Big Problem Formulating... =[
I plan on doing the trubo on my stock engine (about 500rwhp) for about a year until i get enough money for the 408 and TH400.
I am going to be building a 408 8.5:1 using TSP L92 heads.
-Cam: 223 in. 227 ex. 636, 639 115 Lobe Seperation 113 Centerline.
-JGS 50mm WG
-JGS 56mm BOV
-ST80 AR 1.1 T4 (Gonna spool like a bitch outta hell on the 408)
From what i have been reading on the board is that for a trubo that size i would need to boost like 25psi to get my track power. And that might not even cut it even with the meth.
(i have my fuel system, rear end, and eletronics all worked out already)
Any suggestions? I really had a mind set on this build and now it seems to be falling apart...
I guess that i am thinking is that 25psi is very high and i wanna keep it as safe as possible to the engine.Please help and comment if things need to be changed. I need all the input i can get. I keep geting mixed answers.
Thank you for your time!
P.S. i think that the 93 and meth should be fine if you keep your KR in check and should be just fine on the 408ci...
https://ls1tech.com/forums/showthrea...light=speedinc
Check out the speedinc car.. I know that it's a TT but you get the idea.. This is only through like 20psi...
https://ls1tech.com/forums/showthrea...light=speedinc
Check out the speedinc car.. I know that it's a TT but you get the idea.. This is only through like 20psi...
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And if you can make an efficient 25psi through a 408. Good god that's a ton of power. 25psi through a 408 is soooo much boost. S88 made 20psi on a 370ci and made 1000whp!! Better turbo yes... but that's still nutso.
If your raceweight is 3800lbs and you trap 135 mph you are making 800 rwhp.
If your raceweight is 3800lbs and you trap 135 mph you are making 800 rwhp.
dyno numbers mean squat in real racing..
I've made over 1100rwhp with 370ci motor.
That was at 25 psi and there is no way I would try that on pump and meth.
I was pushing quite a bit of water like that and finally blew a gasket running 118 octane fuel.
Right around 1000rwhp w/ 370 cubes and a S88 @20 psi
The above was thru. Powerglide and S60 rearend.
Be sure your fuel system is up to the task.
Kyle
If I did a 408ci and tried to max it out on 93 and meth (which I would not do personally) I would run 8.5:1 compression and figure on 14-17psi to hit your goals.
I'm not much into dyno numbers, except that I went 9.4 with 680rwhp with the blower, and I went 9.4 with lower boost than my 867rwhp numbers, I just want to start running some 8's when it gets nice again.
Get a good converter too.




to get deep into 9's