I am starting to put my stroker to gether and I was wondering what you guys set your ring gap at.The instructions say .0003 to .0004 for every inch of bore. What do you guys think?

I think I would need to know the piston brand, the ring/bore size, the thickness and style of the rings, the application it's for (street, street/strip, blown, race only etc.)and whether or not any power adders will be used.
for your average street combo .004 per inch is normal for the top ring and .0045 per inch for the 2nd ring.

DRAM has it right, more info is needed.
On my current race motor with a 4.375" bore, hardblock, and other factors; I decided to put the top ring at 0.021", and the second ring at 0.024". I have used tighter in the past with less hp.

OK guys I should have put more info so here goes. 496 stroker Ross Dome pistons around 12.8 to 1 comp. all carb NO SILLY GAS around 610 hp + - a few all race childs and albert rings and I think 3/16 thick. Its 30 over 440. Thanks in advance. Please be quick I need to get this done and to the track at least once and then so I can make it to the Cinn. CC event race

Yes you are right its .003-.004 Im not a machinst and Im old and my finger shook to many times.

HAHA I do have one He went to school for high performce engines I am just checking to get some advice from the brains on this site suggest. There are a lot of very smart people on here and the best part the info is all FREE

use .0045 per inch on the top ring and .005 per inch on the second. that would be roughly .020 top and .022 second.

Who's piston, and are the top rings std ring or gapless type?

With the Ross pistons, using 0.020" on the top ring is pretty normal for a 4.36" bore. You can use from about 0.016 to 0.024" on the second ring with no ill effects. The current performance thinking is about 0.002-0.003" more gap on the second than the top ring.

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Please be quick

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I could have gave you this information a couple weeks ago, but you didn't post the question until the last minute!

i agree around .020 on the top and .022 on the 2nd. should about do it.

I'd use .022 top and .028 second...but that's just me

Ok, I'm confused
Why are we giving the second ring more gap than the top?
Doesnt it affect leak down rates?

Pressure gets trapped between the top and second ring and at higher rpm's this can cause the top ring to unseat if the pressure can't escape. So by running more clearance on the second ring it allows the pressure to escape.

Ok well it seems .020 top and .022 second is the winner. But why does the manufactor say .003 and.004 per inch of bore.The guy I race with says keep them tight and you guys seem to run them a little looser ? Can some one please explane this to an old fart?

Enough said. Thanks again.

as one old f--- to another I use .020 to .022 on the top with any bore over .4.3 and .024 to .028(depending on the exact application of the motor and its induction system or power adders and so on) on the second rings. Looser ia always better than to tight on a race engine, especially on ring gaps! My 512 stroker 400 block (9.25 to 1 comp. on pump gas) makes 609 hp on the DTS engine dyno at 5600 rpm with ported 906 heads.

I'm familiar with the trend to run a wider second gap than the first to keep pressure from being trapped between the two rings. But if you take into account that the top ring gap is going to close up more due to being exposed to more direct heat from the combustion chamber, I'd expect setting the gaps the same should have the same effect once the engine is running.

And why would the gap need to be any bigger than the top gap under running conditions, since the only point of this approach is to make sure there is no excess pressure build-up between the two rings that causes the top ring to lose seal? As long as the running gaps are the same, that should result in an equal sized "path" for any unwanted pressure build-up to escape, right? Any larger gap than the effective running gap of the top ring seems like more than is needed to my way of thinking...

brad, in theory your thoughts have some merit. But, under combustion pressure you don't want equal paths. if that's all you have then pressure builds between the rings and the unseating occurs. you can think of each gap as a restrictor, or orifice. the 2nd needs to be larger than the first to keep presssure buildup down.

Only way to know for sure is try it for yourself!!

I certainly dont get any credit or kick back from anyone so my advice is not biased but hard earned I can tell ya that!

Brian

Very interesting thread

Here is the reccomended gaps from Keith Black Pistons. They say the second ring doesn't need a different gap than the top.

http://kb-silvolite.com/clearance_pop.php

So what brand of rings would you use in a bracket car NA making around 600 hp?

"for a combo like that we would recommend your typical plasma moly ring set. some "brands" are actually made by the same company so i won't get in to the different brands here. some ARE better than others though IMO. the brands that we sell are the very same ones that we use day in and day out with great results."


Thanks, I was hoping that would be the case.
I recently did a budget build up and used Hastings Moly rings and they seem to work fine.

Here is the link to the Speed Pro Link:
http://www.federal-mogul.com/fmeconnect/technicalservices/downloads/1204.pdf

Hastings are TOP NOTCH!

Also you have to see that the material of the rings
are different so it might be thermo/greater expansion

Brad, I'm not sure if I can say it right..but.. If the first gap is just a hair large, becuase you file it for worst case, you will have a small amount of leakage. You also have leakage around ring lads, behind the ring, and a small amount between the wall and ring. Nothing is 100%. So, if a small amoutngets by the 1st ring, you want to make sure it can find an easier path out then by putting pressure up on a ring that isnt designed to seal against that. Think of a damn and a lake. The spillways are much larger than what they will noramlly ever need to pass, because if you were to have a deluge, and limited time for the floodgates to react, you have to be able to pass all out thru one spot..the spillway. In the rings' case, you have a small amount of time to release the pressure bled thru to the second ring. (the piston's upstroke) So you want to make sure there is enough room to get it out. The 2nd ring wil leak all the same ways the top did, but you cant have any pressure between them. So you leave a bigger hole for it to escape.

