noobie question: "squaring" nitrous jetting

3451 Views 24 Replies 12 Participants Last post by Nosman, Sep 30, 2005

fasteach

Discussion Starter · Sep 15, 2005

GREAT forum! can someone please elaborate on the "square" jetting thing for a hapless, rank amateur? through my reading, i've stumbled upon this and would like to hear more about this technique. thanks Duke

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Monty M

· #2 · Sep 15, 2005

What do you mean? Usually when someone says square jetting they mean they are running the same nitrous pill size and same gas pill size ~ 28 - 28 pills for example.... Or are you talking about something else? BTW welcome to the forum..

fasteach

Discussion Starter · #3 · Sep 15, 2005

aaahhh, well i kinda figured that would be it, but it seemed kind of "too obvious". someone had mentioned a noticeable performance advantage to the process on a bigshot plate like i run, but without sufficient knowledge and the voice of experience, i would never stray that far from the suggested setting recommendations from NOS.
p.s. i run a 3300lb w/driver 68 fastback mustang with a 4 speed BOSS302...hoosier quicktime pros and caltracs. [email protected] 1/8 mile, 1.58 60ft on my drive-it-to-work tuneup, on 93 octane...not a dedicated racecar like most of the other posters, so it's definitely a pleasure to be hearing from people who've "been there, done that". Duke

Monty M

· #4 · Sep 15, 2005

Duke you are right on the money to follow the NOS guidelines. Everyone has the trick of the week.. Best bet is to start safe and lean it out a little. I would not try tilting the tune up on it as it will not net you that much more in ET. Have fun and race.. You're on the right track..

YDLUZ

· #5 · Sep 19, 2005

Monty Mikho said:
Duke you are right on the money to follow the NOS guidelines. Everyone has the trick of the week.. Best bet is to start safe and lean it out a little. I would not try tilting the tune up on it as it will not net you that much more in ET. Have fun and race.. You're on the right track..

Yes, nvr go out and run lean as a guy who has slowly and carefully achieved after lots of tuning time. However, also do not just run the nos base tune up without question. I've been helping a buddy who is kind of new to nitrous (and I'm not an expert like Monty) and he was running a 225 shot with the nos baseline tune up and 7.5 psi fuel pressure. He was piggggggggg rich, went from 11.0 na to 10.40's on a 225 shot. We took his fuel pressure down to 6 psi (still plenty) and went up a size or two on the nitrous jet, next pass 9.88 - he was still a little rich too. AND - don't forget many a piston has broke from being too rich. So, read plugs, read plugs, read plugs and tune it slowly and carefully! There is an excellent plug reading article on this site, check it out. Just my 2 cents.

Good Luck!

fasteach

Discussion Starter · #6 · Sep 19, 2005

thats good advice guys, i appreciate it. i've been working on the tune-up for awhile, but my closest track is 120 miles away in immokalee, so i dont get there as often as id like, usually just for the runday sunday events. i'm going this sunday, so i'll lean on it a little and post my results.

TRICK_5_0

· #7 · Sep 19, 2005

YDLUZ said:
Monty Mikho said:

. AND - don't forget many a piston has broke from being too rich.

Click to expand...

Im fairly new to nitrous as well. I know you can melt a piston from being to lean on fuel, but how can you hurt a piston from being to rich?

YDLUZ

· #8 · Sep 19, 2005

Fuel gets traped in between the piston and the cylinder wall, above the compression ring and the top of the piston and causes breakage in that area.

jsj372

· #9 · Sep 19, 2005

So with a pro race fogger with .028's in it fuel and n2o(250 hp level),
what fuel pressure would be a good starting point?

:smt017

8TREEZ

· #10 · Sep 19, 2005

I would start with about 6lbs to 6 1/4 psi and "read read read" your plugs and adjust as needed..... Just my .02....... Maybe Mikho the NOS PRO could chime in on this. :-D

Monty M

· #11 · Sep 19, 2005

Trust me I am not a pro at this stuff.. I have broken my fair share of stuff and Im sure I would continue to do it if I still was using nitrous..

YDLUZ, the fuel actually gets trapped between the first and second ring. It is the reason the top ring will usually be push up and the second ring down. The first ring land usually pushes upwards also.. I have a garage full of examples.. LOL...

