Jadedbird

iTrader: (27)

if i plan on building a bullet proof 408 for boost... would it be better to buy just the block? or pull a complete engine from the junkyard? i dont plan on even using the crank..

wouldnt it be best to buy just the block?

also i am trying to figure out the best heads.. ive always hear 317s but some say they are sluggish until the turbo kicks in...

also what year is the best if i do buy a complete engine (or does it matter?)

96capricemgr

iTrader: (1)

If you want to boost it why are you so hung up on adding displacement?

I would port heads before worrying about buying a crank.

What are you putting it in?

Tainted

iTrader: (9)

Iron block 6.0 found in large trucks and suv's. 317 heads are more desireable because they have a larger chamber.

78buturbo

iTrader: (1)

If you need all the covers and the small things I say junk yard motor ( maybe with spun bearing) to save some $ good luck.

Jadedbird

iTrader: (27)

i know 6.0s are found in gm trucks/vans/suvs.
im not hung up on anything just looking through the threads ive been seeing big power thru the 402 and 408s. but i was going to port the heads. valves, springs, lifters, arp, etc.

ive seen some run 243s because they say the 317s are sluggish

but i plan on either a f1 or 76+ turbo..
id like to runs 9s in a 3800lbs trans am

96capricemgr

iTrader: (1)

NA maybe the 317s could be "sluggish' compared to 243s due to the lower compression.
That really isn't an issue for you since you will be buying pistons which you can use to dial in compression and with the added stroke hell it will be harder to keep compression down as you need to for boost. Not saying you need it very low but it does need to be lower than an NA motor.

Jadedbird

iTrader: (27)

Compression needs to be around 10:1 right?

lemons12

iTrader: (71)

I hope you don't use a stock crank in a 408, that would be odd.

Bullet proof=thick deck heads.... The lower the compression the longer it is going to last. I wouldn't recommend 10:1.

You can run 9s with a 347 just fine with a nice setup. You will also save some weight (115# roughly) with aluminum VS iron.

Sounds like you need to do a LOT more reading to me.

96capricemgr

iTrader: (1)

The importance of aftermarket heads with thick deck is grossly overstated. Look at what guys do with stock longblock engines and boost. Sure it is beneficial at very high power levels, it is just pushed as some vast benefit LONG before it is actually any sort of issue.

Jadedbird

iTrader: (27)

Ive done alot of reading. But just like everything else everyone has their opinions.. Their expierences.. Etc.
i know what the ls1 is capable of. And i know people are pushing 600hp/tq thru a stock ls1..
But an irom block is much tougher and displacement is never a bad thing.. As for weight. The lq4 adds 90lbs.. If the weight was that important, i could (and will eventually) buy the chomoly k member, a arms, relocate the battery and do some trimming to get the weight down to stock.
A guy i cruise with ran 10lbs thru a stock ls1 for months before it went boom. Hes been pushing 17 thru a stock lq4 and the heads still arent lifting i forget how much more power he is makig.. But it makes up for the weight difference.
what compression should i be aiming for?

Tainted

iTrader: (9)

The answer to your compression depends on how much boost you plan on adding.

Jadedbird

iTrader: (27)

20lbs give or take