Boost tolerance per c/r? (408 build idea)
#1
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From: N. Falmouth MA
Boost tolerance per c/r? (408 build idea)
What are the typical recommended limits per c/r? I understand most things depend on the setup, heads, cam, intake and TB... But I'm tossing around a build idea here..
Idea: 408 with forged bottom end with about 10.5:1 c/r (stock-ish). But with dish pistons and a somewhat aggressive blower cam. I can run it NA and have some good power out of it until I get around to have the money for a blower/charger.
Either an LQ or LS 6.0 block with a 4" crank, using the same top end I am running now and get some GOOD deads when I can. Basically budget build the bottom end/block and drive it for a while and piece everything together over time.
So..... A somewhat higher c/r for NA, but can handle a bit of extra air when I'm ready for it. Am I better having a lower c/r and have it SCREAM on boost or have a mid-range c/r that will run good on NA? I COULD get my 243 heads shaved to up it for now, when I get the GOOD heads, aim for a 72cc CC...
Ideas? Questions? Problems?
Idea: 408 with forged bottom end with about 10.5:1 c/r (stock-ish). But with dish pistons and a somewhat aggressive blower cam. I can run it NA and have some good power out of it until I get around to have the money for a blower/charger.
Either an LQ or LS 6.0 block with a 4" crank, using the same top end I am running now and get some GOOD deads when I can. Basically budget build the bottom end/block and drive it for a while and piece everything together over time.
So..... A somewhat higher c/r for NA, but can handle a bit of extra air when I'm ready for it. Am I better having a lower c/r and have it SCREAM on boost or have a mid-range c/r that will run good on NA? I COULD get my 243 heads shaved to up it for now, when I get the GOOD heads, aim for a 72cc CC...
Ideas? Questions? Problems?
#3
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^ I'm not planning crazy boost numbers. Prolly within D1SC capabilities.
As far as powerwise, I'm thinking maybe 650rwhp on max boost. Not sure exactly what it's capable of with 10.5 c/r. I know on low c/r a turbo'd 408 can make 900rw with a lot of extra air.
The car is just a cruiser for now. It gets driven once a week during the normal season, but I want it to be somewhat streetable. It's got a h/c LS1 now. Just seeing that these 6.0 blocks are pretty cheap and figure "why not." (yeah, I'm a little late to that game and getting tired of having old tech small bore.)
I may switch to turbo eventually... but for the time being, a blower is a little easier to deal with.
As far as powerwise, I'm thinking maybe 650rwhp on max boost. Not sure exactly what it's capable of with 10.5 c/r. I know on low c/r a turbo'd 408 can make 900rw with a lot of extra air.
The car is just a cruiser for now. It gets driven once a week during the normal season, but I want it to be somewhat streetable. It's got a h/c LS1 now. Just seeing that these 6.0 blocks are pretty cheap and figure "why not." (yeah, I'm a little late to that game and getting tired of having old tech small bore.)
I may switch to turbo eventually... but for the time being, a blower is a little easier to deal with.
#5
Keep in mind that stock LS2 10.9/1 engines run just fine at 8 psi of boost. Bob
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#6
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From: N. Falmouth MA
^ That's what I was thinking too... Just wondering what's the physical limitation when adding more to a c/r that is mid to high. Detonation? If I figured on a 10:1 c/r I could get away with about 10#?
#7
With a centrifical supercharger you can run more compression than you can with many other types of forced induction. At 10:1 you could easily run 10 pounds of boost. Bob
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#10
As BADLY as i wanted to have my first motor built, it will sadly have to wait til next season apparently and i'm now doing the same thing you are pretty much. I have a 402 with 11.2:1 cr with the 62cc tfs 235 heads on it now and am looking hard at the AFR 245's to get my cr down to about 10:1 and just swap cam and p'rods and throw 10#'s through a turbo at it and see what it will do. I've spoken to quite a few people and all say 650rwhp is likely where i'll be at which i can live with without coming $5000 out of pocket and having to worry about selling a shortblock i have no room to store.
LMK how this turns out or watch for my post, depending on who gets boosted first! GL!
LMK how this turns out or watch for my post, depending on who gets boosted first! GL!