Understanding a fuel system...

[DeLo360]

So for the past two weeks i have been researching turboing a 420a. I have actually learned a great deal about almost every aspect as to how a turbo works in a car, and what i need to get done in order to turbo my 420a.... well almost. Through my research on the forum here and 2gnt, i have found much info on the fuel system.

My problem however arrises with the terminology, and some of the functions. I understand the purpose of a fuel pump and why i woudl need a bigger one. But after that i'm lost... too many terms thrown around (fmu, sfmu, portfueler, magasquirt, bigger injectors, etc). I dont quite understand what i need and what everything does.

I'll say this. When i start gathering parts i want to do it once, except for the IC and perhapse the turbo (I dont knwo if i want to go internal or external wastegate to control the psi to 7 initially). My overall goal is a 300hp daily driver. I have someone fully competent to tune my car (built a 700hp mustang) so i would liek to go the megasquirt way.... but i just dont understand enough about the fuel system to know what i need and why i need it. I dont want to jsut buy parts... i want to knwo what they do.


Sorry for the length,

Dave

 

[selmerguy]

you built a 700 hp stang and don't know what a fmu is???

there are a few bolt on combinations of fuel stuff that works. if you break it down what you want the fuel system to do is provide the right amount of fuel in the combustion chamber to mix with the quantity of air. (a/f ratio) the fuel pump is a must upgrade for your turo project and it's easy. if you only want to do your fuel system once and your final goal is 300 hp you will need to spend some money. (hope your motor is built) a 12:1 fmu is good to about 10 psi on stock injectors any more psi and your stock 195cc(not sure about the size but should be close) can't handle any more fuel. with the fmu you still use the stock fpr. a sfmu takes the place of your fpr and is tuneable. i am not sure what psi it is good for but i have friend running 15psi using one. the sfmu has many tuning options like idle fp and boost ratio. the megasquirt system is a fuel system computer that seems to be the best(imo) option for the higher hp 420a's. i have heard it is hard to install but easy to tune with. the portfueler is made by hrc and i think it is about 1000 dollars or so. i have seen alot of people say it runs rich. you can get away with running a little rich and be ok but if you run lean it makes heat the motor goes boom!

you might want to check and see if all my info is correct but that is my understanding of the whole thing.(i don't understand much)

 

[XMasta19]

you built a 700 hp stang and don't know what a fmu is???

I have someone fully competent to tune my car (built a 700hp mustang)

umm, I believe that means he was talkin bout a buddy of his

If you really are serious about your 300hp goal, then go ahead and throw out fmu and sfmu from your memory banks. Then prepare yourself for lots of time and MONEY. Decide on whether you want the megaquirt or portfueler. If you go with megasquirt, there will be accessories that need purchasing. One of which would be bigger fuel injectors (they spray the fuel. the bigger they are, the more they can handle. the more boost you wanna run, the more fuel you're gonna need) Well, you need to figure out where exactly you wanna go with this, and the vast array of knowledge is sure to come. There's TONS of info out there in cyber world, and in the brains of us losers who surf it all day

 

[DeLo360]

umm, I believe that means he was talkin bout a buddy of his

If you really are serious about your 300hp goal, then go ahead and throw out fmu and sfmu from your memory banks. Then prepare yourself for lots of time and MONEY. Decide on whether you want the megaquirt or portfueler. If you go with megasquirt, there will be accessories that need purchasing. One of which would be bigger fuel injectors (they spray the fuel. the bigger they are, the more they can handle. the more boost you wanna run, the more fuel you're gonna need) Well, you need to figure out where exactly you wanna go with this, and the vast array of knowledge is sure to come. There's TONS of info out there in cyber world, and in the brains of us losers who surf it all day

Thanks for clearing that up man... yeah that was a friend of mine i was talking about.

Well, the thing is i know about 90% what i want to do with my car. I understand that ultimately it will cost me a good amount of money. So my goal will be reached in stages. This is what i mean (each number is a seperate stage):

1. Suspension ~ $900

2. Custom Turbo Setup (5 - 7psi, including megasquirt) ~ $1400

3. Drive Train (clutch, LSD, 3.55 Neon tranny) ~ $1500

4. Custom Exhaust (magnaflow mufler) ~ $500

5. Howell performance engine rebuild kit ~ $2200

6. Fuel system upgrade (injectors) ~ $???? No idea about this


So this is where i am... i guess i about know how i want to approach this. 18X8 wheels and tires will be in there somwhere befroe step 5. I already have the resources and direction for step 1, and am just waiting for this stupid semester to be over and i can begin dealing with my car. Basically, I want to approach step 2 in such a way that i really dont have to replace anyhtign in the turbo set up, but all i will need to do is add to it when i am ready for my HP goal (this will be step6). Which is pretty much why i started this thread.

