanol in it as standard.

What is E85 or “Flex Fuel?”

From Wikipedia’s E85 page:

E85 is an abbreviation typically referring to an ethanol fuel blend of 85% ethanol fuel and 15% gasoline or other hydrocarbon by volume.”

E85 is a specific kind of Flex Fuel. Flex Fuel, though, instead of being a specific 85% ethanol by volume, it can be varying ratios of ethanol to gasoline, 51% to up to around 90% depending on the station you are at, area you are in, or the time of year it is. E85 is Flex Fuel but not all Flex Fuel is E85.

What is important to know about E85/Flex Fuel?

  • It’s corrosive. Fuel lines, pumps, seals, o-rings and the like all need to be designed to work with ethanol otherwise the fuel can eat away at the material and cause leaks. This is mostly a problem on older cars designed and built before ethanol was a common additive and automakers were designing components to be compatible.
  • It’s hygroscopic, meaning on a chemical level it seeks out water and absorbs it (similarly to brake fluid). This is important to know because you don’t want higher concentration ethanol fuel sitting in your tank for long periods of time because water will collect and enter the fuel system. The same thing can happen with gasoline, but it is more of a concern with ethanol.
  • It’s got a lower energy density compared to petrol. If we light a cup of gasoline on fire, more heat is going to be given off than if we light off a cup of ethanol. In order to get the hydrocarbons in ethanol to generate the same heat as gasoline, you need more fuel than you would straight gasoline. About 25-30% more in fact. So that translates to a pretty significant increase in fuel consumption.
  • Ethanol has oxygen in it. This adds to the lower energy-density issue because in the ethanol molecule there is less “room” for hydrocarbons, and more oxygen is available in the mixture which serves to lean out the air-fuel ratio. Even MORE fuel is needed to make the air-fuel ratio work out. It’s not bad for power, but it just makes the engine really thirsty. It’s true there is more oxygen in ethanol and so more power can be made; just understand that it means more fuel is needed to make the chemistry work out.

Why would you want to use ethanol-blended fuel in your hot-rod Honda?

Ethanol has a higher-octane rating than gasoline does. E85 has an octane rating of around 105. This means you can run higher cylinder pressures without the risk of detonation (in a nutshell, the fuel is much less prone to “lighting itself” and causing knock).

Not only is the octane higher, but it has a high latent heat of evaporation—meaning as it atomizes it removes heat from the intake air. (In other words, when the fuel is injected and it vaporizes, it cools the intake charge. Ethanol cools more than gasoline does.)

So is my Honda is going to make more power if I change the fuel to an ethanol blend?

Yes, but there is more to it than just what you put in the tank. Your car needs to be set up for ethanol fuel to effectively use it. Plus, the fuel costs less than gasoline will but you will be using significantly more of it (nobody told you the MPGs are going to drop?). It won’t make economic sense to convert if you won’t reap enough of the power benefits.

A lot of Hondacar drivers have NA setups (as in—they are not using power adders such as turbo- or super-charging as a means of adding more air to the engine). If you have an NA setup and aren’t running high compression—like at least 12:1 or more—the power benefit to you is going to be smaller, because 91 octane and a good tune is all you need. Sure, you’ll be able to run a bunch more timing advance which will feel great, but the fuel cost is a lot to consider for that benefit. Because NA stands for “Normal Air” going into the engine. (Actually, it means Naturally Aspirated, but in lay-terms Normal Air makes the point clear that the air-charge is not boosted).

If your engine is boosted turbo- or super-charger we have more to talk about. Adding boost adds oxygen to the mix and adding more fuel will make more power. Adding boost can be risky because if your fuel octane rating is not high enough detonation can occur and cause damage to the engine. So for higher boost, high-octane ethanol is going to hook you up! You’ll be able to add more boost to the engine and have much lower detonation risk which is really going to make power.

Cooler air means more power and is safer

Also, ethanol has a greater cooling effect when it vaporizes than gasoline does, so that is a solid benefit in any case. If you are running an NA car with moderate compression but are beating the piss out of it all the time, you might find your car running a little tighter as cylinder temps are controlled just a little better.

Also since ethanol is not as volatile as gasoline the combustion is cleaner and smoother as it pushes on the pistons. Many converts say their engines run smoother and the power delivery is easier to manage with ethanol in the mix.

Ok, so I have been sold on ethanol. What do I need to know to get going?

You’re getting excited—just put the wallet away for one more second, though. The first thing you need to ask yourself before buying anything is what mix of ethanol will you be using?

