Bigger injectors on stock engine?

[95mustanggt]

I don't have an adjustable fuel pressure reg. yet, but I'm trying to think a little further down the road. I know that I will have to upgrade my fuel system when I get my car where I want it to be, but I don't wan't to have to buy a bunch of "in between" parts.

For some reason I have heard bad things about 24# injectors and MAF's so I was thinking about the 30#'s. I know it may be more fuel than I need, but If I were to add a low pressure blower or power adder after my combo I would probably still be ok.

Thanks for all the responses guys.

[HORSEMEN RACING]

95Mustang,
that would not be a bad ideal really to get the fuel system first,that way it will keep your spending in check. For example with what I plan on doing is going 255 in-tank fuel pump,that way unless I am making some serious animalistic power I will never need another fuel pump.

Really to be honest the fuel system is probably cheaper to upgrade than any other high performance part out there.

95Mustang I would just tailor the fuel system to how much hp you want to make.

That is pretty much the only advice I can give you,avoid the bigger is better,and you should be alright.

I do not understand how a 24 pound injector with a calibrated MAF sensor can be bad??? I think someone might be thinking that the stock MAF sensor will compensate.

[RPM427]

near stock engine: 19 pounders better

Near stock engine spraying 125 dry shot: 24 pounders better with AFR, 190+pump, and recalibrated MAF sensor

[keakua]

if you really want to find out what you need here's some math to help you out...
first estimate horsepower: 300 your shooting for?
next (BSFC) brake specific fuel consumption: .45 is lean, .55 rich (use .5 as an average)
then duty cycle of each injector. keep in mind that they are rated at 100% duty cycle (DC) in regards to output, but greater than 80% (.80) will kill the life of the injector.
NC (# cylinders): 8
here it is: [(HP x BSFC)/NC]/DC= injector size
[(300 x .5)/8]/ .80
=23.44 lbs-hr or 24# injectors.
thats assuming you have the pump and regulator to max out the injectors. cranking up PSI can only spit out as much fuel as the injector can flow. i maxed out my 24# injectors at 392 hp on the dyno before putting a hole in a piston. up to that point 24s are a safe bet. especially since jumping to the next size is about 200$ more expensive then the 24s. stock injectors will get you safely to about 250 hp. i learned my lesson the hard way, you dont want to max out your fuel supply unless your fiance doesnt mind not getting an engagement ring cause you spent the money fixing your motor.

[Chipdog]

What happened to your shraeder valve? Is it that same one that my 92 came with? If it is mine is just sitting in my tool box after a Fuel Pressure gauge install. Your more than welcome to it if it helps.

Chip

[95mustanggt]

Originally posted by Chipdog
What happened to your shraeder valve? Is it that same one that my 92 came with? If it is mine is just sitting in my tool box after a Fuel Pressure gauge install. Your more than welcome to it if it helps.

Chip

Thanks chipdog. I got another one from Ford for only $5. Installed it and it and found my FPR is shot. I think I'll get an Aeromotive Adjustable one.

As for my injectors I'll leve them for now I guess.

[HORSEMEN RACING]

Originally posted by keakua
if you really want to find out what you need here's some math to help you out...
first estimate horsepower: 300 your shooting for?
next (BSFC) brake specific fuel consumption: .45 is lean, .55 rich (use .5 as an average)
then duty cycle of each injector. keep in mind that they are rated at 100% duty cycle (DC) in regards to output, but greater than 80% (.80) will kill the life of the injector.
NC (# cylinders): 8
here it is: [(HP x BSFC)/NC]/DC= injector size
[(300 x .5)/8]/ .80
=23.44 lbs-hr or 24# injectors.
thats assuming you have the pump and regulator to max out the injectors. cranking up PSI can only spit out as much fuel as the injector can flow. i maxed out my 24# injectors at 392 hp on the dyno before putting a hole in a piston. up to that point 24s are a safe bet. especially since jumping to the next size is about 200$ more expensive then the 24s. stock injectors will get you safely to about 250 hp. i learned my lesson the hard way, you dont want to max out your fuel supply unless your fiance doesnt mind not getting an engagement ring cause you spent the money fixing your motor.

I have a question since 30 pound injectors are the next size up,where is this ad that says 30 pound injectors cost 400 dollars? The most I have seen 30 pound injectors is $299.

Fancy math is cool and all that,but at least get the price of the injectors right.

[Mustangbelle306]

It seems like Mustang owners more than any other hobbyist group loooooove to pump more fuel into their engines

Although my knowledge of engines is pretty elementary, I always assumed you increase the injector size corresponding to increases in air flow (intake, heads, etc) Am I wrong? Because I don't see where enough flow in your setup would even come close to requiring 30#, even 24#. I dont have heads yet, but with my setup I'm fine with 19#

[95mustanggt]

Originally posted by Mustangbelle306
It seems like Mustang owners more than any other hobbyist group loooooove to pump more fuel into their engines

Although my knowledge of engines is pretty elementary, I always assumed you increase the injector size corresponding to increases in air flow (intake, heads, etc) Am I wrong? Because I don't see where enough flow in your setup would even come close to requiring 30#, even 24#. I dont have heads yet, but with my setup I'm fine with 19#

Belle, I would be doing this only to avoid buying a set of 19# injectors and then turning around and spending $$$ to buy a set of 24 or 30# injectors. But like I said the problem is more in my FPR than injectors (so far), but I like to think ahead to avoid spending carelessly.

[keakua]

"Fancy math is cool and all that,but at least get the price of the injectors right."

carl, at least you got the point, thanks for posting something usefull