Anybody heard of using the crank out of a 4.3 lt1 caprice to de-stroke the lt1? wondering how a forged bottom end w that crank would do with an le3 package

 

Why would you want to de-stroke it? You cannot turn over 7000 with stock computer...a 350 will spin past that no problem.

 

Interestingly enough.......putting the 4.3L LT1 crank into the 5.7L counterpart creates a total displacement of.............

302 cubic inches.

I think that is pretty cool considering the first Zapper's were 302's.

I've seen it done in a couple of magazines, they claimed around 350 horse with no other mods. I'm sceptical about that - but none the less.........it would be neat to do.

 

Just wondering if anybody has played around with this combo........Seems like with the right combination it could be a fun motor. Solid roller with some good heads might make a screamer.........

 

Add me to the short but growing list!!

 

Well, it's a cast crank for one thing. Doesn't make any sense to me.

Rich

 

Ditto on that Rich. People can say what they want about piston speed, but in every case that I've seen dyno or track tested, increased cid means more power and vice versa.

Mike

 

My car came with that 4.3L motor and after it madeway for an LT1 I gave the crank and rods to another b-body guy who did build a 302. Oddly enough the LONGER L99(4.3l) rods makeup the stroke difference and he used those with stock LT1 pistons. Runs fine and is down on power about the same amount it is down on displacement. As covered the stock 350 crank can handle all the revs the pcm can, this crank being cast aint going to handle the over 8K you would probably have to turn to make the ultra shortstoke worthwhile. Interesting idea and one that is NOT new and has been done. Not something particularly worthwhile though.

The guy who built one from some of my old parts is a MASTER of going fast for cheap and he did this project dirt cheap. paid me shipping costs on the crank and rods, paid to have the pistons pressed to the rods, then just gaskets and bearings. It runs and last I heard it was in the tow rig another Caprice he uses to tow the race Caprice to the track.

 

sweet , thanks for the info, It was just an idea and I wanted to throw it out there and see if anybody knew anything about it. I didnt say it was the holy grail of speed (with everybody getting all pissy) Just thought it sounded cool.

 

one of the chevy high performance magazines did this with the ls1. it rocked a total of 475 hp with no other mods...and a whopping 525 with ported heads. guess what happens when you increase the compression in a stock ls1...you get 475 hp...and guess what happens when you add ported heads. i'll give you a second to think about it...times up. you get 525 hp. the only problem with the de-stroked engine is the fact that the rpm/max hp has increased by about 2k rpm. so...instead of making max hp at about 5500 it's at 7500 with a max rpm of 9000.

i would think it's a waste of gas. why would you want to spin a 350 up to 12k when you could theoretically gear it and get the same times with a 350 that max'd at 7.5k but had more power???

the only think keeping you from spinning up to 9k now is the valve train. the rockers/springs arent capable of going that high. replace rockers with high quality rockers and get some good springs on there and you could reach 9k rpm on an otherwise stock motor...oh, you'll need to fix the opti problem too. you'll have to go with a new setup...delteq or ltcc. the opti is no good after about 6k rpm. the coil can't keep up.

 

Guess I've been riding high revving 600's too long....just sounded cool but thanks guys for all the input..... Wish I had a parts car to do it with anyway just to see how it would "drive"

 

It could be a fun combo, but with our cars being so heavy that is not really something youd want to do... Youd be lacking a lot of bottom end torque that you need to get the car rolling. Youd need short gears/high stall converter to get the car off the line. Then youd have to keep it up in the revs to keep it pulling. I personally think the fact that it would be a unique setup would make it a whole lot of fun but not as practical a lot of people want. I out run a lot of big block cars in my nova with a 355 but I shift it at 8400 the big block guys are shifting just shy of 6600... They are doing it with a lot less wear and tear on the motor, but they still cant believe they are getting waxed by a 355..