Landracing Forum
Tech Information => EFI Questions => Topic started by: KZScott on April 02, 2009, 02:01:36 AM
-
question for the nitrous guys. My understanding is thats its best to run 10-12psi on the fuel side and decrease the jet side as opposed to running say 6psi fuel pressure and bigger jets (to get the same AFR). please tell me WHY :? :-D
my uncle and i had a debate about it, and neither one of us could quite remember the exact "WHYS". his opinion was based on a well respected IHRA pro-mod (car)guy telling him 6psi max, and Im basing my opinion on LSR (bike)guys.
need some ammo for the debate, and i would also just really like to know
thanks!! :cheers:
Scott
-
you to seriously do a search on nitrous on this board... There are two threads which are very informative about the subject.
6 psi max is from a quy who hasn't sprayed nitrous for 4 miles constantly... It's called making the motor live for extended perioud of times. Stainless on this board is a good person to ask for specifics or JoeA
Jon
-
http://www.coldfusionn2o.com/calculator.html willie buchta
-
Nice calculator, I input our N20 combo info and based on the gas jet answer and a previous experience the motor might make it a mile or so before something fries... I would probably round up to the next jet and then use a jet one step richer than they recommend for a LSR situation. It did tell me the correct HP increase...
But that does not answer your question.... :|
Higher pressures seem to spray more consistently.... now before everyone jumps up and says huh... when I say that here are my thoughts from our experiences. You will always have some variation from fuel pressure, the minor variations affect volume and pattern. The higher the pressure the less it seems to be affected. You want consistency... I always suggest flowing your system, measuring and calculating the results. Don't trust the numbers the drag racers use(calculator), the number your buddy used, the numbers JoeA used or the numbers we used. Your system is unique, read the threads again on this site. What worked for one guy may blow you up. Be aware, N20 will blow you up sooner or later, all you can do is try to make it later... :|
If you set up a problem in the calculator with 10 PSI it will give you a Jet, then change it to 6, it will give you a larger jet. That is because the N20 requires at least 5 times its weight in fuel to leave the aluminum pistons and stainless valves in their solid form. You notice I said weight... fuels have different weights, but the orifice doesn't know that. Set it up for a specific fuel and always use only that as the enrichment. So always start rich, but not too rich, give gas 6 times the weight of the N20. That might be a little rich for a 10 second spray, and you may get 5% less HP than the perfect ratio, but you will be glad you started there for a 20 second spray.
Your experience may vary...