8.7:1 or 9:1 - Help Me Decide
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From: Phoenix, AZ
8.7:1 or 9:1 - Help Me Decide OK, here's the deal. I plan on getting this engine:
http://www.automotiveperformance.net/_wsn/page2.html
I'll be upgrading to the ARP rod bolts, as well as the head studs. Ported/prepped oil pump as well as a camshaft will also go in. Camshaft I'm thinking of something like 228/224, 560-570 lift, 115LSA, 3 degrees ground in. Initially I will be running the stock LS1 heads with 918's 'cause I can't afford to do them right away. I plan on going with something like TEA Stage II's at a later date.
I have crappy 91 octane here in AZ. I'm thinking of going to 8.7:1 CR with the pistons . . . do you think that's too low? I'm thinking if it seems low after I get it all in I could raise it up later with heads, right? What will be the limit of boost on this configuration, with either stock heads or the Stage II's? I want to run as much boost as possible on pump gas. But let's say that my max boost limit is 14psi . . . would I be getting enough of the benefit of the lower CR? Or am I better off going with 9:1 CR? I just don't want to go too low, and then find out that I can't take the boost up enough to make up for it because the heads will lift, or any other problems I might face.
I also know that the lower the static CR, the more doggy the car will be in the lower rpm's until the turbos spool. What other things can affect this doggy behaviour, ie. can a cam make a difference?
And oh yea . . . APE has the LS1 AND LS6 blocks . . . which one would you say is better? I have heard that the LS6 block actually isn't as strong, but wanted to see what everyone here thought. And obviously the core I have is LS1 . . . if I want to get the LS6 block do I need an LS6 core, or will APE accept what I have?
Let's hear your suggestions, guys!!
- Dug
http://www.automotiveperformance.net/_wsn/page2.html
I'll be upgrading to the ARP rod bolts, as well as the head studs. Ported/prepped oil pump as well as a camshaft will also go in. Camshaft I'm thinking of something like 228/224, 560-570 lift, 115LSA, 3 degrees ground in. Initially I will be running the stock LS1 heads with 918's 'cause I can't afford to do them right away. I plan on going with something like TEA Stage II's at a later date.
I have crappy 91 octane here in AZ. I'm thinking of going to 8.7:1 CR with the pistons . . . do you think that's too low? I'm thinking if it seems low after I get it all in I could raise it up later with heads, right? What will be the limit of boost on this configuration, with either stock heads or the Stage II's? I want to run as much boost as possible on pump gas. But let's say that my max boost limit is 14psi . . . would I be getting enough of the benefit of the lower CR? Or am I better off going with 9:1 CR? I just don't want to go too low, and then find out that I can't take the boost up enough to make up for it because the heads will lift, or any other problems I might face.
I also know that the lower the static CR, the more doggy the car will be in the lower rpm's until the turbos spool. What other things can affect this doggy behaviour, ie. can a cam make a difference?
And oh yea . . . APE has the LS1 AND LS6 blocks . . . which one would you say is better? I have heard that the LS6 block actually isn't as strong, but wanted to see what everyone here thought. And obviously the core I have is LS1 . . . if I want to get the LS6 block do I need an LS6 core, or will APE accept what I have?
Let's hear your suggestions, guys!!
- Dug
I would go 8.7:1 with the 91 octane. It's not that hard to increase compression and considering the size of your turbo's being 'doggy' shouldn't be much of a problem.
I run 8.7:1 on a Supercharged 383 all-bore and it has been working out well for me. I like that I can run 24 degrees of timing on pump gas and not have to worry about dinging.
Good Luck
I run 8.7:1 on a Supercharged 383 all-bore and it has been working out well for me. I like that I can run 24 degrees of timing on pump gas and not have to worry about dinging.
Good Luck
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From: East Side Performance! mASShole
I already went threw this. go to the lower cr. you can make up for power with boost if fuel will let you. Also a little change in head gaskets can bump cr up or down.
good luck.
ps.. my new set up is 8.75
good luck.
ps.. my new set up is 8.75
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Thanks guys . . . I'm glad I got you all to help me figure this out! I was leaning towards the lower CR anyway, just wanted to check . . .
