Generation III Internal Engine - working out a long term plan for an LS1

Getting on up there in miles and with all these go boom threads lately I'm getting nervous, that and I'm getting tired of the stock piston slap lol. My goals are basically a 400-500 RWHP (I would love 600, but don't think it fits into my other goals) engine that has very good street manners, and attains decent gas mileage (nothing crazy obviously). So I'm thinking of more cubes to offset any driveability issues with some larger cams, I know it can be done on stock cubes and maintain great DD abilities, so going larger has to make it even easier right? What are my CI options with the stock crank, and can it handle that power RELIABLY for a long time? or do I need to be looking at other cranks and going on to stroking it too? Oh yes.. usage.. street and strip car mainly. it's a weekend driver but its the DD if anything happens to my wife's car (thus the need for street manners). Help me narrow down my options fellas! budget - I want to keep the build under 10 for sure.. but estimate a 7500 build leaving me room for headache avoidance

Just get a rebuild w/ a forged bottom end and put a procharger on.

In your case, I'd say shop around for a great deal on an lq4/9, since you can get them very cheap and rebuild that.....I guess the next steps would depend on how much you honestly want to spend.

Just remember to include in your budget an extra $300+- for all your gaskets and the price of a tune, and if you are running an automatic a higher stall and tranny cooler.

I'd also recomend put as much money into the bottom end as possible, then build from there, even if it means throwing your stock heads and intake back on a fully forged stroker till you can afford to upgrade to a better top end......id rather know I have a rock solid bottom end that can take anything I could thirsting at it later down the road

I've been debating grabbing a junkyard LQ4/9 up for a long time.. they're a dime a dozen around here with all of the HD trucks around lol. But I think I really want to keep the weight down on the nose. FI is out if only from a pricing standpoint. I want to keep the build under 10 for sure.. but estimate a 7500 build leaving me room for headache avoidance lol. Looking at texas speeds options I found a rotating assembly and top end I liked really well. and assuming I take care of the tear-down build process myself it falls right in line. IIRC it was a 383 rotating assembly. Price wise for the rotating assembly it wasn't a lot more to move on up to a 408.. what does that entail for my block though? or is it even better to get a pre-assembled short-block and go from there?

I certainly wouldn't mind having an LS1 sitting around in case I find the project car I've been looking for (early 70's bird) sometime after I finish up the formula

And she is staying an M6 after this also, so no worries about stall and killing the trans.. the rear-end.. well that's another matter LOL

If the nose weight is what is stopping you from buying an iron block it is only an 87 lb difference, which can be made null if you swap in a tubular k member and relocate your battery to the back :)

Rebuild your block with forged rods and pistons, send your stock heads to AI for porting. Add a Supercharger and voila, 600 horses can be summoned. Keep compression around 9.5 or so.

everybody has deep pockets don't they? LOL. forged rotating assembly ~ 2500 3500, procharger ~5K? AI headwork ~ 1K for CNC ... ok well that doesn't sound too bad, but it feels like I'm missing something there somewhere, and that procharger price is probably way off, as its not something I've looked into.


87lbs difference from aluminum to iron block doesn't sound too bad, but again to drop the weight back down you're losing the budget portion and probably diminishing returns at that point, and the nose is already hefty enough :P. Same deal with SC options... about 50lbs more there too. If you can't tell I'm partial to NA LOL. I'm not against a S/Ced 383 though, as that will leave me room if I decide it's not working out later to change the cam and drop the FI, but again the pricing throws FI out, especially after machining etc for a 383.... now a stock built LQ4.. how much boost can they handle? a SC 6.0 putting out 500-600RWHP and being mild mannered on the street sounds tempting... but again.. $?

predator, that power level in your sig is something I would be happy with... numbers like that are what make me debate doing a forged 347 assembly with killer heads (215AFR's) and a mild cam for now... That would leave me room to grow into FI later if I ever decide it fits into my plans

predator, that power level in your sig is something I would be happy with... numbers like that are what make me debate doing a forged 347 assembly with killer heads (215AFR's) and a mild cam for now... That would leave me room to grow into FI later if I ever decide it fits into my plans

That power level does not come cheap normally aspirated. I have close to 10k$ in the motor.

