jtwoods4
Member
As the size of the exhaust system increases does the engine gain or lose power? For example, I have an L34 396 V8, what effects does a 2.5 inch vs 3.0 inch exhaust have on the engine performance/power/etc....
Exhaust Diameter vs engine power
- Thread starter jtwoods4
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dcozzi
Veteran Member
Bigger exhaust supports more power but there is a point of diminishing return.
You start to lose lowend torque when header primaries are too big and when the rest of the exhaust flows too freely as well. The cam profile also has a big effect on this. Lots of variables to think about.
As a general rule, I like to think 2.5" all the way back to the rear bumper is good up to 500HP. After that, 3" can give you noticeable gains.
Some people say 550HP is where you should start using 3". I had 523HP at the crank on a 406" motor and going from 2.5" to 3" made a difference. Sounds waaayyy cooler too.
You start to lose lowend torque when header primaries are too big and when the rest of the exhaust flows too freely as well. The cam profile also has a big effect on this. Lots of variables to think about.
As a general rule, I like to think 2.5" all the way back to the rear bumper is good up to 500HP. After that, 3" can give you noticeable gains.
Some people say 550HP is where you should start using 3". I had 523HP at the crank on a 406" motor and going from 2.5" to 3" made a difference. Sounds waaayyy cooler too.
76z28
Veteran Member
3 inch will give you more top end
DEPENDING ON APPLICATION
2.5 is the way to go though
that is what i just put on mine SOUNDS AWESOME
DEPENDING ON APPLICATION
2.5 is the way to go though
that is what i just put on mine SOUNDS AWESOME
jtwoods4
Member
I bought the car with 3 inch exhaust so I am wondering if I will get better performance with 2.5 inch, I am changing the CAM back to almost stock (little bigger) from the massive thumper that is in there now. 396 engine
[email protected]
Veteran Member
jtwoods4 said:
Yes it will.
NYH1
Veteran Member
Are you going to keep the 396 in the car? Or do you plan on putting a higher power 454, 496 or 502 in it sometime down the road?
If it were me and I was going to keep the mild 396 in it, I'd go with 1 3/4" full length headers and a 2.5" full length dual exhaust system. There are a bunch of difference exhaust systems out there for gen II Camaros. I went with the Flowmaster system that uses the transverse muffler. It sounds great and has a lot more ground clearance.
If it were me and I was going to keep the mild 396 in it, I'd go with 1 3/4" full length headers and a 2.5" full length dual exhaust system. There are a bunch of difference exhaust systems out there for gen II Camaros. I went with the Flowmaster system that uses the transverse muffler. It sounds great and has a lot more ground clearance.
z28rod
Veteran Member
john lingenfelter did extensive exhaust tube dia. hp tests, he found that 2.5" tubing would support up to like 500 hp before needing 3"dia.
Rick WI
Veteran Member
Restriction is lost power. Tailpipes especially are a power grabber. You really can't have too big of an exhaust, just poor tuning and lack of space.
Going with a small cam 2.5 would be better than the 3.0 it has on it now.
This is nice to know,I wasn't thinking on doing a 3".
