I see dozens of threads discussing the correct ring gap for N20 motors. ...
What I don't see is why the gap has to be that way or what happens if it's not.
Does it even matter for a <200 shot?
Are we talking slightly less power, or are we talking about breaking stuff?
The reason I ask is that I had a forged 383 built last winter.
It was built for N/A but should easily handle extra cyl pressure if I wanted to go N20.
(4-bolt studded main, ARP head studs, half-filled block, ARP19 fasteners, forged components, etc...)
Problem being that the rings were not gapped with N20 in mind.
The answer should help me determine where to go next when I tire of this particular setup and want more
Bore (in) 4.030 in. Top Ring Thickness 1/16 in. Second Ring Thickness 1/16 in. Oil Ring Thickness 3/16 in. Oil Ring Tension Standard File Fit No Gapless No Top Ring Material Iron Top Ring Facing Material Plasma-moly Second Ring Material Cast iron Second Ring Facing Material Phosphate coated Oil Ring Material Stainless steel
i don't recommend running a Plasma-moly ring with nitrous the ring is not built for it and you need to run a ductile iron or stainless top ring rule of thumb for gaping rings for nitrous is .006 per inch of cylinder bore. so if you have a 4.00 bore * .006 you have a .024 ring gap
Last edited by G Engines; 10-25-2009 at 05:01 PM..
i don't recommend running a Plasma-moly ring with nitrous the ring is not built for it and you need to run a ductile iron or stainless top ring rule of thumb for gaping rings for nitrous is .006 per inch of cylinder bore. so if you have a 4.00 bore * .006 you have a .024 ring gap
Understood, but what happens if I don't? and when does it start to matter?
I wouldn't recommend spraying more than a 200. You need to know how much gap is in the rings. If its to tight there would be a chance of the ends butting and breaking the ring.
__________________ 2001 Camaro SS 5.07@139 on 275's Callis Road Racing-Tanner Racing Engines-Virginia Speed Race Cars-RPM Motorsports-Applied Nitrous Technology
I wouldn't recommend spraying more than a 200. You need to know how much gap is in the rings. If its to tight there would be a chance of the ends butting and breaking the ring.
Ok, that's the information I was looking for.
So if I want to run a big N20 shot, I have to pull the motor apart and install properly gapped rings.
Man, I really wish I'd thought of that when we were building this thing
Oh well ... my own fault.
So now I weight my options if I want to run single digits. A) Bigger N/A setup - only have to pull the heads and cam, power all the time, but deal with having a huge cam. B) N20 setup - have to pull the whole motor, power on tap. Could keep a smaller cam and existing heads. C) Forced induction - have to swap heads for ones with bigger chambers, power all the time. Have to deal with FI "clutter" in engine bay.
forced induction can do the same thing to the rings as nitrous. more cyl pressure = more heat. rings expand as they heat up, and the ring gap needs to be bigger to compensate for that.
i'd say just run a 200 shot and have some fun. thats enough for a serious drop in ET. : )
someone beat me to it but yeah that's the reason you open up the ring gaps for spray....
.024 might work for NA but depending on how big of a system you're gonna run you might go 30 or 32 or more....
the increased cylinder pressure and heat causes the ring gap to close up. If they are too close you can snap the ring or the ends could i suppose cross over themselves.... it'd be bad either way....
__________________ THE OUTLAW
1995 Camaro Z28 1LE West Coasts Fastest LT1 period.. CSM Racing Engines 383 LT1, AFR 227's, SR Cam, Jesel shaft rockers, Lunati crank, Oliver rods, sngl plane, Accufab TB, Nitrous Pro Flow plate, ATI TH400, Moser 9", FAST XFI
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someone beat me to it but yeah that's the reason you open up the ring gaps for spray....
.024 might work for NA but depending on how big of a system you're gonna run you might go 30 or 32 or more....
the increased cylinder pressure and heat causes the ring gap to close up. If they are too close you can snap the ring or the ends could i suppose cross over themselves.... it'd be bad either way....
wat he said. in my motor i belive we went with 32 or 34. the rings came with a chart and it specified how much gap for wat amount of spray. i plan to start wit a 200 till i get more budget for a DP
someone beat me to it but yeah that's the reason you open up the ring gaps for spray....
.024 might work for NA but depending on how big of a system you're gonna run you might go 30 or 32 or more....
the increased cylinder pressure and heat causes the ring gap to close up. If they are too close you can snap the ring or the ends could i suppose cross over themselves.... it'd be bad either way....
This is partly true the increased cylinder pressure does require a larger ring gap but only to a point, I would have no problem running a 500 shot on a .024 ring gap i build a lot of nitrous engines it will be fine. if i was to build an N/a engine i would gap my rings .004 per every inch of bore. not .006 Our promod runs 4 systems and our ring gap is only .038 on the top ring it has never butt the gaps together and has no excessive blow-by.
Well that sucks
I guess I'll just have to settle for 9's until I feel like cracking the motor open again.
I guess I can still build the direct-port manifold and just run a smaller progressive shot or something until then.
It's not like I was going to wake up some morning and decide to flip the switch and to 400HP all at once LOL
Too bad too ... so much time and money invested in this thing.
It's a shame that we overlooked something so simple.
some good info here. I have a forged 347 that I'm building with diamond nitrous pistons with hell fire rings. The most I think I will spray is 200 but you never know, might go with a 2 stage dp kit. What do you think a good ring gap would be for a high compression engine that will see a 150 shot for starters but might go as hich as a 300 2 stage dp kit
Impact of improper ring gap 
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