In California, vendors pay about 4x less tax per gallon when they sell fuel that is less than or equal to 15% gasoline, so in a round-about way, suppliers are incentivized to keep it 85% Ethanol or higher. Therefore, California tends to have a consistent blending of E85 that you can have a fixed “tune” for.

Other states are not consistent in this way. It is a lot more common to find Flex Fuel in various stations, wherein the ethanol content can vary between 51% and 90%. And when you take winters into account the blend really favors gasoline so you can start the engine in cold weather (because of the lower energy content in ethanol, you might find that cold-start “kick” lacking in many places that aren’t California). So the region and season can play a role in the fuel mixture.

Unless you have a regular fuel source that sells consistent fuel, you might find yourself in a bit of a tuning-pickle. The AFR (air-fuel ratio) needs to be adjusted for the varying ethanol content you might encounter. Putting different blends in a car not rated as a “Flex Fuel” vehicle could have some issues.

We solve the problem with Parts and Tuning!

  1. Buy a tuning computer to give you engine management ability.

Before you get started, you will need some kind of fuel tuning, engine management, or programming tool to calibrate the computer to tell it how to handle the mods you will be doing. In most common Hondacar cases, this means a reflash tool from popular brands Hondata or KTuner. These modules can re-write the stock computer mapping to make your setup run correctly. You can also use great AEM computers which completely replace the stock computer for tuning in more aggressive applications. Of course, all the above are available from Heeltoe. We can help you determine what is right for your build.

1) Buy larger fuel injectors.

After you have your engine management figured out you need to handle the increased volume of fuel you need (to make up for the lower energy content, additional oxygen molecules, and the presumed increase in overall air to the engine with power adders). To add more fuel to the cylinders you will need larger fuel injectors. The injectors aren’t physically bigger, but they will inject more fuel needed to overcome the extra oxygen you are adding and the reduced energy density of the ethanol fuel. Because of the extra capacity we say they are “bigger.” There are a few brands that Heeltoe promotes—Deatschwerks (just say DW if you want), Injector Dynamics (or ID), and Fuel Injector Clinic (or FIC), even factory Honda RDX (doesn’t stand for anything afaik) injectors may work great for milder NA builds—and can set you up with the necessary plugs to get them installed in your engine.

2) Buy a larger fuel pump.

The fuel system needs to maintain pressure, and since adding larger injectors will flow more fuel from the system the factory pump may not be able to “keep up” with your engine’s fuel demands. You will need a higher capacity fuel pump to make sure the fuel system has enough flow when those injectors open to keep fuel at a steady pressure when the injectors open. Many direct-replacement in-tank and in-line fuel pumps are available from Heeltoe, from DW, Walbro, Radium Engineering, and AEM. (AEM is nice because they have one especially for E85 applications, aside from just being “compatible”)

3) Buy a flex-fuel sensor (especially if your ethanol fuel-days are not going to be consistent).

And if your ethanol content is going to be varying then it is a good idea to add a flex-fuel senor to more-or-less convert your car to a Flex Fuel vehicle. A flex fuel sensor will detect the amount of ethanol in the fuel, which you may want if you won’t be tuning for a specific ethanol mix. These sensors can talk to whatever tuning module you are using and adjust the computer’s parameters accordingly to give you the most performance for the amount of ethanol in the fuel. This is pretty cool because it means that you don’t have to worry so much about what fuel you put in the car because it might be incompatible with your tune; the tune will fix itself! Heeltoe has components from KTuner, AEM, and others that really help your custom setup but also offer brands like PRL which have direct drop-in PnP setups for some applications.

4) Go get a tune to make all the above work right!

And last to mention but probably the most important thing you need is a professional tuner! Someone who can calibrate your ECU program to handle the different fuel and power mods you are adding. We listed a tuner last but really, we recommend researching this facet of the job first. Someone local with access to a dyno is the best, but you can also arrange an e-tune or remote-tune. If you are planning to raise boost significantly, we strongly urge a dyno visit even it is a bit of pilgrimage to get it done.

In conclusion:

E85 and Flex Fuel can be really great friends to have in the tank when you are after making the most of your mods. They can allow you more creative freedom with your ignition and cam timing and allow you to cram more boost into your engine, all of which will result in noticeably more power. The fuel will help the performance engine run smoother and cleaner overall. There is a cost to the benefits in the form of added fuel consumption and investing in a few parts but at least the bits you buy it aren’t too costly (assuming your car’s factory fuel system does not need to be completely redone to the ethanol doesn’t turn your hoses to goo).

