about how many turns should I take out the FMU for 36# injectors. My manual only mentions 30# ers.
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about how many turns should I take out the FMU for 36# injectors. My manual only mentions 30# ers.
nobody uses an FMU at ALL?
i have 42#'s and i don't use mine at all. i tried it a various settings and finally gave up and removed it. car ran pig rich all the time, and wouldn't start when it was warm. Ken
I guess I'm a little ignorant about the FMU, isn't it only used when under boost?
hmmmm, you could be right. never thought of it like that. but since i removed it the car does run better. wonder why? ken
When I finally get around to affording to tune the car, I think I'm still gonna use the FMU, and set it 1:1 to mimic cartech's boost sensitive regulator.
hmmmmmm, now theres a thought. let us know how it works out. ken
Dear PO-PO 5.0:
I use the FMU with 24 injectors and 12 psi of boost, and it works perfect!!!
I get about 85 psi of fuel pressure under full boost, and have no complains ....
I use 75 mm throttle body, thypoon intake, 76 mm CL air flow meter...
The FMU from procharger is boost sensitive, restricts the fuel return line depending of the boost.
The best way to adjust the FMU is to have a fuel pressure gauge installed, try to go with only half a turn and see how it works, keep your eye on the fuel pressure and make sure it goes up once the boost comes on.
Be sure it goes back to normal pressure when boost goes off .
Of course the FMU will only work if you have a GOOD fuel pump of about 255 lph.
I hope my humble comments helps you.
Best regards
pablo
I know how the FMU works, but the ATI manual doesn't mention any type of setting for 36# injectors. In reality, I don't need the fuel to come up very much. I basically set the thing for 30# injectors, and have just driven it pig rich for the time being. I have a fuel pressure gauge, but not a boost gauge (sad huh?). the fuel pressure comes up a bit, but since I don't know how much boost I'm making its tough to say what the rate is!
Well, since you have it set at #30 injectors, all you would need is to play around with it from there to turn down the FMU a bit under boost... you'll just have to screw around with it till you get it right. A boost gauge might be a good investment :) Good luck with it.
A boost gauge, a twEECer, and a wideband. I just have to get rid of a few things out of the garage so I can afford all of this.Quote:
Originally posted by WA2FAST
Well, since you have it set at #30 injectors, all you would need is to play around with it from there to turn down the FMU a bit under boost... you'll just have to screw around with it till you get it right. A boost gauge might be a good investment :) Good luck with it.
Yea, I hear ya. I have a TON of things in my garage that I need to snap some pictures of and sell here soon too. Too much stuff that is worth good $$$ and other people could get some good use out of and I need to fill the hole in my pocket too :)
Dear PO PO 5.0:
i forgot to ask you about the air flow meter on your car...I hope you have the air flow meter calibrated for those 30# injectors..if not you might have a very rich condition.
Just wonder..
Take care.
Pablo
its a C&L, and it has a 36# sampling tube.
Dear PO PO 5.0
Glad to hear that you have a CL calibrated unit for those big injectors...36 injectors are big, and you would need a good flow heads, and some more to handle that kind of fuel.
By the way,...you are using the white restrictor and check valve on the procharger FMU? if not you would have problems when you decelarate the engine, since the fuel pressure would be very high once you lift your foot form the pedal.
Take care
pablo
The motor has some worked iron GT40's, and a 513/529 cam so I think I meet the airflow requirements of those injectors. Yes I am using the check valve in the hose going to the FMU.Quote:
Originally posted by pablo
Dear PO PO 5.0
Glad to hear that you have a CL calibrated unit for those big injectors...36 injectors are big, and you would need a good flow heads, and some more to handle that kind of fuel.
By the way,...you are using the white restrictor and check valve on the procharger FMU? if not you would have problems when you decelarate the engine, since the fuel pressure would be very high once you lift your foot form the pedal.
Take care
pablo
I honestly don't beleive the 36# injectors are too much for what you have, alot of times cars can go lean quite easily especially when being untuned. I would say until you can get the car on a dyno and have it tuned, keep the fmu on.
As for the setting, pretty much what everyone else has said, a fuel pressure guage is a good tuning tool, set the base fuel pressure, then work with the FMU with throttle blasts. I would first of all make a mark on the FMU dial so you can tell how far you have turned it, and it gives a good reference point. Try working in 1/4 turn increments to see how this works for you.
I wouldn't imagine you need a whole lot more than 65psi of fuel pressure under boost, but again its all up to the tune.
good luck
Dan
I don't plan on EVER removing the FMU. Even when I do get a wideband I'm still leaving the FMU setup for a 1:1. In the meantime, I do have a fuel pressure guage its just the boost gauge I'm lacking which should be here tuesday. Hopefully this will clue me in on what kind of fuel pressure I should be seeing. I kinda wonder if this thing really makes any boost up here in CO.
I live in Thornton Co, and with the 9# pulley I'm getting 6# @ 5500. Where are you at po-po?
Boost gauge should be in tomorrow. I'll tell ya what I make when it goes on.Quote:
Originally posted by klondike93
I live in Thornton Co, and with the 9# pulley I'm getting 6# @ 5500. Where are you at po-po?
Question... why do you never plan on getting rid of your FMU? You sound like you feel very strongly towards that... is there a reason?
From my research it would appear that having a 1:1 boost reference is benefical to tuning. I guess I'm not adamant about it, but it seems silly to buy a boost sensitive regulator when I already have an FMU.Quote:
Originally posted by WA2FAST
Question... why do you never plan on getting rid of your FMU? You sound like you feel very strongly towards that... is there a reason?
I totaly agree... you don't need a boost sensitive regulator at all with an FMU, that would be like putting 2FMU's on your car. The reason I was asking about the whole FMU thing is because FMU's are just a band-aid for an in-adaquate fuel system... if you have the proper injectors, you don't need a FMU at all and there is no 'blip' in the curve because of a sudden spike in fuel pressure that happens with even a 1:1 setup.
I have a gss340, and 36# injectors. In reality I don't need the FMU at all at my 6 psi, but from my research, I've seen that having the 1:1 aids tuning? Although, I guess 99% of chipped, blown cars don't even worry about it.
Nah, it doesn't aid anything at all. If you are having your car tuned on a dyno and a custom chip burned, you don't need one at all, you will find that tuners have to tune around FMU's. Generally the FMU is good if A) you don't have the fuel system to support your power level (which you more than likely do), and B) if you are not going to get it dyno tuned. You may want to think about that, I have a feeling you will be better off if you don't need it.
i just had my 94 D1SC dynoed yesterday, we did not use the FMU, as my tuner described the fmu as "a band aid on a bullet wound". it does the job, but there are better ways to correctly fix the problems. I pulled 470rwhp at 5500rpm and the curve was still climbing when the 42# injectors maxed out. so i need a fuel system upgrade now.
Nice! Good work... sounds like your car is gona' be a beast when it's all said and done. Funny thing, is that is how I describe FMU's to people that don't understand why they are and are not needed... I say it's simply a band-aid on an inadaquate fuel system... if you have injectors/fuel pump/rails/lines that can handle the power load, you don't need anything else.
BTW---- after my dyno we ended up with 50# base fuel pressure, on 42# injectors, no fmu, PMS assisted fuel curves. we maxed the injectors out at 470hp at 5500 rpms and it was still climbing. we stopped rather than use the fmu because we were nearing the danger point of explodeding the block. ken
Yea, my car needs to get back on the dyno (soon to come), but my tuner drove it and said that it has to be close... he is concerned about that as well.