30# injectors? too big?

[ronstang94]

My fuel injectors are cracking and leaking, so its time to replace them. The only engine parts worth mentioning are a CAI, typhoon manifold, catted X, and catback. Im gunna get a Pro-M maf calibrated to go with the new injectors. I plan to do the heads and cam at some point down the road. I know that 24# injectors would be enough for my current goal of 300hp, but I want to leave myself room to grow. So, i was thinking about 30# injectors.

Any reason why 30# injectors would be a bad idea with my current setup?

How far can 24# injectors go? 350hp?

How far can 30# injectors go?

any other info would be greatly appreciated

 

[BlackVert]

even though many people say both keith (pokageek) and i should have 42#, we both have 30# injectors.

 

[nmcgrawj]

Why not grab some more 19s from the junk yard until you're ready to step up the combo?

 

[302Feen]

My fuel injectors are cracking and leaking, so its time to replace them. The only engine parts worth mentioning are a CAI, typhoon manifold, catted X, and catback. Im gunna get a Pro-M maf calibrated to go with the new injectors. I plan to do the heads and cam at some point down the road. I know that 24# injectors would be enough for my current goal of 300hp, but I want to leave myself room to grow. So, i was thinking about 30# injectors.

Any reason why 30# injectors would be a bad idea with my current setup?

How far can 24# injectors go? 350hp?

How far can 30# injectors go?

any other info would be greatly appreciated

24's would be too much at this point. All you really have is the typhoon intake on stock heads which is kinda mismatched anyways.

19's will be plenty at this point and 24's will give you room to grow.

Just don't go thinking that adding "larger" injectors will help you GAIN HP. Injectors don't MAKE HP, they SUPPORT it.

 

[revhead347]

It'll run, but probably not the best. I know that 24lb/hr injectors would work fine, and will support 350hp. If you think about it, a Cobra engine comes with 24lb/hr injectors, and really doesn't make much more power than a GT.

Kurt

 

[ronstang94]

Why not grab some more 19s from the junk yard until you're ready to step up the combo?

Leaking gas all over my engine is sketchy to say the least. If a couple are starting to crack, I cant trust any of them anymore, they are all ready to be replaced. I also cant trust these kinds of parts from the junk yard. no way to know for sure if they are about ready to start leaking as well. I would much rather buy new.

24's would be too much at this point. All you really have is the typhoon intake on stock heads which is kinda mismatched anyways.

19's will be plenty at this point and 24's will give you room to grow.

Just don't go thinking that adding "larger" injectors will help you GAIN HP. Injectors don't MAKE HP, they SUPPORT it.

I know that larger injectors wont gain me any HP. When a part breaks I like to replace it with a part that gets me closer to my goal. I dont want to waste my money on stock replacement parts and then have to pay for the parts that I wanted later on when im also paying for all of the other parts that I want to put my combo together. I would rather pay little by little than a lump sum at the end.

I just want to know if there will be any idle issues / drivability issues / or any issues at all from installing larger than currently necesary injectors and MAF?

 

[nmcgrawj]

Leaking gas all over my engine is sketchy to say the least. If a couple are starting to crack, I cant trust any of them anymore, they are all ready to be replaced. I also cant trust these kinds of parts from the junk yard. no way to know for sure if they are about ready to start leaking as well. I would much rather buy new.



I know that larger injectors wont gain me any HP. When a part breaks I like to replace it with a part that gets me closer to my goal. I dont want to waste my money on stock replacement parts and then have to pay for the parts that I wanted later on when im also paying for all of the other parts that I want to put my combo together. I would rather pay little by little than a lump sum at the end.

I just want to know if there will be any idle issues / drivability issues / or any issues at all from installing larger than currently necesary injectors and MAF?

I can understand that.


The problem you're gonna have is the maf calibration. You will probably need a tune to make it run decent.


How far out are your planned upgrades?

 

[ronstang94]

I thought that as long as you have a MAF calibrated to the correct size injector then you dont need a tune?

It will probably be atleast three more years until I can do everything that I want to on the car, when I finally finish school. or sooner if the engine blows up

 

[revhead347]

I thought that as long as you have a MAF calibrated to the correct size injector then you dont need a tune?

It will probably be atleast three more years until I can do everything that I want to on the car, when I finally finish school. or sooner if the engine blows up

Up to 30lb injectors you can do a recalibrated MAF, and it works well enough.

Kurt

 

[GDawg]

I have my OEM 19# injectors that are in fine condition if you want to make me an offer. Do you need an OEM fuel rail or K&N FIPK 2? Lol, I still have lots of my original stuff in my garage since I put my blower on. Btw, I run 24# with my 1.7L blower but I don't know what HP I'm making.

 

[nmcgrawj]

3 years? lol...

i would just get on the millions of mustang websites and hunt someone down who is upgrading and to snag up their old stuff.

 

[Black95GTS]

3 years? lol...

i would just get on the millions of mustang websites and hunt someone down who is upgrading and to snag up their old stuff.

Agreed with above. Or a junkyard and pull them, they'd probly charge you around 5 bucks per injector.

Adam

 

[302Feen]

I thought that as long as you have a MAF calibrated to the correct size injector then you dont need a tune?

It will probably be atleast three more years until I can do everything that I want to on the car, when I finally finish school. or sooner if the engine blows up

I've heard two different explainations on bigger injectors...

I've heard even if you have the correct MAF the engine will still run rich.

On the other hand, I've heard that as long as the MAF matches the injectors it should still use the required amount of fuel.

I've just seen people put larger injectors and matching MAF on their stock engines and have it run REALLY rich and have idle issues etc.

