Go with the 408.. As for the 100lbs in the front. I sure as heck don't see any issues from it. Suspension is fine tires are fine I don't know the down falls if you were to go to the track..

 

370 iron would be my preference

 

why would you want a 370, other then it would allow the reuse of the stock crank with the iron block, to save $ I assume....?

 

Ya that could save a little over a grand. But in my opinion, if you are going to spend 3 grand for a new shortblock, why not spend another grand and get a bigger (better) one?

 

Well to answer both of you guys its like this.

As far as money that extra 1k for the 408 is more like 4500 for a 402. My car is a street machine that likes the track. Being so I need to keep the weight off the front end for handling purposes. So the iron block became a moot point to me wich leaves out the 370 and the 408.

I was gonna go with the 370 due the increased cubic inches and cost effectiveness of it but ruled it out for the weight reasons. Yes its only 300 lbs more and if I was going in a straight line all the time that wouldnt matter so much.
But I push in corners now so I'm not gonna add weight to the problem.

I have a 99 ls1. So I dont have a core for a 402 which make it more expensive to do than a 408. 3k on the sb is just the tip of the iceberg when I looked at the big picture. My bottom end is breaking up somehow so I'm gonna need new parts to complete the short block. Plus I think a cam change might be in order with the new motor being completely forged w/arp's everywhere. I like my current combo a lot and dont want to lose any torque down low but the g5x3 is intriguing me

I ordered a 347 from LME. LME feels very confident that 7100 rpms and a 300 shot would be no trouble at all.

 

I agree with the 7100 part.. but 300 is alot of spray.. if it's set up right and the tune is safe it will probably be o.k., but the shortblock is only part of the problem.. lifting the heads is gonna probably happen first unless you are going with 1/2 inch head studs and all that... which I would doubt.

I agree with the alum route, as the weight is a big factor, made the decision for me as well, nmoreso because I didn't want to have to try to push the extra 70 lbs, my goals are possible, but not easily reached, and 70 lbs less weight was a good way to help the cause.

 

Neither i would go with the ls2 402

 

The ARP head studs should help. Most likely it wont see a 300 shot, my current system is limited to 250. I'd like AFR's or the likes but you know how that is. Money changes everything.

 

always does... damn $ LOL.

 

buy a used iron block, save the money a bit and get the k member to get the weight back. I wouldn't buy a used aluminum block as they tend to move around a bit. I just picked up a iron block for 100 bucks with the crank and lq9 heads. not bad in my book.

 

300 lb k member difference? I thought the difference between aluminum and iron was 300 not 90?

 

the iron block is about 70 lbs heavier then the alum. the k member will drop 1/2 of that back off, and if you do the a arms too, then that's another 12, but it's unsprung weight.

 

 

Well if I had the money I would have gone 402. Instead I went LME 347.

 

lol

 

408 Iron and TT the beast.

 

What is the weight differece between the aluminum and cast iron block? Someone said 70lbs. I was thinking 100lbs. myself. The 383 may have enough hp to make it the better choice due to weight savings vs. horsepower.

 

I think it is 70lbs. I don't get it though. Everyone keeps talking about iron blocks as if they are the only ones that will hold HP but people have taken the aluminum blocks way up in power without issues. With the 6Liter LS2 blocks, WHY would anyone use the iron 6Liter blocks anymore?

 

You can get a larger bore initially, with an iron block. LS1's and LS6's require sleeves after 6.6L I believe. I think .030" over on a 6.0L iron block is 402 anyway, but you can take more material, how much I'm not positive. The 415 will be a torque monster anyway. Does it offset the weight of the block? I imagine over 600 crank hp it will fly anyhow. 4 bolt main is key here anyway.

 

Between the two you have listed, I would to with a 408 iron-block hands-down. The cost difference is minimal, and the power difference can be significant. The 402 cid LS2's are a nice choice as well, but they'll be more expensive. Our 408 cid short-blocks start at $3,599 vs. the 402 cid LS2 short-blocks at $4,199. The iron-blocks won't have near the distortion in the cylinder walls under high pressures that the aluminum blocks do, but the aluminum blocks will take quite a bit. We've made right at 1,000 RWHP with our 404 cid LS2 stroker in our '05 twin turbo Corvette.

Feel free to give us a call or e-mail me at trevor@texas-speed.com if you'd like a quote on a short-block. We have quite a few 408 cid short-blocks in stock and ready to ship!

Trevor
Texas Speed & Performance