Up the fuel pressure

Aaron Pedroza

Registered User
Ok, what do you guys think? I have been told that it is better to run higher fuel pressure through our injectors for better atomization. I also like the idea so I don't have to buy new injectors. What I am wondering is how to tune for this. I have been told that the EEC doesn't recognize pressure. So is it right that all I have to do is change the injector size in the EEC to what the higher pressure to the injectors is equivilent to. ie increase to 60 lbs on a 36# injector so change the EEC to read it as a 45# injector? Or even have MAF calibrated for a 45#?
 
new injector size = ((new pressure)*(injector size)) / 39.5

example
36# injectors @ 60psi would be equivilent to 55# injectors.

54.68 = ((60)*(36))/39.5 = 1.519 * 36


Aaron

Warning - I am not exactly sure, at this time, how to recalculate the low injector slope. It is very dependant on the minimum actuating time on the injector but a linear scaling should get you close enough for a good idle quality. The EEC code is very convoluted and I need to study it a lot more
 
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Well, I have one of those ProM Optimizers for my MAF so I can adjust high and low rpm. I don't want to do it unless I am at a dyno with a wide band fuel/air gauge but I may just try this to save a little cash if the general consensus says it will work.
 
Aaron,

It will work for WOT, but will provide too much fuel at part throttle and idle. To operate at that pressure you will need a 255 lph Forced Induction pump. Even the regular 255 won't flow enough fuel at high pressure.

David
 
The units that mess with the MAF sensor signal are only a band-aid. You really need a tuner to make it work properly.

A lot more than basic A/F ratio needs to know about the injector flow. You will get harder starts and tip-in will be wrong if you only use a MAF type adjustment.

Aaron
 
I remember looking into the flow numbers a while back. I remember after 60lbs is when the flow really drops off, that's why I chose that pressure. I remember that the Walbro 190lph pumps flow 145lph @60psi which is just about what I need it to flow. What I don't quite understand is why it will cause probs with idle and part throttle if it will work at WOT. What's up with that?
 
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Hey Aaron, where did you get that calculation? I have a few calculators here and they are all telling me different numbers. All at like 44.3#'s with pressure up to 60 lbs. Also if you know, what pressure are FMS injectors rated at?
 
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