99FLHRCI Posted June 5, 2009 Report Share Posted June 5, 2009 When I went to tech school I seem to remember a discussion about the max recommended fuel pressure to apply to an injector. Above that pressure you run a risk of overpowering the spring that closes it and the computer loses control of the injector. Does anyone know where I can find this information? I am running Precision Turbo and Engine 440cc injectors. I called them and the only advice they would give me is to use a rising rate regulator (1:1) and set my pressure for 43.5psi. They said the regulator would handle the rest. I am not using a rising rate. I would like to use these injectors, an AEM adjustable regulator (20psi-max pump output), a Walbro 255lph pump (I believe 80psi max) and Hondata. Currently it has been suggested to use 550cc injectors. I would like to know what these can put out at max flow and compare that to 550's. Also, Precision recommends a 90% duty cycle, everywhere else seems to be 80%. Any reason not to plan 90% if that is what they suggest? Thank You Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted June 5, 2009 Report Share Posted June 5, 2009 never go over 70psi with a injector...they start getting funky up around that psi... there is a nice write up on this on the net some where..i'll have to dig for it later.. Quote Link to comment Share on other sites More sharing options...
Brandon Posted June 5, 2009 Report Share Posted June 5, 2009 never go over 70psi with a injector...they start getting funky up around that psi... there is a nice write up on this on the net some where..i'll have to dig for it later.. TJ it is based on what your base fuel pressure is, just like PTE explained I am sure. Injectors have come a long way in engineering. The with your blower you will have a rising rate regulator which will raise the level of fuel pressure 1 psi for every 1 psi of positive vacuum. Rob, I know what your saying with the 70 PSI rating, but for example on 4 bar GM fuel systems they run 58.8 static pressure, and often times in the performance industry you will see over 70 psi at the injector, and with the proper sizing and tuning, there should be no repercussion. Another example is an EVO running 35 pound of lbs, so it just depends on the injectors more so. Quote Link to comment Share on other sites More sharing options...
99FLHRCI Posted June 5, 2009 Author Report Share Posted June 5, 2009 So since I am planning on 8 psi of boost (supposedly what the kit is rated at however it mentions 9 in the instructions) I would expect to see 51.5 psi at peak on a rising rate regulator? I am not planning on using a rising rate regulator (Is it required?) Would this mean that the adjustable regulator should be set to 51.5 and then the computer would use less duty cycle at lower boost to limit the fuel? Quote Link to comment Share on other sites More sharing options...
koolrayz Posted June 5, 2009 Report Share Posted June 5, 2009 A boost referenced regulator is just allowing for the fuel pressure to compensate for the pressure rise in the manifold. In other words in an N/A aplication if the fuel pressure is 43.5 PSI, the fuel pressure is 43.5 PSI above the intake manifold pressure. If you are running 20 PSI of boost the net difference is now only 23.5 PSI. It doesnt allow more flow it just allows the flow to stay at the same level Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted June 5, 2009 Report Share Posted June 5, 2009 From experience, do not use an FMU. Have the car properly tuned with bigger injectors. I see 72psi fuel pressure at peak boost and have no issues, although my 60# units are close to full duty cycle again. I'm gonna be going with the new Ford 83# injectors. Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted June 5, 2009 Report Share Posted June 5, 2009 Hi Ray, I <3 you. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted June 5, 2009 Report Share Posted June 5, 2009 TJ it is based on what your base fuel pressure is, just like PTE explained I am sure. Injectors have come a long way in engineering. The with your blower you will have a rising rate regulator which will raise the level of fuel pressure 1 psi for every 1 psi of positive vacuum. Rob, I know what your saying with the 70 PSI rating, but for example on 4 bar GM fuel systems they run 58.8 static pressure, and often times in the performance industry you will see over 70 psi at the injector, and with the proper sizing and tuning, there should be no repercussion. Another example is an EVO running 35 pound of lbs, so it just depends on the injectors more so. i under stand that. but im talking not running 70 plus psi at all times. thats why i steer clear of dry systems now that ramp FP to deadhead(80-100psi at times) cause it plays hell with injectors.. but then each setup will be different. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted June 5, 2009 Report Share Posted June 5, 2009 A boost referenced regulator is just allowing for the fuel pressure to compensate for the pressure rise in the manifold. In other words in an N/A aplication if the fuel pressure is 43.5 PSI, the fuel pressure is 43.5 PSI above the intake manifold pressure. If you are running 20 PSI of boost the net difference is now only 23.5 PSI. It doesnt allow more flow it just allows the flow to stay at the same level thank you..i think i covered that some where in this thread http://www.columbusracing.com/forums/showthread.php?p=963488#post963488 Quote Link to comment Share on other sites More sharing options...
DOZZER Posted June 6, 2009 Report Share Posted June 6, 2009 I'm gonna be going with the new Ford 83# injectors. More Ford parts to make your GM go faster.. I see a trend. Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted June 6, 2009 Report Share Posted June 6, 2009 More Ford parts to make your GM go faster.. I see a trend. I sold my 8.8, so bite me Quote Link to comment Share on other sites More sharing options...
DOZZER Posted June 6, 2009 Report Share Posted June 6, 2009 I sold my 8.8, so bite me Thats okay. I know deep down you wish you had a Mustang. So then you could go fast. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted June 6, 2009 Report Share Posted June 6, 2009 I sold my 8.8, so bite me so did you want to order a moser 12 bolt instead of the 9" Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted June 6, 2009 Report Share Posted June 6, 2009 Yes. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted June 6, 2009 Report Share Posted June 6, 2009 ok so you want high dollar fail got it.. now you want that lifetime warranty posi i can get for those? i mean true life time warranty. they are putting 1200hp threw these things, and its much more streetable then a locker. Quote Link to comment Share on other sites More sharing options...
smokinHawk1647545499 Posted June 8, 2009 Report Share Posted June 8, 2009 i ran some 42lb injectors up to about 85-90psi a couple of times down the track allowed me to run 135mph on some 42's i promptly got some bigger injectors, like about 96's Quote Link to comment Share on other sites More sharing options...
CRed05 Posted June 8, 2009 Report Share Posted June 8, 2009 Get a rising rate FPR. Quote Link to comment Share on other sites More sharing options...
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