Ring gap question
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Ring gap question
Anyone see any issue with running 21 top, 23 second ring (Iron/napier)on a stock cube LS1 forged short block for the street running 12-14lbs boost?
I was a little concerned with the ring gap mentioned by the builder, so I researched it to death and am seeing a trend to a .0050 top and .0055 second x bore.
Not wanting to second guess, but I don't want a street engine engine with a bunch of blow by.
Thoughts?
I was a little concerned with the ring gap mentioned by the builder, so I researched it to death and am seeing a trend to a .0050 top and .0055 second x bore.
Not wanting to second guess, but I don't want a street engine engine with a bunch of blow by.
Thoughts?
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
By 21 and 23 do you mean .021/.023"? Below are Wiseco's recommended gaps although the formatting got jacked up on the paste.
Top ring2nd ringOil railMost standard engines 0.0040.0050.015Modified engines or Nitrous Oxide 0.0050.00550.015High performance racing 0.00550.00530.015Racing with Nitrous / Turbo 0.0060.00570.015Blower / Forced induction 0.0070.00630.015
Then you multiply the number by the bore size.
Top ring2nd ringOil railMost standard engines 0.0040.0050.015Modified engines or Nitrous Oxide 0.0050.00550.015High performance racing 0.00550.00530.015Racing with Nitrous / Turbo 0.0060.00570.015Blower / Forced induction 0.0070.00630.015
Then you multiply the number by the bore size.
Last edited by 5 Liter Eater; Jan 9, 2014 at 10:30 AM.
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
I tried to get info to contact the ring manf., but the builder says he used diamond pistons and rings made for him, and did not seem to want to give out the actual manufacturer. I spoke with Diamond and they said the same (talk to ring manufacturer, but did give out the .021/.023 recommendation IF it was his car)
I don't have the paperwork since it is a build.
5LE
It's .021 and .023, just taking a shortcut typing.
I sent the builder the Wiseco site recommendations, but he will not stand behind the motor if he runs that so I can't risk it.
Another builder recommended .017 / .019, which almost seems TOO small.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
I think .031 is too much, but a couple thousandths isn't going to exponentially increase your blow-by. I like to run on the top end of the recommended gaps because you butt rings once and you're done.
Factors that affect the ring gap. The bore size, the ring material, any ring coatings or treatment, how far down the top ring is from the top of the piston, how much heat it will see (nitrous, boost, fuel type etc.).
Factors that affect the ring gap. The bore size, the ring material, any ring coatings or treatment, how far down the top ring is from the top of the piston, how much heat it will see (nitrous, boost, fuel type etc.).
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
.031 seems a litle big. And .021 seems tight. Per Wiseco for FI they should be .028/.025 but that seems like an old guideline as it's not thought the second compression ring should be larger than the top, so I donno.
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Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
The Wiseco website I looked at had .0050 first, .0055 second x bore size for street boosted engines, so around 19/21.
I would be very comfortable with 22-23/24-25, but if I recommend that to the builder and anything happens, it will put me out of commission for a while.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
What do you think about the total seal rings? Someone had mentioned going with total seal, but I had read some bad reviews on them AND I don't see many guys posting them in their builds.
The Wiseco website I looked at had .0050 first, .0055 second x bore size for street boosted engines, so around 19/21.
I would be very comfortable with 22-23/24-25, but if I recommend that to the builder and anything happens, it will put me out of commission for a while.
The Wiseco website I looked at had .0050 first, .0055 second x bore size for street boosted engines, so around 19/21.
I would be very comfortable with 22-23/24-25, but if I recommend that to the builder and anything happens, it will put me out of commission for a while.
Wiseco is running nitrided steel rings. Not the same as the ductile iron TNT ring you've got. I've known of the head machinist at Thompson for a long time if it's still Trevon. He's no spring chicken and no idiot. They're in my back yard, been building motors for a while and I haven't heard anyone raising hell about them yet. Although the gap is higher than I would do, I think (hope) you might be surprised at how little a few extra thou matters on your blow-by.
Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 408
From: Montreal
St. Jude Donor '13
I am far from an expert, and don't know if ring gaps are different from and LS1 to and LS2, but I will throw this out there.
LME, who seems to know what they are doing, used .023 / .025 on my forged short block built for boost. Its working perfectly with no blowby. Stainless top ring, napier second.
LME, who seems to know what they are doing, used .023 / .025 on my forged short block built for boost. Its working perfectly with no blowby. Stainless top ring, napier second.
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Pro
Joined: Nov 2007
Posts: 661
Likes: 2
.23/.25 for ls1 bore...people with this setup making over 200hp/hole, could go smaller for a little less power though. "build it too tight and everyone will know, build it too loose and you'll be the only one who knows."
sidenote: I think crank case vents are often overlooked on 90% of the builds in this forum.
sidenote: I think crank case vents are often overlooked on 90% of the builds in this forum.
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
It is common knowledge that all the risks are building them too tight. And there is no generic answer, so usually it is best to follow the manufacturers instructions.
As for never have the 2nd gap larger....will if you use gapless top, 2nd gap will always be larger.
So not sure how Total Seal could make a comment like that, although maybe their comment was about a specific ring set ?
As for blowby, if you have it, I really cant see it being down to ring gaps. It's nearly always ring/bore seal. The gap, even a large one is miniscule by the time it passes by the ringsets.
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
The radical part is the fact that everyone that post (especially me) is concerned with gap, in regards to blowby, and anything in the .030 range is seen as too large, while this says gaps even in the .045 really had no more blowby than .015.
The builder said "total seal brand steel rings", so I don't think it is their gapless ring (I have asked him), and if that is the case, it DOESNT show a .070 on the website
In regards to venting crankcase. All I am running is "vents" and it concerns me when a builder says I will need to run a vacuum pump on the build (new engine)
What rings are most guys using on blown applications?
The builder said "total seal brand steel rings", so I don't think it is their gapless ring (I have asked him), and if that is the case, it DOESNT show a .070 on the website
In regards to venting crankcase. All I am running is "vents" and it concerns me when a builder says I will need to run a vacuum pump on the build (new engine)
What rings are most guys using on blown applications?
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Total make a huge range of rings, all come with instructions relevant to them.
They do conventional rings, gapless top, gapless second and any appropriate combination of them ( never both gapless though )
As for "need" to run a vacuum pump....what sort of power are you expecting ?
When you get to the stage of needing a vacuum pump....I'd say you'd need to be pushing pretty damn hard, ie well into 4 figures.
They do conventional rings, gapless top, gapless second and any appropriate combination of them ( never both gapless though )
As for "need" to run a vacuum pump....what sort of power are you expecting ?
When you get to the stage of needing a vacuum pump....I'd say you'd need to be pushing pretty damn hard, ie well into 4 figures.
Burning Brakes
Joined: May 2011
Posts: 1,216
Likes: 56
From: Houston Texas
Different ring materials are going to have different growth rates. There is not a one gap fits all. I would speak with the piston/ring manufacturer and go with that recommendation. A machine shop isn't going to have that data unless they've got it from the source. So again, all back to the manufacturer. I'm with Bret on the gap, I would prefer to be on the big end then close a gap. New rings are cheaper than new block/pistons/rods or more from closing a gap.
I used the Mahle recommended rings from them for the custom 2618 turbo pistons of theirs i'm using. I'd have to look back through notes, but 4.007" bore and I want to say they had me gap at .028" on top for 1000+whp. Smaller on second ring.
I used the Mahle recommended rings from them for the custom 2618 turbo pistons of theirs i'm using. I'd have to look back through notes, but 4.007" bore and I want to say they had me gap at .028" on top for 1000+whp. Smaller on second ring.