Low tension rings- How much HP & MPG are they worth?
 

Years ago I read about the many improvements in the LS1, on how the ring tension was lower than other car makers would dare try. This gave a significant power advantage and better mpg.
Anyone try them;dyno them;see a dyno comparison? or any mpg info?
:cheers:

Most drag (friction) comes from the rings. Anything you can do to reduce drag will improve efficiency. Thinner rings in stainless with less radial thickness are the trend in the OEM so I'm sure they have the data to back it up. I'm not talking about gas port or rings intended for a race application. Those are very different and should not be used on a normal street engine.

Low tension rings
 

My 2001 C-5 convertible came with low tension rings from the factory. Although I do not drive the car a lot, (16,000 miles since 2002), I found it would use a little oil between oil changes which were usually about 2000-2500 miles apart. I would change the oil once a year to keep the warranty valid, and my engine was using about 1 quart between changes. I then learned that Chevrolet had a service bulletin on the oil consumption, and they would change the rings if I complained. Although it kinda pissed me off at first when I learned the reason of the oil consumption, I decided that instead of the dealer replacing rings in my new car, I would just add a little oil now and then. I will say that the engine runs fantastic and maybe it is a little faster because of the low tension rings. I found out that in 2002 the Corvette engines had different rings installed at the factory, maybe because of the oil issue in the past. By the way, I never see any exhaust smoke, only a little black on the chrome exhaust tips. Since the car runs so strong, I have just decided not to worry about it and just add a little oil every now and then.

afaik, in last 10-15 yrs, every/all motor regardless of make has OE thin lower tension ringpak.

iron head vortecs 4.3L v6 & 5.0/5.7L v8 have lower tension ringpak, narrow too 1.5mm,1.5mm,3mm. zillions in vans & trucks. They work great over about 13-year history. And, those I've pulled apart show markedly little bore wear.

Lower tension rings can work because of better bore machining/honing techniques that yield straighter bores, w/ tighter tolerances & better control of hone-pattern/finish. Simply slapping a thin aka lite ringpak in a bore that's prepped the old way won't last long.

jackson
thanks for your reply.
is a sunnen CK-10 w/honing plate sufficient?
any comments on bore finish? fine? mirror?

When I built my new engine I set it up with 1.5mm,1.5mm,3mm low tension thin ringpak. That was 5 years ago with no issues. I wish I could give you HP numbers though as I dont have them.

If your using synthetic oil I understand it won't show smoke out the exhaust so if thats true that could be the reason.

Hone plate required. CK10 aok ... but any tool must be well-maintained. The finish depends on what type stone is used ... not simply grit but what stone's made from. What ring is made of/faced with has everything to do with desired finish. Follow ring manufacturers' MOST RECENT recommendations. It's not rocket science but there's MUCH more to it than a plate & finish. One thing I've seen that seems helpful is ... after honing ... say the stone hone WAS turning clockwise ... go in afterward with a flexbrush hone and turn it counterclockwise a few strokes ... in reverse of what stone had turned. This helps knock off the high spots & helps create a desired plateau finish. Too shiney is bad; won't hold enough oil.

also, take a look at articles such as these three:
http://www.enginebuildermag.com/Arti..._finishes.aspx

and:
http://www.enginebuildermag.com/Arti...d_sealing.aspx

and:
http://www.enginebuildermag.com/Arti...rformance.aspx

from a whole host of ring articles here:
http://www.enginebuildermag.com/Sear...rm=piston+ring

lotsa good, reliable pro tech info in engine builder mag ... but you probably won't find it at a newstand ... it's a pro trade mag; your local machine shop probably has a free subscription. If ya really wanna know about rings finish etc ... there's plenty at ebm to keep you busy ... & pretty good concensus too ... unlike too many threads here.

fyi ... thin ring can mean two things ... how wide the ring groove (Y) is & how deep it is (X) ... ring depth on ring referred to as "radial thickness" ... that's become thinner also.

more hp & mpg ... yes ... how much, I dunno ... but nowadays they've all got thin OE ringpaks ... less friction.

They claim 70 percent of friction in an engine is caused by the rings
using at least thinner rings makes good sense.
mahl piston and ring sets come with 1.5 thin rings for a good price.

Think how much easier it is for the oil pump to pump thin syn oil.

:thumbs: i read the 1st 3. i see there is plenty room for improvement on my rebuilt in '94, '74 355. It is an old school set-up, forged LT-1 pistons w/ 5/64 rings, medium tension. It has SpeedPro R-9343-035 rings, .012" gap on top. I went too far on 3 of the 2nd rings, to .015", that turns out to be better than the .012 on the rest :lol:
I liked the 4cyl 0.8 top ring - 62 mpg :eek: i guess with a v8 i'd be lucky to get 31 mpg :D
I get 18-19 mpg now w/4.11, so i'm not complaining.
Thanks for all the links! Great reading for any gearhead!

yep, 2'nd gap wider than top gap is SOP todayright, seems you got great results no matter how you got there.:thumbs:

Thanks for that piston info!
My 61 engine only has 7k on it, bored 030 on a CK-10 honed to a fine finish w/hone plate. Do u guys think a hand hone would be good enough to try a low friction ring set up? Using some oil is not a problem, i only go 500mi/yr.
If i could get mpg into the 20's i maybe could make some wager money, and pay for the pistons :lol:
some guys here think efi is needed for good mpg. i think is is more from efficiency.
Thanks guys for giving me a new project to think about! :cheers:

In your conditions-usage only ... 500 mi/yr & oil-drinker ok ... I say go ahead & try it ... but otherwise, No.

Before it's honed but with hone plate torqued to that block, I'd be interested to see bore taper data. It may or may not remain straight.

FWIW, my hi-po street 427 BB makeover is getting standard tension 1/16" top and second rings (moly/iron), and will be honed (should clean up at .005" over) with proper plates and studs. As I'm not trying to squeeze every last ounce of power out of it and don't plan on tearing back into it for at least 20,000 miles (and plan to put more that a handful of miles on it each year), I'm not willing to experiment with thinner and/or lower tension rings. On the other hand, if I were building it up strictly for track days that might well be a different story.

:cheers:
TSW

I am looking for a way to compare engine friction.
I checked with a tq wrench on front of the crank, takes 60# to slowly move 1/4" cold, same hot.
I plan to look for some circle track "claimer" pistons. I want to bump up from 9.7 to 10.2-10.9 and use hi-test instead of 87. And use low tension rings, as thin as available. I see it has blow by at 200F, so i see it really should be hot-honed :cheers: