If I wanted to run approximately 7 or 8 pounds of boost, what type of FMU should I use/get. HELP!

 

Vortec

 

Would you know my compression ratio? Haha, It's funny, I used to think I knew so much about my car untill i seriously started looking into slappin' a turbo on.

 

i dont even know why anyone would want to run a FMU nowadays....
so crude..

do yourself and your fuel system a favor and just chip your ecu for boost.

 

I've been told to steer clear of FMU's at all cost. I thought the crudest thing people used nowadays were SAFC systems......

 

FMU = toasted injectors

toasted injectors = not enough fuel

not enough fuel + boost = engine exploding in near future

get it? just get bigger injectors and spend some money on a chipped ECU, crome (free), and some good tuning, and you'll be making a lot more power and it will be MUCH more reliable.

 

from an fmu user....you can get a 255 fuel pump, run a 12:1 fmu, run a fpr with stock injectors and you'll be ok for a while. until you start leaning out and turn up the boost

 

Do you know any sites for me to check out ECU's? Approximately how much would one cost?

 

$200 for an FMU which will make much less power and eventually burn your motor up.

~$300 for injectors and ~$300 for tuning which will make much more power and be reliable pretty much forever, just like stock.

save $400 now, spend $2000 on a new engine later. your choice.

 

I bought a vortech fmu for 40 bucks and wasnt going turbo just yet, but how useful is this on a stock motor and what if I get a set of 550cc injectors. will the fmu be able to be useful??????????

 

i mean, you can't turbo at all without an FMU or larger injectors + tuning, but really even with FMU you really need tuning, otherwise it will run like crap. so really if you have larger injectors forget the FMU. it's useless. just get some tuning done and enjoy .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">i dont even know why anyone would want to run a FMU nowadays....
</TD></TR></TABLE>

yea exactly, there are so many other options besides fmus, check valves, and afcs now, i just dont understand why anyone would even consider those old options anymore

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Deluzional &raquo;</TD></TR><TR><TD CLASS="quote">

yea exactly, there are so many other options besides fmus, check valves, and afcs now, i just dont understand why anyone would even consider those old options anymore </TD></TR></TABLE>

why don't ppl consider ball bearing instead of the old t-series. ppl consider the other options cause it's available and because of price. i mean why do you choose piggy back fuel management units over motec, haltech, or aem? they all work. just to an extint because things are limited. but none the less, to answer the poster's question, a fmu will suit their needs.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oclooc &raquo;</TD></TR><TR><TD CLASS="quote">I bought a vortech fmu for 40 bucks and wasnt going turbo just yet, but how useful is this on a stock motor and what if I get a set of 550cc injectors. will the fmu be able to be useful??????????</TD></TR></TABLE>

i don't think you can use your 550's and fmu. that's just too much fuel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by undercoverdc2 &raquo;</TD></TR><TR><TD CLASS="quote"> i mean why do you choose piggy back fuel management units over motec, haltech, or aem? they all work. just to an extint because things are limited. but none the less, to answer the poster's question, a fmu will suit their needs.

</TD></TR></TABLE>

I only suggest to look elsewhere, because others including myself have destroyed motors due to the use of these piggyback systems. Sure they are suffice enough for apps, but as far as reliability, i would never look back to any piggyback system

 

ok so my theory that a afc is better than a fmu is right then. I explained that you can turn up fuel via a afc (I think) to my friendbut they tell me otherwise.. and so basically I shouldnt use the fmu that I have.. what purpose does this crap have then... Im getting confused?????????? mannn

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oclooc &raquo;</TD></TR><TR><TD CLASS="quote">I bought a vortech fmu for 40 bucks and wasnt going turbo just yet, but how useful is this on a stock motor and what if I get a set of 550cc injectors. will the fmu be able to be useful??????????</TD></TR></TABLE>

It isn't useful at all. What type of Vortech FMU did you buy? I'm not even sure that you can hook up a boost dependent FMU to a non-boosted car. If you can, it won't do anything.

If you are going to run a set of 550cc injectors, then the car won't even run with the FMU at the 1:1 level with no boost. Too much fuel. My car didn't run with even 440cc ones. There's no point to installing any of these things until you do get that turbo.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oclooc &raquo;</TD></TR><TR><TD CLASS="quote">ok so my theory that a afc is better than a fmu is right then. I explained that you can turn up fuel via a afc (I think) to my friendbut they tell me otherwise.. and so basically I shouldnt use the fmu that I have.. what purpose does this crap have then... Im getting confused?????????? mannn</TD></TR></TABLE>

Why do you want to turn up fuel? More fuel doesn't equate to more power. Engineers have set the ECU up perfectly to balance out between gas mileage and performance. Any modification to this, and you will be sacrificing something. A stock engine has pretty much the best combustion that can be had with technology today. Adding more fuel won't do anything. You'll just run rich and have the car bog down. Combustion may or may not be complete, and you run into a whole mess of new problems that the ECU cannot/isn't meant to accomodate for.

An AFC doesn't actually increase fuel. It tricks the MAP sensor by altering voltage to the sensor. It's difficult to explain, but you can't pump more fuel into an injector that's already going at 100%. You might be able to squeeze out a TINY TINY amount, but nothing nearly enough to accomodate a turbo.

You can, however, use an AFC to tune DOWN your fuel. It's always better to get LARGER injectors than you need and tune them down, rather than get smaller ones and tune them up. First of all, you can't, and second of all, why? Injector prices don't vary that much as the flow increases.

