Alang

iTrader: (1)

As far as the dash lights, you are correct that is just the ABS/Stability control system getting confused because the front wheels aren't spinning. I had a baseline dyno last week, and the same thing happened. Once the fronts start spinning again, the system getd un-confused and the lights go out.

Vlad

Well your setup has 45deg after cats, than 45deg entering X, than 45 exiting X. Corsa has smooth, smooth, and then 45.

I wish I can experiment myself with all stuff that I said, but I don't have my own muffler shop...

You didn't say what do you think about resonator suggestion, btw.

Vlad

articfury

Vlad,

The bends are not nearly 45 deg. Rusty was very cognisant of my request to keep the pipes as straight as possible.

As for your resonator suggestion, we originally were not going to do the transverse setup. But we couldn't find a muffler that we had access to that would work for the space requirements. There really isn't much room in there for two mufflers and two resonators. We thought about angling two mufflers out, which sounds like what Thom did. I just preferred to aesthetic of the twin transverse exhaust, like the Amuse for our car and several exhausts on the NSX.

In general, for the current, and near-term, horsepower of this car, we felt like this system would flow plenty well enough. If I start doing some major NA upgrades (or FI for that matter) then changes would be needed at some point. Right now, I feel the ECU is our biggest hurdle.

JD

z327

I believe the theory behind a X pipe is to create a scavenging effect or a pulling of the exhaust gases. With a V8 or V6 engine that fires form one side to the other you can increase horsepower by crossing the exhaust from one side to the other. Many racers have used headers that combined exhaust ports from different sides of the engine.

Don't know if a X pipe that far from the exhaust port will really create much of a scavenging effect. You might see more of an impact on torque than horsepower.

12SecZ

After reading this I am going to finish my exhaust *and* install the Injen before I Dyno.

This brings up a seriuos question.

It's 45 degrees here at night.

How could a DynoJet (even with fan) simulate 45 degree cold air rushing in to the Injen Intake at 85mph?

I have a feeling that the HP Dyno #'s we see with our CAI and exhaust mods are waaaay lower than real life on the cold freeway at WOT with 45 degree air rushing in!

z461

I believe that there's way more to exhaust tuning than this random guessing people are starting to do w/ custom exhausts. Once you go into crossovers and x-pipes you need to do dyno's and mathematical equations. I would just wait till companies make stuff with proven dyno results as many of these companies (stillen for example) spend thousands of dollars on research at times to provide a correct exhaust for our vehicles. A simple thing such as the bend in the pipe or how far the y-pipe extends can make a huge difference in backpressure and whether the exhaust makes or loses power. The only exhaust mod that i've seen so far that can be done "custom" that makes power is the removal of the resonator.... People need to have some patience..

Track

That is a truly nice set up.

People have commented that mandrel bent would be better. Maybe.
The x-pipe is a good idea, too.
But the main thing is not to go overboard. You can have too much flow. The scavenging effect has been mentioned, so I won't go into that too much.

But what about exhaust velocity?
As the piping gets bigger, the hot, expanding gases begin to slow, this allows more cooling, and cooling reduces that expansion that is pushing the gases down the pipe.
This causes a slowdown and, in the worst scenario, even turbulance.
Also, keep in mind that an increase in pipe diameter increases surface area.
This increases 3 other things (all bad):

1) weight
2) frictional drag (on the exiting gases)
3) Heat loss (radiator effect)

You want the gases to be expanding thoughout their trip through the system until it exits, in a perfect world.

Our 3.5 liters just don't move that much air when N/A.

The main restrictions I see left for you to address are the exhaust manifold and maybe a set of HFC's.

Now, if you go F/I......

12SecZ

I am going to the Dyno tomorow *before* my Injen and High Flow cats are installed. It's an extra 60 bucks but I (and others here) will be glad I did it.

So I will post my Dyno Chart of *current setup* (before redoing the exhaust and Intake mods in my sig)

3 runs tomorow!

Vlad

At least somebody going to do it right!