Ring Pack Thickness: Question

[skinny z]

I've read some dyno results. Magazine published stuff when there were magazines. Some other anecdotal reports as well.

The question is, what's the real scoop on going from a 5/64ths ring to a 1/16th?

Horsepower gains from reduced friction stand out as the obvious benefit. And I suppose that friction is present at all RPMs.

Is there more to it than that?

I've received advice, from both here and elsewhere, that say make the move to thinner rings.
I'd like to heed that advice but I'd still like to know what kind of margins I'm looking at.

[Little Mouse]

Huum once read that 70 percent of friction in an engine is caused by the rings. So going to very thin modern rings of today no doubt a food thing.

[Little Mouse]

Huum once read that 70 percent of friction in an engine is caused by the rings. So going to very thin modern rings of today no doubt a good thing.

[skinny z]

Now, if thin rings allow the rotating assembly to spin like this, I'm all in.

https://www.youtube.com/watch?v=2aYJxjp0src


But, I believe that's a Super Stock engine by Patterson. Certainly more to it than the ring pack. Like $45000 more.

That said, were talking 1/64" in the difference. It counts for something but again, how much?

[ClassAct]

Now, if thin rings allow the rotating assembly to spin like this, I'm all in.

https://www.youtube.com/watch?v=2aYJxjp0src


But, I believe that's a Super Stock engine by Patterson. Certainly more to it than the ring pack. Like $45000 more.

That said, were talking 1/64" in the difference. It counts for something but again, how much?

Friction is heat. More friction is more heat, and it shows up in oil temps.

Thick rings dont seal worth a crap.

There is no reason to even use a 1/16 ring any more. It’s a waste of power. I don’t put much into rollover torque on an engine that isn’t broken in yet, but that’s a different topic.

[skinny z]

There is no reason to even use a 1/16 ring any more.

Did you phrase that correctly?
1/16th compares to 1.5 mm.
How much thinner do you go? 1 mm?
I've seen as thin as .8 mm but I'm thinking that's getting outside what's workable in an everyday (or nearly so) application.

[rfoll]

"There is no reason to even use a 1/16 ring any more. It’s a waste of power." It has always been my understanding the thin rings don't last as long. The auto manufacturers started using them when the fuel injection allowed them to make the rings last longer. The ultra-thin rings and pistons cost more. What is that last few horsepower worth to you on a street driven car?

[Racer97]

I have 2 880 block sbc engines one has the Vortec factory pistons and the other has the 802 crate pistons. The factory Vortec block rotates without much effort. The 802 piston block is noticably harder to rotate. I'm sure there would be a power loss because of the drag.

[Racer97]

Sorry 604 crate

[RDY4WAR]

"There is no reason to even use a 1/16 ring any more. It’s a waste of power." It has always been my understanding the thin rings don't last as long. The auto manufacturers started using them when the fuel injection allowed them to make the rings last longer. The ultra-thin rings and pistons cost more. What is that last few horsepower worth to you on a street driven car?

They're not that much more expensive. If you buy a decent set of hyper pistons and a decent 5/64, 5/64, 3/16 ring pack, you're only a couple hundred off the price of a set of Mahle Powerpak pistons which come with a 1, 1, 2 mm ring pack, are 4032 forged, and a much, much lighter including a lighter pin. In fact, the little bit of price difference would probably end being spent anyway on mallory to balance to cheaper, heavier pistons and rings.

For a street car, thinner rings are still going to seal better meaning less oil transport into the chambers, less blow-by into the oil, less soot and coking, etc... plus less friction means less heat. There's not really a downside. I think any reduced ring life would come from gas ported, low tension rings that you wouldn't want to run on the street anyway.

[skinny z]

"There is no reason to even use a 1/16 ring any more. It’s a waste of power." It has always been my understanding the thin rings don't last as long. The auto manufacturers started using them when the fuel injection allowed them to make the rings last longer. The ultra-thin rings and pistons cost more. What is that last few horsepower worth to you on a street driven car?

Understood. Still it seems to be the trend, street driven or otherwise.
But, what's it worth?

It wouldn't be the ring thickness that's a game changer for me. But the compression height of the piston my "engine guy" suggested (and only suggested as a starting point) wasn't what I was looking for. A substitute piston with the correct height comes with the thinner rings. (ICON 9929 vs Wiseco PTS503A4)
So, this thread exists because of that.
It all comes down to availability at this stage of the game. I'll take what I can get more or less, but if I can refine things somewhat, and the thin rings are part of the deal, then that's what it'll be.

Subject to change without notice...

[skinny z]

I have 2 880 block sbc engines one has the Vortec factory pistons and the other has the 802 crate pistons. The factory Vortec block rotates without much effort. The 802 piston block is noticably harder to rotate. I'm sure there would be a power loss because of the drag.

There's more to it than the rings obviously, but what do those two particular engines come with in original trim?
I was under the impression the Vortec would have 5/64ths? It is from the 90's after all.

[skinny z]

"There is no reason to even use a 1/16 ring any more. It’s a waste of power." It has always been my understanding the thin rings don't last as long. The auto manufacturers started using them when the fuel injection allowed them to make the rings last longer. The ultra-thin rings and pistons cost more. What is that last few horsepower worth to you on a street driven car?

They're not that much more expensive. If you buy a decent set of hyper pistons and a decent 5/64, 5/64, 3/16 ring pack, you're only a couple hundred off the price of a set of Mahle Powerpak pistons which come with a 1, 1, 2 mm ring pack, are 4032 forged, and a much, much lighter including a lighter pin. In fact, the little bit of price difference would probably end being spent anyway on mallory to balance to cheaper, heavier pistons and rings.

For a street car, thinner rings are still going to seal better meaning less oil transport into the chambers, less blow-by into the oil, less soot and coking, etc... plus less friction means less heat. There's not really a downside. I think any reduced ring life would come from gas ported, low tension rings that you wouldn't want to run on the street anyway.

That's all on the positive side for sure.

This engine, when first put together 20 years ago, had a balance job that included a couple of slugs of heavy metal. The rods are Elgin forgings from back in the day and I'm going say they're plenty chunky.
The originally installed Speed Pro hypereutectic piston and pin as an assembly are topping out at 712 grams.
The ICON forged piston that first came up in discussions are lighter by 35 grams. Not sure how that'll shake out or if it'll require rebalancing.
Don't have a weight for the Wiseco.

I'll look into the Mahle Powerpak since the option is still open.

[F-BIRD'88]

I'd spend the money saved on a roller cam.

[skinny z]

It'll be roller again whether there's any savings or not.
Losing a link bar ( if that was the first step of destruction with the COMP roller and their short travel lifters) doesn't leave much to work with. I've got seven lifter sets remaining (as in seven cylinders worth) and they'll be going in the bin. Or if someone has more risk tolerance than I do, maybe there's a market for them.

If all goes according to plan, it'll be a Jones hydraulic roller and lifter setup along with the PAC springs Mike suggested.
That'll eat up a chunk of the budget but if you want to play you gotta pay.

The shortblock should come in under half of the forged 383 I'd planned with a board member here. Maybe I can translate that into the savings.