ProVK

Looking around at options to build a new engine for my race/street car. It will be fitted probably with a pair of 6765 or 6565 Precision turbos with the aim to make 1200-1300hp at the flywheel. Possibly in the future it may see some class maximum 70mm turbos. I'm also hoping to be able to keep the max revs below 7000 and hyd roller cam. I will also be using C16 or E85 when racing and when trying to make the 1200-1300hp. I'm happy to dial the power done below 800hp for the street on pump fuel. I will also run aftermarket rectangle port heads.

I'm tossing up between the following short motor combos.

LS2/LQ9 block with 3.8" crank giving around 390ci - not sure if aluminum ls2 block will handle power or if 4 bolt blocks will give reliable head gasket sealing.

ERL 6 bolt block with 4.125 bore and 3.8 stroke.

LSX block with either 4" Bore and 3.8 or 4.0 stroke or 4.125 Bore and 3.8 stroke.

I think I need to stay away from too many cubes as the smallish turbos may create too much back pressure?

TracyRR

iTrader: (8)

The AES LSX 390 looks like a killer piece!! That would be my vote if you spend a descent amount of time on street tires.

10sec_rx7

just get a iron block and put a 4in crank and a 4in bore, nice 402ci will do everything you want and last forever,

1300hp on c16 was a walk in the park for my old car.. it ran 160+ at 3600lb all day long!

ProVK

If I was to go LSX block what would work best?

4.030 bore * 4.000 stroke
Or
4.125 bore * 3.800 stroke?

10sec_rx7

stick with a 4in crank.. they are cheap and easy to get in AU,

for the price of a complete rotating assembly with 4.030 pistons that is what i would be using..

ill have my car back out again early next month, if the oil system works i reckon 180mph on 25psi wont be a problem..

mdbreaux

LSX iron 6 bolt block, 4" stroke, 4" bore. The 402 is a bad *** engine. I had one with turbos and it is about as much as you can handle on the street, and barely.

chuntington101

Is have a polite word with some like AES, VA Speed or 427 on here. They will be able to best advise you on what you 'could' be using for you combo.

Chris.

AES Racing

iTrader: (6)

Only issue with 4.000"+ stroke, crank starts to flex with high hp.

3.800"/3.825" crank have more journal overlap. Adds strength.

Pistons with 1.200" compression height able to put the top ring down .300, 2nd ring down .250". Short compression height kinda smashes everything together.

Other advantage, 3.800" crank/6.125 rod/1.200" CH, the piston skirt barely clears the bottom of the sleeve with a standard 5.5" bore length. Pistons will last longer this way. 4.000"/4.125" pulls the piston out the bottom of the bore, will wear the skirt over time.