Lotta good posts going down here guys but I have one simple question.

Has anyone been able to come up with a proveable performance increase (before and after testing). I acknowledge what has been said about achieving lower intake temperatures etc. but apart from seat of the pants testing who has real results??

 

2kturkey


Without forcing head-pressure on the system some how (compressed air infusion or wind tunnel dyno), I'm not quit sure how you would get real test results.

Open to suggestions though (within reasonable price range)

 

[QUOTE]Originally posted by tpn
[B]2kturkey

 

They have wind tunnel dyno's...just not around here that I know of. Maybe on west coast or Detroit/Chicago area. Lap times or ET at the strip perhaps as a extra mesure but so many other varibles enter in. I can give that a try by running closed duct ET vs opened duct ET a few times. I 'm willing to do that

I dont know if you would find as big a differance in performance between the assorted CAI designs as you would between installing anyone's CAI to not having one at all. But just a CAI without headers and exhaust (to open up backside of the engine) will not gain that much hp. Still waiting on mine.

"....Breath in...Breath out...." Zen and the art of S2000 mods

 

I

 

CD, you are a gentleman and I appreciate the subtleties of your use and command of language when gently bringing me back on topic.

I guess I look at this in two ways

1. Certainly I am in agreement with your comments regarding ECU retarding timing and reducing power - the insulating mat addresses this issue, however,
2. There are other related areas in which volume and heat of intake air affects performance - this is an area for considerable experimentation.

TPN has created a solution which is designed to address both points 1. and 2. Rick and others have commented on ram air and high pressure cold air intakes. This is my area of interest as I can see benefits in increased volumetric efficiency as well as avoiding ignition retardation.

I do accept, however, that my question re how Mugen worked this out was poorly phrased - my real question was how did Mugen measure the power reduction curve relative to increased intake air temperature. The simple answer I was looking for is that x degrees increase in air temperature = y degrees in retardation = z % power loss. Can anyone give me figures for x, y and z?? - the best I've seen so far is UL's comment of 3-4 HP loss for every 10 degrees temp increase.

Coming back to point 1. above, and looking at it from another perspective, what if one simply disabled the IAT (via a switch or similar) when required (e.g. after warmup) and substituted an analog signal generator which fooled the ECU into thinking intake air temperature was optimum?? - or is this a recipe for engine failure??

 

The actual loss just from air density reductions with increasing temps is 1% for every 11 F. In terms of timing reductions, I'm afraid I don't know. It may not be tied solely to air temp either, there may be a coolant temp factor in there as well.

On the pressure side of things, the piece I like to reference is out of Sportrider magazine back in late 1999. They tested a variety of ram-air equipped motorcycles (that's about all of them these days). I posted some more info in another thread, but the general deal was that at speeds as low as 70 mph some bikes were already building positive pressure in the airbox. At speeds of around 150 mph they were approaching 0.4 psi of pressure.

Now, that doesn't sound like much. In the grand scheme of things, 0.4 psi would be good for about 3% more power. However, they also tested a bike without ram air, and this is the kicker. The bike, especially at higher rpms, was showing a small vacuum in the airbox, to the tune of 0.4 psi. Thus, compared to the mild vacuum, a ram-air equipped bike could conceivable pull 5-6% more power out at speed. And this was backed up by a dyno test where the ram air ducts were sealed and pressurized to the appropriate pressure recorded from the real world test.

Thus, even at speeds as low as 70-80 mph, a good ram-air system could give you a 3% gain by eliminating the normal airbox vacuum. And even below that speed you could at least reduce the vacuum.

That's why I really want an accurate pressure sensor to test our airbox vacuum. Unfortunately, their are no low cost attachments for a Fluke multimeter (unlike temp probes). I'm considering just trying to calibrate a MAP sensor and work from there using voltages and a conversion. If we're pulling a noticeable vacuum in the airbox at speed, any pressurized ducting would be useful.

UL

 

[QUOTE]Originally posted by ultimate lurker
[B]The actual loss just from air density reductions with increasing temps is 1% for every 11 F.

 

This is a freaking bad ass thread...

I would like to add that I have the RM Racing "CAI" in my car right now. The intake sucks in quiet a bit of hot air due to placement, but I really don't notice a decrease in performance. I know there are alot of factors involved...but when I go cruizing with the Houston S2000 crew...I am no slower than anyone else...and we have drag raced many times. I feel that factory air box is restrictive and has a main purpose of keeping the car quiet. My theory to why I am not loosing noticable performance is that the intake is taking in hotter air...but the intake is taking in air easier than the factory box. Overall I am still looking for a good CAI design...hopefully AEM won't fail us. I like the MG Racing CF airbox...but it is a bit pricy.

Has anyone ever thought of cutting a hole on the bottom corner of the air box and connecting a tube pointing downwards towards the bottom of the car (similar to what the MG Racing design has accomplished)?

I have also been pondering if cutting the hood and fabricating some kind of ram air will help. But the design would have to be carefully implemented because of weather...

 

Tanqueray,

I just use my old drag racing correction charts and simulator data. I've never actually run the PV=nRT calcs. Perhaps it has something to do with the fact that P varies with V in a temperature dependent system.

I really don't know, I'm guilty of using a convention that I can't verify. Good question though.

UL