Effect of higher fuel pressure with shorter spray duration?

[Bender]

I've been playing around with my stroker trying to get the optimum performance and was curious as to your opinions on an idea. I'm running the renix based style stroker with injectors that flow 22.7# at 39 psi. I have a MAP adjuster but haven't had to use it. I'm only using the plug colour to determine if it's running rich or lean...not very accurate I know.

I was thinking of raising my fuel pressure to approx 45-49 psi and using my MAP adjuster to compensate if it happens to overfuel. I figured I'd try and make use of the so called better atomization of the fuel when sprayed at higher pressures.

Any thoughts?

I know the 4.0L ran 39 psi up until about 1995 where it switched to 49 psi so I don't see any real problems since jeep ran it above 39 psi stock. I've also noticed several high performance vehicles run higher pressures in the 55psi range.

 

[Flash]

I've been playing around with my stroker trying to get the optimum performance and was curious as to your opinions on an idea. I'm running the renix based style stroker with injectors that flow 22.7# at 39 psi. I have a MAP adjuster but haven't had to use it. I'm only using the plug colour to determine if it's running rich or lean...not very accurate I know.

I was thinking of raising my fuel pressure to approx 45-49 psi and using my MAP adjuster to compensate if it happens to overfuel. I figured I'd try and make use of the so called better atomization of the fuel when sprayed at higher pressures.

Any thoughts?

I know the 4.0L ran 39 psi up until about 1995 where it switched to 49 psi so I don't see any real problems since jeep ran it above 39 psi stock. I've also noticed several high performance vehicles run higher pressures in the 55psi range.

YUP have thought about it a lot, I think it will wok, Would love you you to prove me right.......or Wrong!:yelclap:

I thing you will notice it more at idle and W.O.T.

Flash.

 

[Bender]

It is the increased performance at low rpms that I'm looking for. Most performance modifications don't seem to address the 600-1800 rpm range with high loads which is pretty common for an off-road engine.

 

[tealcherokee]

higher pressure/shorter pulse will atomize WORSE. it forces the injectors to spray bigger droplets of fuel, and its harder for it to mix w/ the air. you should never exceed 10% of what the injectors rated flow is. IE 39psi rated means 42.9 psi max

 

[Bender]

Are injectors more efficient at their rated pressure?

Currently I'm using some Accel injectors rated at 24.4lb/hr at 44.1psi but I'm only running them at 39 psi.

 

[jforse]

I've been playing around with my stroker trying to get the optimum performance and was curious as to your opinions on an idea. I'm running the renix based style stroker with injectors that flow 22.7# at 39 psi. I have a MAP adjuster but haven't had to use it. I'm only using the plug colour to determine if it's running rich or lean...not very accurate I know.

I was thinking of raising my fuel pressure to approx 45-49 psi and using my MAP adjuster to compensate if it happens to overfuel. I figured I'd try and make use of the so called better atomization of the fuel when sprayed at higher pressures.

Any thoughts?

I know the 4.0L ran 39 psi up until about 1995 where it switched to 49 psi so I don't see any real problems since jeep ran it above 39 psi stock. I've also noticed several high performance vehicles run higher pressures in the 55psi range.

Find a shop that has a dyno. Pay for a hours time. Use thier wideband O2 sensor to get it dialed in.

 

[Flash]

higher pressure/shorter pulse will atomize WORSE. it forces the injectors to spray bigger droplets of fuel, and its harder for it to mix w/ the air. you should never exceed 10% of what the injectors rated flow is. IE 39psi rated means 42.9 psi max

I would think, that a short, higher pressure spray, would cause less fuel droplets(or fuel drop out of the air stream) then the same fuel sprayed at a lower pressure for a longer period of time...........

It sure would be nice to have a Dyno prove it

Flash.

 

[Bender]

My truck is an off-road only machine that I trailer around...it won't be seeing a dyno in the near future. Just looking for any experiences with fuel atomization with respect to pressure.

 

[Flash]

My truck is an off-road only machine that I trailer around...it won't be seeing a dyno in the near future. Just looking for any experiences with fuel atomization with respect to pressure.

Thats to bad.....I guess the question remains........

I guess just put it on and (adj pressure req.) and adj the pressure high(remember you have to give the computer time to adj) and then set it low....then you can decide which end of the scale to start at.



Flash.