View Poll Results: Whats the best CR to have for 15-22 pounds of boost?
11:1
8
2.87%
10.5:1
4
1.43%
10:1
20
7.17%
9.5:1
59
21.15%
9:1
67
24.01%
8.5:1
95
34.05%
8:1
26
9.32%
Voters: 279. You may not vote on this poll
CR for big boost...
LOL-a Bronco banner will do just fine on the Black Viper 
I do agree as stated earlier in this thread that a little higher compression for a blower would be better, I was just stating the facts that a lower compression build can yield high numbers, well astonishing numbers to be exact if you can run 7's. I got a S85 turbo so I dont have as much lag in the low end as a larger turbo would, in fact the S85 kicks in pretty fast. As many have stated in this thread, its more the total combo. I bet with you at 17-18psi and me at 20-22 psi it would be a darn good race with other things being equal.
The raiders will never own ANYONE
I do agree as stated earlier in this thread that a little higher compression for a blower would be better, I was just stating the facts that a lower compression build can yield high numbers, well astonishing numbers to be exact if you can run 7's. I got a S85 turbo so I dont have as much lag in the low end as a larger turbo would, in fact the S85 kicks in pretty fast. As many have stated in this thread, its more the total combo. I bet with you at 17-18psi and me at 20-22 psi it would be a darn good race with other things being equal. The raiders will never own ANYONE
LOL-a Bronco banner will do just fine on the Black Viper I do agree as stated earlier in this thread that a little higher compression for a blower would be better, I was just stating the facts that a lower compression build can yield high numbers, well astonishing numbers to be exact if you can run 7's. I got a S85 turbo so I dont have as much lag in the low end as a larger turbo would, in fact the S85 kicks in pretty fast. As many have stated in this thread, its more the total combo. I bet with you at 17-18psi and me at 20-22 psi it would be a darn good race with other things being equal.
The raiders will never own ANYONE
I do agree as stated earlier in this thread that a little higher compression for a blower would be better, I was just stating the facts that a lower compression build can yield high numbers, well astonishing numbers to be exact if you can run 7's. I got a S85 turbo so I dont have as much lag in the low end as a larger turbo would, in fact the S85 kicks in pretty fast. As many have stated in this thread, its more the total combo. I bet with you at 17-18psi and me at 20-22 psi it would be a darn good race with other things being equal. The raiders will never own ANYONE
A Raiders sticker will look better on your black viper! A match made in heaven!
8 Second Club
Joined: Jan 2004
Posts: 504
Likes: 1
From: Bay Area, CA
And you believe everything you read-especialy coming from a magazine? You think he's going to spill the beans on all his secrets?
Now all of a sudden everyone's bringing in 7 second full out race cars? You know the ones with air to water intercoolers, giant fuel pumps, giant feed lines, fuel cells, stand alone computers, etc, etc, etc,....
Go ahead run 8.1 run 25psi and let me know how your fuel system likes it when you ask it to run another 25psi more than the stock 45 or 60-so like 85 psi in pressure-just pray they never let you down.
I'll take my pump gas 10.1, 912 rwhp with a baby blower F1A making 17-18psi through an auto any day. PUMP GAS BABY!!!!!!
Now all of a sudden everyone's bringing in 7 second full out race cars? You know the ones with air to water intercoolers, giant fuel pumps, giant feed lines, fuel cells, stand alone computers, etc, etc, etc,....
Go ahead run 8.1 run 25psi and let me know how your fuel system likes it when you ask it to run another 25psi more than the stock 45 or 60-so like 85 psi in pressure-just pray they never let you down.
I'll take my pump gas 10.1, 912 rwhp with a baby blower F1A making 17-18psi through an auto any day.
PUMP GAS BABY!!!!!!In this case. the facts in the mag are true and that is my compression. No reason to "lie" about what my car has... after all.. even if someone bought my motor, they would still have to make the package work in his/her car right?
Wow..that was a long read! Maybe the facts were true in your case, but anyone can see why someone would say "don't believe everything you read.." I've seen articles on cars that I know, and not all of the facts are true... as I'm sure others have also.
I believe that this thread will go no where, as it is going to be opinions on what to do with your motor. There are several different ways it will work, some choose one, some choose the other... opinion arguements never go anywhere, other than in circles..
Some people want to run a lot of boost and a low cr. you'll have to run more boost to make the power. Others want a higher cr and less boost. Both can make power. I wouldn't be worried about running a certain # of boost, a little higher cr would spool the turbo's faster, could be good on the street as less lag, more fun to drive. Then you have the blower guys, who could have belt slip issues and not want a cog drive set-up, so a higher cr and less boost makes sense.
