STARION
20+ Year Contributor
- 193
- 0
- May 30, 2002
-
Nova,
I'm just posting this out of curiosity.
I was talking with some people about ideal compression ratios on turboed 4G63's. It wasn't much of a discussion really, just an argument between 8.5:1 and 9:1.
Anyhow, I got to thinking about the current statement people are making that we can go to a higher compression and that when the V8 guys tell you that you should lower compression that their theory is old school. I thought nothing of it, then today I was browsing around looking at some of the larger BB turbos that I could never afford, and reading the specs.....I come across one that says something like: Will support 40 psi to well past redline. Well...while I may be taking this out of context, lets say I did want to use the turbo to its full potential efficiency and support 40 psi to my redline. Clearly, I have all my supporting fuel mods and bolt-ons. Now lets say that I have forged 9:1's, well forget pump gas, 116 octane goes in the tank....the car knocks with 40 psi on tap (does it actually? I don't know, lets just say it does hypothetically). Now, lets say the car is tuned to its optimum and it's not enough, so there is still knocking/pulled timing. This would leave me to lower the boost....but I don't want to lower it, I baught the turbo for 40 psi and thats what it will make. This puts me where, to either lower compression or find a fuel that burns even slower (methanol, alcohol, whatever..) or try to create a slower burn with propane, or alky injection. I'm thinking that to spool this thing within a reasonable amount of time, I will want to keep the 9:1's in place (not thinking nitrous). So I have cut out my options only to leave me with methanol or alcohol. Now, getting to the point, I really can't think of a DSM running methanol or alcohol...what am I missing. We have to use psi for our power, I haven't known any DSMer to lower compression, and some of the fastest dsms couldn't possibly be making these huge HP numbers upwards of 600 on anything less than 30 PSI. Maybe were not tuning hard enough.
I also thought I would mention the really extreme tuning levels. I have heard that funny cars run in the area of 4:1 compression to allow for more psi. Can they get away with this because they are s/c? Say, on a 4G63 if you had some 4:1 pistons made in an effort to allow for more psi, what sort of consequences would exist? would the turbo just never get spooled or what?
sorry for the long post....anyone feel free to correct me where I am wrong here and feel free to move this if it's not advanced enough.
I was talking with some people about ideal compression ratios on turboed 4G63's. It wasn't much of a discussion really, just an argument between 8.5:1 and 9:1.
Anyhow, I got to thinking about the current statement people are making that we can go to a higher compression and that when the V8 guys tell you that you should lower compression that their theory is old school. I thought nothing of it, then today I was browsing around looking at some of the larger BB turbos that I could never afford, and reading the specs.....I come across one that says something like: Will support 40 psi to well past redline. Well...while I may be taking this out of context, lets say I did want to use the turbo to its full potential efficiency and support 40 psi to my redline. Clearly, I have all my supporting fuel mods and bolt-ons. Now lets say that I have forged 9:1's, well forget pump gas, 116 octane goes in the tank....the car knocks with 40 psi on tap (does it actually? I don't know, lets just say it does hypothetically). Now, lets say the car is tuned to its optimum and it's not enough, so there is still knocking/pulled timing. This would leave me to lower the boost....but I don't want to lower it, I baught the turbo for 40 psi and thats what it will make. This puts me where, to either lower compression or find a fuel that burns even slower (methanol, alcohol, whatever..) or try to create a slower burn with propane, or alky injection. I'm thinking that to spool this thing within a reasonable amount of time, I will want to keep the 9:1's in place (not thinking nitrous). So I have cut out my options only to leave me with methanol or alcohol. Now, getting to the point, I really can't think of a DSM running methanol or alcohol...what am I missing. We have to use psi for our power, I haven't known any DSMer to lower compression, and some of the fastest dsms couldn't possibly be making these huge HP numbers upwards of 600 on anything less than 30 PSI. Maybe were not tuning hard enough.
I also thought I would mention the really extreme tuning levels. I have heard that funny cars run in the area of 4:1 compression to allow for more psi. Can they get away with this because they are s/c? Say, on a 4G63 if you had some 4:1 pistons made in an effort to allow for more psi, what sort of consequences would exist? would the turbo just never get spooled or what?
sorry for the long post....anyone feel free to correct me where I am wrong here and feel free to move this if it's not advanced enough.
