HawkZ28

I've done a LOT of reading various posts here and elsewhere- are the pistons rocking and wearing out cylinders at BDC, causing oil consumption, etc a truly a thing of the past, or is it reduced with updated piston designs but will be more evident with extended street miles and shorten the life of a shortblock vs a 3.622 stroke crank?

I'm ordering parts soon for my 6.2L, and it isn't going to cost any more to run a 4" crank, but I need the bottom end to have the 200k+ longevity and reliability of a SBE. I don't want to pull it to do this all over again in 2-4 years, or build another shortblock to be on standby.

Che70velle

iTrader: (6)

You will NEVER get 200k mile reliability out of any stroker combo, no matter what piston design is used. If you want ultimate reliability, don’t mod it. Mod life comes with issues always.

Full Power

You want the ULTIMATE in durability ?
Find a junkyard pull 4.8 Liter.
If you keep oil and coolant in a 4.8, it might last longer than ALL of us.

bobcratch

for curiosity's sake, what kind of mileage would you expect to get out of a street driven LS with a 4" stroke? understood that there are many variables.

HawkZ28

Probably so, but I already own the 6.2 and love the torque over the 5.3 and 4.8.

I understand and am no stranger to that perpetual soiree, but in this case would it be due to the additional forces at the bottom of the sleeve over time or ?

I did speak to a gentleman at Molnar who confirmed/told me to use 4032 instead of 2618 pistons for longevity. That was before I learned that a 4" crank was going to cost the same as all the parts I have to buy to forge the bottom end already, which will cost about the same as a new stock crank and rods.

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Double06

iTrader: (1)

What is the sleeve length on the 6.2? If it is like 5.50 inches that will cause issues in the long run? They do make better pistons for that now but they can only do so much. As a reference point the sleeve length on the LS7 which is a 4-inch stroke is 5.85 inch sleeve or so inches.

Che70velle

iTrader: (6)

4” crank sounds great especially since pricing is the same. Cubic inches are what we want in this hobby…the problem is the OEM aluminum block sleeve length is extremely short. It stops well shy of the actual aluminum cylinder support. (WHY GM…WHY?????!!!) I’m building an LS3 right now for a client out of Florida…Grand Sport C6. He was concerned about 2 areas of this build…lifters and sleeve length. We opted on going with a custom built Molnar 3.9” crank rather than the “shelf” 4” stroke crank that was ready to go. Cost more and tied us up time-wise, but he wanted as much longevity as we could put into a stroked build. He’s not fooling himself and knows full well that it’s not going to last forever. Time really wasn’t an issue on this crank because at the same time, I had Wiseco build us a piston set with custom ring pack, just for this stroke and sleeve length. Just wrapped up the shortblock a couple days ago, and I’m waiting on custom headgaskets before I can get the heads on to measure for pushrods. I take a lot of notes, and that custom piston built by Wiseco, who is at the top of the game in stroker piston skirt design…the skirt comes out of the iron sleeve .652”. That’s a long way out. A 4” stroke gives us 12 more cubes here, but accelerates skirt wear even more. This car is a street car but will get the **** ran out of it. He put more in the stage 4 trans, diff, and carbon fiber prop shaft, from RPM Transmission than most spend on complete engine builds. In fact, he’s already told me that when this one blows up, we are going to sleeve a block and go LS7 max-effort build.
Im rambling here, but just saying that I’m right in the middle of this 3.9” vs 4” stroke dilemma with an OEM aluminum block, and there’s no good answer, even with the best parts, if 100% reliability is wanted. Driving style will help determine the reliability factor a ton here, but if your not going to run it hard…at least sometimes…then don’t bother stroking it, in my opinion.
Im sure I’ve started a rant session here, where guys are about to start posting up stating that their 4” stroke build in their Oem aluminum block build has been dead nuts reliable for 100k miles and doesn’t use a drop of oil, etc etc. Truth is, all LS engines use a half quart or more between oil changes from new. Every one I’ve ever owned has at least. It’s the janky PCV setup that does it. So in reality, a little oil usage is normal here, which the piston rock at BDC will cause eventually.

Che70velle

iTrader: (6)

Lew, that is indeed a 5.5” sleeve.

Keith

Molnar has 3.75 and 3.9 options. I bet DSS has a piston for both of those.

You could also do an L8T crank(3.858") Mast had put together some rotating assemblies with them.

Old Buzzard

"Truth is, all LS engines use a half quart or more between oil changes from new. Every one I’ve ever owned has at least."
This is a 5.3 in my beater 02 Sub.
300K on it... Right on schedule w/ a qt between changes.