bigftruck

So i spun #1 rod bearing on the dyno with my stock bottom end ls1. Perfect opportunity to go bigger/better so this week i take delivery of my new 408! New build will be
lq9
wiseco -10cc dish pistons rings gapped for a 200 shot( will be 11.1-1 comp)
compstar rods and crank
Stage 2.5 prc 5.3 heads unmilled
ms3 on 113lsa
42#lucas injectors
walbro in tank upgrade
fast ported 92/95 combo
1-7/8 Lt's with true duals dumped
ls7 lifters / chromoly 7.4 pushrods

My question is how bad will my heads choke down flow on the bigger cubes? I am just swapping all the brand new parts from my 347 to the new 408. Any thoughts or experience with a similar setup is greatly appreciated. Any ideas what power this combo is capable of?
__________________

sroach20

iTrader: (31)

how high are you planning on taking the rpms?

bigftruck

i plan on taking it to 6500 or so

sroach20

iTrader: (31)

you should be fine with them. they have good numbers and you will have some tight compression that will love the gas.

JakeFusion

iTrader: (7)

They're at least 220cc volume heads, so they will be okay to feed the engine (plus they flow pretty good). If you can have them opened up for a 4.00" bore, it would help, but you'll be okay.

odarabla

iTrader: (1)

You'll be fine but I wouldn't keep that cam. You will be leaving power on the table with that cam.. I am building a 408 as we speak and I am going to use the Trick Flow 215cnc heads I have now.. I am getting someone to custom spec/cut me a cam shaft to use these heads with that motor. I am also switching from a ported fast 90mm to a ported Victor jr. with the elbow to make sure I can pull the air needed into the motor to make power.. I should be able to spin the motor and still make power to around 7000rpm (give or take a few hundred rpm) and the power under the curve is going to be insane from what I can tell..
Good luck with the build!!

jegten

iTrader: (22)

OP-good luck with the build.

bold faced-could you please elaborate on this? thanks!

odarabla

iTrader: (1)

By opening the port size it should help the heads flow better but to make this work you should also do a valve job and increase the size of the valves.

DVS99TRANS

iTrader: (7)

Hey fella, I have the EXACT SAME COMBO AS YOU Except that my MS3 is a 114LSA. Torque down low is going to be amazing with this setup I think, especially with the PRC heads.

So much for being original for me I guess Anyways, the heads will do fine and there are quite a few that have broken 500whp with these heads on 402/408s. You can always upgrade later, that is what I am doing. Skimp out on the heads for now and save up for a set of 255cc ET heads My 408 is going in next weekend finally.

bigftruck

thanks for the replies everyone and the advice. I am running low on funds for the build, so the heads and cam will have to do for now. I might be leaving some on the table but a nitro daves 200 plate kit should take care of that

on a side note: what would be a good stall for this combo as i am doin a th350 swap at the same time. I was thinking an ss4000?

Jason 98 TA

iTrader: (4)

We've seen 500rwhp 408s with those cylinder heads so I think you'll be fine. Ideally one day you can sell those things & upgrade to something like the PRC 237cc head. They recently made over 30rwhp more than a leading aftermarket casting cnc 225cc head on back to back engine dyno testing!!