rog06s2k

It is very efficient, just not at a low VTEC crossover, even with the TODA torquie-kun header + Magnaflow catback I had a major dip with the TODA reflash, with the Berk HFC it hits hard at 4300 rpm...

Good job Gernby, by the way your numbers are on par with mine, expect the Berk 63mm HFC to behave just a bit less like a 63mm test pipe.
Cheers

Gernby

So you're saying that the HFC got rid of the huge dip in power at 5K?!? That would be AWESOME!

rog06s2k

Mmmmmm, not sure about the 5000 rpm dip, until now I didn't know about that dip, I have the Torquie-kun, look at the graph, they redesigned it to take care of that, now I know why...can't feel no freaking dip!
http://www.toda-racing.co.jp/en/product/ex...0c-torquie.html
My best guess is that in your setup, it will behave +/- like the test pipe (both 63mm), but then again with your intake + exhaust setup, may be the Helmholtz god will smile at you, hopefully.
Cheers
Rog

Gernby

I see the dip you're probably talking about on Toda's page, but I doubt it's the dip I'm talking about. The dip I'm talking about happens only if VTEC is engaged below 5500 RPMs, and it happens right at 5K. The car feels like you just drove into a 50 MPH head wind, and the engine starts sounding "bad", then a couple hundred RPMs later, it goes away.

Gernby

BTW, it looks like I'll have an opportunity to repeat the test using a stock, untuned CR. That will confirm whether these results have anything to do with my car just being "weird".

bpaspi

The OEM is a real good catalyst. But it's still a 400cpi cat.
A High Flow Cat has only 100cpi.

But it depends on the overall volume and facing area. An aftermarket HFC should provide the same dimensions to act efficiently.

Disgustipated

This.
The hfc or tp always needs to match the catback's diameter or the results would be redundant.
I'd really like to see gernby get ahold of a 3" single and matching hfc/tp. I think the overall midrange and peak would be a good amount higher than a 63mm.

Gernby

Why do you think the pipe diameters need to match? I may find that matching diameters is better when I retest the 70mm test pipe, but I haven't seen any reason to think it will be better than the 60mm test pipe.

If I had access to a 3" exhaust, I guess I'd test it, but I definitely don't think it would give different results than I've gotten with the 70mm. If a 36% increase in cross-sectional area shows no gains, then why would a 60% increase show gains?

Vitt

BTW, gernby, you mentioned somewhere that you also have a Hondata heatshield gasket. How long have you had it and did you ever take your IM out and take a look at it? I was thinking of getting one too. But on the R&C forum a while back there was a thread with reports that it was falling apart after a certain amount of use. I wonder if it only happens if the car sees extended periods of high temp.

Disgustipated

my question is... every Honda engine (like the k20i posted previously) makes good gains as the exhaust diameter goes up.

and why wouldn't you match the pipe sizes? i would think one wants as much flow as possible after the header.