If you want to give it a shot then go for it. But I'm just saying if it were me I'd just find some cheap 19# injectors and use them for now.

 

[final5-0]

Like most things I guess

Application has a lot to do with an answer that takes into consideration
the different ways one could give helpful info here

Having said that ... I would answer first with ... It depends

Two things to consider when talking about size of injectors

1 Formula details
2 Fuel pressure

1) Those formulas you find all over the net to determine inj size use
fwhp NOT rwhp

2) You are gonna use one or the other to control the injectors

a mechanical means (afpr)
b custom tune

a) If using elevated pressures the inj will act as if it is bigger
b) using a custom tune is usually done with OEM pressure
therefore that needs to be taken into account

I like to do it like Ford does it

OEM pressure
Inj size with a bit of breathing room
Make adjustments as needed in the pcm

I agree with the above peeps

19's and OEM meter will work dandy
24's and caled meter will work pretty good
30's and caled meter will most likely idle and cruise a bit fat
and
Cold starts will be done with REALLY fat mixtures
but
You most likely can drive it
also
Your pcm load factors are gonna be all outta whack
but
We won't go into that here

36's and larger will not work so good with no tune

Summing up

At OEM fuel pressure 24's are close to the limit for most street combos
at the high 200's to 300 hp to the wheels

Remember ... stick trans combos with 350 motor is only 297 wheel

Just a bit more info to think about

Grady

 

[ronstang94]

Like most things I guess

Application has a lot to do with an answer that takes into consideration
the different ways one could give helpful info here

Having said that ... I would answer first with ... It depends

You are gonna use one or the other to control the injectors

a mechanical means (afpr)
b custom tune

a) If using elevated pressures the inj will act as if it is bigger
b) using a custom tune is usually done with OEM pressure
therefore that needs to be taken into account

I like to do it like Ford does it

OEM pressure
Inj size with a bit of breathing room
Make adjustments as needed in the pcm

19's and OEM meter will work dandy
24's and caled meter will work pretty good
30's and caled meter will most likely idle and cruise a bit fat
and
Cold starts will be done with REALLY fat mixtures
but
You most likely can drive it
also
Your pcm load factors are gonna be all outta whack
but
We won't go into that here

36's and larger will not work so good with no tune

Just a bit more info to think about

Grady

Thanks for all of the replies and good info. Im definately thinking about just trying to find some used 19# injectors now. I still want the 30#ers but if I cant get it to run right, it definately isnt worth it. I would want to do it "the way Ford does it" and I want to get the tweecer rt, but dont have the money for that right now. An adjustable fuel pressure regulator sounds like a cheap easy fix. Is it a real solution to the problem? or is it like a jimmy rigged solution?

 

[Zero Signal]

I really wouldn't go bigger than 24s without a tuner and willingness to have idle and starting issues. Turning up the pressure will help with atomizing the fuel, but without a tuner, it will still have issues and will run rich in open-loop (i.e. when it's cold and at wide open throttle). The way I see it is once you have done enough to the motor where you NEED a tuner, you will have maxed out the 19# injectors anyway. So until then, don't bother.

 

[Itkix]

I really wouldn't go bigger than 24s without a tuner and willingness to have idle and starting issues. Turning up the pressure will help with atomizing the fuel, but without a tuner, it will still have issues and will run rich in open-loop (i.e. when it's cold and at wide open throttle). The way I see it is once you have done enough to the motor where you NEED a tuner, you will have maxed out the 19# injectors anyway. So until then, don't bother.

+1 over 24's need some type chip.

 

[final5-0]

I really wouldn't go bigger than 24s without a tuner and willingness to have idle and starting issues. Turning up the pressure will help with atomizing the fuel, but without a tuner, it will still have issues and will run rich in open-loop (i.e. when it's cold and at wide open throttle). The way I see it is once you have done enough to the motor where you NEED a tuner, you will have maxed out the 19# injectors anyway. So until then, don't bother.

What John said

Sticking to the 94-95 pcm's

They are load based where the Fox body pcm's are rpm based

Having said that ... The pcm determines load from the meter's output

When you move away from OEM 19's & meter and use the aftermarket
meter's cheat method (running a larger set of inj's and meter with no
pcm adjustment) of matching meter to inj size the load reported to
the pcm starts to become skewed

With 24's it is not too bad
but
As you move to 30's the error grows larger
and
With 36's and 42's ... it is WAY OFF

So you see ... there is a WHOLE LOT more going on here than most
are even aware of in this situation

It is most important to understand this fact :Word:

That whole aftermarket meter cheat method was developed for the
Fox Body Stangs and their RPM BASED pcm's

So you see ... you are using a method not designed for our 2 year run
of pcm's found in our cars here

anyway ............

For a mild combo at say mid 200 rwhp levels ..........
You can run 19's at elevated fuel pressure

24's and a meter caled to match them run at elevated fuel levels have
supported 300 rwhp or a bit better but those inj's are being worked for all
they got to give ... and in some cases ... beyond

Finally ... Like John said

When you start modding you will run out of inj (OEM 19's) pretty quick
You always reach fuel limit before meter limit .........

One of those things where you can prick your finger
and
Write it on a white sheet rock wall

As a matter of fact ... the OEM meter will take you to around the 300 rwhp
mark if you have pcm access

Summing up ... you can somewhat tune a 94-95 with dizzy twisting and
playing around with fuel pressure

BUT

There is only so much you can expect from that method

So Ron ... have we caused you to think about anything

Grady

 

[ronstang94]

yes lol. thank you.

I picked through the junk yard and grabbed a couple fuel injectors for cheap. they are off of a 94 4.6 thunderbird (newest ones i could find)