300WHP Supernatural 3.XX Coming Soon! (Page 10/54)
Will MAR 18, 08:42 AM

quote
Originally posted by La fiera:

Well with the higher comp ratio the thicker rings can take more abuse over a longer period of time. Also they flex less under higher compression ratio.



Rings don't "flex" unless the piston flexes, but they can twist in the grooves if the side clearance is too wide.
Cut side clearance down to .001 and thin rings work better than thick.

[This message has been edited by Will (edited 03-18-2018).]

La fiera MAR 18, 08:44 AM

quote
Originally posted by mender:

Endurance road course. Chumpcar (now Champcar) to be precise. The double row timing chain installed during the rebuild was starting to get loose and the valve guides and seals were also worn but the ring and valve seal were where they started.




You mean the Cloyes Double row chan stretch in that little time?!! Wow!
Will MAR 18, 08:47 AM

quote
Originally posted by mender:

Lower drag from the ring package is free horsepower.




A thin ring (especially gapless!) with lateral gas ports can seal BETTER than a thick ring under a wider variety of operating conditions. Not only is the reduction of drag a reduction of frictional parasitic loss, the better ring seal results in a higher IMEP... the engine actually *makes* more power in addition to reduced parasitic loss.
Will MAR 18, 08:54 AM

quote
Originally posted by La fiera:

You mean the Cloyes Double row chan stretch in that little time?!! Wow!



Porsche has studied engine wear and found that 1 mile of racing use puts the same amount of wear on the engine components as 1,000 miles of street use.
When you compare that to the fact that 24 hour endurance cars cover 3,000 miles in a race, you can gain an appreciation for how tough Porsche engines are.
La fiera MAR 18, 09:50 AM

quote
Originally posted by mender:

Lower drag from the ring package is free horsepower.




Totally agree amigo!
But with today's Tribology breakthroughs there are ways to mimic and improve the low drag from any ring package.
La fiera MAR 18, 09:55 AM

quote
Originally posted by mender:
Endurance road course. Chumpcar (now Champcar) to be precise.



Got any in-car videos?! I'd like to see those. I did a Chump Car 24h race a couple of years ago and that was awesome!
mender MAR 18, 10:17 AM
This is the start of the race we won at Spokane. Green flag at about 14:00 and pass for the lead at 27:30.
https://www.youtube.com/watch?v=pDcr5-I33WU
That was my co-driver's first road course race and you can see that he backs off several times just before the main straight, making it much harder for the Fiero to out power the other car. He also overrevs the car on his downshifts; memory tach read 6600 rpm, fuel cut was 6300 rpm and shift light was 5500 rpm. After seeing the video and a short conference he worked hard on getting that under control.

And this is the middle of a run at the Ridge. That was where the MAF was causing extreme lean conditions, engine backfired hard and broke one engine mount and also the exhaust. This is after chaining the engine down and welding up the exhaust. I called it after pulling a spark plug and seeing some pepper on the insulator.
https://www.youtube.com/watch?v=mXPu2cp_LPQ
Same driver, still downshifts too early and drags the engine rpm up past the 5500 mark but not as bad. The worst was a rental driver that missed a downshift and spun off into the gravel at Laguna. Memory tach read 7600 rpm after that one. We had the fastest lap of the weekend but couldn't seem to stay on track for more than a couple hours at a time from self-inflicted issues.

I have more video but haven't put it up. I think there's another of my other driver but he was pretty slow.

[This message has been edited by mender (edited 03-18-2018).]

mender MAR 18, 10:31 AM

quote
Originally posted by Will:


Porsche has studied engine wear and found that 1 mile of racing use puts the same amount of wear on the engine components as 1,000 miles of street use.
When you compare that to the fact that 24 hour endurance cars cover 3,000 miles in a race, you can gain an appreciation for how tough Porsche engines are.


I guess we did okay then.

Average speed for those racing hours was about 70 mph so close to 6,000 racing miles on a lowly GM engine.
Blacktree MAR 18, 11:09 AM

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Originally posted by mender: The trend now is toward thinner rings so that they seal better by conforming to the cylinder wall and have less friction. A win/win.


Yep, and this is a decades-long trend. If you look at the 60-degree V6 family, you'll see the piston rings become progressively thinner as the years go by (while the compression ratios and power outputs go up). If you dig back through history, you can see the ring thickness gradually shrink from 1.5 / 2.0 / 4.75mm down to 1.2 / 1.5 / 3.0mm. (top ring / second ring / oil ring).

The GM High Feature V6 takes that trend even further, with 1.2 / 1.5 / 2.5mm rings. And just to put things in perspective, the 3.6 liter V6 in the 5th-gen Camaro was rated for over 320 HP.

Side note: I think it's great that we can talk all this "engine geek" stuff in this thread.

[This message has been edited by Blacktree (edited 03-18-2018).]

mender MAR 18, 07:03 PM

quote
Originally posted by Blacktree:

Yep, and this is a decades-long trend. If you look at the 60-degree V6 family, you'll see the piston rings become progressively thinner as the years go by (while the compression ratios and power outputs go up). If you dig back through history, you can see the ring thickness gradually shrink from 1.5 / 2.0 / 4.75mm down to 1.2 / 1.5 / 3.0mm. (top ring / second ring / oil ring).

The GM High Feature V6 takes that trend even further, with 1.2 / 1.5 / 2.5mm rings. And just to put things in perspective, the 3.6 liter V6 in the 5th-gen Camaro was rated for over 320 HP.

Side note: I think it's great that we can talk all this "engine geek" stuff in this thread.



Yup, my Fiero has the LFX 3.6 sitting in place now, just waiting for some spare time to do the final wiring. I've been impressed with GM lately, their recent production line stuff looks a lot like the race stuff I was doing only a few years back!

And yes, geeking out on engine tech is always fun. So what's the deal on tribology and rings?