na specs are 18/20 nitrous ones are 20/22. they are currently ground to 18/20.

From what i have seen it fitting these bastards in the cylinders 20 thousands is very small, and i would think that even under normal heat the rings would heat up and close that since its so small. and then there my vision, that can really 2 thousands make a big difference? seems so minute to me.

 

2 thousands of an inch is a lot in the world of piston rings

 

damnit!

im not sure if i can convince him to change the gap. he did seem pretty firm on it, that it was the best for me, and hell hes doin it for free for me.

anyone honestly think that i can run a 150 shot on this config? what is stock gap?

 

Like I said....youll be fine at 18/20.....just stay at a 150 or less shot. Stock specs are .010-.016 for the top and .018-.026 for the bottom.

 

40k??

That's a crock.

Speaking from experience, I have found that a little wider than "optimal" ring end gap will not hurt a thing. Found I had ~.030 on a top ring one time... weekend before that the car turned a 9.6 @ 143 mph, just like it had for the past 8 months. Combustion chambers were clean, no oil contamination.

Not recommending that you go that wide, just saying that it's not necessarily detrimental to be a tad wide.

-Mindgame

 

Alright that makes me feel better.

Derrick is running 175 on his stock short block, so i think i should be ok. I've got better pistons, thicker ring lands, and more gap than stock.

I was also talking to another guy up here, and we discussed that the altitude may effect it some b/c my cylinder pressures are gonna be lower than ur guys down at sea level. bandimere can get to 12k DA in the summer. and the rings will wear, and expand and slowly increase that gap, which should happen before i put the nitrous on so i should be good.

 

mindgame, can you check out my cam post?

http://web.camaross.com/forums/showt...hreadid=140912

thanks

 

my machine shop (not engine builder) said the same thing-

he also said a bit bigger is better thana bit smaller, espcaily in an FI street driven car. Better to burn a tad bit of oil than have then "connect" and break in heat...

any comments?

 

Well, oil control is mainly the job of the oil ring... some of it also falls on the 2nd. Standard tension rings are the way to go for a street car and you shouldn't have any oil problems going that route. If you want to be a bit more "trick" you run a light tension ring, but you'd better get some depression in the crankcase.

Then again, even between the "standard" tension rings, some have a bit more tension than others.... so experience plays a part too.
Bottom line and of the most importance is bore concentricity. If the bore is not round, then the engine will have problems and won't make near the power it could. Take a fully machined block and square the ring in the bore. Now turn off the lights and use a pencil light.... there should be no light visible around the perimeter of the ring/cylinder bore. If there is, then you have a problem. Should be this way down the bore as well... at least in the travel.

-Mindgame

 

You could always just call the ring manufacturer. My last motor I had planned on running a lot of n2o, so I gapped them at .060" ouch.....wonder how much n/a rwhp I lost.

 

so mindgame, you think that i will be ok with 18/20? they are je pro seal rings

 

With a 150 shot?

I didn't check the pistons to see if they are a nitrous type with a lower ring height but .018-.020 should be just fine as long as you don't start trying to push a 200 hp shot.

-Mindgame

 

see thats what i dont understnad. derrick is running 175 on a stock motor. i should be able to run more than that for a number of reasons:

more ring gap
better rings
better pistons
better rotating assembly

or am i not getting something here?

EDIT: I tried to check out JE's PDF of all their sbc pistons but it was corrupt file. it work for anyone else?

 

I'm showing it to be a -16cc piston... what did you calculate your static comp too?

Doesn't show to be a nitrous piston which isn't the end of the world.... it aint gonna break just because it's not a "nitrous" piston.
I was just curious to see whether or not it had the lower ring positioning. SRP's ring placement is a little bit lower than stock anyway.

On what other people are doing..... well everyone knows someone who is pushing limits and getting away with it. I don't think a 200 hp shot is out of the question. The main thing there is having the proper timing retard, A/F ratio and plug heat range. You can keep the engine alive if those things are addressed. Even the most expensive forged piston will die a horrible death if things aren't right. So, don't sweat it.... just hang out in the nitrous forum and learn how to tune the engine to keep it together.

-Mindgame

 

mindgame


I was planning on pulling i think its 1 degree for every 50hp? so 4-5 degrees of timing on a 200shot. and some colder plugs.

it is a dished piston. about 10.72 on the CR might be a tad bit more as i dont know the exactly volume of the CC, that was with using a 55cc chamber. dynamic CR with the 230/236 is 8.35

whats a good way to find out cc? fill it with some oil?

quench distance is .044 is that good?