As the title says, got my S2000 tuned recently. Car has a K&N intake and a 70mm test pipe. Made 226 hp and 162 lb-ft at the wheels.
According to the tuner, the K&N is actually robbing some power at the top end, so I need to source an OEM airbox + filter at some point, to get that back. Anyways, enjoy the video!

 

Ain't that 3500rpm VTEC great?! How the car should have come from the factory.

Has the car passed California smog since the tune? Just curious, mine passed in Ohio (via the ODB2 port, no tailpipe sniffer) and it's not required in my county in Virginia.

-- Chuck

 

That is about the same as I saw on mine with the Karcepts tune. My experience was the intake means almost nothing, header maybe a little but the HFC was a big part of that tune. I ran the tune for a bit before I got the HFC and it had a big power dip due to it. I am sure that could have been tuned around but not sure if the overall results would have been as good. I am running stock exhaust past the cat.

 

Haha I actually smogged the car recently (before the tune), so I'm good for about ~2 years. I suspect by then though, the car will basically be 100% track-only.
But I did smog it with the Hondata "tuned" off the shelf map, and it passed without a problem!

 

Yeah the intake definitely costs power actually. The inner diameter is smaller than the factory snorkel as well, which I didn't know.
I think I'm gonna pick up an OEM airbox in the near future and maybe get the top end re-tuned.

 

The extensive Gernby research demonstrated how lowering vtec really requires hfc or tp to avoid that dip. Seems its more of a resonant frequency thing, not an actual flow thing.

Really all you need for this effect is the hfc or tp, and the decent fp tune, woth vtec lowered for best overall power under curve.

Intake, exhaust (other than cat) doesn't produce much extra gain. Until you spend big on a really good header, or certain intakes, stock is difficult to beat. Even then, you're doubling the spend to add the header for not much additional gain. Or a similar amount for the intake. A catback exhaust also costs a lot abd doesn't add much power.

The hfc or tp and flashpro and tune is the sweet spot.

 

Did the tuner explain the dynamics of this at all? Any info would be appreciated.

I think there's too much heat soak on the K&N.

 

That was also reiterated by Brian K on the Karcepts setup I have. HFC was the most important piece. I am running the PLM header as well with mine.

Biggest advantage of aftermarket exhaust (behind the HFC) is weight. But I also hate the sound of a lot of the single exhausts due to drone and the cost is silly on a lot of them. When I care about being more competitive, I just remove the whole rear section on mine since I have it flanged with a VBand clamp right before the Y on the rear. I just replace the whole rear section with a turndown at that Y. That was class legal for STR and actually does not sound that bad (and does not drone as bad as some exhausts I have heard). Just removing the y pipe and two stock mufflers removes 44 lbs from the rear of the car from when I weighed it.

I have never really considered a test pipe. I did not and still do not live where we have to do smog, but for one, you had to run a cat in STR and also, I am not really into completely removing emissions stuff on a car I drive on the street. There is not a lot of benefit over just running a good HFC and I am not creating more pollution than I need to be by keeping a cat. I am a gearhead, but I do also try to be somewhat responsible

 

Yeah, there's a few things going on. First is the resonance caused by the K&N at high flow/high RPM. Makes it difficult to tune past about 8000 RPM.
Another thing is the velocity stack/venturi that's on the OEM intake, which doesn't exist on the K&N - again compromising flow.
Also the ID of the K&N at the smallest point is smaller than OEM - again compromising flow lol.

And as you mentioned, there's a ton of heat soak on track. It's been improved with the addition of my hood vents, but still worse than the OEM airbox would perform..

 

But it sounds cool and some people actually like how it looks. Who cares if it allows more silicates into engine!