Ring gap n2o

Hey guys, got my rotating assembly to the shop and was wondering about how to set the ring gap. Je says .0045xbore for street strip and .0070 for nitrous race.
It will be a street strip N/A motor with the intent to drop a 100-125 shot of juice in it now and then. Here's the setup
383 .030 over
Arias pistons 10.75-11:1
Je rings
Stock rods with arp bots
Stock forged crank
Mopar .590 cam
Fully ported 452 heads
Street dominator intake
No carb yet

If you are going to spray it, gap it for spray. You don't want a ring to butt up.

Well for that little NOS use you could get by with no extra I have sprayed way over 500 on a 440 with .022 top
These days NOS means multi stage and gobs of gas so that .007 is right for Street Outlaw kind of blast but...for what you want to do no big deal set it about .020-.021 top and let her rip never look back--
I still say that for decades strong race engines ran with tighter second ring gaps--these days they say open second ring to reduce flutter--OK OK it may flutter at 7500 -9000 RPM but IMO it ain't no big deal on a street strip Mopar of average build--I like to keep second ring tight
I can honestly say it "may " make a difference on a high winding big RPM ball buster engine but on average I think keep em tight and go on with it!
And the secret to the .590 is where you degree it in--done right it is one of the best all time Mopar grinds ever made--For a drag only we like that cam in samller inch at around 100-101-- and about 105 in a 500 plus inch--
do that and it will yank the slober out of your mouth! Retarded that cam is a noodle! Trust me in your CI I would install it at 100-101--
You will not need that NOS if you have the right converter and have enough gear!
Good Luck!

Car has 3.91s in it now with 4000 converter, and I was planning on putting cam in at 102 if I could, well see how advanced I can go depending in piston clearance.

And thanks for the feedback guys

The only thing is with nitrous and boost, many say they will always run this amount or that amount. It's too easy to turn it up so almost everyone ends up trying it. I wouldn't go all the way up to the .007 since that is on the extreme side and probably only needed for a huge shot like mentioned. Maybe split the difference just in case you spray more??? This is probably my thought process since I had rings gapped for something mild and got greedy. I had a couple rings butt and it popped two pistons apart. Crabman seems very knowledgeable from posts I've read so listen to him. I'm just saying never say never as far as trying more than you anticipate.

So .0045 is roughly .020 so what If I used both your advice and I went .023 top ring and called it a day. What about the 2nd ring?

As mentioned.........while you might START with a 150hp shot or so, they will inevitably get bigger.

I would consider .023 to be a little too snug. I am also one of those who gaps the seconds wider than the tops.

You didn't mention ring material, but if you intend to spray it, don't use plasma-moly coated rings

Thanks for chiming in Monte, the rings are ductile iron with moly coating.... And I don't think I'd ever go over 100-125 with this setup

Monte
Would you expand on staying away from plasma-moly coated rings please. I am doing a refresh this winter and would have made this mistake. I am relatively new to nitrous and not spraying a lot. Thanks again for the free refills at DW.
Ross

Plasma-Moly is a coating on the ring. That said, at some point or another, that coating WILL flake off in spots and reduce ring seal. Nitrous use, will greatly speed up this flaking off process. Guys can talk all they want about proper tunes, not rattling the motor, small shots, etc, etc, etc, but the fact remains, you WILL flake if off in a nitrous motor, don't care how small the shot is. When the moly flakes off, you have a ring seal loss. Ring seal loss in a nitrous motor, no matter how small, is BAD news. Oil allowed into the combustion chamber, will dilute the octane rating of the fuel as much as 50% and it takes VERY little oil for this to happen. In plain English, your 110 octane fuel, becomes about 50 or 60. This now makes your(even small) nitrous sprayed engine WAY overtimed and results in hurt pistons.

Nitrous is NOT what tears up motors. Poor tunes and poor preparation is what tears up motors

^ well that puts it into perspective

Moly rings, in my opinion are a way overhyped product. There is no such thing, AS a Moly ring. It is simply a coating that is placed ON the ring and that ring is usually made from ductile iron. They are promoted for the lubrication purposes of the Molybdenum coating and the fact they seal quick and well. Now, do they seal any quicker or any BETTER than just a quality ductile iron ring......NO. And how much extra lubrication do you need on a surface coated with oil.

Rings are typically made from 3 materials. Cast iron, ductile iron and steel. While the "tool steel" rings have a reputation of being hard on bores, being for race only, etc............the fact of the matter is that likely 95% or more of new car engines, COME with steel top rings these days. So much for the "wears the bore" argument.

So what do YOU need is the question. The top rings primary function is to seal the combustion. So the more power you make, the more durable this material needs to be. For most applications, a ductile iron ring does the trick, just what grade is the question. The vaunted "Hellfire" ring, is in fact ductile iron, just a different grade of it............so obviously ductile iron will be fine in a most any application. The second rings job is about 80-90% oil control and 10-20% assisting the top ring in sealing the bore. So after addressing the oil/nitrous mix issue in my previous post, it becomes apparent that the SECOND ring and it's material is the REAL important choice here. For a nitrous motor, I like a "napier" ring. This is NOT a special material, but the outer "cut" on the ring which allows it to be a better scraper ring, to control the oil. This can also be and usually is, a ductile iron material. The oil control ring is obvious, but NEVER opt for a "low tension" package in any motor you intend to spray. Regular, medium or high are the only tensions you want here.

