Jeep Strokers

What causes more wear to an engine: the increased side-loading of short rods, or the increased cold temperature clearance of forged pistons?

Got a set of 6 you are free to get as paperweights if you like. Long rods .050 pistons side worn the fuup out and rods included no extra charge for the spun bearings either. Its about machining and maintenance.

Frankenstien wrote:Got a set of 6 you are free to get as paperweights if you like. Long rods .050 pistons side worn the fuup out and rods included no extra charge for the spun bearings either. Its about machining and maintenance.

I only understood the last five words.

Had long rod engine with Forged pistons I picked up knowing it needed a rebuild. Took it apart and pistons had sever side wear damage to the skirts and then some. Also had spun rods as well.
I went with short 707 style rods and hyper pistons this time and 0.060 this set as well. There are many different opinions of long vs. short rods and wear etc.

Gristleheart wrote:What causes more wear to an engine: the increased side-loading of short rods, or the increased cold temperature clearance of forged pistons?

I don't think there's a clear answer to that question. Suffice to say that improper machining, assembly, break-in, and maintenance are the biggest determinants of premature engine wear.
Today's forged pistons are made from an alloy that requires less piston-to-bore clearance (typically 0.0035") making cold start piston slap less of an issue.

The more I read about this elsewhere, the more I find that forged pistons are detrimental to engine longevity. A clearance of 0.0035 is still twice as much as cast pistons require.
Will the block last 300,000 miles with cast pistons, before it needs rebuilt? Probably.
Will the block last 300,000 miles with forged pistons, before it needs rebuilt? Probably not.
Will it last 150,000 miles with forged pistons, before it needs rebuilt? Maybe. 100k is certainly reasonable.

These vehicles are all old now, so getting an additional 100-150k out of the engine is probably enough for most folks. But I plan on keeping and driving mine for a long time yet to come. And if I can build this to get 250k or more, then I think that's what I'm going to plan for.
Sure, cast pistons won't long at all in an engine that's boosted or sprayed. But I'm not doing that, and neither are most other folks here. There doesn't seem to be a cost savings with forged pistons. The performance gains of using long rods is probably negligible for non-race applications. And, if I'm not mistaken, the forged pistons generally can't be dished as much as cast pistons. Is there some other benefit to forged pistons that I'm missing?

Gristleheart wrote:These vehicles are all old now, so getting an additional 100-150k out of the engine is probably enough for most folks.

I built my stroker almost 11 years ago and I'm nearing 80k miles on it. These days I'm barely doing 4k miles/year in the Jeep so it'll take me another 5 years to reach 100k miles at that rate.

Gristleheart wrote:Is there some other benefit to forged pistons that I'm missing?

Yes. The ability to build in a lower quench height for better detonation resistance.

Cheromaniac wrote:Yes. The ability to build in a lower quench height for better detonation resistance.

Can you get the same results by using a thinner head gasket and decking the block? With cast pistons allowing for deeper dishing to lower compression, that will help prevent detonation, too, right?

Gristleheart wrote:Can you get the same results by using a thinner head gasket and decking the block? With cast pistons allowing for deeper dishing to lower compression, that will help prevent detonation, too, right?

Yes you can but you'll need to plan for using shorter pushrods to correct for the increase in lifter preload so check the required length before you order.

Frankenstien wrote: ↑April 8th, 2015, 7:56 pm Got a set of 6 you are free to get as paperweights if you like. Long rods .050 pistons side worn the fuup out and rods included no extra charge for the spun bearings either. Its about machining and maintenance.

Sorry for bringing this up again but...it sounds like an oiling problem to me. Pistons and cylinders are lubricated from oil slinging off the crank. Lack of oil to the bearings means lack of oil to the cylinder walls.

Brianj5600 wrote: ↑January 27th, 2020, 8:24 pm

Frankenstien wrote: ↑April 8th, 2015, 7:56 pm Got a set of 6 you are free to get as paperweights if you like. Long rods .050 pistons side worn the fuup out and rods included no extra charge for the spun bearings either. Its about machining and maintenance.

Sorry for bringing this up again but...it sounds like an oiling problem to me. Pistons and cylinders are lubricated from oil slinging off the crank. Lack of oil to the bearings means lack of oil to the cylinder walls.

Not enough Oil getting splashed on the cylinder wall isn’t the problem. Too much fuel is. Gasoline isn’t a good lubricant.

Russ Pottenger wrote: ↑January 28th, 2020, 12:08 pmNot enough Oil getting splashed on the cylinder wall isn’t the problem. Too much fuel is. Gasoline isn’t a good lubricant.

Gas also diluted the oil and took out the rod bearings?