What can I do with high compression?
Thread Starter
Intermediate
Joined: May 2015
Posts: 44
Likes: 1
What can I do with high compression?
My sbc engine runs at about 11:1 right now and from what I've read it seems useless to put a low boost turbo or a supercharger.
I'm already running high compression forged Pistons etc etc.
What have you guys done with your high compression engines?
I'm already running high compression forged Pistons etc etc.
What have you guys done with your high compression engines?
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
If you want to put a blower or turbocharger on it you'll have to lower the compression ratio to around 8 to 1 because an 11 to 1 would cause detonation under much boost.
Race Director
Joined: Nov 2006
Posts: 19,445
Likes: 353
From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
Identify your objective and then build your engine accordingly.
High compression engines are old school and usable with high octane gas and low mpg. Which was the 50-60-70's.
Nothing wrong with that. I grew up old school and love it.
But if you want new technology you will have to change the bottom end of the motor.
Or just go LS swap and sell/save the high compression engine.
IMO
Good luck
Bman
High compression engines are old school and usable with high octane gas and low mpg. Which was the 50-60-70's.
Nothing wrong with that. I grew up old school and love it.
But if you want new technology you will have to change the bottom end of the motor.
Or just go LS swap and sell/save the high compression engine.
IMO
Good luck
Bman
Safety Car
Joined: Jan 2009
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From: anchorage ak
Racer
Joined: Oct 2014
Posts: 289
Likes: 62
From: Hanover Township PA
Spray the crap out of it if you want more power. FI isn't an option really unless you lower the compression. A thicker head gasket can lower the compression but it isn't going to get you to 8 to 1. Maybe 10 to 1.
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Race Director
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From: PARADISE
St. Jude Donor '09-'11-'12-'13-'14
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
Since when is 11-1 compression old school a lot of the new performance engines are 11-1 from the factory and with aluminum heads will work on pump gas..
I agree if adding boost is the plan you are probably looking g at a piston swap.
I agree if adding boost is the plan you are probably looking g at a piston swap.
Le Mans Master
Joined: Jan 2006
Posts: 6,502
Likes: 138
From: Butler Pa
Race Director
Joined: Nov 2006
Posts: 19,445
Likes: 353
From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
He has a sbc with 11-1 cr and wants to run boost.
Most people know that is too high to safely run boost without some other precautions to prevent detonation.
Like aluminum heads or higher octane fuel.
He did not say he had either.
And I know that 11-1 cr engines are coming off the present assembly line. But how many are running boost?
As to old school comment - I said HIGH compression engines. Back in the 60's we ran 12.5-14 to 1 cr in many of our sbc. Most of the time with modified iron heads and sunoco 260. Nowadays we have easy access to aluminum heads but you need practically racing fuel to get the octane we could buy on the street.
That is the old school vs modern day comparison.
If this guy is asking these kind of questions, it is obvious that he does not have a LOT of experience in this area.
Telling him to go ahead and run boost on a 11-1 engine without other information like heads, cam specs, head gasket thickness, age of motor, etc.....is setting him up for a possible detonation.
That is all.
Better informed than to find out the hard way.
Bman
Racer
Joined: Oct 2014
Posts: 289
Likes: 62
From: Hanover Township PA
It would be cheaper to replace the pistons than a years worth of C16. Maybe e85 and a water/meth spray kit but even thats limited.
The OP really only has 3 choices.
1) keep the motor like it is and use n02 for more power.
2) replace the pistons for a lower CR.
3) Sell/trade the motor for a motor with lower CR.
Even if running boost on an 11 to 1 was done you couldn't run more than a few psi (like 4 and pushing it would be 6) and not worth all the time and money you would spend on a turbo or S/C.
Personally if I would going to run a boosted motor I would just drop in an LS1/LQ4/LM7 motor and boost the snot out of it.
The OP really only has 3 choices.
1) keep the motor like it is and use n02 for more power.
2) replace the pistons for a lower CR.
3) Sell/trade the motor for a motor with lower CR.
Even if running boost on an 11 to 1 was done you couldn't run more than a few psi (like 4 and pushing it would be 6) and not worth all the time and money you would spend on a turbo or S/C.
Personally if I would going to run a boosted motor I would just drop in an LS1/LQ4/LM7 motor and boost the snot out of it.
Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
Spray it and get a timing retard box that activates when the NO2 does. No problem. Need approx. 2 degrees per 50 HP and tune from there. It helps to run a real high octane race fuel in a dedicated nitrous tank if you spray hard. Read plugs to tune.
