408 Questions??????

[bigwhitecobra]

I'm thinking of building a 408 with AFR 205's custom cam, favoring the exhaust side with .525" of lift. Atleast I think I want that much. I've gotten quotes from some of the better racing shops out there and all have estimated 570 or so at the flywheel. Now I also have a Vortech YS-trim and after cooler making 14# of boost that is on the car now, with a 306. The idea is to run in the True Street Class at FFW. I want to run solid 9's and maybe dip into the 8's.

With this combo do you think I'll have drivability issues with this much power? What size injectors should I run with. I'm thinking something in the 50-55# size. Any suggestions with Throttle bodies and MAF? What intake should I be looking at? Coast High Performance EFI Spyder. but I don't want to kill the bottom end completely. But I do want the top end charge that the Spyder will give.


Decisions decisions decisions. Anyway, thanks for listening. Later.

[sn95gt19]

kinda sounds like you want the best of both worlds, which can very well be a major pain in the a&&.


if built right i would think you would have no problem running 9's
im in the same boat as you, i have a 347 8.5:1 w/victor intake(FI) and i was going to go turbo but the darn time involved in making the kit made me decide against that. i am going to pick up a ys trim (i have to make my own kit though, custom) w/20+ lbs
i take it your staying fuel injected.....to convert a carb intake with the elbow would probably cost a lot, i would pick up a victor 5.0 intake and have a shop do some port work on it. with this intake you'll probably keep "some" lowend power, probably not a lot but more than the spyder type intake.

with my 347 combo and 20+lbs of boost im probably going to end up running 72# injectors. (i have a pms, w/ low impendance driver) do you have any kind of engine management?

for the throttle body i would look into an ACCUFAB, they make some nice pieces with blowers in mind. i just picked up a 90mm for a fox body. (i have to convert my tb to the fox style to make the ys fit right) add a MONSTER (90mm+) mass air and your ready to go.

i would get a cam with more lift than .500, the afr 205's peak air flow numbers are around .600. i am going with the afm b451 cam, they dont disclose the exact lift until you get the cam but he told me that its a little over .600.

hope i didnt confuse you more...........good luck

[bigwhitecobra]

i wasn't sure that I would have enough piston to valvle clearance to go much higher than .525 or so, but hey if I can get a .600 or better without any flycutting of the pistons, so much the better.

I've heard lots of rants and raves about the Performer RPM, and I think that may be the one for me. Who knows?

As far as engine managment goes, I have a stock computer, which may be getting replaced with a Speed Brain. I have a 6:1 FMU, wich is on it's way out the door. Boost Retard, MSD-6AL. You know the usual stuff. I'm concidering using the FAST system and simplify under hood.

I know I still have alot of decisions to make, but I'm getting closer to a final draft. Does anyone have some dyno #'s on different intakes with blower applications? it would help out alot. Thanks anyway. Later.

[tarmon8r]

i dont think you recognize that fact that you are biulding a big block, so you need big block airflow. I run a victor jr intake on my stroker 396, .040 over, and have plenty, i mean plenty of bottom end. and its carburated, no blower, and is ungodly. your combo has a whole set of rules now. with your 408.

I do have a couple thoughts for you to ponder?


what size headers are you going to run on your 408?
i have 1 3/4" on my n/a nitrous assisted.
what about you? blown 408 with how much boost?
and what do most blower build ups always rave about? have a good exhaust system, so you are now talking about 1 7/8" headers or bigger and how much do you think those are going to run?


kooks = about 600- 700 bucks, undipped

now, how about your transmission?
5 speed or automatic?
how much torque do you think a blown 408 is going to make?
way more than what a tremec is rated for. and your going to need to hell of an AOD or C-4 with appropriate converter ($1500 combo) if your lucky


not trying to be devil advocate, just speaking from experience, and hope to make you aware of some different perspectives.

but that blown 408 should put you well close to 700 horsepower i think, you should be well in the 9's with traction

[bigwhitecobra]

As far as Tranny's go, I'm going with a custom unit from either Jerico or Richmond. I know I want a manually shifted car, so that sorta limits it. Gear selection is still up in the air, but I think I want a 2.95 first, and a 0.8* fifth, and 0.63 sixth. Oh yeah, six gears to bang, baby!!

Of course that's going to run in the 5-6 grand range, but it's worth it. And by the time I rebuild a T-5 or even a TKO, I'll have 5-6 in it.

Exhaust. I have a friend of mine that makes headers, and he and I have talked about it and 1 7/8 " Long tubes are what we are leaning towards. I'll be going with a 3" Bassani X with out cats, and a MAC flow path cat back(love the sound).

I've had 3 quotes from engine builders that promiss 570hp and tq all motor. Now, add 14# of boost and that comes to high 800's, flywheel. subtract drivetrain loss and you have about 780-800. Not too shabby.

I'll keep you posted on things as they come about. Later.

[ChunkFunky]

A 9 second car is a serious race car... I cant imagine going standard on that... I dunno alot about 9 seconds cars... so maybe I'm wrong... but the faster you go the less room for error there is.. I would think an automatic would give you better times and more consistant times ... not to mention alot faster shifts...
-as

[sn95gt19]

an automatic setup for a 9sec car isnt going to be very driveable, i think he said that he wants to drive it on the street.

check out this video
:http://www.yerot.com/~aweil/andrewvsalp.WMV
this is a 348 with a ys trim w/only 15psi
im sure it would be faster with an auto......but whats the fun in that?

[ChunkFunky]

geez... i would hardly think a 9 second car would be drivable eitherway... forget first gear... might have to start it in third
-as

[sn95gt19]

driveable-------YES

reliable-------HELL NO

[bigwhitecobra]

Heh heh, drivable. Barely.

Yeah, reliable. Riiiight.