Now what about the block? LS6 or LS1, and does my core matter?
Now what about the block? LS6 or LS1, and does my core matter?
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iTrader: (37)
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From: East Side Performance! mASShole
weired that nogo replied, he must have free time now.
NoGo and OSR1 are the ones who talked me into the 8.75 fyi
I dont think ls1 or ls6 makes a huge differance, others may disagree but im fine with my ls1
NoGo and OSR1 are the ones who talked me into the 8.75 fyi
I dont think ls1 or ls6 makes a huge differance, others may disagree but im fine with my ls1
id go with the 8.7 for your 91 octane.
you could view it as: do the 9:1 for the street making good power (not as much as the 8.7:1) and good spool less doggy then when you want more boost/power fillerup with some octane then crank up the boost.
you could view it as: do the 9:1 for the street making good power (not as much as the 8.7:1) and good spool less doggy then when you want more boost/power fillerup with some octane then crank up the boost.
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Originally Posted by Noyzee
weired that nogo replied, he must have free time now.
NoGo and OSR1 are the ones who talked me into the 8.75 fyi
I dont think ls1 or ls6 makes a huge differance, others may disagree but im fine with my ls1
NoGo and OSR1 are the ones who talked me into the 8.75 fyi
I dont think ls1 or ls6 makes a huge differance, others may disagree but im fine with my ls1
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From: Phoenix, AZ
Now what would you guys say the safe limit of boost on stock heads vs. TEA Stage II's would be . . . I'm not talking about octane, but rather the limits of the engine, or heads lifting, or blowing a head gasket, or whatever problems crop up at higher boost levels.
Originally Posted by ChevyNo1
Now what would you guys say the safe limit of boost on stock heads vs. TEA Stage II's would be . . . I'm not talking about octane, but rather the limits of the engine, or heads lifting, or blowing a head gasket, or whatever problems crop up at higher boost levels.
Some hit it earlier some don't
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OK, so it's more of an HP level rather than boost . . . doesn't matter how you make it. Is that right?
With that in mind, how much power would you expect an 8.7:1 motor to make, stock heads and stock intake, with let's say 14psi, and 91 octane? Most of the budget motors ( such as the one I plan on getting ) say they only support a max of like 700fwhp . . . what is the first thing to go if it can't handle more than that?
With that in mind, how much power would you expect an 8.7:1 motor to make, stock heads and stock intake, with let's say 14psi, and 91 octane? Most of the budget motors ( such as the one I plan on getting ) say they only support a max of like 700fwhp . . . what is the first thing to go if it can't handle more than that?
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From: East Side Performance! mASShole
Save the rear for me? hey you know what i can do to a rear!! I reckem and good to son!
I did a budget build as well. i do have gtp, ESP Freshend 6.0 heads The old ones not the ls6 ones. They kissed 300 cfm flow with a mild cam and about 11 psi on a stock cube,crank,rods, dimond pistions arp bolts and 8.75 cr I just missed 600 rwhp and tq.
I know she has more in it with more boost and NoGo is my tuner so he helps once i hit that maf maxing thing. other then that power is great. Im sure the heads help but i mean maybe 50 hp give or take.
I did a budget build as well. i do have gtp, ESP Freshend 6.0 heads The old ones not the ls6 ones. They kissed 300 cfm flow with a mild cam and about 11 psi on a stock cube,crank,rods, dimond pistions arp bolts and 8.75 cr I just missed 600 rwhp and tq.
I know she has more in it with more boost and NoGo is my tuner so he helps once i hit that maf maxing thing. other then that power is great. Im sure the heads help but i mean maybe 50 hp give or take.
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that block will handle alot more then 700hp people are doing 550-600 on stock bottom ends. You can`t tell me the forgings in your new motor will only hold an extra 100-150hp. I think you`ll be fine up to about 750rwhp.