Header and Exhaust Sizes
Thread Starter
Pro
Joined: Nov 2010
Posts: 602
Likes: 32
From: Old Bridge, NJ
Header and Exhaust Sizes
I've been trying to get a grasp on how the various exhaust sizes/combinations affect performance. Looking at the Corvette Forum track results provides a little info when people give their setups, but not often do they mention exhaust and header sizes.
For example, with headers, two common sizes of primaries are 1 3/4" and 1 7/8". Does the smaller limit maximum achievable power?
How about exhaust pipe diameter? Is 2.5" limiting?
Are these limits in the 700+ hp range such that, if you are building a motor to 600hp you are better off using smaller diameter?
Interested to hear from people making 600whp on 2.5" exhaust and/or smaller primaries.
How about the differences in the effects on N/A motors vs. S/C motors?
For example, with headers, two common sizes of primaries are 1 3/4" and 1 7/8". Does the smaller limit maximum achievable power?
How about exhaust pipe diameter? Is 2.5" limiting?
Are these limits in the 700+ hp range such that, if you are building a motor to 600hp you are better off using smaller diameter?
Interested to hear from people making 600whp on 2.5" exhaust and/or smaller primaries.
How about the differences in the effects on N/A motors vs. S/C motors?
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 25
From: Austin Texas
The further back from the exhaust valve you get the less important the diameter. Stock 430 HP 376 Cu In LS3 has mufflers with a single, less than 2" outlet (unless it has the NPP mufflers).
Instructor
Joined: Sep 2010
Posts: 219
Likes: 1
From: Winnipeg
For 90% of people, a 1 3/4" primary paired with a 2.5" xpipe will more than suffice. Post collector, a 3" pipe all the way back would be ideal. Header primary diameter, and design is more crucial than anything IMHO from what I've researched. There are a ton of great threads addressing the same questions/concerns that you have. Extreme applications may use 1 7/8" or larger primaries, but like I said... it's not necessary and can actually hurt performance. Just my .02. 
