Hot Rods How much power can be gained with rings?

I'm just a hack and I don't build motors professionally, so anything other than a stock styled ring are out of my comfort zone.

How much power can be had with these new zero gap or low tension rings? Are they worth the hassle for a drag car motor? I tend to run the small cid engines, so every last drop counts.

 

Gapless rings are often used on boosted motors for obvious reasons. I haven't tried them on a naturally aspirated motor.

I like the new plasma moly rings. They are really easy on the block. I don't know that you could measure the difference from cast rings by the seat of your pants, but I imagine that they free up some torque.

 

Here's some good info that have been reading.
http://www.enginebuildermag.com/2011/02/how-piston-rings-affect-horsepower/

Not sure how these gapless rings work.

 

A few years ago we built a small block without the second ring. Used a standard expander on the oil ring but .030 smaller rails on it. In order to keep oil usage low we silver soldered the squirter holes on the rods and ran very tight side clearance on the rods and mains. Fuel pump was used as a vacumn pump. It ran with only 30 psi oil pressure and it ran damn good. but it was towed around at the track and never ran on the street. If you talk to the people who really get into this they will almost always tell you the finish on the cylinders is very important to make power. A friend runs 180 degree water thru his block when it being machined ,especially honing. I think there is a lot of power and longevity in the wall finish and matching rings . My friend pays huge money for his rings. Just my opinion.

 

I've used nothing but Total Seal zero gap rings for almost 20 years (gapless 2nd ring). They cost more but seal so much better. Better sealing means reduced blow by and increased performance. If you're a guy who checks cylinder leakage as one indicator of engine condition, you'll be impressed. As a bore wears, conventional ring gaps increase but not with the zero gap rings. Normally aspirated on gas, or blown on alky. They're my first choice.

 

How do you check cylinder leakage, under racing conditions? I kinda doubt it's the same as the leakage you see on a cold engine that is not running.

 

All hype IMO,
Roundness of bore (at temp) is more important. If the ring gap per app is correct and heat from the engine running closes the gap (but does not butt the ring) to a couple thou or nearly zero, with the piston traveling XXX inches per second, At 1000rpm idle the piston is traveling 10ft per sec and at 8000rpm, the piston is traveling 80 ft per sec. How much comp/blow-by do you lose thru that .002 gap that has a top ring gap and an oil ring gap along with it beside the oil on the cylinder walls at 8000rpm????

 

Back before Total Seal rings, my small Chevy powered Anglia ran the best when the ring ends showed signs of touching.
Now with the various Total Seal rings, I don't have to worry about screwed up cylinder walls from ring ends butting..!

Mike

 

Another thing we don't seem to hear anything about...ring tension...seems to me, that most of the drag on a ring occurs when the piston is near TDC, pressure is high, and the combustion gasses are pushing the ring hard into the cylinder wall (the gas goes over the ring and behind it). calculate the force of the gas at some high pressure, pushing against the area of the back of the ring, which is close to a square inch. That's a lot of force. A thinner ring will have less force on it, hence less drag.

It's an interesting subject. I run old fashioned junk in mine, they seem to work ok, but there are guys going faster than me with modern technology. Everyone draws the line where they're comfortable.

 

I use a sealed pcv system, it basically draws crankcase vacuum from the intake thru a pcv valve. When the engine draws it's own crankcase vacuum thru the right sized orifice, if a cylinder gets hurt you see a reduction in crankcase vacuum. This has worked very well for me, i was able to detect hyper piston cracks before the pistons came apart. When's the last time you caught a broken hyper before it took out the rest of the engine?



This engine had a $100 set of pistons and a $700 super stock style 1.2mm gapless top / napier second / 12lb oil ring set, you can see the groove spacers still in the grooves...



The car only lost a tenth, but lost a lot of crankcase vacuum so i knew it had a cracked piston.



Without the crankcase vacuum, the low tension rings went thru a qt of oil in about 100mi. With 15"Hg of crankcase vacuum drawn thru a pcv valve, it got 800-1000mi/qt.

There is power and efficiency in the ring set. The above short block with low tension rings requires 13ft/lbs to rotate. A short block assembled with conventional rings might require 35ft/lbs to rotate....a 22ft/lb difference. If you are spinning that short block to 7000rpm, that's a 29.3hp difference. If you are cruising around at 2500rpm, that's a 10.5 hp difference. Low tension rings make the engine easier to spin with less hp consumed as friction in the bores. Not only does the engine run cooler, but the bores last longer too. Not much gains in crankcase vacuum by itself, but running crankcase vacuum allows you to enjoy the benefits of lower ring tension than you would otherwise be able too...that's where the real gains are.

 

I'm just trying to educate myself on what's available.

 

""The car only lost a tenth, but lost a lot of crankcase vacuum so i knew it had a cracked piston.""

I assume drag race so when are you measuring vacuum?