Oh and yeah... some of you may not agree with the order of steps (probably step 3). But the way i see it if i'm gonna have the tranny out for the clutch, i might as well so the LSD and all in all the tranny conversion to 3.55). Also keep in mind that the only labor i will be paying for is for step 4.

Ok so if you have some good imput on the fuel system approach, or on anything else please post. I'll stop typing for now.

Thank you guys,
Dave

 

[BigRand]

http://www.dsmtuners.com/forums/showthread.php?t=181051

In that link(overboost link in that thread), it talks about turbo'ing NA cars....and has some articles related to how to calculate your correct injector size.

Also....how are u gonna get a megasquirt kit and all its accessories AND A CUSTOM TURBO KIT for $1400?
with the unit, and all the stuff your need your already sitting at $1000, I'll assume you already own a laptop to run it.
GSgoingfast is building his turbo kit for under a $1000 so even if you did that your still sitting over $1400.....its good that your doing reaseach thats awesome.

 

[DeLo360]

Actually, i read that article in the thread about a day or so ago. As far as the $1400 goes... maybe my thinking is wrong but it was fro that same purpose i wanted info about the fuel system and megaquirt so that i can adjust that figure accordingly. I did a search on megasquirt and read up on it at its main site. They sell all of the parts to the system unassembled for like $180.... and if i wanted to buy it fully assembled it will run $500. I also know there is a guy on 2gnt that does it for $400.

Someone currect my thinking, but after the turbo(everythign else) is put together for the fuel system wouldnt all i need be a better bigger fuel pump, megasquirt, and some sort of a bypass to keep the computer from seeing boost. The injectors can wait until i decide to boost more right? If that is the case... i dont see why $1400 is not enough. There must be somethign i am missing.... oh keep in mind the manifold and everythign will be custom... the only thing i will purchase is a T3, used SMIC, and blowoff valve.

 

[truECLIPSE]

if you are going to run it at the track or just at WOT a lot you are going to need some new axels with 300whp. or you could just wait until they break

 

[Quasimondo]

Simple block diagram of a modern fuel system.

[FUEL TANK]>>>[FUEL PUMP]>>>[FUEL FILTER]>>>[FUEL INJECTORS]>>>[FUEL PRESSURE REGULATOR]>>>[RETURN LINE TO FUEL TANK]

We all know what the fuel pump and fuel filter does. We all know what fuel injectors do, they spray fuel. In order for the injectors to spray their fuel, they need lots of pressure (at least 40 psi). They have that pressure due to the high flow volume of the fuel pump which flows much higher than the electric or mechanical pumps of yesteryear, and because of the fuel pressure regulator.

Fuel pressure regulators work to maintain pressure in the line by constricting itself and choking off the flow of unused fuel through the return line and back into the tank. They regulate flow based upon the amount of vacum in the manifold. More vacum in the engine indicates a closed throttle and tells the regulator to open up and let more fuel return to the tank, lowering pressure across the injectors. Less vacum (an indication of a more open throttle) tells the regulator to close up and restrict flow, increasing pressure across the injectors and supplying more fuel to the engine.

So where do terms like FMU, SFMU, AFPR, etc. come in?

They come in when it comes to engines with forced induction. Because forced induction pushes more air into the engine under boost conditions, having a normal fuel pressure regulator that maximizes it's fuel pressure to the injectors only when there is no vacum present still provides an inadequate amount of fuel under high boost conditions. A FMU and it's many different forms compensate for that by continuing to restrict fuel return to the fuel tank beyond what a normal fuel pressure regulator can and raises its fuel pressure along with the increased manifold pressure. With the increased fuel pressure, the injectors can now supply the extra fuel needed for an engine under boost.

As for your other terms, megasquirt is an aftermarket engine management system, and injector sizes are both reserved for another lesson for another day.

 

[GSGoinFast]

Actually, i read that article in the thread about a day or so ago. As far as the $1400 goes... maybe my thinking is wrong but it was fro that same purpose i wanted info about the fuel system and megaquirt so that i can adjust that figure accordingly. I did a search on megasquirt and read up on it at its main site. They sell all of the parts to the system unassembled for like $180.... and if i wanted to buy it fully assembled it will run $500. I also know there is a guy on 2gnt that does it for $400.