Looking for more power? You’ll get it with ethanol! How much will depend on your total setup. Heeltoe is in your corner to make sure you do it right.

Time for a beer! Cheers for reading and remember, Heeltoe is In Your Corner!

Special thanks to David Walker who provided a lot of info and editorial help to polish a lot of the swirls out of this article.

Engine Heeltoe Explains

Heeltoe’s Take On Alloy Crank Pulleys for Honda/Acura Engines

Aluminum crank pulleys have been a popular upgrade for tuners for ages. Today, there is still a lot of hay made about the detrimental effects of billet crank pulleys on Honda engines because of removing a mystical item called a “harmonic balancer.” Heeltoe’s contention is that while harmonic dampers and balancers are important on many engines, Honda engines by-and-large aren’t equipped with them. Run your billet crank pulley with confidence and enjoy the revs!
First we do a quick weigh-in on various pulley brands, specifically for the K20 application (citing the TSX K24A2 in the video). It was surprising to see just how light these pulleys are!

Saving weight off the crank really helps the engine rev and sending more power to the wheels. The benefit is faster acceleration and better response.
Some of these pulleys are smaller than stock, called “underdrive” pulleys, which have even less mass and spin the engine accessories (power steering, alternator, and A/C compressor) more slowly. This reduces parasitic drag. For the MOST power gain, get an underdriven pulley!

But there is some discussion online about these pulleys harming the engine. This video also includes a general info lecture on exactly what the suspected issues are and why we don’t really subscribe to the doomsday-sayers.

It is a highly debatable issue (even though many find their viewpoints to be strictly undebatable). The fact is, we’ve never seen actual evidence to support claims of engine damage that weren’t muddied with all kinds of other variables. We’re still waiting for the missing link in the “I installed a pulley” and “I had an engine problem” tale…so for that reason, we aren’t subscribing to the idea. 

Engine Heeltoe Explains

Product Announcement: New Lost Motion Assemblies for the J-Series V6 from P2R

P2R Lost Motion Assemblies (LMAs) will replace the factory Piston style LMA found on the 01-03 J series like the J32A2. They will also fit the 04+ J series. The LMA is designed to pre-load the VTEC rocker when the VTEC is off. The P2R LMAs are designed and produced to the highest quality standards using hardened tips and have been WPC friction treated to give extra wear resistance. Sold as a set of 6. These have been tested and proven to work in P2R’s race cars over the last several years.

P2R P354 Lost Motion Assemblies for the Honda J30/J32/J35/J37 Honda V6.

To understand a little more about what this does you need a little understanding of how VTEC works. Basically, normally an engine uses multiple cam profiles for a given set of cylinder valves. So on a 4 valve head with a single overhead cam configuration, there is a set of cam lobes for the intake side and a set for the exhaust side. VTEC incorporates a second set of lobes on the intake side which have a different profile for a higher performance level. All these lobes have their own rockers, and the engine “switches” the cam profile by locking the rockers together (using oil pressure). 

As you can imagine, when the “low” rockers are on, the high rocker is just freewheeling against the cam not doing any work. Once the rockers are locked together, the “high” cam lobe actuates the “low” rockers. This usually happens at mid-range RPM and is computer-controlled.

When the RPMs drop back down, VTEC disengages the high cam rocker from the low rockers, and you are in “low mode” again. This action can cause some “flopping” or free play in the high-cam rockers.

The Lost Motion Assemblies dampen and preload the “high” cam rocker because unlike the low rockers, it does not have a valve to counteract its movement when cam actuates it. It’s an important part of making sure the VTEC action is smooth, noise-free, and seamless.

In aggressive driving or with more performance cams installed, the need for the LMA to do its job well is even more important. Aftermarket performance applications benefit from aftermarket performance LMAs!

Thanks to P2R for releasing this solution!

Engine Heeltoe Explains Universal Fit Blogging

Will a Cold Air Intake Suck Up Water and Hydrolock My Engine?

A performance intake system is one of the first things people buy to improve the performance of their cars. For the most, the “cold-air” class of intake is preferred as it is known to bring in denser, cooler air than “short rams” for the maximum gain in power. Oftentimes these cars are daily use, and it also comes up fairly often that cold-air intakes are questioned for use in rainy or wet areas because of the risk of engine damage.

A recent email from a customer asks it all:

“I understand that heat soak is possible with short ram & can slow me down, but the possibility of hydrolocking on a brand new car [with a cold-air intake] doesn’t sound very appealing to me. All my friends have very conflicting opinions on this & I’m basically caught up in the middle!”

