View Full Version : Explaination of why...
Red2KCougar
02-07-2002, 01:02 AM
A dry nitrous setup doesnt work with a returnless fuel system. I know it doesnt but I've never heard the reasoning behind it. When I was at the track this past saturday this guy hooked up a nitrous line and there was this little hos that just sprayed it right into the intake, it was a firebird witha clear airbox and it sprayed right up under the intake like the drilled a hole through and put it there, why couldnt we do something like that?
Trevor, you want to field this one? You could probably explain it better than it- Sufficed to say that when you inject more oxygen (from the nitrous) into your engine, you have to compensate with more fuel to balance the stoichometry. The guy you saw with just the nozzle also had some sort of an FPR intercept that dumps more fuel into the system when the N2O is on, otherwise he's incredibly stupid and will blow the engine if he continues to run like that.
From my understanding, the dry kits like the ZEX have a control box that hooks between a vacuum source and the FPR on a return system. When the nitrous is on, vacuum to the FPR increases, causing more fuel to be dumped in. Not an incredibly exact science, but it keeps it from going boom. On a returnless system, you don't have an FPR- It's all controlled by the fuel pump? Trevor- That's where I need help.
Cougarsales
02-08-2002, 01:22 PM
The only returnless system I currently know of is the Venom VCN-1000 or VCN-2000. I have the 1000. It doesn't use fuel pressure to control A/F ratio. It is real neat. It uses your stock injector duty cycle. What it does is after your first burst of fuel it adds a second variable duty cycle to your fuel injectors. That is how it compensates for the increased O2. The timing and the lower intake temperature is then adjusted via the control module.
DemonSVT
02-10-2002, 03:50 AM
Because a dry system uses raised fuel rail pressure to supply the extra fuel needed.
No FPR on a returnless car.
The extra fuel would have to be added via an auxillary nozzle (wet system) or in conjunction with the PCM via injector/fuel pump control (Venom)