I finally decided on a modified zz502 for my 'Velle. Now I need to figure out what diameter exhaust to put on. The motor will have ported heads and a little more cam--have about 550HP. This car will be street driven so I need something that won't kill torque but still let it breathe. Should I go 2.5" or 3"? Would a 2.5" be enough for that motor?

Thanks guys! graemlins/hurray.gif

From the research I have done on this site over the past months, it seems to me that the 2.5" pipes should be the best choice for a street driven 502, but there should be plenty of expert advice to follow. I am glad you posted this as I am wanting to verify that 2.5" will work well on my 500hp 454 combo for street/strip. graemlins/waving.gif

I have dyno max ceramic coated 1-3/4" headers with 3" pipes in/out Dr. Gas X Pipe into 3" blow master. I'd reccommend the 3" pipe MAX for the "Street driven" 502. I had stock 2.25" dual exhaust and the engine breathes so much better with the new set up.

Breathing is everything, go with the 3" system. Bigger than that is overkill but smaller isn't going to be enough for that engine to reach full potential.

I'm by no means an expert on the subject but I've read several posts by people alot smarter then I am on the subject before selecting my 3 inch mandrel bent setup behind my 454 (.60 over). My car is primarily a weekend cruiser and if I'm losing any torque then my tires and the rest of my car has yet to get the message. My car pulls real strong. I would recommend the 3 inch system.
By the way I should be making around 500 hp with mid to upper 500 lb ft of torque. graemlins/thumbsup.gif

3 inch is the way to go........2 1/2 is to small and 4 is to much...IMO......I have 3 inch with H pipe and flowmasters that dump at the axle.....

Also ...If your looking to put a bigger cam in than stock I have one....Email me ....

I would use 2.5 inch pipes on it if it's a street car, spending most of its time between idle and 5000 RPM. The head pipe from the end of the taper on the collector to the front of the muffler should be 3 inch longer than the header primary tube. A crossover (2.5 inch) should be in the system as close to the collector as possible. The mufflers need at least 8 inches of 2.5 inch tail pipe to scavenge the muffler.

For sure, running 3.5" down to 3" and out to 2.5" for a lil' ol' 440ci. You need 3".

I went from a non-mandrel 2.5 inh system to a mandrel bent 3 inch and went from 12.0s@110 to 11.5s@115 on a 3900 lb 454 chevelle. It mostly picked up above 5000 rpm(thats where it spent most of its time when WOT). But it was alot louder.

Originally posted by 68chevelle533:
I went from a non-mandrel 2.5 inh system to a mandrel bent 3 inch and went from 12.0s@110 to 11.5s@115 on a 3900 lb 454 chevelle. It mostly picked up above 5000 rpm(thats where it spent most of its time when WOT). But it was alot louder. Well, that about slams the 2.5" theory in the toilet graemlins/clonk.gif I was mistaken, sorry. If a 454 (or 502) big block can gain 1/2 a second by only changing from 2.5" to 3" exhaust, I'm sold. Anyone looking for some new 2.5 in 2.5 out Summit turbos ? :D I'm going 3" graemlins/thumbsup.gif Maybe I just found my other 25 HP ??

Thanks for the replies. Looks like I'm going 3"! graemlins/thumbsup.gif

THANKS!

Hey what do you guys think? Will Texas70 2.5 exhaust work well with my mild 350 small block that is only street driven?

72' Malibu Convertible

GMC_Dude - yes!

GMC_Dude - That sounds like the right setup to me!
graemlins/beers.gif

Originally posted by ben70:
Thanks for the replies. Looks like I'm going 3"! graemlins/thumbsup.gif

THANKS! www.torquetechexh.com (http://www.torquetechexh.com)

Ben,

3" mandrel bent, I use a Torque Tech setup.