Someone currect my thinking, but after the turbo(everythign else) is put together for the fuel system wouldnt all i need be a better bigger fuel pump, megasquirt, and some sort of a bypass to keep the computer from seeing boost. The injectors can wait until i decide to boost more right? If that is the case... i dont see why $1400 is not enough. There must be somethign i am missing.... oh keep in mind the manifold and everythign will be custom... the only thing i will purchase is a T3, used SMIC, and blowoff valve.

i believe the megasquirts are sold built for only $300. but you also need 2 GM sensors, aeromotive 1:1 fpr, and i think you need bigger injectors because using a 1:1 fpr with stock injectors wont give you enough fuel for boost. the MSnS can controll very large injectors precisely, because the injector pulse duration is the only thing controlled and the fuel pressure isnt drastically changed(1psi of fuel for 1psi of boost). with small injectors, you run out of time to increase the pulse duration, which means the only other way to increase fuel is to increase its pressure. but the 1:1 wont increase the pressure enough. i may be wrong but i think thats how it would work. Im not sure if you can run a 12:1 fpr with the MSnS or not. But injectors arent really that expensive so its not really that big of a deal.

but theres a lot more to the turbo kit to purchase then just the turbo, BOV and intercooler... check out my tech article...http://www.dsmtuners.com/forums/showthread.php?threadid=181134

 

[DeLo360]

Whoa your article is up... great!!! yeah i've actually been following your project an dother people's for a bit now, just rying to figure this thing out. Yeah, i am aware that there is more to a turbo then the stuff i listed previousely, i just didnt want to make up a whole list... i wanted to concentrate on the fuel system. But now that your article is up... i should be good for the time being.

 

[WHite97RS]

when using megasquirt you must purchase the system itself, plus wiring harness, IAT sensor, Coolant sensor, Injectors, Injector clips. It is suggested you use a the aeromotive 1:1 Fuel pressure regulator when running the MS. If you are looking for 300 hp i would suggest 550cc injectors or larger. The MS is not for amateurs, but is well worth the money in my opinion. Ill put up an article on tuning with the MS in the next month depending on how quick i get my car up and running.

 

[DeLo360]

Yeah the tunning is no problem i have someone to do that for me.... ok ready? dumb question.... what is an IAT sensor?

 

[GSGoinFast]

Yeah the tunning is no problem i have someone to do that for me.... ok ready? dumb question.... what is an IAT sensor?

Intake Air Temperature

 

[DeLo360]

Nice....

Oh and yeah... i added up a bunch of stuff. I'm looking at 2 grand for my setup if i wanted to go the megasquirt way, so i was a little off with my previous $1400 estimate. Also, including that $2000 estimate i'm looking at a T3 turbo with wastegate ($360), Small FMIC ($320)... There is definitely room for me to save some money, but for now i am at $2000.

GsGoinfast, Thanks for the write up... your list is very helpful.

 

[DeLo360]

Ok.... another question,

Where can i get the assembled megasquirt for $300. Also i'm looking at 550cc injectors for about $270. Is that reasonable or can i do better as far as the injectors are concerned.

 

[WHite97RS]

270 isnt bad.... just remeber if you def go with the MS you dont have to worry if they are High or Low impedence injectors. The MS can be purchased from RSautosport.com for 300 bucks, that gets you total fuel and spark control as well as the 3 bar map sensor which can read i believe a lil over 20lbs of boost. But for 30 bucks less i think it is you can just get the normal 2.5 bar map sensor if you dont plan on running higher boost levels.
BUT.....like i said earlier you will also have to purchase a wiring harness, a DB9 cable, IAT sensor and clip, coolant temp sensor and clip, Injectors and injectors clips. So minus the injectors add about 75-80 bucks for the other needed items.

 

[DeLo360]

Ok i checked out rs-autosport.... thanks for the website. Looks like i can get everyting from there so i'm happy. However, i am confused about one thing. They are selling the MS hardware fully assembled for $260, but next to that you see a software section which they are sellign for $250. I'm just a bit confused... does the MS already come with some sort of software, and the $250 is just an uprgade or what?

 

[DeLo360]

Actually i found an answer to my own question and i'm goin to post it so that there is some specific info.

It looks like you can download the megasquirt software (v1.01) for free at megasquirt's home website. There are a few bugs with the software that they claim are evident, but really not a big issue especially for those that dont feel like spending $250 - $300.