Mainly because the aluminum blocks are no where near as strong and don't make as much power. I just went through another aluminum 5.7 block today that has two cracked cylinders.

 

how are you pushing them hard enough to crack the cylinders??

 

It's not me it's you guys! Mostly it's on power adder cars. Detonation can break a lot of things and the aluminum blocks thin cylinders get broken quite a lot.

 

so dont detonate?

 

That does make things so much better if only it were that easy for out LS1tech brothers and sisters!

 

The thing I wonder is how many of the alum block failures are related to people running a decent power setup ( say 600rwhp ) and end up having a failure due to the tune being too close to the ragged edge fo they can get a # out of it, or it's due to a tune that is close, and they get a bad tank of gas or whatever.

 

Probably true JL. The aluminums though do move around more and break more than the irons for whatever reason but they are lighter as well. I think people are worried about the mains and stuff and I am more worried about the old stly aluminum blocks cylinders mainly. The LS2 is siameesed and somewhat stronger at least.

 

That's what I ended up doing, an LS2 402. I used the best block parts I could, L92 studs thruout the entire motor, etc.etc.. I think it's solid enough for my use.

At this point the only possible regret I have is not going to an edlebrock intake with an intakelbows.com elbow to put the TB in a stockish location.. probbaly gonna end up doing that next year in the hunt for more power, or at least try it. That, and probably have kook's fab one of those slick stainless true dual exhaust setups that I can easily drop the cats out of for the track, as I think that would be better then my QTp catted Y and LM setup I'm running now.. but that's all a different topic really.

 

i'm assuming this is because the cylinders don't "balloon" or distort as much as aluminum?i'm looking at getting a shortblock next year and am leaning towards an iron block 370,mainly for cost reasons.

 

Deuce,

Yes you're right. Some people do have good luck with the older aluminum blocks under more sane boost though and they last forever. If you are mean to them though they will break easier usually.

 

what's really the level for say an ls2 block where it becomes an issue? I see several people that are pushing them near that 1000 hp mark, and there's probably several more that are running them near 1000 flywheel.... with say a N/A setup, or a setup that will see somewhere between 100 to 250 of nitrous, is the block really a weak point? I keep all mu tunes on the very safe side of things keep in mind

 

i don't know what the HP limit would be,but i would think the majority of failures come from guys pushing the limits as far as tuning and constant abuse from racing.but the LS2 has siamesed cylinders,so those are definately stronger than older LS1 blocks.

 

JL,

I think the LS2 blocks are stronger and the cylinders are stiffer too. The only thing about them is if you do have some failure you may not be able to hone it out since the liners are still very thin but besides that I agree that they are much better than the older non siamesed blocks.

 

erik just built my new 408ci, I had kicked around the idea of a 383ci. With a 383 the best you can hope for is around 470rwhp which is crap. I would go with a 408ci, which I did.

Thomas

 

427 baby!

 

Hopefully it will never come to anything more then a rehone for new rings someday, until I start spraying it I'm not really too worried.. and even then I'm not too concerned... eastside built it, and they know how to put reliable nitrous setups together.. with the 200 or less worth I'll put to it I don't see me hurting it.. I don't see myself ever getting greedy enough to really push it hard enough. So far for a nitrous motor it's doing pretty well, 10.8 @ 123.9, at 3580 lbs.. and still spinnign quite a bit, rims in the tires, and the tires on the track. We think by putting a set of 28x10 et drags on the car and screwign them to the rim, 10.5 isn't out of reach with no more weight reduction then what it will take to get it back to where it was without the cage.

 

I'm running a 423 iron block with a 150hp shot to come

 

how did you get to 423 CI?

 

383 Stroker here, 465RWHP 430LBFT unlocked converter.

I was gona go 408 but i got a great deal on machine work and the kit so i had to take the offer. Plus i am very amazed at how much power shes making, still on the stock 2.73 rearend, but thats going to change to a 9" here in a few weeks.

 

So for somebody running a car with over 700rwhp (includes 2x150 stages of nitrous) would you say iron is the better choice? Right now I'm spraying 150 on the stock LS1 block. I've been waiting to add on the second stage until I figure out what block will be able to handle the abuse. At first I was leaning towards a 402, but this thread has me thinking 408 is the way to go. And would my AFR 205's still be good with either setup, or would 225's make more sense???