02sslayer

iTrader: (4)

hey all,

i am wondering how much boost you could throw at a forged 408. im talkin the right rods, crank, pistons etc...

thanks guys, i appreciate the help

evo462

iTrader: (27)

Is the question you're really asking, how much power can you make and not blow up your engine? I don't understand the preoccupation with a certain PSI number.

Atomic

iTrader: (37)

I throw 20 at my 402 every time I drive...been doing that for over a year.

lmt0705

iTrader: (7)

going to come down to what heads your running.

02sslayer

iTrader: (4)

that too, but im really asking how much a lq4 408 can handle as far as boost goes. id like to se 800-1000rwhp if i go this route
are u running an aluminum 402? i dident think the aluminum block could handle that much boost
thats another thing, i have no idea what heads i would be running. ive always been an NA guy so this world of boost is all new to me. i guess id throw on sme L92 or afr 225s?? i really dont know. do u have an idea what a good set of heads are for a motor like that?

I8UR4RD

iTrader: (16)

20-22 lbs

1100-1200whp

Atomic

iTrader: (37)

Nope, iron lq9 block. You want the best flowing heads possible with a turbo, just like NA.

Cam72aro

iTrader: (28)

It's the 4 bolt heads that are the limit. When cylinder pressure get to high they flex and start pushing water. At 800-1000 you shouldn't have any problems.

87silverbullet

iTrader: (11)

An aluminum block can handle 20-22 lbs Its not that much of an issue. You will lift the heads before the block gives you any problems. Mark Koehler of the Ohio Boys ran a stock LS2 block one year to 35 psi before the stock cylinder liner cracked and he ran 7.99 like that.

Stock L92's and AFR's are on different ends of the map as far as heads go.
L92's flow air but they have a thin deck and tend to lift when trying to throw alot of boost at them and when trying to get aggressive on the tune. AFR's flow a ton and have thick deck for boost but the price of them is double that of and L92. If you want a good flowing thick deck stock head it would have to be the LSA head. The aftermarket heads would be AFR, TFS, MAST, PRC, and All-Pro. The one thing about All-Pro, you are going to pay $$$$ but they are the only ones I know of with a 1 inch thick deck on some of their heads.

02sslayer

iTrader: (4)

thanks to everyone for all the info. i know alot more about boosting a motor thanks to you guys.

i wonder if i could have extra holes drilled in the block to accept the 6 bolt heads? do you guys think i could get away with 18-20 PSI on the LQ4/9 or on the aluminum block? id rather put boost to an aluminum block 402 instead of a 408 if i coud still reach my goals

I8UR4RD

iTrader: (16)

It would be best to grab an lsx block from the get go, then skip straight to 427 or 434 anyways. Thats what ill be doing next go around.

87silverbullet

iTrader: (11)

You can't just drill the holes. Material would have to added to the block to make it a 6 bolt setup. ERL does it to stock blocks all the time. I would do an aluminum ls2 block as a 385 setup from AES. It would get you a better piston in the bore and trust me, you won't miss the 17 cubes under boost.

02sslayer

iTrader: (4)

i am leaning more toward the lsx 427 with an F1 procharger. just thought id check inti the 408 to save some money on the build. if i dont go boost route ill probly build an LSX440 NA
thats some good info. im finnaly learning about boost lol. i would love to buuild on an ERL block but i do not wana spend that kinda cash. some people say the LSX block is no good but ive heard alot of good about it too. so im gonna go that route

87silverbullet

iTrader: (11)

Just want to give you an idea of price difference of the 6 bolt superdeck and an LSX block. You might find an LSX for around 2200 at the cheapest (that was awhile ago I looked at that so it might be more now)and an ERl superdeck is 3500.

The ERL block comes with ARP main studs and the LSX does not. That's a little over 300 bucks right there. The ERL block is hand honed on the deck surface and the LSX is not. Plus there will be alot more machining than just that on the LSX compared to the ERL. So, now the price gap is a little closer and one more thing, the LSX block is 140 lbs heavier than an ERL block. Reckless, a mod on here weighed all the GM blocks and the 6.0L truck blocks were 110 lbs heavier and the LSX was 140.

Atomic

iTrader: (37)

Did he make a thread about it? I couldnt find one, and that sounds like an interesting read.

BMF_Racing

iTrader: (6)

x2 I also would like to read.

87silverbullet

iTrader: (11)

He said he made it a sticky. Here ya go.

https://ls1tech.com/forums/generatio...ls-blocks.html

stevieturbo

Ultimate power is dictated by blower for the most part, not cubes.

IMO I'd prefer to keep nice thick bore walls for a more rigid block, and you simply dont need a 4" crank.

Plus with a shorter stroke, the piston doesnt drop out of the bore as much at BDC.

One of AES 3.825" cranks and an LS2 block would make plenty of power and be a strong affordable platform.

As for the 4 bolt argument. ARP make a much stronger head stud in standard M11 size. or you could go for 1/2" studs.
Both easier and cheaper than 6 bolts, and will be a good improvement over normal ARP studs

That's assuming you might have an issue with them in the first place. Many push very hard with regular ARP stuff and have very few problems.