What’s the smallest nozzle (or orifice in general) you guys have run in an mfi system with a 10 micron post pump filter? What if it was 100 micron?

I have run as small as ,019 in a 16 line setup with small nozzles in hat and bigger ones in runners. This way if you do get a plugged one it has lot less effect on engine.

Remember that the smaller the nozzle area total is the smaller your main will have to be to build enough pressure to get required fuel to engine.

Go to FIE web site click on tune up calculator and run some numbers for fun and you will see how even cpl nozzle sizes will run pressure up and require smaller and smaller main jet.

http://fuelinjectionent.com/

This message has been edited. Last edited by: wideopen231,

We use the 63 micron filter from FIE after the pump. No filter on the inlet to restrict/cavitate the pump.

https://fuelinjectionent.mysho.../fuel-filter-element

I try to size my nozzles to get at least 110+ psi at the port line distribution block.

Recent tune up was 123psi@7500 using a .031 Kinsler screened nozzle.

Been as small as.028.

Nozzle sizing will depend on pump flow and desired pressure.

Like 68427 . I size mine for pressure I want. I like to stay in 150 psi range. Pressure you use will have little if any effect on performance in most cases. All of my flow charts are based on 150 and I like higher pressure. Some have run north of 200 psi. I don't find it beneficial especially with alcohol and injected. Now with blower and/or nitro pressure can make difference.

I have played around with smaller nozzles to help with over rich at low end. Since pump is spinning less it will not generate pressure to make small nozzle flow like it will on high end with lot more pressure. In case you can't tell this kind of stuff is something I love to tinker with, which happens to be a big problem, for someone use to heads-up and going bracket racing. I spend hours playing on homemade flow bench or should say device a friend has. Good thing he lives far enough not to be easy access.