 

Been running Total Seal rings in my VW for years; they probably don't make a measurable amount of power for a mild street motor such as mine, but I think they help make more consistent power over the lifespan of the motor.

 

Gapless? Little if any. Skinny, low drag, low tension? A chunk. Enough that I wouldn't be talking about if someone else hadn't already.

And hypers scare the f#ck outta me. I'll admit, I have them in the motor in my truck, but every time I wind it up, I wonder...

 

Total Seal makes a ring and spacer set for Stock Elim racers so you can use a skinny top and Napier second in the stock 5/64 grooves. Nice stuff.

 

So, anything special have to be done to run these? Just add spacers in the ring groove?

 

Over 460 passes on a 477. A leak test showed a worst of 3% or 97 psi cold, the rest 98. That cylinder was cracked (a typical BBC Mercury Marine issue on cyls 6 n 8). I ran Total Seals in that one on TRW slugs with no special prep, just a proper bore finish. My case vacuum was provided by the headers through the valve covers (like smog valves). Strictly drag stuff, nothing exotic, no street time. I'd use em again and never look back.

 

Bill Jenkins claimed they increased oil consumption that a certain amount of blowby was needed to keep the oil ring clear.

 

Pros and cons have been argued for years but my take is that everything is a compromise. If you have deep pockets and are building for that last .1 HP then go with the low friction super duper stuff since you realize it will only last a few passes. If you want a dependable street engine that will get you down the road for years then old school stuff is proven and cheap. It's your call just be prepared to live with your decision.

 

It's not a street engine. Strictly track use.

 

I prefer the gapless rings. I leak my engine on a regular basis. I have seen the difference. I use a deck plate for honing. we also leave the block on the hot tank over night to warm it up before honing. some claim there is distortion when only one deck plate is used. I have to try bolting a plate on each side. some also claim the bolts holding the deck plate on have to match the depth of the bolts or studs used to hold the head on.

 

The Total seal rings have changed greatly since the Bill Jenkins days..! Plus there's many ways to run each of the various styles of ring packages.
Point...they now have rings that will "somewhat..." conform to out of round cylinders..!

Mike

 

They put narrow rings in new hondas.

 

Squirrel has already alluded to it, leakdown numbers dont necessarily correlate to what is actually happening in a running engine. Which isnt to say I dont do leakdown tests, but if you see them as the final word, you are leading yourself down the garden path.
I do agree that gapless rings will maintain good leakdown numbers longer than a cutting edge conventional ring. I am less convinced that a blowby meter on a dyno test will confirm that they are actually sealing the cylinder better under combustion pressure.
Fwiw, Car Craft did a back to back test about a decade back, and gained around 6 hp with gapless rings on a 400+ hp 355, but the whole deal was a bit crude, and not what I would consider cutting edge in terms of cylinder wall prep and so on. Its probably safe to say that a typical hamber might pick up 5 hp with gapless rings. Its also safe to say that if he goes to narrow rings with a napier cut second and a low tension oil ring, and gets a decent vacuum in the crankcase, he can expect to pick up 25hp. So, see post #14

 

might consider gas port-pistons...
in my LAST 283 we had BRC 13.6 to 1's back in 1972...
hi winding little beast it was...

 

It will make power. And reduce top ring life substantially...

 

Most importantly is what the engines intended use, you state for a drag application only. George and squirrel made very valid points about gas porting and ring tension.
As a machinist point of view, a round straight bore is essential as we all agree,mains torqued head plate and a warm block,or hot honed is favorable as well.
Proper finish and break in sometimes out trump the trick parts a lot of the time.
On smaller bores ring sealing is less of a issue than a larger 4.5 and better bores.
A clean chamber is the goal,oiling will promote detonation more so than anything.
So a Napier second is a give in and gapless top is the only gapless ring I would run.
Low tension gains on a small bore are less than a large bore.
Ring flutter on second ring will reduce oil control so larger than top gaps are recommended.
My point being in your application I would focus on a good seal first and low tension second.
Total seal will sell any ring type individually,they will assemble something to fit your bill,just be seated when they give you a price.

 

Reminded me of this
http://www.hotrod.com/articles/hrdp-0910-piston-ring-tech/

 

So what "special prep" are you guys doing to the cylinder walls? I am planning a teardown on the Fly this winter, so I thought about upgrading pistons, rings etc.

 

Solid info there^^. One other thing that bears mentioning, the rpm that the onset of ring flutter occurs at will be affected by the mass of the ring. When the ring unseats in the land, it won't seal. In plain English, skinnier rings will maintain an effective seal at a higher rpm than thicker rings.
We could also talk about "mapping" the bore distortion from underneath with a head torqued on the block, then trying to duplicate the same pattern by varying torque and thread depth engagement with the torque plate attached, but I think that's probably outside the scope of this thread.