19lb or 24lb Injectors

[Vamp89]

K guys I need help. WIll my 19 be enough to feed my motor or should I use 24's.I have an ajustable fuel regulator and I know I'll have to get new fuel rails. Whats done is I have a stock motor except for the following.CompCams 5.0 Xtreme EFI XE282HR cam,FMS underdrive pulley's,MSD Ignition with Blaster Coil,Crane roller rockers 1.7 and roller lifters,Trick Flow Street Heat Intake,70mm throttle body,C & L 73mm mass air meter,BBK cold air kit,electric fan, flow tech x-pipe with flow master american thunder.Should I also get a 190 or 225 fuel pump??? All sugestions greatly Appreciated and Thanks

[lx mike]

first of all you won't need new fuel rails if you change injector size. you will need to get your mass air sensor recalibrated for the new injectors. are you still usingthe stock heads?? if so a nice set would make that thing scream with the mods hou have done right now. a 190 fuel pum p will be fine unless your gonna go wild with the engine later on.

[88workcar]

You do not need rails to change injecters. You do not need injecters for what you have, although a regulater would be nice. And that is WAY TOO MUCH CAM for stock heads.

[tmoss]

ditto what 88workcar said...........

[Jeff Chambers]

If you've got plans of taking the car further in the future (e.g. better heads), then I'd go straight to 30# injectors and mass air combo and a minimum of 255 lph pump. I'd look for a good tuner in your area to get it all dialed in when you're done.

[Vamp89]

Thanks I know the cam is way to big for stock heads, just not getting enough overtime to pay for new heads right now but will have them this year. There are also plans for a turbo or procharger next tax time. If I can convince the wife. lol

[Dark_5.0]

Originally Posted by Jeff Chambers

If you've got plans of taking the car further in the future (e.g. better heads), then I'd go straight to 30# injectors and mass air combo and a minimum of 255 lph pump. I'd look for a good tuner in your area to get it all dialed in when you're done.

You would seriously run 30# injectors on a motor with stock heads?

With what about 15 psi of fuel pressure.

[Jeff Chambers]

Just like a carburetor, the engine will only use what it needs. I'd rather run an injector at 60% duty cycle safely then push it to 95% or higher duty cycle. If the MAF is calibrated properly (or custom tune done), then you'll get the same fuel delivery for a given amount of airflow whether its 19#, 30#, or 42# injectors....assuming you haven't pegged the meter or saturated the injectors. As a matter of fact, if he's planning on a supercharger/turbo on down the line, why not go straight to 42# injectors with a Lightning 90mm MAF now and save getting new later? Buyfordracing.com has a 42#/90mm combo going right now for $349 to your door. Hard to pass up.

[Jeff Chambers]

Originally Posted by Dark_5.0

You would seriously run 30# injectors on a motor with stock heads? With what about 15 psi of fuel pressure.

Changing fuel pressure is passe'. Adjustable regulators are a bandaid fix for an improperly tuned setup. Where do you change fuel pressures on a returnless system? The injectors are calibrated for 39psi drop, so operate them there! If your A/F is off, then deal with it in the MAF transfer function where you should. The computer will eventually learn a correction for fuel pressure that has been changed, that's why you always end up going back and changing it again!

We run 60# injectors in high horsepower blower cars without any adjustable regulator at all, yet they manage to pass smog tests. Why? Because the system is tuned to operate efficiently from idle all the way to redline.

[Vamp89]

Anybody know if the Ford Racing GT40X Turbo Swirl Heads are any good?

[Jeff Chambers]

Not really very good. Compare their out-of-the-box numbers with other aluminum heads and they're pretty low on the list. Go with Trick Flows or Edelbrocks. The Brodix ST50 head is a good head too if you want to stick with a traditional in-line Windsor.

[Vamp89]

Cool, I'll look into that

[Vamp89]

I also have a question about my ajustable fuel pressure regulator,t does not have the connection where you put the vacum line on from the intake. Do I just plug it or get a different one, its a holley regulator.

[tmoss]

Originally Posted by Jeff Chambers

The computer will eventually learn a correction for fuel pressure that has been changed, that's why you always end up going back and changing it again!

Of course this is correct Jeff, but I would qualify it by saying it tunes out the fuel ONLY if the engine did not need it - and it does it with the adaptive control feature of the computer program.

[Jeff Chambers]

True, but the limits to adaptive learning are reached pretty quickly. Adjusting fuel pressure is a poor way to control A/F though. I had a car on the dyno the other night that changing fuel pressure a mere 2 psi (from 38 to 40 psi) changed the A/F from 13.1 to 12.1! Can't tell you how many cars I see come in running 48 psi of fuel pressure yet they can't understand why the car is hard to start and the fuel mileage is in the dumps.

[Coupe50h]

while we are on this subject, jeff or someone know where my fuel psi should be set?

right now it's at 34 psi wot, I have 24's and the mods in my sig. It seems stronger around 40 psi though? has not been dynoed yet.

thnx

[Jeff Chambers]

Set it at 40 psi with the vacuum off.

[Dark_5.0]

I prefer to get the correct injector size for what I have instead of getting bigger injectors than what I need and pay a tuner to make them work.

Different strokes for different folks.

[88workcar]

Jeff I took your advice, set the fuel at 39psi. The 30s are over for my car right now, something went right with this mass air stuff, I went 12.20, 12.09, 12.02, and even 11.98 @ 113. Sun. The more I drove it the better it got.

[Dark_5.0]

Originally Posted by 88workcar

Jeff I took your advice, set the fuel at 39psi. The 30s are over for my car right now, something went right with this mass air stuff, I went 12.20, 12.09, 12.02, and even 11.98 @ 113. Sun. The more I drove it the better it got.

Nice,

What injectors are you running?