Best fuel pump and injector size?

[sfcadams]

Here is my current setup. 87 LX Coupe with factory 5.0 and T-5 tranny. I have Paxon 1220SL that I will eventually put on it when I get home. Car currently has the stock 19lb injectors and stock fuel pump. My question are what would be the best size fuel pump and injectors for my setup. There is currently no other enigine mods on the car. I was thinking maybe 190lph pump with 24lb injectors but want to make sure I get it right the 1st time. Any suggestions would be great.

 

[sfcadams]

Everybody asleep? lol

 

[WHT306]

I'm not sure on injectors but i would go with a 255 lph fp on n/a engins theyare good for over 700 hp

 

[skunk21]

24's will not work on a boosted motor even on a totally stock motor that's boosted. The 1220Sl on a stock motor with a tune( I'm hoping you get a tune done after) could net you really close to 300hp or over depending on the tuner/motor. I would go with 39lb/hr injectors and a 190 or 255 l/hr pump. the 39lb injectors will run up to 430hp@ 90% duty cycle on boosted motor which could leave you some room for gt40p's and gt40 intake or something. you get get away with 30lb injectors but they run 330hp @90% boosted which would put you close in my book.

 

[90lxcoupe]

42lb injectors and a 255 pump, the 42's can be found cheap used, and dont require a modified connecter.

also look into getting the car professionally tuned

 

[sfcadams]

Ok but should I go to bigger injectors (42 or whatever size) and a bigger pump while my motor is still NA? I would assume I would just install and dial in the pressure with a fuel pressure regulator, correct? What would I dial in the fuel pressure at while my motor is still NA?

 

[BYRDPE]

Ok but should I go to bigger injectors (42 or whatever size) and a bigger pump while my motor is still NA? I would assume I would just install and dial in the pressure with a fuel pressure regulator, correct? What would I dial in the fuel pressure at while my motor is still NA?

as 90lxcoupe stated....go with the 42s and a walbro gss340 which is a high pressure 255lph pump.
you will not be able to "dial in" your fuel pressure for boost without a tune of some kind.
if you install the larger injectors while still n/a you will run too rich at idle.
stcok fp is ~39 with the vacuum line disconnected and plugged.

 

[sfcadams]

Ok so basically I shouldn't install the bigger injectors while I am still NA, correct? What about installing the bigger fuel pump? Should I wait and do that along with the injectors when I go to install the Paxton?

 

[BYRDPE]

Ok so basically I shouldn't install the bigger injectors while I am still NA, correct? What about installing the bigger fuel pump? Should I wait and do that along with the injectors when I go to install the Paxton?

you will have issues if you install the injectors and don't get it tuned. if you will not be driving it until you get the sc bolted on and tuned then by all means go ahead and install them.
you can go ahead and install the fp. it will not hurt performance.

 

[sfcadams]

Ok sounds good. Can someone enlighten me on when an adjustable fuel pressure regulator would come into play? I would assume during a tuning session....

 

[BYRDPE]

Ok sounds good. Can someone enlighten me on when an adjustable fuel pressure regulator would come into play? I would assume during a tuning session....

yes...you will need one for tuning purposes. you can install it prior to the tune if you want. get a fuel rail gauge also so you can dial the pressure to ~39 until you have it tuned for the sc.

 

[sfcadams]

Sounds good to me!

Any suggestions on brand/model # of fuel pressure gauge and adjustable fuel pressure regulator to get?

 

[skunk21]

Sounds good to me!

Any suggestions on brand/model # of fuel pressure gauge and adjustable fuel pressure regulator to get?

The Kirban performance products fuel gauge kit KP-1441 is one of the best ones.

I like the Aeromotive fuel pressure regulators myself the 13103 is a good choice 35-70psi.

 

[sfcadams]

Might be a dumb question but how does the Kirban KP-1441 mount? It says no shrader valve removal is necessary so I guess that means it uses an adaptor?

 

[skunk21]

Might be a dumb question but how does the Kirban KP-1441 mount? It says no shrader valve removal is necessary so I guess that means it uses an adaptor?

correct

 

[millhouse]

Sounds good to me!

Any suggestions on brand/model # of fuel pressure gauge and adjustable fuel pressure regulator to get?

Unless your current FPR is broken…keep the stocker. You do not tune with fuel pressure…but with the computer itself. Any reputable shop is going to see that you have an adjustable FPR and have you set it to the stock 39lbs before the tune anyways.

Again, keep the stocker and save the cash for some of the other upgrades needed.

As for installing the fuel pump…I’d wait until your closer to installing the supercharger. You have no need for it now…so you’re better off saving it’s life for when you’ll need it.

 

[2000xp8]

Before you touch anything, i'd convert the car to Mass air, people screw up the maf conversion often enough by itself, make the car run right as a maf car, then add the SC setup because trouble shooting with the SC on there will be twice as hard.

