iDomN8U

FYI: Spoon has a transition exhaust from 60mm to 70mm in the resonator, not very important to this discussion, but I thought I'd mention it.

starchland

props to doing the research. Is the resonance of a test pipe due to it being hollow? I would imagine a test pipe allows greater exhaust velocity, this must be helping with the gains as well, no?

Disgustipated

I'm a bit confused, but everytime i posted in your thread that matching your tp/hfc with your exhaust size was important, you said i was wrong. now you're saying i was right? I'm confused.

And happy that matching my 3" exhaust with a 3" hfc was worth the effort, as i thought it would be.

H22toF20

Great testing and write up, Gernby. If I had the resources, I'd be doing this as well

I'll post this in this thread as well. Everything after the collector is a restriction. Aren't you glad I harassed you about the 60mm test-pipe?

SoloSpeed101

Good read. I have a question. I have a MY06 so my best bet for tuning is the Flashpro? I was thinking about getting a Apex'i NEO or VAFC II for tuning on a budget. Should I forget about the Apex'i and save up for a flashpro? If I were to go SC down the road, should I even bother with the flashpro? Or maybe something like Haltech... I want to hear your $.02

Gernby

Clearly I was the one who was wrong. However, I'm pretty sure I wasn't saying "you are wrong". I believe I said things like "I don't see any reason why the 60 wouldn't flow as well as a 70 if it's already bigger than the header", or "why would a 70 be better than a 60?".

I still need to read through the exhuast thread again, and I'm sure I'll find a few things I need to apologize for. Maybe not as many as some would like, but I'm sure I'll find something ...

Reckon

Good information. That means that I should go ahead and purchase the TP I have been wanting. I have a 70mm all the way through Invidia exhaust and I was going to get the 70mm Invidia TP. I thought about getting a new header as well but I haven't had a chance to research that.

Unfortunately, I won't have any means to tune it. I don't believe there is a good local tuner by me so hopefully I can still get some decent gains and not hurt anything running that setup.

Gernby

Since the '06+ AP2's run so friggin' lean in stock form, you would not be able to use a NEO / VAFC type piggy back for anything other than lowering VTEC engagement. You wouldn't be able to do any fuel tuning with it. The FlashPro is absolutely the way to go, and it works great for FI applications. Aside from a few "exotic" features like boost control and nitrous control, it will perform as well as any other standalone ECU.

Since this thread isn't about tuning, if you have any other questions about the FlashPro, feel free to send me a PM.

Gernby

If you don't have a way to lower VTEC, then I honestly believe it would be hard to justify a Test Pipe. The performance benefit is so small with the stock tune that it just doesn't seem worth the risk of getting caught, the soot buildup on the back of your car, the bad smell, and environmental "damage".

Gernby

All intakes and exhausts have different harmonics / resonant characteristics that make them perform better or worse at certain RPMs. That's why every combination of parts generates different shapes of torque curves. My PWJDM intake gives a broad resonant hump on the high cam between 3500-4500 RPMs, then another narrow hump at 6500. Having the catalyst (brick) in the middle of the stock exhaust seems to ruin the resonance of the exhaust, which causes a big resonant dip in power at 5K. Removing the catalyst from the exhuast eliminates that resonant dip.

I understand why exhaust velocity would be very important to turbo applications, since that translates directly into boost. I guess I could also see exhaust velocity being important for scavenging in a header, but I don't see any reason for veloticy to be beneficial after the collector. If anything, it seems to me that you would want the exhaust to cool and slow down after the collector, since that would reduce back pressure. Of course, this is just speculation on my part.