YDLUZ

· #12 · Sep 20, 2005

Monty Mikho said:
Trust me I am not a pro at this stuff.. I have broken my fair share of stuff and Im sure I would continue to do it if I still was using nitrous..

YDLUZ, the fuel actually gets trapped between the first and second ring. It is the reason the top ring will usually be push up and the second ring down. The first ring land usually pushes upwards also.. I have a garage full of examples.. LOL...

No shit...why is it such a big deal not to go too far down on the compression ring??? I believe what you are saying, I just thought the fuel would get trapped on top of the compression ring, then leak past it and then start tearing shit up from there.

Learned something new today - Thanks!!!

Monty M

· #13 · Sep 20, 2005

The problem is when the rings are too far up the pistons. They are moved down the piston to keep them away from heat. High nitrous usage pistons usually use around .300" - .350" down.. Some go as far as .450" down.. If your rings are seeing too much heat, its a good idea to move them down.. But remember you may run into compression height problems if moved too far..

YDLUZ

· #14 · Sep 20, 2005

Monty Mikho said:
The problem is when the rings are too far up the pistons. They are moved down the piston to keep them away from heat. High nitrous usage pistons usually use around .300" - .350" down.. Some go as far as .450" down.. If your rings are seeing too much heat, its a good idea to move them down.. But remember you may run into compression height problems if moved too far..

We are on the same page and if we were not you would be right, I'm 99% sure of that - I say that out of respect for your knowledge!

The problem I was referring to I learned from a buddy to has a high $ Pat Musi heavy nitrous piece, compression ring is .300 down just like you said and Musi said he does not push it down further because of the fuel trap it creates can cause problems. I realize the reverse side is getting the ring away from the heat and giving the piston more thickness in a critical area. I'm sure not all of the experts agree on this and my knowledge came from just that one conversation.

HellBent

· #15 · Sep 21, 2005

My best Big Shot tunes were pretty "square". If you tune with the jet rather than the fuel psi you're going to end up pretty close to square on a Big Shot anyways. But every combo is a little different.

YDLUZ

· #16 · Sep 21, 2005

Me too, square has been a blessing for my tune up!

Mark Nealen

· #17 · Sep 27, 2005

HI

I have a 1984 camaro with bbc 454 std bore trw pistons 10.1compretion th400 trans 373 gear 3280lb. I recently hurt the motor but Im not shure what the cause was. I run a fast lane nos setup with a msd programable 7 ingnition. I was runing A 250 shot nos vp fuel c12 in tank and c16 in nos fuel cell, and I beleve I was safe on the fuel psi. I pull 11 degres out and that puts me at 29 plus I pull 11 more out and bring that back in over 2 seconds. I also run the auto light spark plugs ar3933 And I have never seen any oil burning out the tail pipe. As it turns out I burnd #7 & #2 right at the valve releif but not past the top ring. 1st burn doun for me and would like to know the cause. I did hit the rev limiter hard with the nos activated :shock: Could this have caused washing of the cilinder or ring flutter? any thoughts on this

Thanks Mark

Zeke1

· #18 · Sep 27, 2005

Hey Mark go to the NO2 VP fuel made just for nitrous alot safer than C16, and from what I hear you might want to check the fastlane stuff over alot of people seem to have problem's with him and go get the pickup for the individual cylinder timing and take 3 or 4 degree's out of #2 and #7 cylinder's, are you going to Orlando ?

fasteach

Discussion Starter · #19 · Sep 27, 2005

well it was a typical race day for me...car ran within .015 of its best pass right off the trailer, dead-nuts consistency in the 60ft, and the incrementals...so i decided to lean on it. well ive apparently found the limit of the fel-pros sealing capabilities, cuz its the second time its happened at 225. at 175 ive never had a problem. the good news is that cometic makes a direct replacement for my application, and theyre reuseable...i asked the tech. he said as long as the embossment sits .010-.015 thicker than the gasket thickness, youre good to go. oh well, thats racing i guess

Duke

8TREEZ

· #20 · Sep 27, 2005

Rev-Limiter + NOS = Problems...... I never had good luck with the C-12 either both motors I lost were on C-12..... I know several people who have lost motors on a .047/.053 tune 100h.p. running C-12 It has never been good to me.... I run C-16 on motor and spray with no problems so far.....

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