Maybe the answer is to try and not let any cows in the barn at all, a.k.a. gapless top ring.
but Speed pro says that is just a gimmick and doesn't work as well as a larger second gap.

Brad, all of your questions and concerns were answered earlier in the thread. the only problem i see is your either reading right past it or choose not to believe it.
why do you think speed pro, JE and many other companies tell you to open the 2nd gap larger than the first?

here's a link to an article about it. http://www.aa1car.com/library/ring_end_gap.htm

or maybe read the ring gap recommendations from someone else here; http://www.jepistons.com/pdf/piston_instrc4032.pdf

I'm sure i could find at least a hundred articles like these and if you search long enough i'm sure you'll find something that will contradict them.
i think your barn door and ufo analogy is funny but far too simplistic. real world trial and error makes me do what i do with regard to ring end gaps. I don't know of any other way to explain it to you.

How about this mr.hawk
IT WORKS.........and some of the best in the business use the wider second ring gap w/ great results like...MORE H.P. AND TORQUE!!!

oh, okay brad. i get it now. maybe the pressure is coming from the your UFO ufo or the cow farts. who cares. the bottom line is it works. i told you it works, others told you it works, but that's not good enough for you. i posted articles you could read that tels you it's recommended. you could've even done a little research on your own but NOOOOOOOOOOOOOO. none of that is good enough.
what more do you want? it's 12:21 a.m. and it's dark outside. do you need a good explanation as to how that can be also?

at least Don Hines got his question answered.

Brad, trust me buddy, it works (larger ring gap on the second ring to allow the top ring to stay against the cylinder wall)

Unless you are running significant(over 175ish) quantities of nitrous then the rules are reversed. You run a larger gao at the top ring and smaller on the second. Sorry just felt like

Honestly, I thought it was a no brainer. The larger second ring gap ensures the trapped gasses have a quick exit, and the larger gap allows this. This would essentially be a trade off, a slight loss in ring seal, as opposed to a greater loss due to ring flutter etc.
My
AL...

Guys, it's a mindset thing... what I get paid to do is ask "Why? Why not? Are you sure? How do you know that's the way it should work? Can we do it any differently and improve things?" and then document the piss outta the findings.

Yeah, I've seen lots of people SAY "run wider second gaps because it works", but I haven't seen much / any (or am I overlooking stuff?) documented testing to verify HOW it works, which is what drives my questions. People can draw up one hypothesis after another, but validated test results usually carry a lot more weight for me than opinions.

BTW, nothing that anybody here linked was any more than recommendations as to gap specs, not actual test results.

BTW(2), as I've said many times, I never learn anything the easy way.

BTW(3), 440Jim is supposed to be providing me info re: an article he says includes the type of testing I'm asking about. I'm definitely looking forward to reading it.

this does not show actual test results but here it is anyhow from sealed power

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Notice: Most of the second ring gap recommendations are larger than the top rings. Recent testing has proven that a larger second gap increases the top ring's ability to seal combustion. This larger "escape" path prevents inter-ring pressure from building up and lifting the top ring off the piston allowing combustion to get by. Many engine builders have reported lower blow-by and horsepower gains at the upper RPM ranges with wider second ring gaps. Also, almost every new car made is using this inter-ring pressure reduction method to lower blow-by and emissions and to increase engine output.

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Again, not specific test results, but an article written by a Sealed Power application engineer:

Closing the Ring (Information) Gap
Engine Builders Creating Maximum Power
By Managing Ring Gaps Through Proven Technologies
By Scott Gabrielson

Ask any successful engine builder in NHRA or NASCAR competition about his recommended end gaps for the top and second piston rings and you'll probably hear "no comment." And for good reason.

It's impossible to overstate the importance of running with exactly the right end gap if you're hoping to create a perfect combustion seal over the course of a race, be it a quarter- mile pass at an NHRA track or a 500- mile super speedway event.

The fundamental principal behind maximum ring performance and efficiency in a racing engine is sealing all of the compression with the top ring. This fact is born out through the proven pressure dynamics between the top and second rings:

The top ring is sealed against the cylinder wall and the bottom of the ring groove by the pressure differential created during the piston's combustion cycle. As pressure increases above the ring and between the ring's inside diameter and the piston groove, the ring is forced downward and outward, creating a tight seal over a wide range of engine rpm. Even though it is often called a "compression" ring, the second ring in a racing engine should not be counted on to seal combustion gasses, but simply to scrape excess oil from the cylinder walls. In order to utilize the second ring for additional combustion sealing, it is necessary to virtually eliminate the ring's end gap. This, however, is disastrous from a compression standpoint: With a small (or no) second-ring end gap, combustion gases become trapped between the second and top rings. As the piston moves through its power stroke, these gases will lift the top ring off its land, causing extreme loss of seal and promoting ring flutter.

