FI fuel system

[Blizzard242]

Ok. A couple of questions. One question arose when I was searching around for which size fuel injectors I should get and where I should get them from.. But anyways someone has a FMU they were selling because they picked up HPtuners. Does that mean I don't need an FMU if I get HP tuners? I was lost with the FMU anyways, or rather exactly what it does to help. I'm getting HP tuners anyways so do I need this FMU? Crap, I'm gonna go look around in the stickies some more but if anyone could help me understand I'd appreciate it.

[ninety4three4]

Re: FI fuel system

FMU or fuel managment unit is a boost referenced fuel pressure regulator, for example on a 6:1 FMU for every pound of boost increase the FMU allows 6 PSI more fuel to flow to the rail, if you are getting HP tuners then you probably dont need one cause the 3.8's probably have an electrically controlled fuel pressure regulator that can be adjusted with HP tuners but do not hold me to that as for the injectors try this chart http://www.witchhunter.com/injectorcalc1.php4 this is a decent calculator for getting a injector size based on anticipated power levels

[redfbird99]

Re: FI fuel system

FMU or fuel managment unit is a boost referenced fuel pressure regulator, for example on a 6:1 FMU for every pound of boost increase the FMU allows 6 PSI more fuel to flow to the rail, if you are getting HP tuners then you probably dont need one cause the 3.8's probably have an electrically controlled fuel pressure regulator that can be adjusted with HP tuners but do not hold me to that as for the injectors try this chart http://www.witchhunter.com/injectorcalc1.php4 this is a decent calculator for getting a injector size based on anticipated power levels

fmu is still needed with HPTuners, i acctually have one for sale for 60 bucks if the maker of this thread wants it. I am selling it because I recently switched my injectors to go along with my powerdyne kit and no longer need the FMU.

here is the link to my for sale thread.
http://forum.camarov6.com/showthread...115#post792115

[Blizzard242]

Re: FI fuel system

I have one already, came with the turbo kit I bought.. I just didn't know if the previous owner of the kit didn't have HP tuners and was using the FMU as a bandaid. Thanks anyways.

[ninety4three4]

Re: FI fuel system

ok like i said i am not lucky enough to use HP tuners for tuning so sorry on my incorrect information but i hope the other info i gave you helps...

[Blizzard242]

Re: FI fuel system

Yeah, ninety4 you helped me understand it a little more. If I actually understood it all I could actually use that calculator.

[ninety4three4]

Re: FI fuel system

basically put in the goal horsepower you are looking to make at the flywheel, number of injectors which is obviously 6, a BSFC of .62 it explains that in the first asterisk, and a duty cycle of 80% which will leave room for future mods, if you go 100% you can get a lower lb/hr injector but no room for more HP and more chance of going static (maxing them out) and blowing up

[Blizzard242]

Re: FI fuel system

Wait wait.. so lets say I just get a high lb/hr injector. It'll run fine if it's tuned right? Like lets say I get a really really fast processor for my computer (which would be the injectors in my car) and I'm running software that doesn't require all of that power (mods done to my car) it's not gonna hurt anything? heh Understand lol. Oh god, I might have confused myself.

[redfbird99]

Re: FI fuel system

Wait wait.. so lets say I just get a high lb/hr injector. It'll run fine if it's tuned right? Like lets say I get a really really fast processor for my computer (which would be the injectors in my car) and I'm running software that doesn't require all of that power (mods done to my car) it's not gonna hurt anything? heh Understand lol. Oh god, I might have confused myself.

i think i know what your saying, no it wont hurt, you just wont use the entire capacity the injectors can handle.

[DegrezzE]

Re: FI fuel system

Wait wait.. so lets say I just get a high lb/hr injector. It'll run fine if it's tuned right? Like lets say I get a really really fast processor for my computer (which would be the injectors in my car) and I'm running software that doesn't require all of that power (mods done to my car) it's not gonna hurt anything? heh Understand lol. Oh god, I might have confused myself.

So say if you get 65# injectors when you really only needed 45# injectors to accommodate your fuel needs, as long as you program your cars computer for 65# injectors with HP Tuners or whatever, its not going to hurt your car.

[ninety4three4]

Re: FI fuel system

basically as long as you tune the computer correctly for the injectors you have everything would be fine, the only thing that would happened if not tuned is youde be dummping WAY to much fuel in, if you go to small you will not get enough fuel in and cause lean problems, lean + forced induction = BANG, always have a experienced tuner help you tune your car if you have never done so, the only thing is the bigger you buy i would say the more expensive so just get something closer to what you need according to the calculator and other opinions of engine builders, the calculator is a guide not a bible, let me know what youre expected rear wheel horsepower goals are and i will try to help you the best i can

[97rs4life]

Re: FI fuel system

a FMU is not needed if you have upgraded injectors and tuned for injectors with hptuners. The fmu is for the guys running stock injectors and 6psi of boost.

[Blizzard242]

Re: FI fuel system

Honestly, I don't know what I'm expecting for HP. Hopefully at least 300. That's at least with the ****tiest geustimate you could ever have. I'm adding a turbo, camshaft, driveshaft, gears, lsd, blah blah blah.. blah blah. I'm gonna go all out on this car besides major overhauls. I do not want to ever have to pull the engine out for any reason. I need to get my hands on a copy of HP tuners so I can at least go through the program and see what I'm dealing with. I'm not a complete idiot when it comes to math but I don't know the equations i'll need yet. Ahhhhhhhhhhhhhhh!! this is frustrating but worth it.

[ninety4three4]

Re: FI fuel system

well nothing effects flywheel horsepower besides engine modifications, i think 350 is a good estimate for reliable flywheel horsepower if you dont want to pull the engine, however tuning errors, bad gas, computer hickup, or just plain mechanical failure could casue a problem in the engine which would require disassembly and possible removal from the car so if you dont want to remove your engine i dont think anything other than bolt ons are a good idea for you since shiit happens when you start playing with forced induction ask anyone here on the forums with a turbo car they can attest to that

[Blizzard242]

Re: FI fuel system

Yeah, so I'll just stop doing any modifications to my car. Uh No. Maybe I should have said I don't want to have to pull the engine out for performance mods, not repairs. And as far as I know, the mods that I want to do to my car DO NOT require you to pull the engine. Yeah, I'll tell you whats good for you. #(%*& #(%&&%#@ %&#@%* #@%&( I suppose I should just ask for a refund from this site then because who the hell needs help installing bolt ons. Thanks hun! Don't take any of that to heart. I understand that you're trying to help but telling someone to stick to bolt ons is a little bit insulting.