Atleast the thread was informative.
I believe that this thread will go no where, as it is going to be opinions on what to do with your motor. There are several different ways it will work, some choose one, some choose the other... opinion arguements never go anywhere, other than in circles..
Some people want to run a lot of boost and a low cr. you'll have to run more boost to make the power. Others want a higher cr and less boost. Both can make power. I wouldn't be worried about running a certain # of boost, a little higher cr would spool the turbo's faster, could be good on the street as less lag, more fun to drive. Then you have the blower guys, who could have belt slip issues and not want a cog drive set-up, so a higher cr and less boost makes sense.
Atleast the thread was informative.
it still amazes me how people are so fixated on where their boost gauge needle points to. maybe its like loud exhaust,.... if it's loud - it must be fast.
my 10:1 6.0L on E85 will see as much boost from the twin turbos as it needs to run 9's/ whether thats 5psi or 25psi. My 9.8:1 5.0 stang motor saw 18psi on a daily basis with pump fuel and meth and it loved every minute of it. My vote would be for 9.5:1 minimum, but it's against my nature to take a poll
my 10:1 6.0L on E85 will see as much boost from the twin turbos as it needs to run 9's/ whether thats 5psi or 25psi. My 9.8:1 5.0 stang motor saw 18psi on a daily basis with pump fuel and meth and it loved every minute of it. My vote would be for 9.5:1 minimum, but it's against my nature to take a poll
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Since this thread is still going I guess I'll share what I decided to go with. I took a large turn around. I decided to go all the way down to 8.5. Now I still believe it has the potential to make more power at a higher cr, I chose the safer route only because I'm not using the D1 anymore. I stepped it up to an F2. Now with the potential for 30psi, I'm not too worried about the extra power I would make with the higher cr. I still would say it is the best option to go with a higher cr if you want to stay at a lower boost level but once your making enough boost, there is no good reason to be risky. I'd rather have a little room for error than the extra 50-100rwhp more I might make with the higher compression. It's funny how once you start dishing out 10-20 thousand dollars on a set-up, safety starts to become a little more of a concern! I better put on my flame suit because I know, I'm a hypocrite.
there is no one "right way" to do this. And on a blower car it may not be significant. But on a turbo car I want the engine to make as much power as possible given the circumstances before the turbos come into play so spool up is a non issue. I remember my 911 turbo had a 3.3L 7.5:1 engine... if you ever caught me off boost you could walk faster than that thing. Once boost came on it was a different story but i don't like the light switch effect of that set-up. My Eclipse turbo was the same way, either all off or all on! I'll let everyone know how my 10:1 twin turbo 6.0L turns out. I may have to eat my words but i don't think so
there is no one "right way" to do this. And on a blower car it may not be significant. But on a turbo car I want the engine to make as much power as possible given the circumstances before the turbos come into play so spool up is a non issue. I remember my 911 turbo had a 3.3L 7.5:1 engine... if you ever caught me off boost you could walk faster than that thing. Once boost came on it was a different story but i don't like the light switch effect of that set-up. My Eclipse turbo was the same way, either all off or all on! I'll let everyone know how my 10:1 twin turbo 6.0L turns out. I may have to eat my words but i don't think so
Since this thread is still going I guess I'll share what I decided to go with. I took a large turn around. I decided to go all the way down to 8.5. Now I still believe it has the potential to make more power at a higher cr, I chose the safer route only because I'm not using the D1 anymore. I stepped it up to an F2. Now with the potential for 30psi, I'm not too worried about the extra power I would make with the higher cr. I still would say it is the best option to go with a higher cr if you want to stay at a lower boost level but once your making enough boost, there is no good reason to be risky. I'd rather have a little room for error than the extra 50-100rwhp more I might make with the higher compression. It's funny how once you start dishing out 10-20 thousand dollars on a set-up, safety starts to become a little more of a concern! I better put on my flame suit because I know, I'm a hypocrite.
