i have started saving up for a motor rebuild... i keep hearing about a 408ci iron block er sumthin... is this an ls2 block? if so wouldnt this entail pretty much a full blown engine swap? motor mount conversion, electrical conversion/ and pcm modification??? i want to have a good strong motor, and am wanting to spend 5000.00 or less... would i be better off machining my ls1 block, and rebuilding it w/ high perf. parts?

maybe some links to engine tech articles, n stuff will help... im a total newb to gm, and feel like an outcast, lol... i know alot about modular ford engines, because i had a built up mustang before i had my new baby...

i tried doing searches for articles/past threads, but really dont even know what to search for....

i understand if you have a need to flame me for this thread...

trey

 

is a genIII 408ci iron block from a truck? or a gto er sumthing? if it is will it bolt into place where my ls1 was?
im wondering b/c i think a 408 iron block would be more reliable, and make better power? am i correct in this thinking?

 

i see that HPE has a 408 short block for 4000.00... would this motor work with the topend from my ls1? what about pcm compatability?

trey

 

All the motors you see us talk about around here will bolt in place of your existing motor. The 408 iron block uses a block from the GM 6.0 truck. It's bored .030" over and a 4" stroker crank is used to get the 408 cubes. Most people that go with iron have heavy power adders because the iron is stronger than aluminum. Another great deal these days is the LS2 402. This uses the new 6.0 block from the GTo and vettes and utilizes a 4" stroker crank. Now you get the cubes and keep the weight off. All LS1 topends will bolt to these motors, but they'll be deffeating the purpose if they aren't ported. Watch the group purchase section for better pricing. I've seen aluminum 402's go for $3200 before. Then you'd have some cash left over for a good cam and some decent heads and intake. After it's installed, you will need to have your PCM tuned. HPE and MTI are 2 in your area that can tune. You'll have to keep in mind that the clutch and rear probablly won't last real long after the install, so be ready to upgrade that next.

 

i am not real interested in any heavy power adders... im interested in a very strong all motor car that will be daily driven, and taken to the track every blue moon. maybe slap on a 100-150 shot nitrous... i figured a 408 would make good power, and be reliable/long lasting...
i will see if i can pull up some reading on h/c for both these motors... maybe p/p ls6 heads, and ls6 intake manifold?

 

For a N/A, minor power adder, I'd get the aluminum 402. No need for the 80+ lbs. the iron adds if your not gunna need it. Reliability will be the same with either no more than your doing. As for H/C, intake, telling the engine builder your wants and driveability concerns will be best on the cam. They can choose one for you. Ported LS-6's or a set of AFR 225's would be a excellent choice. LS-6 intake will be a minimum. A FAST 90mm set-up would be best.

 

how much $$$ difference is there b/w the 408 and 402? maybe i should be looking into just rebuilding my ls1? or stroking it? i want to stay under 5000.00

 

If you search the forums and type in "402", "408" or stroker you will get more threads than you can read in 2 nights. For less than $5000 I would build up the LS1. Slap on a big cam (TRex, MS4, G5X4), high flowing heads (AFR 225s, ETP 215s, Dart 205/225, etc) and a good intake (90/90) with full bolt ons and the right suspension/gearing/weight and you'll be in the 10s NA. A 408/402 will cost much more than $5000 to build. $3500 for the block, $2300 for the heads, $1000 for cam, and another $1000 for intake.

I hope you don't expect your rearend or transmission to last more than a week or so either. Doesn't it suck being addicted to speed? Much more expensive than drugs...

 

difference between the iron 408 setup and the alum 402 is about 500 bucks, and 100 lbs of weight.

 

i dont think ima be able to dish out the money for a 402 or a 408.... ima have to stick with my ls1 motor....

thanks for yalls help though

 

was thinking about using a stock stroke crank iron 6.0 block and boring the **** outta it... maybe pickup a used 6.0 block from somewhere, and having a machine shop build it for me....

 

You can't really bore the **** out of a 6.0 block. Anything over .040" over has to be sonic tested. .060" is really the max you can get out of one with a good clean block.

