My compucar kit list 63/43 jet sizes for a 150 shot, however, a couple of online calculators say my fuel jet size should be a 38? I even lowered my fuel pressure in the calculator, and upped the N2O pressure to try to duplicate the worst case lean scenario, and it came up 38. If that is the case, then 43 will be totally pig rich. What do you guys use for calculators, or do just run what came with the kit? It just seems like it will be way too far off....

 

where did you find an online jet calculator?/

 

i dont use a calculator,never saw to be honest.

I started with what they called for,made a pass or 2 (usually 1/2 track or on the street) and read the plugs. I stepped down the fuel jet till the surging stopped and the plugs looked good.

 

lt1camaroman93- here ya go... http://cosmik.org/calculators.htm

RacinLT1- To be honest, if I depend on my plug reading skills I'm gonna melt some pistons. I really am gonna try to get over to NE Dyno next week and find out on their wideband-equipped dyno. That should give us all an idea how accurate the calculators are.

I really think these companies go super fat on the fuel jets so that if the occasional bonehead runs 87 octane, they won't smoke their motor and blame the vendor. But being that rich has gotta cost some power....

 

The only way to find a true jet pattern for any nitrous kit is to have the entire nitrous kit and fuel system flowed. Once you have those numbers your able to calculate what jet size to use assuming you have determined what N/F ratio to run. Other than that I would start with the manufacture recommendation. Call the company the kit came from and fine tune from that point.

If you run that nitrous kit to fat you take the risk of a fuel wash.

 

Thanks for the replys. I hope to find out for sure on the dyno in a week or two. I let you know how it turns out.