5mall5nail5

This is a hypothetical build question.

So I am flirting with moving from BMW stuff in my car to an LS3-based motor. Looking at around 427. I currently have a singly 76 T4 so I'd be picking up a second for twin 76's on ~427. Is there enough cylinder wall for reliable boost with a 6 bolt head? I want to stay aluminum block for weight. I have a pretty exotic BMW engine setup (2, actually) that I could part out or sell to fund this setup quite easily.

Without getting too crazy, what rods, what crank, and what pistons would you run (I am partial to Wiseco myself). What liners/sleeves? And, after all of this I'd like to run a moderate spraying of nitrous - maybe 250 - 300. No target horsepower but I like having a powerful street car (mine is currently 700 RWHP on pump gas in my BMW on 2.8L). What is a typical "low compression" ratio for an LS3 with moderate boost. Our motors are 10.5:1 stock so going to 8.5:1 is typical. How do the LS3s go?

Thanks all

Tainted

iTrader: (9)

id watch going over a 4" stroke, people have had side skirt wear with the long strokes.

5mall5nail5

Yeah I picture sticking around 4.125" bore and 4.0" stroke.

Whats the cylinder wall thickness like at 4.125" bore?

Tainted

iTrader: (9)

ive got no idea. It varies block to block, its best to have it sonic checked before you go boring it out. also I dont think youre gonna get near a 4.125 bore without sleeving it

5mall5nail5

Sleeving is fine. I am currently running a 2.8L BMW motor out at 700 whp on pump fuel so I know all about the associated complexity and such, just newer to the LSx format. I like the LS3 but if I am going to make it worth my while I want to be over 400ci with 6 bolt heads and enough meat between cylinders to not push gaskets out.

Tainted

iTrader: (9)

then a sleeved block is the way to go.

also, you could have the ls3 block bored out some, maybe to 4.080? maybe more?

Anyways, an ls3 with 4" stroke is a 416. plus they have the benefit of the longer skirt

turbotuner20v

If you're looking for parts, I'm selling a rotating assembly that would make the LS3 416ci. (4" callies crank, callies H beam rods, 4.070 wiseco pistons spec'd for boost)

KCS

iTrader: (20)

I'd stay with a smaller bore, say 4.070", and maximum of 4" stroke crank. Boost and nitrous can wreck havoc on headgaskets so I'd want to keep some meat between the cylinders.

5mall5nail5

I am in flirting stage but shoot me a PM with your asking price

lemons12

iTrader: (71)

I would hope a 4XX CI motor with a turbo/twins and a 200-300 shot would easily put down over 9XXRwhp. That is a low guess.

A 416 with a 300 hit should put down over 800Rwhp.

How much are you actually looking for? Any specific goal? It gets to a point where for a street car there is "too much" power.

87silverbullet

iTrader: (11)

So wait, let me get this straight. You want to run boost and then hit a 250~300 shot on top of it? Why not just turn up the boost? You are asking for trouble trying to put all that together and tuning it. Just turn up the boost and add meth or put racefuel in or if it is available run E85.

Also, To get a better piston in the bore I would use a little shorter stroke crank something like a 3.825 or 3.900.

If you are going to sleeve it and get the 6 bolt done to the stock block I am assuming you are going to let ERL do it. After that I would send it to AES racing and let them do their 410 cu in setup on it. You will have a 2000hp capable shortblock and be able to run whichever head you want. At 410 cubes you wont miss the difference of it being 416 or 427 and it will be more reliable with the 410 setup.