Bobby G

iTrader: (13)

I am thinking about selling my forged piston TMS shortblock and getting a 408. How is the reliability? Do you lose a lot of gas mileage?...Im going to drive it on the street......not a trailer queen.....How much HP and TQ more do you get? ATK has a pretty good sale right now....thinking about it....any input would be great....thank you

03Sssnake

iTrader: (20)

I would roughly expect a 10% increase in power, 40-50 HP and nice fat TQ increase. You shouldn't really lose an reliability, assuming its built with quality parts.

KCS

iTrader: (20)

If you reuse the same heads and cam, you really won't see any more peak power, but peak power will occur at a lower RPM and you would gain torque across the entire RPM range, so the car will still get faster.

Bobby G

iTrader: (13)

I was thinking some Ls3 heads and ls3 intake.....that should feed it

Tuskyz28

What heads you running now on the 370 ?

Bobby G

iTrader: (13)

Ai 226

Tuskyz28

Even with those heads it should run well on a 408 motor. I have seen ported 243 heads do well on 408 motors depending on who ports them. If I was you I'll use the heads you have now and invest in a custom cam from a guru.... tooley, pat g, Ed curtis, etc......

cuisinartvette

modded 408 mileage should be the last thing on your mind lol