I'm going to disagree with the 42's, i'm of the opinion that you use the injectors for the setup you have now, not just stuff in the biggest set.
When you use the right injector and meter for the job, other than timing, the car pretty much tunes itself. If you need a dyno tune for it to run right, that means you screwed up somewhere.
Selling a meter and injectors if you add h/c/i is not the end of the world, if you shop well and use ebay sometimes it's an even swap if you upgrade.

Since it's a return fuel system, you might as well use the gss340 pump.
For injectors you would probably be good with 30's maybe 36's.

 

[millhouse]

Before you touch anything, i'd convert the car to Mass air, people screw up the maf conversion often enough by itself, make the car run right as a maf car, then add the SC setup because trouble shooting with the SC on there will be twice as hard.

I'm going to disagree with the 42's, i'm of the opinion that you use the injectors for the setup you have now, not just stuff in the biggest set.
When you use the right injector and meter for the job, other than timing, the car pretty much tunes itself. If you need a dyno tune for it to run right, that means you screwed up somewhere.
Selling a meter and injectors if you add h/c/i is not the end of the world, if you shop well and use ebay sometimes it's an even swap if you upgrade.

Since it's a return fuel system, you might as well use the gss340 pump.
For injectors you would probably be good with 30's maybe 36's.

The setup he has now dictates the use of stock injectors. There is no need to upgrade until he get’s the supercharger….at which point 42lb injectors would work great. Perhaps they would be a bit of an overkill…but they will leave some room to grow none the less.

With that said, if he puts a supercharger on it and wants some reliability and peace of mind…he needs a tune. There is no guarantee that his afr’s are going to be correct for a forced induction setup. The car most certainly won’t tune itself for the ~ 11.5:1 AFR’s typically necessary on forced induction applications.

Again, keep the stock injectors…MAF and fuel pump in until you do the upgrade.

 

[2000xp8]

The setup he has now dictates the use of stock injectors. There is no need to upgrade until he get’s the supercharger….at which point 42lb injectors would work great. Perhaps they would be a bit of an overkill…but they will leave some room to grow none the less.

With that said, if he puts a supercharger on it and wants some reliability and peace of mind…he needs a tune. There is no guarantee that his afr’s are going to be correct for a forced induction setup. The car most certainly won’t tune itself for the ~ 11.5:1 AFR’s typically necessary on forced induction applications.

Again, keep the stock injectors…MAF and fuel pump in until you do the upgrade.

You do realize that the unit he's using is about the equivalent of an A trim right? He'll have 300rwhp and 42 lb injectors, not the brightest idea. Even the 300rwhp is generous considering paxton only rates the kit at 275hp (unknown if rwhp or flywheel, what's the difference they are both under 300hp)

So everyone that upgrades their mustang with anything at all might as well use 42's too by that logic.

Running it on a dyno is fine and all, but what exactly is that going to do?
You told him not to use an Adj fuel pressure regular, so basically you set the timing and it's done.
A chip is just going to be a huge waste of money, i've seen dozens of these cars on the dyno, none needed a chip to run right.

 

[millhouse]

You do realize that the unit he's using is about the equivalent of an A trim right? He'll have 300rwhp and 42 lb injectors, not the brightest idea. Even the 300rwhp is generous considering paxton only rates the kit at 275hp (unknown if rwhp or flywheel, what's the difference they are both under 300hp)

So everyone that upgrades their mustang with anything at all might as well use 42's too by that logic.

Running it on a dyno is fine and all, but what exactly is that going to do?
You told him not to use an Adj fuel pressure regular, so basically you set the timing and it's done.
A chip is just going to be a huge waste of money, i've seen dozens of these cars on the dyno, none needed a chip to run right.

Regardless of the power level….with a tune it should drive like stock if using 42lb injectors with the proper MAF meter. The cost difference between smaller injectors and the 42lb-ers is negligible…so do it right and do it once. If he then decides to upgrade to an aftermarket set of heads…he only need to re-tune the combo. Likewise with upping the boost.

As for the tune, YOU DO NOT TUNE WITH AN ADJUSTABLE FUEL PRESSURE REGULATOR FOR WOT!!!! Doing so will screw up his closed loop table…which will subsequently re-tune the changes out. Because the WOT table is based off of this…it is not a long lasting tuning method for anything that sees regular use. To assume that simply throwing on a matching MAF meter and injectors, adjust the timing and he’s good to go is laughable (and absurd).

Also, there is far more to a tune than simply adjusting the timing. A burned chip is the ONLY way to ensure a 100% accurate tune across the board under all load/rpm ranges. Yes, some get lucky…but many others blow their headgaskets after a day or two of f’ing around on the street.