Hello ya'll,

This NOS system is an older one (1985ish) that was just installed on a drag car. It came with 3 different stages of jets.

Stage I
Fuel jet 052 - NOS jet 059

Stage II
Fuel jet 073 - NOS jet 082

Stage III
Fuel jet 110 - NOS jet 110

The drag car is a '70 Plymouth Duster (sorry it's Mopar, ). It's a 383 with a 440 crank, automatic that weights 2800# with a driver. I have an intake meant for a Dominator with a 2" adapter plate for an 800 Holley.

Then there is a 3/4" NOS plate that goes under the carb. Each spray bar has 8 pin holes to dump nitrous/fuel.

OK, here is what I found. First couple of runs without NOS, I find that the car has lost about 0.15 seconds of ET and 2 MPH.

The system probably added 40 pounds to the car, and I can see that with the NOS plate, intake volume was increased maybe too much and affecting lower RPMs a little. But giving up almost 2 tenths seems a little high.

With the system activate (Stage I) good times! I engaged it after the 1-2 shift with a gain of 0.4 sec and 5 MPH. My partner did a launch with Stage I and had a gain of 0.5 sec and 5 MPH (*NOTE he let off the NOS button for about 3 seconds after the 2-3 shift - brain fart).

Last season the car would run consistent 11.0s at 123 MPH. This season the car runs 11.2s at 120 without NOS, and has had a best of 10.72 at 126 with NOS.

This seems like a lot of gain with the Stage I shot (assume 50 hp increase).

 

So what are the questions? I assume the last statement is meant as a question, and no that doesn't seem like a lot of gain because those jets should net you somewhere betwen 100 and 125 hp, not 50, in which case it doesn't seem like a lot.
BUT heres a suggestion for you, the larger jet should be the fuel, and the smaller the nitrous, so from your stated jetting, you have them backwards, switch 'em around and you should get a real gain . Good Luck
John

 

Yeah, I should of asked if all was good. Got lost in the forest of stating facts.

The jets are color coated. Blue for the fuel and red for the Nitrous - I think.... I look later at the car.

 

Dunno about the color coding, most of the actual jets I've seen have been just plain brass or steel, the color coding is on the fittings. And on the fittings it's been red for fuel and blue for nitrous. But check out this jetting chart from NOS.

http://www.holley.com/HiOctn/TechSer.../NOSTech4.html

And this parts chart from Nitrous Express, which clearly points out the red color coding is fuel

http://www.nitrousexpress.com/instal...sysinstall.pdf

Keep in mind that NOS usually jets their kits a bit on the rich side for maximum safety as opposed to max power.
Good luck.
John

 

My bad - the red was for fuel and blue was for Nitrous. I pulled the jets and just wrote numbers down without comparing them to the source.

The Nitrous solenoid is blue with blue lines going to the blue spray bar.

The fuel solenoid is red with red lines going to the red spray bar.

Kinda idiot proof!

My other concern was that the car gets squirrley! Off the line the car is straight and feels good. But the partner had a heck of a time controlling the car after the 2-3 shift and later down the track. Without NOS, the car handles great and drives straight. The leaf springs are new and the car is aligned.

This was on a Wednesday "test and tune" night, so there are a lot of street driven cars that show up. Maybe there are a lot of little leaks that make driving the car with the extra power more interesting. Come to think of it, there were a couple of 9 second cars having traction problems, so that may be it.

 

oh heck yes, nitrous does tend to introduce traction problems.