Before we get to the response, I’ll explain a little about the reason for the concern.

Why are CAIs a concern?

Cold-air intakes (CAIs) work by placing the air inlet down behind the bumper cover, away from the engine bay where hot air accumulates. Because the air filter is low and closer to the ground, there is a concern that it might suck up water, and hydrolock the engine.

In a very brief explanation, hydrolocking is a catastrophic condition where water enters the engine’s cylinder. This is a problem because engines operate by creating an air-tight cylinder to compress gas and control combustion. Water is non-compressable, so if the cylinder on the compression stroke is full of water it will break the engine. Most commonly, the connecting rod will bend or break, and most likely cause the piston to break or tweak inside the bore causing it to get jammed (or locked). Hence the term hyrdolock. So, one should definitely avoid sucking water into the engine!

So how real are the risks?

Our reply puts it in real, honest terms:

“The hydrolocking issue with cold-air intakes has been blown out of proportion. While it is a real possibility, the chances of you actually encountering that scenario are very slim. Unless your daily commute involves fording small creeks or pools, that is.

“In all seriousness, you would have to be driving through deep water, fully submerging the filter, for this to be a real threat. You’d also have to apply common sense and not drive through floods. We would not hesitate to use cold air in a place where it rains heavily all the time (we have a store in the Portland, we know rain). You do need to be mindful that if you’re driving through a freakishly deep puddle, it might be time to re-evaluate your route.”

It’s a deep concern

In a cold air system where the filter is placed near the ground, the amount of water that is required to submerge the filter is usually 8-10 inches or more. Hold a tape measure up to your leg to see how deep that is. You would not likely drive through water this deep, and so you really should not have an issue if you can avoid driving in such deep waters.

Furthermore, the engine is going to want to stall if it tries to suck up water. The deeper you go, you might find that more throttle is needed to push through the river, but more than that you are just going to ingest more water. If you are driving through water and the engine starts bogging, don’t floor it. Shut it down!

But, I’m a special case…

The next argument made is typically regarding special cases where the filters aren’t just lower to the ground because of the CAI, it’s “really really” low because the car is lowered a lot as well.

“My car is really low though…the water would not need to be really deep for me to have an issue then?”

Well, how much lower than the next car is yours? My car is lowered 2″ and yours is lowered 3.5″ That means if my car is “safe” in 8″ of water, yours is only “safe” to 6.5″? the point is the same. Whether the car is stock height, or lowered 3″ isn’t the point. The point is, try not to drive through water deeper than you would walk through in rain boots.

But, aside from the issue of driving a car at an unsafe ride-height, this argument can also be made about water being just a little bit deeper than you might think. In other words, the false judgment of how deep the water is causing issues more than the filter being a little lower to the ground because of your static stance life.

The best rule of thumb is if you cannot see or tell how deep the water is, avoid it. Go around or go another way. There are possibly times when you have no choice, but that would not preclude you from having an issue even in a completely stock car. At the end of the day, floods cause issues for cars. A cold air intake is not likely to work against you dramatically.

Keep your splash shields and fender liners

Are your fender liners and splash shields in place? They should be. If they are, this won’t get you out of the flooding issue because those shields aren’t water-tight. But with them, the filter is going to be pretty well protected from splashing water.

It can happen that the filter may get WET, but not actually suck up water. The filter, if installed properly on the car, is covered in the front by the bumper, and the bottom and sides by a splash shield. If you remove the splash shields from your car (or they are torn off by scraping along the ground or poorly fitting wheels), it is highly recommended not to install a cold air intake.

Without splash shields, the filter will be exposed to water and will surely become saturated in rain. This will not cause a hydrolock, but the saturation of the filter will not allow air to pass through. Without air, the engine will suffocate and stall the engine. Aside from the fact that driving with the filter exposed so close to the road will dramatically accelerate dirt accumulation and generally lead to poor performance.

So to sum it up

  • Driving with a cold-air intake in the rain will not cause your engine to hydrolock.
  • Driving with a coil-air intake without splash shields and fender lines will cause you problems.
  • If you aren’t able to avoid driving through water deeper than 6-8 inches deep, a cold-air probably isn’t for you.
  • Don’t lower your car too much and then worry about performance concerns, because the low-life and the #gridlife are mutually exclusive.

Engine Heeltoe Explains

Is a J37 manifold beneficial on a J32/35, or port the stock parts?

