16 nozzle bs 8 nozzle screw psi fuel system ??

I have run both the 8 and the 16 nozzle systems. The only advantage to a 16 nozzle system is more even EGTs at idle but who runs a race at idle. I much prefer the 8 nozzle system for simplicity in tuning and the idle EGTs are close enough. Figure the total area of each of the two nozzles for a cylinder and find a single jet with that same total area. No need to flow the system. You can also do it using Total GPM of the two nozzles and find a single jet with the same GPM. I have the jet charts if you need them.

 

PB is roots only so is a 8 nozzle system. PX type motors have gone both ways and prefer the simplicity of the 8 nozzle system. Don't get me wrong because the 16 nozzle system also works. I don't think there is a difference in power between the two, one is just simpler than the other.

 

We are talking screw blower fuel setups so putting a lot of fuel into the hat to seal or lubricate the screw blower is not required. Some fuel is used to cool the mixture.

 

Tom Conway was pretty much the one who pioneered the modern day 16 nozzle system in the alcohol cars. Specifically Top Alcohol Dragster. The theory is to have the 'dribblers' to even up your cylinders at stage (part throttle, swapping feet on a clutch - no WOT two step). The smaller CID dragster motors like to have all the cylinders lit at stage, so it is a very functional system if you are trying to have all cylinders lit in the 600+ EGT range at stage.

The conventional 8 nozzle system remained more in the TAFC's that had more torque and had a few cylinders out (cold/wet) at stage by design to calm the car down off the line. As mentioned, this is a simpler system that is easier to manage.

The train of thought with the converter cars running a 16 nozzle system is running the dribblers at a lower pressure than the dragster style system in hopes of evening the cylinders up at idle. This helps achieve a cleaner idle that doesn't blubber as much.

 

Dale I agree with the standard configuration of that you are talking about and not running them lean and overheating but they don't need more than the standard is what I am saying. There are no stripes to seal or lubricate but you don't want it to heat up and expand so you have metal to metal contact especially on one that has been coated. Screw blowers do not have the internal friction of a roots blower so they do not need as much fuel in the hat to cool things down

 

will, not sure what you are saying about a converter car because with the poppet settings on a 16 nozzle system they are all wide open on the Two Step which is what counts. Never had a blubber problem with 8 nozzles if the BV is adjusted correctly

 

What I was getting at is with the way the 16 nozzle system was set up, staging at part throttle, you could adjust cylinder temps at stage by swapping area from the dribbler to the port side or vice versa. Granted the ports were usually starting to open as well, but you could fine tune the part throttle staging egt's.

With the BV at WOT on the two step, you really don't have any adjustability on just the stage side.

I have had to put a check ball in No. 2 on a converter car 8 nozzle system to keep it from loading it up.

The 16 nozzle deal just gives you another fine tuning adjustment knob.