themack56

iTrader: (70)

can i put a 4'' stroke on a brand new ls1 block with standard bores and what would be the cid?

Gearhead1

381.9 CID and yes I think it can be done.

themack56

iTrader: (70)

can a 4.100'' stroke be installed on a ls1 block

moeZ28

iTrader: (7)

I believe a standard LS1 block needs to be clearanced for a 4 inch stroke. but i could be wrong. when i was contemplating a forged crank, i thought i found that the biggest i could go was a 3.900" crank without clearancing the block.

Hemi Killer

iTrader: (6)

Yes. THere's a guy on here running one. With the 4.100" stroke I beleive it's a 392-394ci, depending on what bore you have.

ROCNDAV

iTrader: (100)

You can put a 4.125 crank (or even a 4.250, but those aren't advised) but the block needs to be ground in a few places to clear the rod bolts. ALso, if you aren't getting a kit, you have to make sure the #8 Piston will be notched to clear teh reluctor wheel.

Search the archives, there's tons of info waiting to be found

OkieDave

I have a scat kit w. 4.125 and the only prob was the windage pan. Its a 6.0 block. Nice kit too!

NAVYBLUE210

4.0" is the longest stroke I would put in a factory sleeved block,
The extra few inches is not worth the reduced reliability/longevity
In my opinion. Just my .02

Know It All

What reduced longevity? It's no worse than a 4" stroke.

Darth_V8r

iTrader: (4)

Um....?

Know It All

What are you confused about? Maybe this will help...

Probe Pistons PN 14970
Stroke: 4.00"
Compression Height: 1.115"

Probe Pistons PN 15007
Stroke: 4.125"
Compression Height: 1.053"

Wiseco Pistons PN: K464XS
Stroke: 4.00"
Compression Height: 1.110"

Wiseco Pistons PN: K450XS
Stroke: 4.125"
Compression Height: 1.050"

Notice how the pistons for the longer stroke are all shorter?

Darth_V8r

iTrader: (4)

It looked like your post was saying a 4" stroke was no worse than a 4" stroke. Now I mean what you see

JakeFusion

iTrader: (7)

That's not the problem. The issue is piston rock at the bottom of the sleeve.

Even though the piston is shorter, that only helps with not pushing it through the head. The bottom of the piston is still in the same place (unless you run a different rod) and is being pulled further out of the cylinder, leading to the piston rock. This wears the bottom of the sleeve and causes issues eventually.

And the LS1 sleeves are the shortest of all GM sleeves.

I'd only consider running a 4.100" crank and no more and only in the LS2/3/7 blocks.

Know It All

You run into piston rock issues when the major diameter of the skirt is pulled out of the sleeve. The compression height is shortened on the longer stroke pistons to move everything up, including the major diameter, so it doesn't come out at bottom dead center.

Have you ever measured pistons before? You are supposed to measure at the major diameter in order to set your piton to wall clearance. The spec sheet that comes with the pistons tell you where to measure, for example it may say 1.30" below the bottom ring groove for a stock stroke. A 4" stroke may say measure at 1.10" and for 4.125" stroke it may say measure 1.045". The major diameter moves up the piston as the stroke is increased.

slowsol95

iTrader: (1)

He didn't just make all that up, additional wear from 4.1" stroke cranks in factory sleeves is pretty well documented here. Diet coke's ls3 build is the most recent one that comes to mind. He had to tear down his original ls3 427 build at 5k miles and took pictures of the scuffing already on the cylinder walls. It was bad enough that the engine had to be rehoned to 430 cubic inches to put in a new set of rings. Look it up for yourself. This is quite recent too with the supposed better/improved piston designs that the aftermarket has come up with to solve the problem. No matter how much you bandaid it, you can't cheat physics. Now, if someone is building a street/strip or weekend car that sees limited mileage, a 4.1" stroke may not be a bad option if you keep in mind it will start consuming oil and need a rebuild around 50k. If this is a daily driver or something that sees a lot of miles every year, the trade off in reliability isn't worth the little extra power you get. Diet coke himself agreed with this statement after having two 4.1" stroke ls3 builds.

Know It All

I guess if it's on the internet, it must be true!!

Just buying the better pistons doesn't mean it won't have problems, you still have to build the engine correctly using good machining practices. Diet Coke had worse wear than I've ever seen; his is not the norm. There are plenty of 4.1x" stroke builds that have very limited wear; at least much less than Diet Coke's build. You just don't see those posted all over the internet because there's nothing wrong with them and there's nothing to scream about...or maybe you just didn't notice it. Keep an eye on the Classifieds and when you see someone selling some used pistons for a 4.1x" stroke build, take a look at the skirts. You'll see what I mean then.

Now explain the physics we're band aiding here. What causes the piston rock? What is the fix? What does that fix do that moving the major diameter of the piston up or reducing the stroke doesn't do?

Bonjour!

slowsol95

iTrader: (1)

Since you are the 4.1" stroke stock sleeve guru, what facts do you have to prove that his is not the norm? Cite some sources then, I was able to for my case off the top of my head. Just because you said so doesn't mean **** to me or anybody else. Prove your case if you feel so strongly.
Since you are an expert as well as an *******, you should know that more stroke means more distance to travel for the piston and piston speed goes up. Additional piston speed means the piston has to change direction faster at bdc. Not only that, but the longer stroke also adds more rod angle into the mix. No matter if you make the piston shorter or not, it still sees more side load than a stock stroke or 4" stroke crank. Thats going to accelerate wear no matter how you look at it.
Like I stated in my earlier post, there is a place for 4.1" stroke builds if you know the trade offs and are ok with them. But there are trade offs and it's not right for everyone. If you're so confident, why dont you offer to assemble his engine and warranty it for the problems mentioned?

KCS

iTrader: (20)

You need to chill out. It's one thing to argue, but childish name calling isn't welcome.

Know It All

Like I said, if it's on the internet it must be true right? It has to be posted for you to believe it? Who is going to tear down an engine that doesn't have any problems? My proof is that you have ONE documented case where someone had problems when there are thousands of those cranks out there in use.

OK so first off, piston speed is ridiculous. Big blocks run well over 4.250" strokes without issues or frequent rebuilds. They often come in crate engines with warranties too.

As far as side loading, apparently there seems to be little to no effect. It doesn't matter what sleeves you are using, the "increased sideloading" is that same. The longer sleeves won't fix that and ERL and others sell them 4.1/4.125" strokers regularly without reliability issues.

There are trade offs, I agree with that, but it's not what you say they are.

ben husen

i have a 4in stoke in my ls1 and i had to clearence the block i guess u may not "have to" but them rod bolts get a lil to close for comfort lol