 

i can get around 370 cubes on stock crank?

 

Yea, that's normal. You can get 13 more with a 4" stroke in a LS1 block though. Just depends on what you want to do.

 

i would like to do a 383, but i keep thinking that a iron block is gonna be much more reliable, and more powerful. i want something that i can dog on constantly on the street, and have it last... just seems like an iron motor would last longer?
about the stock stroke crank. i figured a less of a stroke would mean less piston travel, in return a more reliable motor?
was wondering if the truck iron block has the same crank as the ls1? so i would be able to reuse my crank? maybe get it checked & m.fluxed, maybe polish kit?

 

yes you can reuse your ls1 crank in the iron block... but the iron block will not make any more power, and as for the strenth/reliability.... unless you are trying to push it really hard, you probably don't need the iron block for reliability. I'd say somewhere around the 1200 hp pl;us range is where the iron block would probably become a good idea.

I knwo for a fact that the motor's in 2 of the fastest nitrous cars in the country last year were running regular/standard ls1/6 blocks with no girdles or anythign goofy and had no issues with block strenth... both cars were spraying the cars hard, and had no block related issues at all. One of the cars ran a best of 9.40 on a single stage 300 shot and was a 346 CI setup, the other ran 8.95 on a 2 stage setup and was a 383 setup. Unless you have goals beyond that, wether it involve boost, nitrous or a massive solid roller high compression n/a setup, I wouldn't worry about block strenth with the alum block.

Some will not agree, and will have valid points about the iron block being more stable etc.ec wiich are true, but in order for these things to really be a factor, I think you have to be pushing the envelope pretty hard, harder tehn most will or are willing to.

 

im not really set on anything, im just using yall to help me make up my mind in which direction to go. i just think overall, an iron block would be all around better? seeing as i can get more displacent on a stock crank. im still not hell bent on keeping the stock crank, just makes more since that a stocker would make the motor all around more reliable?
let me start a new subject...
what engine combo would be a better driver on the street, or does it only come into effect when you have a fata$$ cam and massive ported heads? like i said before i want a motor that will be very street capable. would i have problems with a stroked ls1? or say a large displacement iron block? it will be running all O.E. equipment like a/c and power steering.

keep teh info coming, u guys are the ****!

trey

 

I can't keep either in stock but the irons are more popular here in Houston as they are big and have no issues besides weighing more. no one seems to have actually weighed the two blocks so far but from shiping them I do not see any 100 pounds. A lot of the LS2s I have seen have had noticeable core shift in the cylinders and do not hone as nice as the iron blocks do at all. I think these are the surplus blocks most of the shortblocks I have seen are made from on these LS2 deals.

Good sleeved aluminum blocks are alright but bad ones aren't. At one point we had done most of the 9 second and faster NA cars at SAM and more than a few of the guys on this website picked up power and went faster after going to the iron block from some of these earlier aluminum deals. One guy on here had some pretty big blowby on big stroker sleeved engine and after changing to iron picked up over 20 hp and had no real sealing issues after that. he also dropped into eth 9s NA after that as well. We could have ran an extra header tube off the breathers on that one and after the iron block conversion it barely had a wisp of blowby coming out those breathers.

I see a lot of guys posting on how aluminum is just as good but it isn't even close. NO ONE runs aluminum blocks to make more power because invariably they lose power especially the higher in total power you go in every form of racing. Again in street form it probably doesn't matter but the iron is still more reliable for sure. Is it worth the increased weight though? That is up to you. The aluminum blocks are certainly lighter and the cylinder integrity of the aftermarket sleeved aluminum blocks is very good like the Darton stuff etc. but the production blocks like the regular LS1 and LS2 are just not that good from personal experience.

 

preciate it... and i was actually gonna get with yall and get some $$$ figures.

trey

 

i have spent 2,000 rotating assem,1,000 ported heads,900 into the iron block,and 275 on a cam,+all the little **** like tune 650, injectors 250,thypoon intake soon 475,tb ?,moser axels 235,and im forgetting something? thats rite about 5 g's there.... a 347 would what i would do in your situation