So the way I see it......WHY run a "coated" ring if it really gains you nothing and has the potential to cause you a problem. Just a WHOLE lot of folks have drank the "moly ring" koolaid over the years and is no doubt every ring companies highest seller

MONTE


what rings would you recomend for nitrous use

what should they be gapped at for the amout of nitrous used

Learn something new every day ... thanks for the info on rings Monte.

As I stated, a quality ductile iron top ring. You can go with the "Hellfire" which is a ductile iron ring that was originally constructed for diesel applications. This tells you the ring was designed for a high cylinder pressure, high stress environment. While a very good nitrous and boosted application ring, it is also just a good all around ring for most any HP combo. It seals quick and really good, plus won't break the bank on price. For a second ring, again ductile iron would be the choice with a Napier cut on the outside edge. A standard tension or higher 3 piece oil package and you have a good enough ring set for any amount you ever wanted to spray. It also won't cost you a ton, seals as well as the Moly top ring and won't cost you any power over the Moly coated, if that is a concern. And more importantly, has no coatings to flake off and cause issues.

"Hellfire" is just what Speed Pro calls the ring, but other companies have the same material. Total Seal calls it a TNT ring.

On gaps, I would rather have it wide as narrow, so I usually opt on the side of caution. .006 per inch of bore will suffice for about anything except motors with VERY large amounts. If you know you are going to keep power levels lower, you could go with .055 per inch, but I would not go any tighter. I am one that is a believer in the larger second gaps, because I have actually SEEN it be better. It helps relieve the pressure between the top and second ring, which promotes better ring seal and it doesn't have to be high rpm to do it. Some doubt it, but the blowby meter doesn't lie, at least not to me, so that's how I do it.

Now do you NEED the Hellfire ring for smaller amounts, no, not really and about any ductile iron ring will suffice, just stay away from Moly coated. But the way I see it, knowing that oil and nitrous is a huge No-No, the rings is NOT somewhere I would save a dime in a motor I knew I was going to spray..........Just my opinion

I know we have all heard many people say they have Chromoly rings in their motors. That simply is not possible. Chromoly is a high carbon steel and that material is NOT used in ring construction. Any steel ring is "tool steel". So when they say that, they are just somewhat uninformed, as what they likely have is the Moly "coated" ring of some sort. Now there is a such thing as a Chrome/Moly ring and what this is, would be either a cast or ductile iron ring that is hard chromed and has a Molybdenum impregnated face. These rings are not used very often, if at all in performance applications

I ask my wife that when I am gone and my poor old body cremated that I wanted her to toss a spoon full of my ashes down the intake of a race engine that is wide open--that way I can finally get a real look at what goes on in there
Good school on ring material there Monte

I am normally against most "conventional wisdom"
It is a character flaw I guess

Rings, ring material, how they work, tension, etc, is just like every other part of an engine. Be that cams, valvetrain, whatever. To make it WORK and make it work RIGHT, you have to understand HOW it works and what it is supposed to do. Too many guys just throw random parts together because they are supposed to be good, without any basic understanding of what they are supposed to do, or the over all goals of the combination.

As for rings, that is why I laugh when guys put ALL their stock in how a motor leaks down. Sure it's important, but once you understand rings, their job and what they are SUPPOSED to do, you see how the leak down is only a tiny part of the equation.

As stated, the top rings JOB, is to seal compression. Nothing more, nothing less. Especially in the case of a gapless top ring, we see guys touting super low leak down numbers and proclaim the motor TIGHT. Depending on the amount the ring is down on the piston and how far down in the bore the piston is, a leakdown test means you are checking ONLY the top rings integrity as it relates to about .200-.300 of the total bore. Well, unless the bore at the top, or the ring is damaged, it SHOULD leak great.......it's gapless. But does that test tell us anything about the second ring, the oil ring, or the rest of the bore? I have seen motors leak less than 5%, with a the second ring completely pinched and part of the oil ring knocked clean off, be laying in the pan and the motor smoke like a tar wagon. So when I comment, that the leakdown is just not all THAT important, I get hammered. I never said it was NOT important, I only said that it is not the be all end all number. On the flip side, I have seen nitrous motors, with lots of ring gap on both the top and second ring, leak 50%, yet the car runs like a raped ape. The reason for the low leakdown, could be that the gaps are somewhat aligned at the time of the test. Roll the motor a few times and that number might be 10%. Some of this stuff is why I put more stock in a pumping pounds test, than a leakdown number............Bottom line, to be successful as a builder OR a tuner, understand HOW the parts work and WHAT they are supposed to do. You don't get it, find someone who does

Thanks for the info Monte, I like to learn new things!!!