this is interesting post to me a few reasons. the stock 2.0 is a "long stroke engine" 88x85mm. stroke is longer than bore dimension. The 2.4 engine is a tractor engine really. 100x86.5mm. massive stroke increase over the 2.0. I was concerned about bore wear on my very first 2.4 I built. I took the trouble to add oil squirters to the block. I also took the trouble to drill my set of eagle rods and rod bearings to spray the bore like the factory does it. factory rods squirt oil on the wall to combat this potential wear. most of your favorite engine builders wont even push using oil squirters on the 2.4. dumb if you ask me. that engine gave me fantastic service.

I have never liked the long rod motors. simply dont think the extra length makes a significant reduction in side wall loading. not worth building custom pistons and rods for. now that I hear the skirt has to be made shorter I am really shaking my head. you want all the skirt length you can get in a stroker engine. unfortunately most piston designs shorten the whole skirt to clear the squirter. bad idea. better to have to take the time to clearance the skirt to clear in one small spot rather than shorten whole skirt.

most side skirt wear is a result of dry/cold starts and higher compressions. was this engine hard to start at all? I currently have some Mahle 2.3 pistons that really loosened up due to impossible hard hot starts with id1000s. the loosened at about 5k. milked them to 20k but they are really noisy now.

personally I would likely just run this engine as is. It will last a lot longer than you think. there is no easy fix here. DO NOT TRY AND HONE and reuse. that is very bad advice. just run it like it is. I dont know who is pushing bore is too tight but that is just incorrect. the bigger your piston to wall clearance is the larger this problem becomes.

 

I would measure the bore in that area and compare it to different places in the cylinder. The fact that the shorter stroker pistons skirts don't have much contact with the walls will make them wobble in the cylinder and that may be causing the wear.

 

what is the notch in the top of piston #4 from?

i am not an engine builder,but that looks like excessive wear to me for 600 miles.i just took a 2.3 apart with 7,000 miles and the wear on it wasn't as pronounced as this one.

 

stock 2.0. never modded. ~5k miles

 

The engine never gave me any issues starting. Honestly like a turn or two and it would fire right up.

I guess it really depends on what the issue is being caused by, which is just someone's best guess at this point.

It could be:

A) Shorter Piston skirt, piston is moving around causing excess wear. If this is the case then yes, the larger the PTW, the greater the problem becomes.

or

B) PTW is too tight, causing excess wear. If this is the case, simply honing if the bore isn't too oval, getting new pistons, and regapping a little looser would solve the issue.


At this point I'm really not sure, but every engine builder I spoke with claims it looks like the latter, and the PTW does represent that. But I feel there is no way to accurately say that it is more likely A than B at this point.

Seeing as there are so many LR 2.4Ls floating around without one mention of the issues caused by the shorter piston skirt I can't really see how that is more likely to be the cause of the wear.

All I know is I saved up a lot of money and bought a motor that just isn't "right", any way you look at it, and am a bit upset about it.

 

When building another motor from the scratch (not using any parts from this), how can this be avoided?

 

I am not on board with B).
when piston to wall is too tight and piston is being forced into the wall the the piston will gall and your bore will be ruined instantly. piston rubbing steel creates overheated aluminum condition pretty much instantly. = galling

pistons and rings actually dont touch the cylinder wall at all in a normal running engine. they ride on film of oil. you can take an engine apart with 200,000 miles on it and still see nice cross hatch patterns.

there is nothing to stop the piston rocking at start/low rpm running. at that point there is not enough oil to keep the skirt from slapping the wall. longer stroke = more slap, shorter skirt = more slap, shorter rods = more slap, higher compressions = more slap, and most definately greater piston to wall = more slap.

 

And this is why I ask questions. That's very useful.

This is what I'm gaining:

To prevent slap......start welding things?

But in all seriousness, what you're saying is that the wear I'm experiencing is inevitable?

 

AWD, I think the point you're missing is this:

The motor is worn this bad in 600 miles with no boost. My buddies beaten to death 100K mile stock block didn't look even a quarter this bad.

When I start making power the pistons are only going heat up and expand more, wearing straight into the cylinder walls even more.

If this is purely a problem due to having a short piston skirt, then why is this the only LR 2.4L showing up with this premature wear? Technically every long rod, short piston combination should have my same wear issue but I've never seen a single picture or concern to this date.

I donno.. If that was the problem I think we would've heard about it by now and this wouldn't look so shocking.

 

...

 

Merhhhh

 

who takes motor apart after 500 miles? not many.


The motor is worn this bad in 600 miles with no boost. My buddies beaten to death 100K mile stock block didn't look even a quarter this bad.

When I start making power the pistons are only going heat up and expand more, wearing straight into the cylinder walls even more.

again you keep inferring that the piston is pushing into the wall from not enough clearance. thats not whats happening here. if it were that mark would be 100mm long. the skirt would be rubbing the whole length of the stroke. get the pistons hotter with boost and the piston will run quieter and rock less. the mark you are seeing is from piston changing direction at top of stroke and it rocks into the bore as it does so.

50% of engine wear occurs the first two seconds of engine running. it takes that long for oil pressure to build.

I am not saying i like the bore wear I am seeing here. what I am saying is even bone stock engines make that mark quite quickly. thats why I posted a picture to show that. I dont think the mark is as severe as you think it is. I already said I would take notes, but run it as is. one thing I would do is be sure the pin offset was installed correctly. that would account for accelerated wear. you might just need to flip the pistons to correct.

 

Was the motor machined with a torque plate? I am not an engine builder, so I am just tossing that question out there.

 

Thank you again for taking the time to respond. You are stating exactly what the builder is stating which makes me feel a little bit better.

Just so I have an idea, what's the rough life span of a motor like this if it sees 600whp?

 

Yessir it was.