sp57supra

Me and one of my friends was talking about a little project useing a l99 from a 94-96 caprice. The idea is to get a l99 and put lt1 or lt4 heads and intake (if thats possible). If lt1, port and polish heads and beef up valve train, if lt4 heads, just stick them on.
we would re cam the engine with good lift and very little over lap. Low copression forged pistons (8.5:1) and mid size turbo, dual ball bearing 67mm. With the low compression the reverse flow heads might even aid in dealing with knock from big boost and heat generated from it. We are thinking a red line of 6500-7000rpm would be nice with the 4.3liter spooling the 67 up pretty quick.

what are some of your thoughts on a set up like this, have any done it? I know a lot of you are all about bigger displacement but im sure some could see the apeal of this idea. Small v8 with good rev range and a modern gt turbo to give it big block bite.

This si just an idea but would like to hear opinions

1997bird

iTrader: (2)

I would use the smaller LT1 castings on the smaller motor. Once you hit boost it will force air through the smaller int runner whether it likes it or not. But until the turbo spools up you will want some port velocity to get things going quicker. You can also pick the LT1 stuff up all day long for cheap.

sp57supra

yes you are right, this would be a forced induction engine so to a point before boost, velocity over volume. the lt1 heads would need a valve train beef up to hit 6500rpm regularly though right?

A-man930

iTrader: (2)

subscribing... cool idea!

slick1851

Sounds like a cool setup

LT1MAN

iTrader: (6)

i think you should use a short stroke and make it a high winding little nitrous eater. a v8 turning 8,000 rpms sounds disgustingly wonderful.

1997bird

iTrader: (2)

In my 97' Bird I used to spin my motor to 6600 rpms all the time without any problems. The only thing that I had modified on my stock internals was to put a set of Comp roller tip 1.6 RR's on it.

SincalT/A

iTrader: (16)

keep rpm's low and work on more boost remember you are dealing with cast crank.this really all depends on your goals but the info is out there.i think it would be a great idea!look at some of kenny duttweilers motors do a search on (buick v6 in hotrod magazine).i know it not the same engine but is the same concept!

sp57supra

didnt know l99-lt1s-lt4s, had cast cranks, im used to dealing with a strong forged crank in my supra's 7m engine. Whats the reliable power limit of these cast cranks?

Took a look at some compressor maps for a garrett 67mm turbo. The 4.3 liter with this turbo should flow enough air for 560hp at 6500rpms and 15psi. This is of course just generous ball park figures not taking into account loss from heat, pressure drop and so on.

I see 2jz supras making around high 500s to low 600rwhp with 67mm turbos. 450-500whp would be cool for the 4.3 engine with better spool up than the little 3 liter im used to

A-man930

iTrader: (2)

The crank will hold enough if you prep everything well enough... Look into cryo treatments (97% increase in strength). Someone mentioned Buick V6s, there are guys running the lowly stock cast iron crank making plenty of power, without touching the bottom end...
Also remember, forgings are heavier than castings, so theoreticly you could spin this little sucker pretty high with a well-balanced lightweight assembly... then again, you are doing FI... Idk, just thinking out loud.

SincalT/A

iTrader: (16)

dont let me scare you with the cast crank deal.a well balanced rotating assemby will easily handle the power you are shooting for.keep it out of detination and you will be suprised what cast can handle. keep rpms low boost up this is a whole diffrent animal then the 2jze.