The secret to more power, therefore, lies in keeping the combustion gases above the top ring. And although many engine builders in NHRA and Winston Cup competition won't share their secrets regarding top ring clearances and end gaps, the optimum approach can be found simply by relying on a world-class ring supplier that partners with winning teams.

Fact: There are No Shortcuts

Needless to say, the top ring in a racing engine is required to withstand considerable abuse, in spite of the fact that the rings typically are becoming thinner and lighter to minimize frictional horsepower loss.

The best top-ring technology in today's ultra- high-horsepower engines features a one-piece design utilizing high-strength ductile iron with a plasma-moly facing material. The ductile iron material provides the strength and resistance to detonation required in a racing engine.

The plasma- moly facing has a high melting point to resist scuffing, and a controlled application process that enhances ring lubrication. Some manufacturers use an advanced plasma- moly formulation that also has higher bonding strength to resist flaking and ensure extended face life.

Of course, the optimal top-ring end gap for maximum sealing performance is near ze ro when the engine is at normal operating temperature. The trick comes in determining the best installed ring gap, which, as the engine heats up, will close to provide a complete seal. The correct installed gap is a function of the bore size, piston, ring groove location and operating temperature at the top ring.

Are Gaps Really Necessary?

Is it possible to achieve maximum top-ring sealing with a ring that has zero installed end gap? Not as this technology exists today. One recent zero- gap-type top ring design is comprised of two individual pieces - a high strength ring with a separate steel oil rail-type piece sitting within a counterbore. These pieces are positioned so that their gaps are staggered, thus the claim that they have no installed gap.

This approach offers several concerns: Because the ring is in fact two pieces, both must somehow maintain identical contact with the bore in order to seal properly. If the pieces act independent of one another - which is likely in a high-rpm, high- heat environment - ring face contact would not be consistent and sealing performance would suffer. In addition, if the two pieces perform independently, their respective gaps could become aligned, creating a wide escape path for combustion gases.

In truth, the development of a zero-gap-type top ring begs the question: Why would you then need a second ring that has zero installed gap? The latter technology, which has been available for several years, employs a similar two-piece approach. This configuration has received exhaustive study by many of the best-known engine builders in NHRA and NASCAR competition, virtually all of whom have found that this type of second ring offers no performance advantage. The reason, again, is the potential for trapped gases between the top and second ring to lift the top ring off its land. The development of a top ring with zero installed gap, regardless of its manufacturer's claims, is an acknowledgement that the combustion seal in a racing engine must be at the top ring.

Why do these zero-gap-type rings exist? Because it's a free market, and manufacturers can create and promote their ideas as they wish. The question, however, is if this technology were really valuable, why wouldn't the world's largest ring and engine manufacturers offer it?

The answer is simple: real- world testing by these manufacturers- and racing teams -- shows that this approach is not consistent with good ring dynamics and engine performance. At the very least, you owe it to yourself to ask for certifiable test results from any manufacturer that claims to have a "new" solution to combustion sealing. Ask successful performance engine builders whose rings they use in their racing motors.

What's Right for Your Engines? Our company and others offer detailed ring gap specifications/recommendations for a full range of applications. These recommendations are developed through input from thousands of customers and real-world situations. If you rely on piston rings from a major, global manufacturer that has an extensive presence in NHRA and NASCAR competition, you can be confident that the materials and designs you use represent the best technologies available.

When it comes to choosing the right end gaps for the top and second rings in your engines, use the manufacturer's recommendations as your guide. Again, the key objective is to achieve near- zero top ring end gap under real-world (racing) operating temperatures.

If you're looking for short-cuts for more power through a new ring technology, they don't exist. The best engine builders focus, instead, on perfecting the fundamentals of racing-style rings - choosing the right materials from the best-known manufacturers and adapting these technologies to their engines. You can - and should - do the same.

Scott Gabrielson is Sealed Power piston ring application engineer for Federal-Mogul Corporation. He works with dozens of racing teams in identifying the best ring technologies for championship performance.

i was going to mention that the second ring is normally referred to as a scraper but figured that would only open up another can of worms.

"Wanted: UFO ship, of suitable size, to force flagulent cows thru small barn roof openning. Must be capable of holding 60 cows, and posess the equipment suitable for the rapid deployment of said bovines."

I'll put that in the "wanted" ads..My barn is small, maybe it will work for me to quantify the results.

JK Brad...Some of the best quotes from leading engineers is .."why?" of course, that also makes them pretty irritating.

The documented test results were published in Chevy High Performance magazine, with info credit to Sealed Power. Contact the magazine for a back issue of the copyrighted article.

I don't have any more detail.

Well, I bring this old thread back up because I'm in the process of filing rings and remembered this thread so I got curious and called the tech people at Childs & Albert whose rings I'm using and asked. Well, to no surprise he said this was all urban myth, blind leading the blind, yada, yada. To stay with thier recommendation of .004 top and .003 second. Interesting.