LT4 crank with good rods pistons.. safe FI HP level?

I have a spare LT4 crank laying around.. some Eagle H beam rods, and some TRW/Speed Pro blower pistons.. i was planning on putting a short block together for a blower motor.. D1 or possibly maybe a T-trim.. any ideas what this 355 assembly would be good for safely with a great tune? any input. preferably looking for people who have used the stock crank or a stock LT4 crank and pushed it to the envelope and how long it lived! thanks all!

Chris

I can't directly answer your question, but over the years i've gathered that the LT1 crank can last in the 5-600rwhp range (i can't remember the guys who did it, but it's been done a few times). Never seen or heard any kind of "tests" on the LT4 cranks.

I have a spare LT4 crank laying around.. some Eagle H beam rods, and some TRW/Speed Pro blower pistons.. i was planning on putting a short block together for a blower motor.. D1 or possibly maybe a T-trim.. any ideas what this 355 assembly would be good for safely with a great tune? any input. preferably looking for people who have used the stock crank or a stock LT4 crank and pushed it to the envelope and how long it lived! thanks all!

Chris

As mentioned, there have been some guys pushing the stock crank pretty good 550-600rwhp. If you want more than that I'd probably step up to a forged crank. I'm currently looking for a stock cast crank for my budget short block. If you're interested in getting rid of that LT4 crank, pm me.... As far as I know, the only benefit the LT4 crank has over the LT1 is that is has larger fillets around the journals, but then, so do the Eagle and Scat cast cranks.

Mike

what pistons and rods are you using.. this crank has already been balanced to the Eagle H-beams and the TRW/Speed Pro slugs which was a hefty pair to balance and took some mallory to nail down. if you are using the same pistons/rods it might work fine for you with a light balance but if you are using lighter weight components.. you may fare better by going with a crank that has not had mallory added. the journals are stock clean never spun a bearing and were perfect with them polished and standard bearings. It is a nodular Iron LT4 crank from a 96 corvette 6 speed.. crank has about 62,000 miles on it but tested perfect so I decided to use it.. now the cars power goals have been raised and I am re-evaluating the internals for it. let me know about your rods and pistons.. If they are the same I will let her go for $100 plus shipping.

thanks,
Chris

I have the stock crank and rods with arp bolts and main studs(2bolt). The rods were cleaned up and I am using SRP blower pistons, I think the SRP's are alot lighter than the trw's and that may help. I spun it up to 6200 on the dyno and thats all I can really stand. It peaks at 6000 anyways.

I think I was putting down about 315 at the wheels with this blower motor in NA form and I spun it to 6800.

what pistons and rods are you using.. this crank has already been balanced to the Eagle H-beams and the TRW/Speed Pro slugs which was a hefty pair to balance and took some mallory to nail down. if you are using the same pistons/rods it might work fine for you with a light balance but if you are using lighter weight components.. you may fare better by going with a crank that has not had mallory added. the journals are stock clean never spun a bearing and were perfect with them polished and standard bearings. It is a nodular Iron LT4 crank from a 96 corvette 6 speed.. crank has about 62,000 miles on it but tested perfect so I decided to use it.. now the cars power goals have been raised and I am re-evaluating the internals for it. let me know about your rods and pistons.. If they are the same I will let her go for $100 plus shipping.

thanks,
Chris

Chris,

I'm using Eagle 6" H-beams with JE -22cc blower pistons. If you had 5.7" rods with the heavier TRW pistons, it might be a good match. My rods would be a tad heavier than a 5.7", but my pistons are probably lighter. Do you happen to know your total bob weight they used for your balance? So the crank is polished and ready to go, other than balancing?

Can you email me a pic or two of the crank? This would be a real good match for me since I'm not planning to go over 500rwhp with this setup.

bowtie97@comcast.net

Mike

yes the crank is polished.. I can snap some pictures of it.. but it is currently install in the new shortblock.. still bagged never been run.. I would have to dissassemble but thats not a problem.. could do that in a night if you want it.. If not I don't wanna dissassemble incase I decide to run it.. but I can swear to you it is polished and can snap some pics of the bottom of the short block and top so you can see that the pistons have never seen fuel or spark.. :D

I will try and scrounge up my old digital camera!

TTYS

Chris

i will try and find out about the bob weight as well..

chris

Sounds good. I'll look forward to seeing the pics.

Mike

I am in mid swing of painting the garage and setting up shop in my new house.. and painting has taken longer then I had thought..)first coat is taking forever to dry in the cold weather) but just as soon as I get finished I will get to the motor which is on a stand at the very back of the garage box pile. but never the less I will get the pics up soon!

Chris