Fuel system duel or single nozzle

Looking for views on using single nozzle over dual nozzle fuel system TA/FC 526ci 125% overdrive 900 pump? What check valve settings for single nozzle? What jet area for single nozzle? How different is the barrel valve scroll cut for single nozzle? Have had some experience on dual system only. Thanks

[ April 30, 2005, 08:44 PM: Message edited by: Rolme ]

 

This comment is more for the educational value but if you were going to convert from a dual nozzle system to a single wouldnt it simply be a function of matching the nozzle area? What advantage would there be running two verses one of the other way around. Thanks for the help.

Nick

 

Nick, your right. All you do is make sure you have the same area. Your idle check and pump check remain the same. The same goes for the spool valve. The way I've done it is split the total area into thirds, put one third in the low side and the rest in the high side. Then set your port checks at 15-20lbs for the low side and 30lbs for the high side. Of course these are adjusted according to what your data download looks like. When running a 2 nozzle system, an inline filter is a must. Smaller nozzles clog a lot easier than bigger nozzels. Also make sure your pump pressure doesn't get below 150 psi at 8000 rpm under load. Otherwise blower pressure will prevent fuel from coming out the nozzle. You'll end up with a lean condition and BOOM! The higher the pressure the better.

 

Thanks for the thoughts i understand the maths on the area. What are your thoughts on what is happening at launch RPM in a duel nozzle system are all the nozzles flowing or are the high circuit ones still off?

 

Norm Drazy told me that the reason you want a two nozzle system (dribblers and ports) is so that you can control the EGT temps at staging rpms better. There is probably more to it than that. Herb Western Country TAD

 

Herb, that's just one reason. Most of the time when the car is new you start out with 1 nozzle per cylinder. At some point, you run out of adjustability with one nozzle, that's when you go to 2 nozzles. The beauty of the 2 nozzles, it allows you to fine tune each cylinder in different parts of the run. If your egt's are a little hot early in the run, you can adjust your low side check to open earlier. So on and so forth.