pistons to go with 317 heads and a magnacharger?
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pistons to go with 317 heads and a magnacharger? i'm buying the forged 346 rotating assembly from Scoggin Dickey and was wondering which pistons to have them switch out for a lower compression on the engine? from what i've been reading the dish top are the ones i'll need but which brand makes a better piston or are they all as good as eachother? i'd like 9.0-9.5:1 and I plan on running 10 lbs of boost through 317 heads. the cam will either be the TR Blower Cam 214/230 .601/.579 117 LSA or maybe the Speed Inc 226/234 .598/.599 117 LSA. Thanks guys for the help!
Any particular reason you're going so low on the C/R? Is the engine going in a dedicated track car? Truck in my signature is running 9psi and C/R is a little over 10:1. Vette is at 8.5psi and running stock LS3 compression which I believe is 10.7:1. Both are running stock GM pistons. Truck probably has 30K on the LQ4. Vette has about 6K on it. When and if I have to build a replacement, I'll shoot for around 10.5:1. Your motor will run better when not in boost if you can keep the c/r up a little.
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Any particular reason you're going so low on the C/R? Is the engine going in a dedicated track car? Truck in my signature is running 9psi and C/R is a little over 10:1. Vette is at 8.5psi and running stock LS3 compression which I believe is 10.7:1. Both are running stock GM pistons. Truck probably has 30K on the LQ4. Vette has about 6K on it. When and if I have to build a replacement, I'll shoot for around 10.5:1. Your motor will run better when not in boost if you can keep the c/r up a little.
Get some 243 heads and come Diamond -8.6cc dish pistons will get you right around 10.0:1 And will be good for 10psi.
I was running stock heads and -8.6 cc pistons at about 9.6:1 now going to 243 heads that have been work over. also the car will be seeing 14-15 psi. Hope this helps
I was running stock heads and -8.6 cc pistons at about 9.6:1 now going to 243 heads that have been work over. also the car will be seeing 14-15 psi. Hope this helps
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Thread Starter
On The Tree
Joined: Jan 2010
Posts: 110
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From: west coast
Get some 243 heads and come Diamond -8.6cc dish pistons will get you right around 10.0:1 And will be good for 10psi.
I was running stock heads and -8.6 cc pistons at about 9.6:1 now going to 243 heads that have been work over. also the car will be seeing 14-15 psi. Hope this helps
I was running stock heads and -8.6 cc pistons at about 9.6:1 now going to 243 heads that have been work over. also the car will be seeing 14-15 psi. Hope this helps
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for a street car. anything less than 9.3ish:1CR will lose some low end on the street. Of course it depends on your turbo, cam choice and the stall you go with, assuming youre an auto. You are right, the lower the compression the more boost you can run on pump gas but you can run 10 psi on 93 at 9.5. We dont have 93 in Alaska so Ill be trying to run 10psi on 91 @ 9.7 lol. Too be honest, meth is always nice even at lower CR.
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for a street car. anything less than 9.3ish:1CR will lose some low end on the street. Of course it depends on your turbo, cam choice and the stall you go with, assuming youre an auto. You are right, the lower the compression the more boost you can run on pump gas but you can run 10 psi on 93 at 9.5. We dont have 93 in Alaska so Ill be trying to run 10psi on 91 @ 9.7 lol. Too be honest, meth is always nice even at lower CR.
Lol, missed the part about the maggie! I dont know much about blowers or what ranges each of them work in, sorry. I would go with 317s and some mild dished pistons to achieve 9.5ish CR. Realistically, anything over 9 is pretty bearable.
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Last edited by 1slowfbody; Feb 6, 2010 at 01:00 PM.
If you have LT's, dual free flowing muffs, good heads, and either of the cams you referenced, I don't think you'll see 10psi with the mp112. That's not all bad either. You'll still make good power and less heat. Keep the compression up and you'll have a very responsive street machine. I'm assuming you have access to 93 octane. As one of the other guys mentioned, some type of boost cooler or meth injection would be good too.
There's not much difference between the 243's and 317's besides combustion chamber volume. Either will do fine. Just let the folks you're buying your pistons from know which heads you are going to use and they can spec the pistons to the c/r you want.
There's not much difference between the 243's and 317's besides combustion chamber volume. Either will do fine. Just let the folks you're buying your pistons from know which heads you are going to use and they can spec the pistons to the c/r you want.
Thread Starter
On The Tree
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If you have LT's, dual free flowing muffs, good heads, and either of the cams you referenced, I don't think you'll see 10psi with the mp112. That's not all bad either. You'll still make good power and less heat. Keep the compression up and you'll have a very responsive street machine. I'm assuming you have access to 93 octane. As one of the other guys mentioned, some type of boost cooler or meth injection would be good too.
There's not much difference between the 243's and 317's besides combustion chamber volume. Either will do fine. Just let the folks you're buying your pistons from know which heads you are going to use and they can spec the pistons to the c/r you want.
There's not much difference between the 243's and 317's besides combustion chamber volume. Either will do fine. Just let the folks you're buying your pistons from know which heads you are going to use and they can spec the pistons to the c/r you want.
my options are run 91 alone, run 91 with 5 gallons of 10X ocatane or run only the high octane. we don't have 92 or 93. this is why i was reading up on lowering the compression, because we don't have have 92 or 93 