Boost on 10.8 to 1 compression?
Thread Starter
Joined: Nov 2001
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From: The Woodlands, TX
Boost on 10.8 to 1 compression? With the success of the boosted LS2's I was wondering what everyone thinks about putting a blower on a larger cubic inch (383-402) forged motor with compression in the 10.8 range. What types of limits would it have? Would you have to run race gas all the time, or run low boost only?
Assuming you have a good intercooler... I think 7psi is about as much as I'd try to push with pump gas. You could probably get by with 10 psi with alky injection. Of course with race gas you could run a lot more boost, but that would get pretty damn expensive.
The engine would be very responsive and still pull nice with 7-10 psi of boost on top of it. Changing the heads might allow you do drop your SCR a point or so (depending on what you have now for heads), if you did this you could run even more boost.
The engine would be very responsive and still pull nice with 7-10 psi of boost on top of it. Changing the heads might allow you do drop your SCR a point or so (depending on what you have now for heads), if you did this you could run even more boost.
Originally Posted by Bad Habit Bird
With the success of the boosted LS2's I was wondering what everyone thinks about putting a blower on a larger cubic inch (383-402) forged motor with compression in the 10.8 range. What types of limits would it have? Would you have to run race gas all the time, or run low boost only?
I would look into a very healthy methanol injection system.
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Your total compression will be way up if you try to make a lot of boost on pump gas. My guess is that 6psi intercooled would be safe, but you'd have to really watch the IAT's, and try to keep them at or below 125F to be on the safe side.
I would also say 6psi intercooled should be pretty good, if you want to go farther than that new pistons are not too big of a investment in the grand scheme of things when your doing a full F/I setup, or you can always do big chamber aftermarket heads &/ cometic .7x head gaskets.
Originally Posted by Bad Habit Bird
With the success of the boosted LS2's I was wondering what everyone thinks about putting a blower on a larger cubic inch (383-402) forged motor with compression in the 10.8 range. What types of limits would it have? Would you have to run race gas all the time, or run low boost only?
Detonation is a big concern, and temp plays a big factor. At that CR it is very hard to control.
On The Tree
Joined: Mar 2004
Posts: 121
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From: Cleveland
A tuner friend of mine in Oz runs 10.8:1 on a forged H/C 383 at 14-15 Lb w/alky spray with the same blower as mine. Around 700 RWHP on a daily driver. He obviously keeps timing on a very short leash, but get excellent mileage and efficiency out of boost. Gas is very expensive downunder.
Originally Posted by mistermike
A tuner friend of mine in Oz runs 10.8:1 on a forged H/C 383 at 14-15 Lb w/alky spray with the same blower as mine. Around 700 RWHP on a daily driver. He obviously keeps timing on a very short leash, but get excellent mileage and efficiency out of boost. Gas is very expensive downunder.
