Low boost in LS1's
Low boost in LS1's I've seen all the crazy dyno numbers that new cobra's are putting down with like 20 psi and i was wondering why it seems all the boosted ls1's are running at most 10-15 psi? I realize the cobra's have forged internals but is there something keeping the ls1 even with forged internals below the huge numbers the cobra's are putting down? You would think with a bigger 346 ci engine there is more potential to lay down even greater numbers with a supercharger. I'm a newb to the forced induction so if this has been answered already i'm sorry.
12 Second Truck Club
Joined: Feb 2002
Posts: 5,574
Likes: 0
From: Sacramento, CA
The forged internals help greatly with being able to add a ton of boost along with the lower compression that the Cobras have. The #s you might be looking at are stock block HIGH compression LS1s which in no way can compete with a forged LOW compression Cobra motor. If you wanna do comparisions then look at what the fully built LS1s with boost are doing. Seems most are 700-900rwhp range. Then you have the crazy all out C5R guys over 1000rwhp. LOL
I know what you are getting at but it's just different motor setup is all. Forged internal low compression with high boost will always rule over hypercrap pistons, high compression low boost.
I know what you are getting at but it's just different motor setup is all. Forged internal low compression with high boost will always rule over hypercrap pistons, high compression low boost.
TECH Fanatic
Joined: Jul 2002
Posts: 1,218
Likes: 1
From: MI
I would guess that the larger displacement of the LS1 is what is keeping the "boosted PSI" down. The LS1 blowers may be flowing the same amount of air as the blowers on the Mustangs(CFM), but in order for the Mustangs to cram as much air into their (smaller)motors to make the same power as an LS1(bigger), it raises the PSI.
I.E. "To fill a 1 litre bottle with the same volume of air as a 2 litre bottle, the 1 litre must be under more pressure." Just look at the supras, they can run the same amount of power as a 600rwhp LS1, they just have to run 25psi on their small little 3 litre.
Remember, boost is just a measurement of restriction. 5.7 litres is going to take "X amount" of air much more easily, than 4.6 litres.
And yea...low compression and forged internals help.
Hope that all came out in plain english.
I.E. "To fill a 1 litre bottle with the same volume of air as a 2 litre bottle, the 1 litre must be under more pressure." Just look at the supras, they can run the same amount of power as a 600rwhp LS1, they just have to run 25psi on their small little 3 litre.
Remember, boost is just a measurement of restriction. 5.7 litres is going to take "X amount" of air much more easily, than 4.6 litres.
And yea...low compression and forged internals help.
Hope that all came out in plain english.
Last edited by Mike 01WS6; Aug 9, 2004 at 10:36 PM.
TECH Fanatic
Joined: Nov 2001
Posts: 1,986
Likes: 1
From: Centrifugal City
Agree. We're probably flowing as much or more air than those cars. You should measure the CFM instead of the boost air backed up in the manifold. This will show as lower boost, but flowing the same or more air.
You'd have to compare 1 specific setup to another. Cubes, Blower RPM or pulley size, etc. Focus on flow, not boost.
You'd have to compare 1 specific setup to another. Cubes, Blower RPM or pulley size, etc. Focus on flow, not boost.
