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View Full Version : 2.5 vs. 3" exhaust



MBuckner3917
05-17-2006, 10:22 AM
I've got a 69 camaro convertible with a 600 hp 427, stock suspension that has been lowered 2". The headers will have a slip on flange rather than a bolt on piece.

Any recomendations on x-pipe exhaust systems?

How many clearance issues do I face with a 3" system?

How bad will a 2.5" system affect HP?

If I have to choose one over the other I think I'd rather lose a little HP rather than deal with scaping/clearance issues all the time.

Thanks in advance

406 Q-ship
05-17-2006, 12:34 PM
If you spend the time and do the exhaust system yourself from u-bends you can tuck the system tight to the floor and loose very little ground clearence. Actually the pipes back to and including the x-pipe should be the same diameter as the collector, after the collector it should reduce to the 3". I'm assuming that your collectors are 3.5 in diameter, with a true 600hp 427 will be able to use a true 3" system.

rocketman
05-17-2006, 06:39 PM
with that much hp,2.5 maybe to small to let the motor breath.find a good exhaust shop willing to take the time to do it with mandrel bent bends.

vintageracer
05-19-2006, 05:37 AM
If clearance is an issue you can alway use the flattened oval type of pipe used on many stock cars. You can buy all the pieces and fab your own.

I use this on my race cars for ground clearance just in case I go agricultural racing!

Josh
05-22-2006, 07:50 AM
My suspension appears to be the same as yours (dropped 2") and I am also running Kumo's that do not have much sidewall in the front. I have a 3" system and x-pipe from Pypes. The lowest part of the system is the collector flanges, the rest I really worked at tuking up and into the tunnel as much as possible. The flanges do scape on driveways and such that are abrupt. If a ran a 235/ 40 tire up front I do not think I would have a problems.

Josh
05-22-2006, 07:52 AM
https://static1.pt-content.com/images/noimg.gif (http://img157.imageshack.us/my.php?image=17373853tc.jpg)

ahowudoin
05-22-2006, 07:18 PM
I thing to remember is, Its a convertible. It has the brace that bolts to the floor that makes it a tight fit. I had 2.5 on my 67 conv. with a big block and if i lost power over the 3 inch it still wouldnt have mattered because it would spin the tires very easy.

toofun
05-30-2006, 05:02 AM
If you are worried about the brace you can do a couple of different things to help that. One you could make a couple of spacers to lower the brace down to give you the extra room, or you could buy the pre made brace from Hotckis performance. They have a cross brace that is lower for clearing big exhaust pipes. Me myself, I would make the spacers and save myself some coin!(EITHER WAY, I would go with the bigger 3 inch exhaust) The big blocks like to breath!!

Mark
TOOFUN

chicane67
05-30-2006, 10:41 AM
For that CID and power level, 3.5" minimum....

69ratfed
05-31-2006, 05:03 AM
I just changed from 2.5 to 3''. I used a Dr.Gas X-pipe, Spintech Sportsman XL mufflers and Torque Tech tail pipes. I had Flow master 40's before. Man, what a difference. Sounds great at idle (big block rumble), no droning in car when cruising and when you step on pedal the car has a totally different sound. I would recommend this set-up to anyone. I am running a 454 with about 550-565hp. The way the exhaust tucks up under car you cannot see it from the side, my flanges are the lowest point.
In your case with a 2'' drop check on oval tubing from Spintech.
Goodluck.