That power level does not come cheap normally aspirated. I have close to 10k$ in the motor.

that's the kind of info I'm looking for also predator.. If you don't mind me asking, is that with you doing the install, or a shop? Obviously either way that includes machine shop work. That power can be done less expensively for sure.. but not with a new bottom end included.

This is kind of what I'm thinking right now.. you guys tell me how it sounds for a street/strip car. 383/408 rotating assembly (383 if a 408 means re-sleeving, haven't gotten that far researching just yet). Non-forged, NA, MS3 cam, AFR 215s port matched shooting for a compression around 11:1.. assuming I can squeeze all of that within my budget including all the bits and pieces, probably not.. I'll end up compromising on the heads most likely.

that's the kind of info I'm looking for also predator.. If you don't mind me asking, is that with you doing the install, or a shop? Obviously either way that includes machine shop work. That power can be done less expensively for sure.. but not with a new bottom end included.

This is kind of what I'm thinking right now.. you guys tell me how it sounds for a street/strip car. 383/408 rotating assembly (383 if a 408 means re-sleeving, haven't gotten that far researching just yet). Non-forged, NA, MS3 cam, AFR 215s port matched shooting for a compression around 11:1.. assuming I can squeeze all of that within my budget including all the bits and pieces, probably not.. I'll end up compromising on the heads most likely.

Install, tuning by myself (with some labor help). I had a shortblock built. Stock crank. Heads are not the items to compromise on. I would scrap a 383 in favor of stock cubes and the best heads your pocket can buy. My heads were over 3K$ (Cartek 4X).

Have you looked at the TSP shortblocks?

Last I looked they were hard to beat for the dollar. By the time you add up all the costs plus machine work it becomes very appealing to call them up and turn in your old engine as a core.

Have you looked at the TSP shortblocks?

Last I looked they were hard to beat for the dollar. By the time you add up all the costs plus machine work it becomes very appealing to call them up and turn in your old engine as a core.

yes I have, that was my original plan actually. it will likely come down to what kind of free time I have if/when something happens to my engine, or if I just get to do it as a project anyway. If downtime is an issue I will definitely be buying an assembled longblock or at least a shortblock and heads elsewhere (depending on budget again).

As for 383 vs 347... The difference in price of $500 for an assembled short block (from TSP) isn't enough to make or break the heads portion of the budget, but who knows.. lol.

Predator that helps a lot! thank you, at least I know I can definitely get what I'm after in that budget even if it's not larger cubes at the end of the day :P


Back to this shortblock thing... an LQ9 based 421 and LS1 based 383 come in at very close to the same price.. advantages/disadvantages of each? (aside from the weight factor)

It is best for the street to keep the stroke at 4.00. Meaning a 408 would be preferable. More reliable.

I agree with Pred, and I'm partial because I run one :) after you go past the 4.00" stroke you start to get more wear due to how fee the short piston skirts come down out of the bottom of the bore and let the piston rock, and past a 4.30" bore your cylinder walls are getting thin (4.30" bore gives you enough material to go larger the next time) if you run your 408 for 100,000+ mile and want to rebuild it.

when mine goes a junkyard 5.3 and a turbo will be going in, honest if i wanted to buy a motor it would be real hard not to get a block from tsp,there prices like what has been said are pretty fair when ya figure out all the cost of doing something yourself

very nice input guys! so then 408 vs 383? I have a friend that just had his LS2 built into a 408 after a spun bearing in a TBSS, haven't gotten to go for a ride along yet cause his new 4l80e blew the TC on the way home.. It will be interesting to feel that, he's putting down about 500hp through a 3200 stall and 4l80e with his setup, and a VERY mild cam for a 408. as for 383, I'm partial to that engine as that one holds some stigma for me...the next engine in my dads car was going to be a 383 before he just stopped racing and sold his car, would love to build a car he'll be proud of also, and let me tell you he is VERY picky lol! as for 408 and 383.. heads have to be a part of this cost, I can get by with 215s for the 383, but won't I need to step up to a 235 for the 408? more $$$ there also... gotta account every penny while I'm planning haha

I'm looking at the AFR 245s. As of tight now I'm still running my original 241s ported and milled to 57cc chambers to give me 12.5:1 compression, but my cam is a comp 255/263 .624/.624 115lsa which drops my dcr back down to a pump gas friendly 8.22:1.

