Compression Ratio Gurus: some help????
Compression Ratio Gurus: some help???? Planning to go street 408 Twin Turbo but need some help here to decide which parts to combine from what I have available right now. As said its going to be used as a daily driver and occasional racing maybe.
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
How much boost are you planning to run and what fuel(s) ?
Use this calculator to get the ball park:
http://www.csgnetwork.com/compcalc.html
That's the one I use for a prelim calculation. This should get you what you want.
Off the top of my head i'm going to say o-ring it and run the larger combustion chambers. will be easy to run on pump and you can dial the boost way up for when running race fuel/meth
Use this calculator to get the ball park:
http://www.csgnetwork.com/compcalc.html
That's the one I use for a prelim calculation. This should get you what you want.
Off the top of my head i'm going to say o-ring it and run the larger combustion chambers. will be easy to run on pump and you can dial the boost way up for when running race fuel/meth
Last edited by nskyline34; Aug 5, 2015 at 12:23 PM.
Planning to go street 408 Twin Turbo but need some help here to decide which parts to combine from what I have available right now. As said its going to be used as a daily driver and occasional racing maybe.
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
What are your total HP goals(that includes glory runs)
What parts do you have?
What type of fuel are you planning on running?
4" Stroke?
6.125" rod?
4.030" iron block?
what size turbo's?
Thanks for your time. The project will be a 1954 Chevy truck (show, daily and occasional race vehicle). I have already: a 6.0L iron block; bored to .030; a 4 inches K-1 crankshaft, 6.125 compstar rods, as et of JE -28cc pistons and a set of Diamond racing flat top pistons, as et of 317 heads and a set of 243's. Turbos will be Precision turbos 62/66. Which combination of pistons and head should I use?
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How much boost are you planning to run and what fuel(s) ?
Use this calculator to get the ball park:
http://www.csgnetwork.com/compcalc.html
That's the one I use for a prelim calculation. This should get you what you want.
Off the top of my head i'm going to say o-ring it and run the larger combustion chambers. will be easy to run on pump and you can dial the boost way up for when running race fuel/meth
Use this calculator to get the ball park:
http://www.csgnetwork.com/compcalc.html
That's the one I use for a prelim calculation. This should get you what you want.
Off the top of my head i'm going to say o-ring it and run the larger combustion chambers. will be easy to run on pump and you can dial the boost way up for when running race fuel/meth
Premium gas with a boosted setup? E85 for sure.
But I'd either go Flat tops with 317's. Or -28 with 243's. The latter is what I'd do because 91 is the best we get around here.
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Any idea of the CR withe flat top with 317's and the -28cc with the 243's? Remember that will be a twin turbo set up so maybe too high CR is not desirable.
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Verdad Gallardo LQ9's has flat top pistons with 317's ad I think that the CR doesn't reach 10:5:1 and GTO's with flat top pistons and 243's is about 10:5:1. Can you verify somehow your info? Will apreciate.
Planning to go street 408 Twin Turbo but need some help here to decide which parts to combine from what I have available right now. As said its going to be used as a daily driver and occasional racing maybe.
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
1.Flat diamond pistons with 72cc 317 heads or with 65cc 243's? What CR with those combinations?
2.-28cc JE pistons with same heads; 72cc or 243's cc heads? What CR will get with those combinations?
The 28-29cc dish with the 64-65cc head would be about 9:1-9.2:1.
best combo for boost would be the dished with .020" wacked off the 243s
shoot for about 9.5:1 with LS9 head gaskets and head studs
This puts you right in the pump gas streetability range where the engine will still be responsive enough to kick the smaller turbos yet if you go E85 and say 12-14 lbs of boost you'll be safe and powerful. Easy 750 flywheel horse
shoot for about 9.5:1 with LS9 head gaskets and head studs
This puts you right in the pump gas streetability range where the engine will still be responsive enough to kick the smaller turbos yet if you go E85 and say 12-14 lbs of boost you'll be safe and powerful. Easy 750 flywheel horse
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Joined: Mar 2012
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From: South Florida
An lq9 doesn't have a 4" stroke. What fuel are you going to be running? I wouldn't run the -28cc on any motor really. A 9:1 just isn't necessary unless you are looking for huge numbers on pump gas only. But I also wouldn't run flat tops without E85.
TECH Addict
Joined: Aug 2005
Posts: 2,305
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From: Monroe,NY
http://www.ls1lt1.com/forum/crcalc.php This calculator is a little easier to me
The JE pistons with the 243 heads will yield roughly 9.14:1 CR and is definitely not High in CR. That's using the MLS GM LS9 gasket at a .051" thickness.
I'd salvage as much deck thickness as possible and go without milling the heads. Plenty of people making gobs of power at this CR. And he'll have no problems spooling those turbo's like a switch in the lower RPMs. (IMO of course)
Last edited by BlwnLs1GTO; Aug 6, 2015 at 11:10 AM.
That was my point.
The Flat tops will need a larger CC (317's) for a lower CR and a more pump gas friendly boost engine.
Same with the -28 dished piston with the smaller 243's CC head combo.
Both heads are comparable as far as flow. Plus the 243's have a higher resale value that will help pay for more parts. Johnson lifters maybe?
9:1 CR is not too low for a twin turbo setup on a stroker motor looking to make power. (IMO)
The Flat tops will need a larger CC (317's) for a lower CR and a more pump gas friendly boost engine.
Same with the -28 dished piston with the smaller 243's CC head combo.
Both heads are comparable as far as flow. Plus the 243's have a higher resale value that will help pay for more parts. Johnson lifters maybe?
9:1 CR is not too low for a twin turbo setup on a stroker motor looking to make power. (IMO)
Run the JE's with the 243's if you plan on running Premium gas.
That's what I'd do.
If you want more CR, mill the 243's down a little bit and/or use the Cometic Head gaskets that are .040" thick.
That's what I'd do.
If you want more CR, mill the 243's down a little bit and/or use the Cometic Head gaskets that are .040" thick.