[LOL] Yes, that would not be "necessary"....unless it was a 10" turbine helicopter engine outlet. 
'71 Exhaust Tip Question
Thread Starter
Advanced
Joined: Sep 2004
Posts: 81
Likes: 16
From: Phoenix Arizona
'71 Exhaust Tip Question
Does anyone know why Chevy used the same exhaust tips on both small and big blocks? I ask because my big block has a 2.5" exhaust system until the end of the mufflers where it has a 2" outlet. It seems to me that this would cause a restriction. On the small blocks the exhaust pipes are the same size as the outlet pipe on the mufflers but on a big block, the inlet is larger than the outlet.
Did Chevy do this just to be able to use the same exhaust tip on both engines?
Did Chevy do this just to be able to use the same exhaust tip on both engines?
Pro
Joined: Mar 2004
Posts: 640
Likes: 1
From: Mertztown Pa
Does anyone know why Chevy used the same exhaust tips on both small and big blocks? I ask because my big block has a 2.5" exhaust system until the end of the mufflers where it has a 2" outlet. It seems to me that this would cause a restriction. On the small blocks the exhaust pipes are the same size as the outlet pipe on the mufflers but on a big block, the inlet is larger than the outlet.
Did Chevy do this just to be able to use the same exhaust tip on both engines?
Did Chevy do this just to be able to use the same exhaust tip on both engines?
Thread Starter
Advanced
Joined: Sep 2004
Posts: 81
Likes: 16
From: Phoenix Arizona
Yeah, I forgot about the LTI system but nevertheless, it is the same sort of question. Chevy went to the expense of putting a larger exhaust system on and then restricted it with the mufflers and tips. The only other thing I can think of is that the exhaust will be cooler by the time it exits the mufflers so maybe the 2" outlet isn't a restriction.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
It's not really that much of a restriction all the way at the "finish line" of the exhaust system. Remeber the Vette started out as a SBC car and went BB 1/2 way through C2 production, the 2" outlet wasn't that big of a restriction on a SBC car.
I have Corvette Central N-11 mufflers on my 70 LT-1 and they don't seem to hinder performance too much.
I also have run Walker Dynomax direct replacement Corvette mufflers in the past on both BB and SBC Vettes and one Vette ran 12's (72 LS-5 coupe) with the Dyno Max system on it. This was way back in the 80's seems like a long time ago right now
I have Corvette Central N-11 mufflers on my 70 LT-1 and they don't seem to hinder performance too much.
I also have run Walker Dynomax direct replacement Corvette mufflers in the past on both BB and SBC Vettes and one Vette ran 12's (72 LS-5 coupe) with the Dyno Max system on it. This was way back in the 80's seems like a long time ago right now
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Exhaust gasses at the manifold are upwards of 1000 deg F. Heat wants to expand gas, so that's why there is a lot of pressure at that point. By the time it gets to the tail end of the exhaust system, it is between 100-200 deg. F. Cooler gasses compress, causing the pressure to drop [in the same size chamber]. So, the 2-1/2 inch exhaust outlet is NOT the bottleneck in the exhaust system. Putting a 3 inch exhaust tip on a 2" exhaust manifold system is a waste of time.
Le Mans Master
Joined: May 2003
Posts: 8,875
Likes: 3,555
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Exhaust gasses at the manifold are upwards of 1000 deg F. Heat wants to expand gas, so that's why there is a lot of pressure at that point. By the time it gets to the tail end of the exhaust system, it is between 100-200 deg. F. Cooler gasses compress, causing the pressure to drop [in the same size chamber]. So, the 2-1/2 inch exhaust outlet is NOT the bottleneck in the exhaust system. Putting a 3 inch exhaust tip on a 2" exhaust manifold system is a waste of time.
Safety Car
Joined: Aug 2001
Posts: 3,683
Likes: 201
From: Waterford Mi
If you want to change your mufflers and find some with the 2 1/2" outlets then you can buy the tips from Gibson with the 2 1/2" pipes. I did this on my Magnaflow system.
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