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View Full Version : Proper size exhaust needed for GTO...



Roger Poirier
02-20-2005, 12:51 PM
I know I'm asking alot of guestions! However two heads are better than one. I have a 428 bored 60 over, Ram Air IV heads, 850 holly. Hooker Headers 2 inch pipes, 3.5 inch flange. Horsepower will be aprox 425 HP. 410 Rear. 5 speed. Question: What size exhaust do I need? I wiil be running them from front to back. Some vendors say 2.5" others 3". I would think the horsepower and cubes dictate what size to use. Correct? As usual getting it right the first time is my biggest concern.

Always trying to learn. R.P.

zbugger
02-20-2005, 01:44 PM
What camshaft are you using? That will also have an influence on your choice for exhaust. 2.5 would be good, but 3.0 would open up some more power possibilities for you in the future.

Roger Poirier
02-20-2005, 02:01 PM
Competition Cam Specs: Intake Exhaust
Valve Adj. HYD HYD
Gross Valve Lift .497 .507

Duration at 0.50 236 244
Lobe Lift .3260 .3330
Lobe Seperation 108

protour_chevelle
02-20-2005, 04:25 PM
3inch on big block IMO. 2.5 on MOST smallblocks unless they really need to breathe.

-Matt