NEW ASYMMETRICAL FSR Vs. TRADITIONAL FULL ROUND SERIES Rings

[GSTurbo1]

Ok, doing a ring replacement on the 420a... Boosted. I'm about to order new rings from JE and got the option to select which style ring I wanted to install. Any clue what I should go with?

 

[Sebba]

Ok, doing a ring replacement on the 420a... Boosted. I'm about to order new rings from JE and got the option to select which style ring I wanted to install. Any clue what I should go with?

Why are you just doing a re-ring?

 

[GSTurbo1]

a re-reing and two new pistons, compression is 150psi across the board trying to bring it back up

 

[1990AWD]

Never do just two pistons or just rings. Put all new pistons & rings or not at all. Pistons and rings wear together and it wouldn't be healthy either to have two new and two old pistons at the same time.

 

[rr06rs]

Never do just two pistons or just rings. Put all new pistons & rings or not at all. Pistons and rings wear together and it wouldn't be healthy either to have two new and two old pistons at the same time.

Not sure where you heard this. It's perfectly fine to rr-ring a motor using the original pistons, as is it to replace hurt pistons. Just be sure to balance the assembly together.

The asymmetrical rings are for je's new asymmetrical pistons. Unless you're running these, use the full round rings.

 

[WES_393]

The piston ring you will use is determined by the type of piston. JE offers the traditional "round" style piston as well as a piston which is basically missing one side skirt, aka: Asymmetrical. If your using asymmetrical pistons, you will want the appropriate rings for them. If your using the traditional "round" style piston, you will want to order the regular rings.

This pic shows the visual difference between the two. The piston to the right is the asymmetrical version while the left is the traditional round version. However, I'm willing to bet you have the round style pistons considering asymmetrical pistons aren't a good idea for street use.

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I also agree that you should at least replace the rings on all 4 cylinders. Considering the damage done to 2 of the pistons, I would pull and carefully inspect the other 2 for signs of failure and replace if necessary.

 

[rr06rs]

Oh, I totally agree the rings should be replaced on all 4. I didn't think the op meant he was only putting new rings on the two new pistons. I figured all were getting rings with two new and two old pistons, which is perfectly fine. So is replacing all rings on all the original pistons. That's what I meant. Definitely don't only replace rings on any less than all though

 

[GSTurbo1]

I'm going to re ring all of them but I will replace the hurt pistons as well.

 

[1990AWD]

Not sure where you heard this. It's perfectly fine to rr-ring a motor using the original pistons, as is it to replace hurt pistons. Just be sure to balance the assembly together.

The asymmetrical rings are for je's new asymmetrical pistons. Unless you're running these, use the full round rings.

This is learnt from schooling and experience as a mechanic. The ring lands on the piston wear just the same as the rings. I mean if this is just a bandaid fix to get the car up and running, sure, re-ring. It just won't be as good as it could be. Plus, if the OP is pulling the pistons, buying two new, and a whole set of rings, why the hell would cost be cut on two more pistons?

 

[bryanwheat]

This is learnt from schooling and experience as a mechanic. The ring lands on the piston wear just the same as the rings. I mean if this is just a bandaid fix to get the car up and running, sure, re-ring. It just won't be as good as it could be. Plus, if the OP is pulling the pistons, buying two new, and a whole set of rings, why the hell would cost be cut on two more pistons?

There is absolutely nothing wrong with re-ringing pistons and replacing damaged pistons. Your theory about worn ring lands is not really accurate. There will likely be no wear there at all. I've re-ringed engines with 150k miles and the rings fit the pistons as tight as a brand new set of pistons.

 

[rr06rs]

If your ringlands are wearing on your cylinders, you have problems. This is why the rings are there and why there is piston to wall clearance. Ask any race team if they drop new pistons in EVERY TIME they freshen a motor. Better yet, ask a machine shop. I don't know what school you "LEARNT" this at, but you're wrong.

 

[1990AWD]

So you're telling me that a piston NEVER wears?

 

[rr06rs]

So you're telling me that a piston NEVER wears?

Sure it can from piston slap. The skirts aren't what seal the cylinder though. The rings are. Look at the pic above with the fsr pistons. The only part that touches the cylinders a full 360 degrees is the ring. This is why you have piston to wall and ring clearances. If the ringlands rode on the cylinder walls, what would be the purpose of the rings???

 

[bryanwheat]

So you're telling me that a piston NEVER wears?

If the piston to wall clearance is correct and there is always proper lubrication on the skirt of the piston than it will take a long time to wear out. As for the ring lands them selves they will never wear because they do not make contact with the cylinder like the rings do. The gaps on the pistons will likely wear a tad bit over many many miles, but that is measurable and if it is out of spec it would need to be replaced. It is VERY common for someone to replace one damaged piston. Having 3 with 50k miles and one new one won't make the engine run any different or last any less time than with a new set of pistons AS LONG as they are all in spec. This why you measure and inspect everything before deciding to reuse it. IT is also important to note that the top of the piston is a smaller diameter than the skirt area.

 

[1990AWD]

I agree that with proper specs and lubrication, pistons can last a long time, but the piston ring lands WILL wear. I have seen it personally. It is caused by the rings themselves as the rings are a much harder material than the piston. As the piston goes up and down dragging the ring along, the ring switches between riding on the top and bottom of the ring land, therefore wearing off the land. But what do I know, I mainly work with large diesel engines. :rollseyes:

 

[rr06rs]

I have never seen a ring so loose in a ringland that it slides up and down in the gap. That's crazy! I think you're just visualizing the combustion process and trying to stretch at something to support your theory... Why don't you ask how many miles are on some of the peoples re-ring'd and bearing'd blocks and tell me if they're wearing. My block has been through 3 of these processes, has 216k miles on it now, perfect compression, great vacuum, with little blowby, and sees 35lbs of boost, 8500 rpm, from a 67+ lb per min turbo multiple times a day, and makes 587awhp, 462awtq. You tell me how much my pistons are warn. In all these years and miles, I haven't even overbored and my ring gap and piston to wall clearance has only increased ever so slightly do to fresh honing with each freshening of rings and bearings. The amount of wear you're talking about would probably take at least 300k miles of HARD abuse to even be measured!