Need a recipe for LS cubes

I'm starting to plan an LS-something build for around 600 hp for a project (67 LeMans). Since more cubes means lower RPM and more torque for a given HP, I'd like to up the cubes a bit without breaking the bank (i.e. buying an LSX block, buying an LS9, etc) I want to stay all aluminum unless you can convince me that the extra weight won't be significant.

So I guess I'm looking for a good starting point, maybe with mix 'n match stock components and aftermarket or ported heads. 7.0L would be nice but I know that's hard to do without ponying up big bucks for the 4.125" bore LS7s.

Ideas on building an LS with bigger cubes without wasting money?

I want to stay all aluminum unless you can convince me that the extra weight won't be significant.

Im pretty sure the weight ship sailed when you said 67 Lemans!

I have nothing useful to contribute but i am interested in your project.

Vigo wrote:

I want to stay all aluminum unless you can convince me that the extra weight won't be significant.

Im pretty sure the weight ship sailed when you said 67 Lemans!

aaand... you're a snot-face (kidding)

I know on this "miata" forum that classic iron isn't light but they aren't as heavy as you might think. As delivered, curb weight for a 67 LeMans was around 3300 lbs which is almost exactly what a 2nd gen WRX weighs.

Would you put an iron V8 in a WRX?

Here's a paragraph I just liberated from Hot Rod Magazine's web site about building an iron 6.0 truck motor. Note that this information may be dated but I believe it is still useful;

"The all-aluminum Gen III LS1 and LS6 engines displace 5.7 liters (346 ci). Unfortunately, their cast-in-place engine liners make overboring difficult. Although their improved liner design makes them a more viable rebuild candidate, the late LS2 6.0L (364ci) all-aluminum cores are still relatively rare. That left the most bang for the buck: a 6.0L truck engine. Not only are the truck engines much more plentiful than the LS1/LS6 engines that are found only in selected high-perf rear-wheel-drive cars, but in the past most have been based on easily rebuildable iron blocks (max overbore 0.030 inch). Besides, a stock-bore 6.0 nets you 19 ci over the 5.7L car engines."

you can bore the iron 6.0 blocks out and drop in a readily available (and relatively cheap) aftermarket rotating assembly for an easy 400+ inches of displacement.

i know you say you want an aluminum block- an LS2 block would work if that's what you absolutely need to have- but a mildly built 400+" iron block/aluminum head engine will scoot that 3300 pound Lemans around quite nicely.

here is the first hit that came up on a google search for "GM 6.0 stroker kit"..

http://www.coasthigh.com/Chevy-LS-6-8L-engine-kits-s/1343.htm

You can also start out with a 6.2L block from an Escalade.....

If you're replacing heads, cam, crank etc anyway, it may actually make financial sense to start with a LSX block - they are pretty reasonable actually... and then you can get a cool 454 cubes.

novaderrik wrote: you can bore the iron 6.0 blocks out and drop in a readily available (and relatively cheap) aftermarket rotating assembly for an easy 400+ inches of displacement. i know you say you want an aluminum block- an LS2 block would work if that's what you absolutely need to have- but a mildly built 400+" iron block/aluminum head engine will scoot that 3300 pound Lemans around quite nicely. here is the first hit that came up on a google search for "GM 6.0 stroker kit".. http://www.coasthigh.com/Chevy-LS-6-8L-engine-kits-s/1343.htm

Nice stuff on that site, still looking for the "cheap" stuff though...

back on topic. I don't think that going cast iron block will be much of a weight penalty. 100lbs or so? You'll be happier with the 100lbs of dollar bills you just saved.

tuna55 wrote: If you're replacing heads, cam, crank etc anyway, it may actually make financial sense to start with a LSX block - they are pretty reasonable actually... and then you can get a cool 454 cubes.

My first thought as well. If big cubes is what you want, this is the way to go.

Stroke it.

ls3 has the same bore as the ls7. if your building a ls block it's the cheapest way to start a lsx build. all the ls cranks are the same it's the boar that makes more cubes. i would stay away from cast iron, you could add a few hundred pounds adding an iron block that doesn't cool as well as the aluminum. you'll really want the cooling for road racing. if your drag racing iron will be ok, but if you expect your front tires to work i would say away from iron.

