I was thinking 3" true duals dumped before the axels. What do you guys think? I had 2.5" true duals on the 346ci with a H-pipe. Now I want to go 3" true duals with a X-pipe dumped before the axel but the exhaust guy wants to use that nascar style flat tubing instead of regular 3" tubing. He thinks we are gonna run into clearence issues with the regular tubing and the nascar tubing is on back order?? Anyone have any ideas on what I should do?

 

dual 2.5" will do you fine, 3" isnt overkill but honestly, 5" of exhaust will do you just fine. dual 3" is really only goona benefit you if you were making 800+

 

o.k. Geoff with EPS thinks other wise so I guess I'll be going with 3"..

Thanks for the input.

 

go 3 inch you can even go over the axel with it and out the back its not that hard

 

What geoff thinks 3 inch is ok? Sry let me reword wat I meant to say..... ...if u can fit it. Go 3 inch.......if you can only fit 2.5 setup, than do that and dont stress......sorry for not explaini.g lol

 

Geoff is the guy that owns EPS. I have a custom cam from him so he is gonna tune the car to. I can go 3" but I have to use the flat piping like Nascar uses. I don't have a 4L60E in my car I have the th350 instead so it's different tranmission cross members..

 

3" TSP TD's on my 402, seems to be doing JUST fine. Its a ground pounder for sure! http://www.youtube.com/watch?v=a65Wu...eature=related

 

^^^^I agree. Skip the exhaust guy and get the TSP true duals.

 

I can't use it because of the th350 cross member I have on the car.

 

Hell of a nice car bro..

 

What are the dimensions of the Nascar flat tubing? All else equal, 3-inch round pipes flow 60% more than 2.5-inch round pipes, but NASCAR flat pipes, depending their actual dimensions may, or may not flow anymore than 2.5-inch piping.

See NASCAR discussion in:
http://www.epi-eng.com/piston_engine...technology.htm

 

Thank you Sir! I enjoy it!

 

The TSP can be made to fit with the th350. It just takes a little bit of work.

 

It is 3" flat nascar pipe.

 

If you don't mind could you give me a few details about your motor. I am wondering how well my car will run. How much power are you making at the wheels?

I have a LS2 402ci with -3cc relief flat top pistons trick flow 215cnc heads opened up to 4" bore and we did a valve job and dropped in some 2.055 intake valves, Harland sharp 1.7 roller rockers, ported 90mm fast intake, with a nick williams 90mm tb. 85mm lid and 85mm SLP MAS, Futral Hardened push rods, EPS custom cam 246/255-613-632@113+2LSA all this through a PTC built th350 tranny with a PTC 8" 5000 stall converter and a strange 12 bolt rear end with a 4.11 rear gear and 28" tall tires.

Hoping for low 10's @130+mph on the motor.

 

Go with the 3", I'm running the TSP TDs on mine and have plenty of clearence.

 

I see you have a A4 transmission. The guy at the exhaust shop said it wouldn't fit because he doesn't have a manderal bender to make the close radial bends and I have a th350 transmission which has a different rear cross member than the 4L60E. My torque arm connects to the cross member (frame) instead of the transmissions tail peice like the 4L60E. These are the reasons he said it won't fit and wants to use the nascar 3" flat tubing. With the suspension my car a bit of old school rake to it now.. He's going to do the job for $700.00 and this is all stainless steal pipe and all the bends will be welded into place versus being bent with one of those exhaust shop benders.. He says that this tubing doesn't loose flow through the bends like regular 3" tubing would.. Not sure how true this **** is but I do know the guy does good work. He also said that if I insist on having regular round 3" tubing he wouldn't take the job..

 

The flow capacity of 3" flattened pipe, assuming its shape is roughly equivalent to a 3 inch X 1.75 rectangle will be about the same as 2.5-inch round pipe.

 

Sounds like he's just trying to make some money. I would take it somewhere else personally. Guy sounds like an asshat to me.

 

LS2 402, its 11.7:1, PRC stg 2.5 l92's, stock ls3 intake, PTM 92mm TB, Pat g cam, M6, moser 9" with 4.10's 28" tires. 554/510 hp/tq at the rear wheels. Your converter will probably eat quite a bit of power from you car so dont get stuck on dyno numbers. Depending on your cars weight, low 10's will be a cake walk. if you're sub 3k lbs and have a good suspension setup i'm sure it could POSSIBLE do a 9.9x in good weather.