Many Honda and Acura V6 owners look to the grand-daddy of all J-series engine, the J37A4, for OEM upgrade mods. The primary item of focus is the large, Magnesium manifold topping that engine. However, there is some debate as to what the best course for intake manifold and throttle body use is ideal on a J-series engine. It’s well known that earlier J-series had removable plenums and internal trumpets that worked great and could more readily be ported out.

Heeltoe went out and got some information to help clarify things!

We’ll be updating this article as we learn more about the J37 intake manifolds and their applications.

Updated Dec 2, 2016:

This article was originally written to comment on the performance differences between a J37 Magnesium intake manifold versus porting out a factory J-Series manifold. Our expert adviser suggested that modifying the stock manifold was a more worthwhile effort when the cost is weighed out. But the market has decidedly chosen that modifying the stock manifold is too inconvenient when compared to simply buying a new part which works the same or better. Why?

Firstly, the stock manifold is not easily modified. Older J-series engines had removable plenums which allow them to be opened and ported with plenty of access. Anything 2004 and newer, though, is all one piece and is not really able to be opened up.

Secondly, who does the work if you want to send it out? Efforts in getting people to actually DO the work after they smugly comment “bah just get it ported” all seem to disappear when you ask for a reference or contact. Even people who say that “can” do it aren’t readily able to.

Thirdly, there is downtime to consider. If the customer doesn’t want downtime, they need to source a replacement manifold and the “it’s cheaper to port” argument gets thinner right off the bat.

Lastly, nothing in the parts world ever remains static. We’ve just recently revised and redone our manifold packages with new, lower-cost options for many J-series owners. Check out that listing here: HTSpec J37 Magnesium Intake Manifold & Throttle Body Kit, Honda J-Series V6 (ALL Single-Port Exhaust Engines)

HTSpec J37 Magnesium Intake Manifold & Throttle Body Kit, Honda J-Series V6 (ALL Single-Port Exhaust Engines)

Original post:

It is fairly commonly known that by upgrading the intake manifold on an engine, either by increasing volume or reducing restriction, more power can be produced within the engine. This is because air is more efficiently delivered.

As Honda engines have grown in size and power requirements, so have intake manifold volumes. As of this writing, the J37 intake manifold is an increasingly effective upgrade to do on mild and serious engine builds. But, are there real benefits over stock manifolds, or ported and polished ones?

We consulted Andy Gerzina, noted J-series engine guru, for his input. His statements to us, and we paraphrase, were:

Does the J37 manifold produce more power over stock intake manifolds which have been ported and polished?

  • Yes, to the tune of 2-3 HP over the rev range.

Do you generally recommend a J37 intake manifold to people building engines?

  • Since the cost of the manifold is over port work is relatively high (even more after considering a throttle body is added), and the gains are minimal, I find it more economical to upgrade the stock components.

It seems that if someone was starting from scratch and wanted maximum power a J37 package may be feasible.

  • It would depend on the person’s situation. On one hand, money would be saved obtaining used stock parts and modifying them, but it is also more time consuming and demanding of resources other than money. Simply ordering a J37 package may be easier for most users.

Are there any drawbacks to either porting or upgrading to the J37 intake manifold?

  • On Automatic transmission cars, no issues have been recorded or found to be troublesome with J37 manifold and/or J37 throttle bodies. On modern drive-by-wire j-series vehicles equipped with manual transmissions, there are well-documented rev-hang issues with the J37 throttle body, regardless of which manifold it is used in conjunction with. This change in drivability isn’t something one could not live with, but it may be favorable to port/polish the stock manifolds internals if you have a 6MT for seamless operation on the street. Currently, there is no consumer purchasable available adapter to convert a J32 or J35 drive-by-wire throttle body to a J37 manifold to solve this issue. With such an adapter in conjunction with a J37 manifold, performance gains are equivalent to porting a stock 2004-2008 TL/TL-S manifold.

Thanks, Andy, for the clarification!


D-Series Piston Page

The Super D-Series Piston Comparo

Thank you for coming to The Super D-Series Comparo. If you are like me, you like the underdog. The D-series engine has become a sort of underdog in the Honda performance engine scene. Largely due to the installation of bigger and more powerful B-series power plants like the B16A, GS-R, and Type-R variants, the D-series engines usually get dumped in the trash. I look forward to the day when B-series parts get disregarded in this way in favor or the K-series’ popularity. But for now, the D-series is the budget bruiser out there!

