I got 1.2 sec and 13 mph (on a 12 second car) on a 0.051 jet

Something may have been up...


Superchuck, in my limited experience, that sounds like a good start. WHat fuel jet and fuel pressure you plan on running?

No it ran real sweet, rather boring really, all I noticed was that it was all over a bit quicker than usual. I used to run around 12.4's@108 N/a on 98 octane at 36 deg total. I only came back 2 deg, hit it off the line as well and went 122.8, tbh 110/110 was extra safe on the petrol side on those kits as std. back then!.....the chassis was up to it on leafs. A .051 jet was only 125hp if I remember right on the cheater kit, thats half of what I ran, was yours a bone stock motor?

Having a seperate pump for N20 is the biggest important thing you can do, although for 100 shot its not necessary, but it IS when you step it up!!

rb446...you're right, a lot has changed w/ nitrous in the past 25 years. That 110/110 jetting was not extra safe, just extra rich. There's a reason the jet maps are so different now. And running a separate pump for the nitrous is not necessary. One good pump w/ a separate regulator for each stage is all you need.

Yeah thats what I meant, extra safe = extra rich. So todays equivalent NOS Cheater kit or 1 with the same size solenoids would be what in the hp ratings per jet sizes?...I see plates with dual cross bars and all sorts, will have to do some research, so whats the main reason jet maps are so different, retard boxes etc., progressive solenoids?

We don't go much on N20 over here any more cept for some of the Pro-Mod runners and a few Top Sportsman runners, its regarded as cheating by most of the doorslammer guys....I say do what you gotta to win if its allowed, which it is!......I guess there's nothing wrong in being a purist so to say, but.

A lot of guys here are buying big stroker motors at serious $$$$$!!, when they could put together a cheapo 468 chev (sorry), or a Mopar, stick a .600" lift cam and ally heads, x2 .090 thou solenoids and make 1100hp+!!, been done by many when Super Mod was running here, they outran all the big cube N/A boys

The carb is using 72/78 I can't remember the nitrous jet sizes, the kit came with 100/ 150/ 175/ 250 jets. I put in the smallest. Carb fuel pressure is 5 1/2 and I still have the set the pressure for the nitrous, I was thinking the same at 5 1/2. Maybe I should tighten up the spark plug gap?

My car is only used for sportman bracket racing, I'll only use the nitrous for test and tune for a few of those WOOHOOO passes. I already had the kit for something else.

The factory jetting recommendations are generally a bit rich. Looking a the Perf. RPM kit instructions on Summit, 100hp looks like 59N/59F. This will likely be rich.

The old powershot plates called for 47N/53F, I think I reversed them to 53N/47F and got close.



I was a overly conservative with mine and went a step colder plug as well pulling more timing.

They figured out that rich is not safe, so they leaned out the jetting. They went to square jetting and eventually to the nitrous jets being larger than the fuel jet.
Everyone used to just flip flop the jetting, like OUTLAWD said, which made em run a lot better.

A Cheater system will supposedly flow 250 hp max. The orifice in a Cheater nitrous solenoid is only .093", so your 110 jet really did no more than a 93 jet would have. The solenoid was your restriction.

Hey guys, what spark plug do you recommend for my 340 with a 150-175 hit of spray? Im running a w-2 head with the old school trw domed pistons, which works out to be 12.3 to 1 comp. Ive got NGK GR4's right now.

Nitrous question.
Is it better to "under carb" a heavy dosing nitrous engine? Seems to me that you would get a higher oxygen content with smaller throttle plates.
I saw a nitrous specific sheet metal intake with some very small throttle bodies way back when.... Was on a "somewhat" local engine builders car. Very competitive at the time. I wasn't supposed to see it. Always wondered about that.

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Might be minimal, I never tested back to back....but usually any thing you do to increase even the supply of nitrous to the jet helps. I changed from a .116 solenoid to a trash can and the car was totally different.

The old saying "rich is safe" is total bullcrap!! being extra rich can actually be worse than being extra lean. If you read todays jetting the pros prefer little on the lean side and pull more timing.

Hopefully Monte Smith will chime in and explain this better than I can. But I use to be one of those "fat is safe and more timing means more power" dummies also.

Agreed. I pulled 10 degrees on a small hit to be safe, when I went to add it back in, it didn't pick up, so I left it out.

TIMING is what destroys nitrous motors NOT lean. With enough timing out, you can't get one lean enough to hurt it. It will just be down on power, like any other vehicle that is lean. No fuel, no power.

Too many are under the impression that timing MAKES power, it does not. Timing, or spark lead is just where you light the fire based on the efficiency of your engine to get a complete burn. The combination is what makes power, NOT how much timing you run in it.

The "old school" way rich tunes seemed to stand more timing, simply because you were not making near the power you thought you were, because it was dead rich. Way rich, with big loads of nitrous will beat ring lands off pistons faster than you can replace them

Duel wideband o2 sensors are a must.

Thank you for explaining this, I'm going to inform some other dummies I know.

Don't be afraid to retard timing.....I ended up with 8* total....with a ten spread direct port , 4.5 psi flowing and a ten spread plate 5.0 psi flowing...both on at the same time. always retard before you advance .

I banged out rings, head gaskets and Pistons when trying the same tuneup with 12* timing. Just because I thought...how could it run with so little timing ? burn and Learn.....lol

You saw how I ran that Vette. 870" motor on 4 stages with a 13.0 target air fuel ratio. It WORKS

So in order to run the timing to make the power that you need, is the solution to run a chemical system like Snow to avoid that detonation? You dyno the motor to say 1000HP. With all things being constant in the dyno, you make your 1000HP with a specific timing. The real world of changes in air pressure, temp and humidity, you can maintain that timing and HP by using the chemical system to protect the motor from detonation?

Ran the car last night w/ the exact same setup as last time, except for the bigger -6 feed line from the bottle to the solenoid.
The weather was worse last night, yet the car still ran 1 mph faster. ET was almost the same as before. Back in September in better air it ran 8.95 at 149.7 mph. Last night it went 8.96 at 150.6 mph. Much warmer and humid last night...not sure what the DA was.
So maybe the bigger feed line leaned it out a little and gained me some MPH.
It got quicker when I brought the nitrous in faster.
For my last pass I took another degree of timing out and lowered the fuel pressure by about 1/4 lb., but the track went away.

I did I was trying to learn all I could that day from you and Eddie LOL