Compression Ratio

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PortMatch
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Compression Ratio

#1 Post by PortMatch » Thu Feb 09, 2006 3:47 am

On a 350/383 chevy with aluminum heads/intake. What is the max compression before spark knock occurs or turbo blue must be used? Some say 10.5:1 or 11:1, what is the real truth.

DriveWFO
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#2 Post by DriveWFO » Thu Feb 09, 2006 11:59 am

That's an open-ended question. A lot has to do with your dynamic compression ratio, piston design, combustion chamber design, quench, ignition timing, etc.

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jones_performance
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#3 Post by jones_performance » Thu Feb 09, 2006 9:00 pm

cam profile also comes into play as well.

with 9 to 1 with enough timing you will get detonation so it really depends on your whole combo as far awhen you will get detonation on pump gas
Kevin

PortMatch
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#4 Post by PortMatch » Sun Feb 12, 2006 2:53 am

383 (4 Bolt Main), Forged: SRP Pistons, 6" I-Beam Rod, 5140 3.75 Crank. RPM Air Gap (1500-6500 RPM), Dart Pro 1 Aluminum (215cc Intake Runner), 2.05/1.60 Valve, 7000 RPM. 1.5 Roller Rocker, One-Piece Pushrod, Crane Cam (3500-7000) .558/.558 Lift 240/248 Duration. Hydraulic Roller Lifters.

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MOKANRACER
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Pre-ignition.

#5 Post by MOKANRACER » Sun Feb 12, 2006 10:16 am

Whats the piston design? Whats the volume of the head chambers? Typically,with an over bore and stroker,plus 6" rod application, your looking at more compression than a normal 5.7 rod config (350). My 383 is using 6" rods,flat top pistons, with 49cc Darts,and Ive been told by Lunati that I,m around 14:1....

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jones_performance
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#6 Post by jones_performance » Sun Feb 12, 2006 11:37 pm

with reatrded timing i have run 11:1 on pump gas and not had any issues before. not a real radicall engine though either.
Kevin

DRAG GTA
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#7 Post by DRAG GTA » Thu Mar 02, 2006 12:16 pm

need a part number or cam card for the cam. Specifically the valve timing. When does the intake valve cloase?

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