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9.4:1 to 10.5:1 compression

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Old May 19, 2013 | 08:04 PM
  #1  
RWO3's Avatar
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Joined: Feb 2012
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From: Tennessee
Car: '84 Camaro Sport Coupe
Engine: 355
Transmission: 700R4
Axle/Gears: 3.08
9.4:1 to 10.5:1 compression

I might need to bore and get new pistons for my rebuild so I figured I might as well bump up compression. My build is;

Stock Vortec 350 4-bolt bottom end and heads
Comp cams XR264HR duration 264/270 and lift .487/.495
RPM Air-Gap intake
Longtubes
Edelbrock Thunder AVS 650 CFM

Question is, can I get a set of hypereutectic pistons that will raise compression to 10.5:1 and run 93 octane and be done with it? Or would I need other reinforcements aswell? Is 10.5:1 a little high? What about just 10:1 comp?

Thanks.
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Old May 20, 2013 | 12:31 AM
  #2  
RyanJB's Avatar
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Joined: Jul 2011
Posts: 344
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From: Delaware
Car: 92 Firebird, 91 Trans Am
Engine: L31 with HSR, LB9
Transmission: 700R4, 700R4
Axle/Gears: '99 10 bolt 3.90, '01 10 bolt 3.42
Re: 9.4:1 to 10.5:1 compression

Originally Posted by RWO3
I might need to bore and get new pistons for my rebuild so I figured I might as well bump up compression. My build is;

Stock Vortec 350 4-bolt bottom end and heads
Comp cams XR264HR duration 264/270 and lift .487/.495
RPM Air-Gap intake
Longtubes
Edelbrock Thunder AVS 650 CFM

Question is, can I get a set of hypereutectic pistons that will raise compression to 10.5:1 and run 93 octane and be done with it? Or would I need other reinforcements aswell? Is 10.5:1 a little high? What about just 10:1 comp?

Thanks.
I'm sure you could find a set of pistons to do that. It you could have the block and it heads decked to reduce combustion chamber volume and do the same thing. I got a set of 64cc vortec heads that were decked and the pistons are 4cc dish. I have around 10:1 comp and o run 89 octane just fine. 87 has very minimal pinging
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Old May 20, 2013 | 12:54 AM
  #3  
DeltaElite121's Avatar
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Joined: Feb 2006
Posts: 1,366
Likes: 1
From: St.Louis, IL
Car: 1988 Camaro
Engine: 377
Transmission: TH350; Circle D 4200 converter
Axle/Gears: Ford 9"
Re: 9.4:1 to 10.5:1 compression

you'll need to make sure you get your timing dialed in real well, as well as check the dynamic compression ratio on that cam. If the dynamic is sitting to high you'll probably have to back timing out in order to make it acceptable assuming you're not too far "off the deep end" of being tolerable. I'm a little higher than that (not by much; static-wise) and I definitely need to mix 93 and 100 octane in order to keep things happy.. remember - just because you can't physically hear detonation doesn't mean it isn't happening..
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