LOL Thats hilarious can't rmember if it was 9.5 you were going for but that is a huge swing IMO as 8.5 IMO is the lowest any engine should go. I jsut had my 370 finished being built to 8.5 but wish I would have went 9.0 now but will see I might love it as is. If not I got the AFR 225's with 64cc scoped out that would put me right at 9.0 and to top it off put a vic jr and nice elbow on it. We'll see it will be plenty to start with.Thats hilarious though that after that huge debate you went back to 8.5 LOL With a blower I think they should be a bit higher CR IMO and you got an LSX block right so you will be a bit bigger than 40x ci so that should make up for the low end a bit more. However I think you should have went to 9.0 as the lowest with that setup, it will still kick *** though and with pump gas if you can hold the heads down will be able to push import boost numbers with that blower. Good luck though, I won't burn you too much. It will be a monster with whatever CR you choose, its whatever you want to do with it. I wanted a mostly street car is why I chose 8.5 and max power with pump and meth if I need it. No worrying about getting race gas, etc
But my car will be run on E85 and i really think the high comp will be a perfect match. Besides, the limited testing i did with 9:2-1 comp on E85 and the sick amount of timing advance i was able to run while still running 22psi of boost has me giggling like a school girl (example below) 
alcohol is your friend, do not fear the alcohol. Its good for your health, good for your party, and good for your ride. I wish our sorry *** county would get e85. if history is any indication, we'll have it, oh about 10 years after the first station in Miami popped up.
Its good for your health, good for your party, and good for your ride. I wish our sorry *** county would get e85. if history is any indication, we'll have it, oh about 10 years after the first station in Miami popped up. i hear ya. it's hard to believe it's taking this long to spread around down here. nearly every damn vehicle i see has a flex fuel badge on the trunk. not to mention getting race gas power out of $2.84 per gallon moon shine 
that don't stink up your garage or leave black marks on the driveway under your exhaust tips.
that don't stink up your garage or leave black marks on the driveway under your exhaust tips. Flame suit........................................ mothafucka you need a damn fire suit after that rant LOL Thats hilarious can't rmember if it was 9.5 you were going for but that is a huge swing IMO as 8.5 IMO is the lowest any engine should go. I jsut had my 370 finished being built to 8.5 but wish I would have went 9.0 now but will see I might love it as is. If not I got the AFR 225's with 64cc scoped out that would put me right at 9.0 and to top it off put a vic jr and nice elbow on it. We'll see it will be plenty to start with.
Thats hilarious though that after that huge debate you went back to 8.5 LOL With a blower I think they should be a bit higher CR IMO and you got an LSX block right so you will be a bit bigger than 40x ci so that should make up for the low end a bit more. However I think you should have went to 9.0 as the lowest with that setup, it will still kick *** though and with pump gas if you can hold the heads down will be able to push import boost numbers with that blower. Good luck though, I won't burn you too much. It will be a monster with whatever CR you choose, its whatever you want to do with it. I wanted a mostly street car is why I chose 8.5 and max power with pump and meth if I need it. No worrying about getting race gas, etc
LOL Thats hilarious can't rmember if it was 9.5 you were going for but that is a huge swing IMO as 8.5 IMO is the lowest any engine should go. I jsut had my 370 finished being built to 8.5 but wish I would have went 9.0 now but will see I might love it as is. If not I got the AFR 225's with 64cc scoped out that would put me right at 9.0 and to top it off put a vic jr and nice elbow on it. We'll see it will be plenty to start with.Thats hilarious though that after that huge debate you went back to 8.5 LOL With a blower I think they should be a bit higher CR IMO and you got an LSX block right so you will be a bit bigger than 40x ci so that should make up for the low end a bit more. However I think you should have went to 9.0 as the lowest with that setup, it will still kick *** though and with pump gas if you can hold the heads down will be able to push import boost numbers with that blower. Good luck though, I won't burn you too much. It will be a monster with whatever CR you choose, its whatever you want to do with it. I wanted a mostly street car is why I chose 8.5 and max power with pump and meth if I need it. No worrying about getting race gas, etc
just to clarify ; the compression on my 5.0 motor with decked (.040'') stock cast iron heads was right at 10:1. with no intercooler i was able to run 21* timing and 18psi of boost with alky injection with no issues. i still stand behind more comp than 8.5:1..
I bet alot of people are not actually reading the first post before they vote.
"What would the ideal CR be for a built motor to withstand a high amount of boost (say 15-22#'s), for maximum power with race gas?
"
If we are talking max power with race gas I can't see anyone voting for 8 or 8.5:1 for the boost range listed. IMO
The never ending debate continues!
"What would the ideal CR be for a built motor to withstand a high amount of boost (say 15-22#'s), for maximum power with race gas?
"
If we are talking max power with race gas I can't see anyone voting for 8 or 8.5:1 for the boost range listed. IMO
The never ending debate continues!