Exhaust size ?

[69coupe]

What size pipe are you guys using from the extractors back ? Is 2 1/2 " each side to small for a Big Block :confused:
I would struggle to get 3" over the back axle but is it worth the effort for HP gain :D

Plan to use a X pipe after the Gearbox mount.

[rodent]

What size pipe are you guys using from the extractors back ? Is 2 1/2 " each side to small for a Big Block :confused:
I would struggle to get 3" over the back axle but is it worth the effort for HP gain :D

Plan to use a X pipe after the Gearbox mount.

How much grunt?

[69coupe]

How much grunt?

Grunt is around 500HP as is standard ZZ502 crate motor. Revs limited to 6000RPM.

[rodent]

That'd be a coin flip for me, but i'd probably go 3" and run a dog, muffler and crossover to keep the noise down to a dull roar :D
Give Darren @ Di Filippo a call and tell him Jim with the Nova put you on to him :D They're pretty switched on and should be able to steer you straight.

http://www.darrendifilippo.com.au/

cheers
Jim

[troubleshooter]

I'm running 3" fromthe extractors to the mufflers which are low restriction(don't know what brand) and situated just before the diff and with a crosspipe near the centre of the car (67 BB Camaro 450hp at wheels). the mufflers then run 2 1/2" over the diff and the sound is a dull throbbing roar. fantastic note and definately over 100 decibel but acceptable on the street and have been alongside cops and infront of them with no probs. (maybe they were nice ones). Andrew at Yarra valley exhausts in Lilydale has done a couple of these for me and one for a mate (68 Cam) and does a top job ata good price and is quick. Top bloke too, he does lots of hot cars.

[69coupe]

I'm running 3" fromthe extractors to the mufflers which are low restriction(don't know what brand) and situated just before the diff and with a crosspipe near the centre of the car (67 BB Camaro 450hp at wheels). the mufflers then run 2 1/2" over the diff and the sound is a dull throbbing roar. fantastic note and definately over 100 decibel but acceptable on the street and have been alongside cops and infront of them with no probs. (maybe they were nice ones). Andrew at Yarra valley exhausts in Lilydale has done a couple of these for me and one for a mate (68 Cam) and does a top job ata good price and is quick. Top bloke too, he does lots of hot cars.

Thanks Troubleshooter. I think this may be the way to go. I have heard before that as the exhaust gases cool the smaller diameter is ok, so 2 1/2 over the back axle should work :)