I would use a cast iron truck block more then likely. What are you going to be using the LeMans for?

The iron block adds about 100#.

There are some affordable stroker short blocks by Schwanke, Texas Speed, Mast and others. Hard to build it for less yourself.

We have used Schwanke motors in our V8 StockCars, they have been very powerful and reliable.

A friend bought one of the GM 6.2 LS3 hot rod motors for about 7K and is putting it in a 57 chevy. Makes about 500 HP. The 57 is lightened to about 3000 #. Should be a beast for a street car.

93EXCivic wrote: What are you going to be using the LeMans for?

Impressing women.

It will be a street car for fun driving and I may use it to do some vintage road races.

curtis73 wrote:

93EXCivic wrote: What are you going to be using the LeMans for?

Impressing women.

Well then definitely stick with the LSX block so that when you want to put twin turbos on it you'll have those extra headbolts.

I really think I would use an iron block. It is going to be easier to add your extra cubes and cheaper.

To be honest, a stock 6.0 with a homebrew turbo kit would be cheaper than building a big cube stroker setup.

Weren't we just talking about the 4.8 version of this motor with a turbo being an easy route to, what, 500 streetable horsepower?

Edit: Looks more like 400hp but come on now.

pres589 wrote: Weren't we just talking about the 4.8 version of this motor with a turbo being an easy route to, what, 500 streetable horsepower? Edit: Looks more like 400hp but come on now.

I'd say your first number was more realistic. My 06 LR4 made 295hp from the factory in smog form with restrictive exhaust/intake. so expecting a properly put together 4.8 with a turbo would only pick up 100hp over stock is extremely conservative.

Especially when you dump that round lobe cam they put in the 4.8/5.3's for something with some pimples on it.

NineLivesJohnny wrote: ls3 has the same bore as the ls7. if your building a ls block it's the cheapest way to start a lsx build. all the ls cranks are the same it's the boar that makes more cubes. i would stay away from cast iron, you could add a few hundred pounds adding an iron block that doesn't cool as well as the aluminum. you'll really want the cooling for road racing. if your drag racing iron will be ok, but if you expect your front tires to work i would say away from iron.

LS3 bore is 4.06, LS7 bore is 4.125.

I would imagine a iron block LS engine is still going to be quite a bit lighter than a traditional Pontiac V8, so even if you go that way the car will be lighter than stock.

Gearheadotaku wrote:

novaderrik wrote: you can bore the iron 6.0 blocks out and drop in a readily available (and relatively cheap) aftermarket rotating assembly for an easy 400+ inches of displacement. i know you say you want an aluminum block- an LS2 block would work if that's what you absolutely need to have- but a mildly built 400+" iron block/aluminum head engine will scoot that 3300 pound Lemans around quite nicely. here is the first hit that came up on a google search for "GM 6.0 stroker kit".. http://www.coasthigh.com/Chevy-LS-6-8L-engine-kits-s/1343.htm

Nice stuff on that site, still looking for the "cheap" stuff though... back on topic. I don't think that going cast iron block will be much of a weight penalty. 100lbs or so? You'll be happier with the 100lbs of dollar bills you just saved.

"cheap" is a relative term when talking about building big cube engines that will live for any period of time.. $2k for a balanced rotating assembly that is ready to drop into a stock bock after a couple of hundred dollars of machining is a pretty good deal for what it is. slap a GM HOT cam in it and a set of the (sadly discontinued by GM) L92 heads and you've got a grand total of about $5k into an engine that makes around 600hp and will live a good long life. as a comparison, i had about $3500 into a 355 Chevy that was maybe 400hp on a good day, and i got a lot of deals on parts thanks to my connections in various parts departments and used a machinist that cut me a deal because he was friends with my dad back in the 60's. if i had access to the LS engine stuff that's available today back in '99 when i built that engine, i wouldn't have even bothered with the old school small block.

simplecat wrote: To be honest, a stock 6.0 with a homebrew turbo kit would be cheaper than building a big cube stroker setup.

ick. He wanted big cubes for a reason. I like that better than a turbo. I presume he does too.

stuart in mn wrote: I would imagine a iron block LS engine is still going to be quite a bit lighter than a traditional Pontiac V8, so even if you go that way the car will be lighter than stock.

^truthiness.