fletcherdave

Anyone have pics of the underside of a cup car exhaust??? I am getting ready to modify my exhaust for race use, and wonder if it's possible to run the headers straight out the back (not criss-crossed). I wonder if this would be too short and it may suck air and possibly burn valves.

onefastviking

Straight out has been done before. I have a picture somewhere on my computer , I just have to find it. No, burned valves issues.

What year Cup car ? There have been different variations over the years.

fletcherdave

It's a 1999 C2, street car that I am converting to run GTS3. Not a cup car......yet.

onefastviking

Notice my avatar ? ? ?
Moving to GTS4 this year though.

fletcherdave

I'm hoping I can stay in GTS3. I know removing exhaust and A/C are going to give it some more WHP, but i don't want a race car that has to weigh over 3,000lbs. Simplifying the exhaust should remove quite a bit of unwanted weight and heat.

fletcherdave

Nice looking car by the way. Mine has the factory Aero kit option which I will also be removing and hopefully selling.

ltusler

Here are pics of how mine is done. It registered 108db on a Iphone app about 100' from the track. Its louder than a cup at full song, but people seem to enjoy it.

ltusler

I'm going to try this. Traded a 99 front aero bumper cover for it. It may lead to a bit more torque but at the expense of some top end. But thats OK because I can't do my best speed of 154 around turn one at Brainerd anyway, my skirt keeps flying up.

Bill Verburg

RSR unmuffled


Cup muffled


Cup unmuffled


RSR muffled


another inconel Cup muffler

coinboy

I ran open pipes all last year with my 99 C2, and it is just to load. I have now put on two 12" race mufflers and love it. Sounds very much like a CUP car. Did not loose anything on the dyno. my 3.4L has 272 hp at the wheels.

fletcherdave

Excellent......that's the type of info I was looking for. You guys on this site always impress me with your knowledge.

Flying Finn

Here's 997 RSR engine. Same principles apply.
Watch out for not making the header diameter too large.

onefastviking

I don't think that muffler was designed to flow that way, although I could be wrong. The other examples pictured are better ways to do.

ltusler

I thought that too, I'll put a vacume blower on it and see what it does. Worst case I'll cut it up and replace it with some other mufflers. They do advertise an X flow version so I'm hoping thats what it is.

onefastviking

Yeah, if memory serves me correctly that muffler is an "X" pipe internally although by it's design the pipes on each end should both be in and the outs on the other side.
You can go to their website and check how they flow. Better to build your own, and not too hard to do.