Even running these heads the engine is an absolute beast and pulls hard as hell till I hit my 8,000 rpm fuel cut off :)

I'm looking at the AFR 245s. As of tight now I'm still running my original 241s ported and milled to 57cc chambers to give me 12.5:1 compression, but my cam is a comp 255/263 .624/.624 115lsa which drops my dcr back down to a pump gas friendly 8.22:1.

Even running these heads the engine is an absolute beast and pulls hard as hell till I hit my 8,000 rpm fuel cut off :)


WOW, can we just trade cars? LOL. In all seriousness what kind of CI and block are you running? That's way more cam than I would want in anything under a 427 or 408, but how are it's street manners... like what RPM do you get bucking in? if at all..

WOW, can we just trade cars? LOL. In all seriousness what kind of CI and block are you running? That's way more cam than I would want in anything under a 427 or 408, but how are it's street manners... like what RPM do you get bucking in? if at all..

I'm running an iron block 408.....the extra cubes REALLY eat up the larger duration....also running an Edelbrock proflo xt intake and in my opinion this is what really hrlps my set up out. I was running an a4 with a 4,000 stall and after a lot of street tuning could cruise at 1,500 rpms with 0 bucking. Idle is decent at 900 rpms.

Right now my GTO has been in my garage going under the knife for the ladt several months....3 speed manual swap, 4 link, 9", 4.56 gears, tub, full cage and chassis, trying to get the whole csr fown to around 2,500 lbs.

Before my tranny went out the last time I could tub and beat sport bikes, so i cst wait to see what it will do when im done with it :)

ahh, yeah I could see that cam being ok in a 408, and is actually something similiar to what I would go after in that size. If you don't mind me asking what do you have in that setup? And was it something you built yourself and put together or mostly done by a shop? if you don't want to reveal all that much pm is fine too :P

Lol no big secret... I'd guess around $10,000, but that included my tranny too.

2002 6.0L cast iron truck block bored to 4.030"
Mahle forged dish pistons (-4cc valve reliefs)
Eagle 6.125 4340 forged H-beam rods
Eagle 4.000 4340 forged crank 24x reluctor
ARP Main Studs and rod bolts
Mahle rings
King bearings
Comp 255/363 .624/.624 115 lsa cam
Ported/ polished/ milled 241 heads (57cc chambers)
Edelbrock Pro-flo XT intake
FAST 90mm tb
Edge (motron) 60lb injectors
Pacesetter lts
Dual 3" exhaust

The last time I tore it down I sent it to the machine shop to have one rod replaced, aligned bored and balanced. The machine shop assembled the short block for me, then I put the cam and heads on.

I wish I would have had the head put on a flow bench, but didn't.....I ported the hell out of them, then sent the heads to the machine shop to be milled down to 57cc's, and valve job.

I am VERY happy with it the way the car was, and know I will love it even more when the car is 1,000lbs lighter lol.

Lol no big secret... I'd guess around $10,000, but that included my tranny too.

2002 6.0L cast iron truck block bored to 4.030"
Mahle forged dish pistons (-4cc valve reliefs)
Eagle 6.125 4340 forged H-beam rods
Eagle 4.000 4340 forged crank 24x reluctor
ARP Main Studs and rod bolts
Mahle rings
King bearings
Comp 255/363 .624/.624 115 lsa cam
Ported/ polished/ milled 241 heads (57cc chambers)
Edelbrock Pro-flo XT intake
FAST 90mm tb
Edge (motron) 60lb injectors
Pacesetter lts
Dual 3" exhaust

The last time I tore it down I sent it to the machine shop to have one rod replaced, aligned bored and balanced. The machine shop assembled the short block for me, then I put the cam and heads on.

I wish I would have had the head put on a flow bench, but didn't.....I ported the hell out of them, then sent the heads to the machine shop to be milled down to 57cc's, and valve job.

I am VERY happy with it the way the car was, and know I will love it even more when the car is 1,000lbs lighter lol.
with all of your lightening do you ever regret the extra ~90lbs for the iron block?