Which intake would show most fuel efficiency gains?

[Christ]

If you're not sure about which intake to buy, just stick with the stock one. Your OE air filter is designed to flow enough air to satisfy the engine at WOT in most, if not all driving situations, so that's not even worth bothering to consider about. (This is proven, and you can do the math on your own.)

The intake piping itself, technically using smooth tubing, regardless of intake temps, will help out. It takes energy away from the air (more vacuum to move it) when it has a rough surface to travel over. It's negligible. You'll get a better result from spending $1 at the air pump to make sure your tires are inflated to spec (or sidewall max, more if you're comfortable with it.)

If you're going to put an intake on a stock Civic, do it for the sound... or for the noise... or something. You won't get any gains from it otherwise, and even if you did, it wouldn't be worth the money you'll spend.

[zonker]

in my experience, factory intake systems are designed to address four concerns... emissions, drivability, economy, and nvh.

for most modders, be it eco or hipo, the nvh concern can take a much larger back seat to the factory engineered system, so there is usually some room for improvement.

as a general rule of thumb, unrestricted airflow ahead of the maf sensor serves to improve both economy and power.

it's what you do between the maf/vam/iat sensors and the throttle body that makes things more interesting, and can give quite varied results from a modification.

for example, the white rag gets better mpg from a 2.25" dia. aluminum tube (with 144cc injectors) between TB and MAF, and gets more power when i use a 2.75" dia. tube (with 168cc injectors). the smaller tube increases air velocity thru the maf sensor which advances timing and enriches fuel (which i lean back out with the slightly smaller than oe 152cc injectors).

[Sularus]

hey zonker, there is a better way to increase ignition timing. Add some resistance to your IAT and the comp will think it is colder. It will add timing to compensate.

Other than that, it really doesn't matter what TYPE of intake you run. The only thing that matters is to make sure there is a little restriction to intake flow as possible. Measuring pressure throughout the intake and making sure it is as close to even thru the whole system is what matters.

[zonker]

Originally Posted by Sularus

hey zonker, there is a better way to increase ignition timing. Add some resistance to your IAT and the comp will think it is colder. It will add timing to compensate.

Other than that, it really doesn't matter what TYPE of intake you run. The only thing that matters is to make sure there is a little restriction to intake flow as possible. Measuring pressure throughout the intake and making sure it is as close to even thru the whole system is what matters.

In my experience on Fords, IAT only does fuel and not timing, the ect, bap, and maf take care of fuel and ign. timing. trust me, i've played with that as well.

reduction in intake air restriction is important, but at least if not more important is air velocity when working on an intake with a maf or vam sensor. If this was just a filter on the end of the tube like a speed density system, then air velocity would matter less.

BUT, you are onto what my next lil project is for the white rag from a performance perspective... a tps actuated resistor set that will change baro and ect settings when more than 75% throttle is engaged. I did that on my zx2 many moons ago and dyno'd 16hp from tricking the iat/ect circuit (it pulled big numbers because it altered not only fuel and ignition, but exhaust cam timing too thru the vct). I currently sell that item as a "black box", and it works killer.

[rmay635703]

Originally Posted by zonker

for example, the white rag gets better mpg from a 2.25" dia. aluminum tube (with 144cc injectors) between TB and MAF, and gets more power when i use a 2.75" dia. tube (with 168cc injectors). the smaller tube increases air velocity thru the maf sensor which advances timing and enriches fuel (which i lean back out with the slightly smaller than oe 152cc injectors).

Something we are forgetting is harmonic tuning, Diameter and length can affect this. If you have the length to put a long pipe out your intake this does make a very significant effect on power/fuel usage and has nothing to do with intake restriction. Throttle body spacers do this to a very small degree as well. Now if the length could vary with RPM we would have a winner as the effect could then span the RPM band.

Cheers
Ryan

[Sularus]

rmay635703- length of an intake system matters little. The reason throttle body spacers can work is because it affects intake plenum volume. The spacer is behind the throttle plate. Everything before the throttle plate is not too much of a concern. As long as it is all close to the same pressure and offering as little restriction as possible to the atmospheric push.

zonker - the velocity won't help all that much on more moderate cruise speeds that see high vacuum with a very small opening in throttle position. The velocity will be killed regardless. If anything I would create a diffuser type section in front of the throttle plate to help force air past the throttle plate, thus reducing pumping losses. Of course you might have to have a Ram Air intake for that to work.

[zonker]

Originally Posted by Sularus

zonker - the velocity won't help all that much on more moderate cruise speeds that see high vacuum with a very small opening in throttle position. The velocity will be killed regardless.

i agree with your assessment if this car did not have a mass airflow sensor attached to the air filter assy.

The mass airflow sensor has a sampling tube, which is measuring air speed, not air volume.

Am I missing something here or would decreasing the diameter of the tube increase the rate at which the air is travelling thru the maf sensor?

And wouldn't that increased air speed through the MAF sensor translate into it sending a signal for more fuel and ignition advance?

[Frank Lee]

Originally Posted by Sularus

If anything I would create a diffuser type section in front of the throttle plate to help force air past the throttle plate, thus reducing pumping losses. Of course you might have to have a Ram Air intake for that to work.

Hardy har har. You know what's gonna happen if more air is forced past the throttle plate right?

You will let off the gas until the restriction is the same as it was before.

[zonker]

Originally Posted by Frank Lee

Hardy har har. You know what's gonna happen if more air is forced past the throttle plate right?

You will let off the gas until the restriction is the same as it was before.

this is true, but if the air was forced thru a throttle plate on a fuel injected car, the tps would still read the throttle opening as less than what air the engine is actually getting and deliver less fuel, much in the same way a large vacuum leak would, so you'd have a air/fuel mixture change that would reflect a leaner condition.

This is how DIY turbo kits added to a non-turbo designed motor/ecu contribute to engines that go clunk in the night.

granted, you would not need to go thru all that kind of hassle if you just reprogrammed the ecu...

[zonker]

I was just thinking, did original poster JohnnyRun get the easy answer he was looking for at the beginning of this thread? MUAHAHA LMAO