 

thanks alot thats good info but I never said I wanted to up fuel for more power.. I am asking becuase when turdo'd the enginge will require more fuel and I thought the fmu or afc was a sufficient way to do so.... thats all.. I want to start with a basic turbo because as you stated the stock fuel is perfrect enough... so why put on injectors a fpr and a fuel rail right????????? ok so with that being said I will just bolt up a turbo then add those compnents.. I am just trying to situate my primary bolts ons... I just want to get my facts straight and you all are helping so forgive me if I come in the wrong way with my questions....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oclooc &raquo;</TD></TR><TR><TD CLASS="quote">thanks alot thats good info but I never said I wanted to up fuel for more power.. I am asking becuase when turdo'd the enginge will require more fuel and I thought the fmu or afc was a sufficient way to do so.... thats all.. I want to start with a basic turbo because as you stated the stock fuel is perfrect enough... so why put on injectors a fpr and a fuel rail right????????? ok so with that being said I will just bolt up a turbo then add those compnents.. I am just trying to situate my primary bolts ons... I just want to get my facts straight and you all are helping so forgive me if I come in the wrong way with my questions....</TD></TR></TABLE>

I apologize, I misunderstood.

You DO still want to make sure you have extra fuel anytime you put on a turbo. Even if the turbo is small and you're not pushing that much power, you still need more fuel. This is because more air is going into the system. More air means you need more fuel, right? Right.

As people have said, you want to stay away from an FMU. Try to save up for engine/fuel management instead. There are many choices out there, some of which are free (Crome) if you know how to mess with your ECU. The benefit of doing this is the timing control. Our cars, as you know, do not have turbos in them already. There is no way for the ECU to adjust timing when there is positive pressure (boost) in the system. Thus, the head/EGT gets too hot, and bad things start to happen. You get hot spots within the combustion chamber and that leads to even worse things.

If you don't have a large budget in the beginning, you can go with your FMU/AFC, but it won't run as well. You'll get some bogging issues and your power level will be limited. Definitely save for "real" fuel management.

 

BTW, i know first hand why you shouldn't add fuel with an AFC. for starters, as shamoo said, there is only so much you can add. stock, your injector duty cycle max is about 80-85%, so there is room for more fuel, at the expense of injector life. however, when you use the AFC to add fuel, it increases the MAP signal higher than what the engine is actually seeing. what this means is that the ECU will trigger it's WOT fuel settings too early, which causes MASSIVE driveability issues and will make your car SERIOUSLY slow. that's why you don't do it. i always wanted to know, so i tried it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Deluzional &raquo;</TD></TR><TR><TD CLASS="quote">I only suggest to look elsewhere, because others including myself have destroyed motors due to the use of these piggyback systems. Sure they are suffice enough for apps, but as far as reliability, i would never look back to any piggyback system</TD></TR></TABLE>
i hope you're only talking about AFC's and FMU's. crome is not a piggyback and it's 80% of the way to standalone for almost no cost at all. the only things it won't get you is the ability to control additional injectors (unless you really know what you're doing and use one of the auxilliary outputs on the ECU . . .), ability to simply add or delete sensors at will, and such. it's only limited to the stock speed-density format, which for most of us is not a limitation. in my experience chipping can lead to operation just as smooth and powerful as standalone except in the most extreme applications where perhaps fuel will be only throttle position-dependent and additional injectors and nitrous and traction control and more must be used.

 

ok cool so forget all the bs fuel upgrades I was going to do.. I figured since I was gonna do a cold air intake I would need more fuel so a fpr fmu and fuel rail would be good (not good for a small intake like a cold air) but getting them now means when I turbo I wouldnt have to get it then.. so scratch that.. leave it stock then go with a nice t3/t4 turbo and THEN upgrade the nessessary components.. I feel like a moron.. I use to know this like the back of my hand when I my eg.... 5 years later I'm clueless.. this sucks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oclooc &raquo;</TD></TR><TR><TD CLASS="quote">I use to know this like the back of my hand when I my eg.... 5 years later I'm clueless.. this sucks</TD></TR></TABLE>

Blah, everyone has to learn, right? A turboed system is a totally different ball game.

 

Yea I know thanks alot thought.. I have so many threads print from you guys and info I know im going to need.. Im trying to catch up but this turbo thing is going take time and getting to know... glad I got this forum for back up tho... my online mechanics.. thanks fellas

 

well, if you tune with crome or something you can put in the larger injectors and tune the current motor for the larger injectors. if the tuner is good they can tune more than just the fuel maps; the tuner should be able to change the injectory latency settings. not changing this is why some cars with larger injectors idle so poorly. then you could take care of the injectors now and have 1 less thing to do later. of course, then you have to pay to tune it now and again later, so bad for cost unless you tune yourself, but i'm assuming that's not going to happen. just saying it could be done.

oh, and by the way, don't bother getting an aftermarket fuel rail. TOTAL waste of time.

 

I will tune myself once I get back up to date and better affiliated with the setup... so the stock fuel rail is sufficient enough then?????? whats the hype on the aftermarket fuel rails.. I thought the flow in them was better and increased over stock????????

 

hehe it is increased over stock, but you have to understand that there really isn't that much fuel going into the motor in the first place. the overall volume isn't that great, and the pressure is high . . . all in all i'd guess the stock fuel rail is good for several hundred horsepower. thing is anybody with the moolah to make that kind of power has the dough to lay out for stupid crap like a shiny, colored fuel rail.