Hi!

How have you all solved the fuel regulating issue with forced induction?
I can't find any tread about it so I guess you do like me just add bigger injectors and leave the fuel system as is. I haven't measured if the fuel pressure drops during high boost. But I guess it does because I have a Duty cycle of 95% with 89 LBS injectors. My bike makes 210 Bhp but those injector should easy handle 300 Bhp. I know Trask is adding boost to the stock regulator to keep the pressure up.

 

Look up "rising rate regulator" on google. It's the secret behind it all.

 

Yes,on my old bike (yamaha warrior with turbo) I used to have a 1:1 regulator. But its was easy to do as the stock regulator on the bike was outside of the tank. I guess its doable on a harley if you drill a fuel return into the tank. Just wanted to know if anyone have any ideas to share.
Most builds with 180+ horsepower must have the same issue with the fuel.

 

What are you using for a fuel pump?

 

Stock fuel pump and regulator.

 

Wow, didn't know the stock pump could support that kind of power. I would say you probably need a return style system with a boost referenced regulator.

I wonder what a Boost-a-Pump would do for you? (a device that increases the voltage to the pump, forcing it to output more) I use them on forced induction cages and they work. Just an idea....

 

In general the more pressure the less flow when it comes to fuel pumps.
There is also the option to drill a hole and add boost to the stock regulator. I think Trask does that on his builds.
When I get the engine back together I will measure the fuel pressure to see what happens.
There are some aftermarket fuel pumps that should be "bolt on" that flows 265 lph.
Not sure what stock flows??

 

My setup is a carbby so I use an external fuel pump and a 1:1 rising rate regulator thats tied into the boost signal. The regulator is set for 3lbs of boost and the pressure rises in sync with the amount of boost running. The final fuel pump is a Bosh 35lb EFI unit (the original was a cheap 10lb unit that worried me as i felt it could not flow enough gas under full boost)

The Regulator is setup in a bypass configuration so I have a return line that goes to the top of the fuel tank - I'm lucky that there is a blanking plate on the top front of the tank so I just fabbed up a fitting into it.

It all sits on a mounting plate I fabbed up that is locted in the base of the front air scoop. One key to success is to not use cheap chitty parts as if things go wrong here your very likely to loose your motor.

 

What tuner are you using?

 

TMAX tuner with 2bar map sensor