I decided to catch some of these bits on the way to the trash and do a moderate street buildup on the stock D15 in my 95 CX hatchback. The first question that arose in my mind was, “What pistons should I use?” Being a Hardin Honda employee, I took it upon myself to order one of every D-series piston new from the factory for the purposes of documenting them both photographically and dimensionally.

The different pistons are called out by the center 3 digits in their part numbers. These are the numbers Honda uses to classify which engine the part goes in when determining part numbers. The second set of 3 digits I include give information as to what market the parts are from, and super-cession level. An A00 is a North American part while a 000 would be a World Market part. Likewise, a 010 might be a part superseding a 000.

Compression height was calculated by measuring the distance from the TOP of the wrist pin hole to the TOP of the piston (not including any dome or dish) then adding half the wrist pin diameter. Further details regarding measurements will be at the bottom of the page. Without further ado, here are the pistons:

(I am assuming P03 and PM3 are the same since a PM3 came in a P03 box)
88-91 DX/LX, 92-95 CX/DX
total height: 61.76mm
compression height: 30.70mm
flat top

92-95 VX
total height: 57.65mm
compression height: 27.75mm
7.05mm dish

91-99 JDM Civic VTi
total height: 57.65mm
compression height: 27.4mm
1.78mm dish

92-95 EX/Si
total height: 60.00mm
compression height: 30.00mm
3.00mm dish

88-89 Integra
Blacktop D16A3
total height: 58.80mm
compression height: 29.06mm
3.30mm dome

92-00 CX/DX
total height: 50.00mm
compression height: 30.00mm
3.32mm dish

96-00 HX
total height: 49.26mm
compression height: 29.50mm
2.70mm dish

96-00 EX
total height: 49.25mm
compression height: 29.50mm
2.12mm dish

98-00 GX
total height: 49.28mm
compression height: 30.50mm
2.50mm dome

86-87 Integra
Browntop D16A1
total height: 59.80mm
compression height: 30.17mm
.889mm dome

01-03 DX
total height: 46.50mm
compression height: 27.00mm
2.62mm dish

01-03 EX/HX
total height: 46.50mm
compression height: 27.00mm
2.66mm dish

01-03 GX
total height: 47.42mm
compression height: 27.00mm
1.50mm dome

Here are a few things I found while measuring:

  • Bore diameter was the same for all pistons : 74.5 mm (I tested std bore pistons)
  • Wristpin diameter was the same for all pistons at 19 mm except the PDN which has a wristpin diameter of 21 mm.
  • All wristpins were the same length at 56 mm.

Well, here it is so far…I still need to get a hold of a couple more pistons, and a couple pics of the pistons above got lost, so I will need to continue where I left off here. Oh, and before you start giving me a hard time about it, I know some of my measurements are off. The Compression height was easily the hardest dimension to get right. These measurements were meant to serve comparative purposes only. Similar measurements between pistons can probably be assumed to be equal. The conditions under which I conducted the measurements were not ideal. If nothing else, you should be able to get an idea of what you can run in your buildup. Stay tuned!

Hey, check it out! I found a neat Compression Ratio calculator! Kinda fun….Chick here for the calculator!
There is another one here that we use a lot: Click here for the c-speed calculator!

A word about rods:
All D-series engines of similar displacement have equal stroke lengths. Thus, the rod lengths are the same if the displacement is the same, with one exception. The VX rod is longer that the other 1.5L engines, approximately the same as the D16 engines. The D17 engines would have longer rods still, about 3mm longer than a D16 rod.

Here is a list of what I know so far:

  • 88-95 DX/LX/CX all use a PM3 rod (134mm)
  • 88-00 D16 motors use the same length rods, PM6 (137mm). The D16Z6 uses a PG6 rod and the D16Y5 (HX) uses a PE1, but they both superseded to PM6 rods. The only two rods that do not supersede from a PM6 is the P2P (D16Y8) and the PDN (GX motor).
  • The VX rod is comparable to a 1.6L rod in length. The number for the VX rod is P07.
  • D17A rods are 137mm. Compression height is lower than 1.6 pistons ~3mm, deck height is similar from D16 to D17, and bore is equal. The D17A gets it’s displacement from stroke.
  • 1.7L rods are the same from DX to EX (PLM). They are the same 137mm length as the D16 rods, share the same 19mm wrist pin diameter, have the same 45mm rod journal diameter, but have a 19.8mm wide big end, unlike the D16 BE width of 22.6mm. The GX rod has a different number (PMS) but I believe it to be the same length as the PLM.

For fun:
Some pot-smokers that were making fun of me taking all these pics and measurements.

My Measuring instrument:

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