I have tested the effect of removing the air box lid using my performance evaluation method (see my post at http://www.s2000online.com/forums/showthre...hp?threadid=363 ).

So, what is the veredict?

Going from 4000rpm to 7000rpm in 4th (slight uphill), took me 13.76s with the lid on.

With the lid off the same run took... take a deep breath... 14.52s.

Another run (slight downhill) from 6000rpm to 9000rpm in 4th took 10.27s with the lid on, and 10.96s with the lid off.


An unrelated comment: with the lid off there is a very noticeable hum at idle. Did you experience this as well? Or is it just my car?

 

Did you try these experiments under different weather temperature? IMO, I would think that you would get better time under COLD weather.

 

I just did both a couple of hours ago.

Very much so. Today is a bit warmer than when I tested my Mugen headers and exhaust, and some of my times (the midrange) were only fractionally better than what I got with the stock setup a couple of weeks ago! (I also had an additional 15 kgs of fuel).

 

My car has the 'hum' too at idle with the cover off. I believe other owner's cars do it as well.

Mike

 

Like i said, me an s2kmtl raced ... In second gear, i clearly Out-accellerated him.

he had the lid off.

Thanks for the info Luis.
Very informative.

 

Thank you Luis for proving there is more to the Honda air induction system than just volume of air moved.

Lesson to those who did not believe: Engineering at the level that Honda plays at is many times "counter-intuitive". Things are not always like they seem they should be. The intake track not only needs to move massive volumes of air but also that air needs to be cooler than the engine compartment and then it also has to be tuned (like a set of headers).

This engine (and associated systems) are in a very high state of tune and any HP increases are going to be hard fought and not nearly as simple as removing the air box cover.

 

Luis, I pretty much get the same response that you did. I spent all weekend driving the car without the airbox cover. It definitely felt slower with it off. I didn't car for the noise either, not as "sweet" which makes me want the HKS exhaust!