View Poll Results: Whats the best CR to have for 15-22 pounds of boost?
11:1
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8
2.87%
10.5:1
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4
1.43%
10:1
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20
7.17%
9.5:1
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59
21.15%
9:1
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67
24.01%
8.5:1
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95
34.05%
8:1
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26
9.32%
Voters: 279. You may not vote on this poll
CR for big boost...
#62
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I for one am going 10:1 with my 408. I am not sure if that is middle of the road or if it is considered high compression. But I do have specific reasons and needs for this choice, as well as enginering controls in place for it. It is true you are less likely to damage an engine due to detination with lower compression and high boost as compared to high compression and high boost. People just have different needs and goals, as well as driving habits that effect a decision on what compression to run. Realy there is nothing wrong with either aproach, as long as you also take into consideration what that aproach will require to make it succeed.
#63
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But for the rest of us that normally drive our cars on the street every day, and want to be able to RELIABLY fill up at the gas pump and still run 18+#'s of boost without having to worry about detonation, a lower CR is really the way to go. Call me living in the dark ages, but the poll proves I am definatly not alone, and the polls parameters were even on race gas.
#64
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But for the rest of us that normally drive our cars on the street every day, and want to be able to RELIABLY fill up at the gas pump and still run 18+#'s of boost without having to worry about detonation, a lower CR is really the way to go. Call me living in the dark ages, but the poll proves I am definatly not alone, and the polls parameters were even on race gas.
#67
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quit talking about lower compression and pump gas... 4 pages mentioning that and the guy wants opinions on RACE GAS aka NOT PUMP GAS ![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
its about race gas here!! you can get away with more compression since race gas is less detonation prone. With proper tune, meth and intercooling, i THINK you can easily run 15-20lbs on a 9.5-10.5 to 1 motor as long as you use a high octane race gas. Maybe o-ring the block/heads and such because cylinder pressures will be very high
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its about race gas here!! you can get away with more compression since race gas is less detonation prone. With proper tune, meth and intercooling, i THINK you can easily run 15-20lbs on a 9.5-10.5 to 1 motor as long as you use a high octane race gas. Maybe o-ring the block/heads and such because cylinder pressures will be very high
#68
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quit talking about lower compression and pump gas... 4 pages mentioning that and the guy wants opinions on RACE GAS aka NOT PUMP GAS ![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
its about race gas here!! you can get away with more compression since race gas is less detonation prone. With proper tune, meth and intercooling, i THINK you can easily run 15-20lbs on a 9.5-10.5 to 1 motor as long as you use a high octane race gas. Maybe o-ring the block/heads and such because cylinder pressures will be very high
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
its about race gas here!! you can get away with more compression since race gas is less detonation prone. With proper tune, meth and intercooling, i THINK you can easily run 15-20lbs on a 9.5-10.5 to 1 motor as long as you use a high octane race gas. Maybe o-ring the block/heads and such because cylinder pressures will be very high
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I agree to a certain extent, but maybe not that much. Anyways thats what the poll has been for from the beggining and the results show what the majority thinks. I agree that the majority is probably going on the safe side of things, or perhaps didn't read the first post before they polled, thinking it was on pump gas instead of race gas.
#69
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Safe is always good tho. Just goin by what i have seen from a few cars. Guys will fill up on race gas and run their race boost settings which can be 5-10psi more boost over street setups. i dont think 15-20psi is asking too much for a 9.5 to 1 engine on race gas.
I know a guy on another forum building a 30psi boosted F1 charged smallblock and he is around 8.5 to 1 compression but i believe he is using meth and pump gas. Makes sense to me you can add a point of compression and cut 10 psi boost easily with the added benefits of race gas. Meth for more safety if needed
edit: plus you can add a larger cam to help bleed off pressure and lower that dynamic compression. Bigger cam should help make more power anyway so possibly less boost can be used
I know a guy on another forum building a 30psi boosted F1 charged smallblock and he is around 8.5 to 1 compression but i believe he is using meth and pump gas. Makes sense to me you can add a point of compression and cut 10 psi boost easily with the added benefits of race gas. Meth for more safety if needed
edit: plus you can add a larger cam to help bleed off pressure and lower that dynamic compression. Bigger cam should help make more power anyway so possibly less boost can be used
#70
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If your going to use meth with race gas, and i'm assuming it would only be for the cooling affect than you don't want to run anymore than 110 octane. 116+meth will slow the burn down too much.
#75
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I am running 8.8:1 in my car, and it would safely hold 22#'s of boost on pump gas. It is a good combo for someone who wants to make lots of boost on pump gas.
#76
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11:1 - race only on C16 22-24# boost
9.5:1 - street/strip 91 octane 14-15#'s
8.5:1 - DD, occasional runs at strip. 12-14#'s 91 and 18-20 on race gas.
Mind you this is a bit on the safe side due to losing a LSx FI motor 4 years ago and 8000+ DA. Sorry about the altitude thing again.
-Tim
#78
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Nahh, its cool no regrets. I will be able to turn the boost up even more and not have to worry about it. I am going for durability/longefity too
I still think it will be great and glad I never went with 9.2 but maybe 8.7-8.8 which really isn't that much of a difference. This is my first serious build so I think its even better I went with this. If its not enough, LOL, I'll bump it next time but I am sure it will be. If I upgrade anything it will be the turbo and/or turbo kit
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#79
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Nahh, its cool no regrets. I will be able to turn the boost up even more and not have to worry about it. I am going for durability/longefity too
I still think it will be great and glad I never went with 9.2 but maybe 8.7-8.8 which really isn't that much of a difference. This is my first serious build so I think its even better I went with this. If its not enough, LOL, I'll bump it next time but I am sure it will be. If I upgrade anything it will be the turbo and/or turbo kit ![Grin](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_grin.gif)
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