Fuel Injectors

[MOMO96Z]

What are some good fuel injectors that are out their.

[Injuneer]

What size do you need?

For a stock engine, and applications up to 400HP, the stock 24# Rochester (RP) injectors are fine. They fit correctly, and provide the spray pattern the intake manifold and head runners were designed for. RP makes a 28# injector, from the LT4 that will buy you a little more headroom, maybe 450HP.

Beyond that, people tend to use the Ford SVO injectors in 30# or 36# sizes. They actually flow about 5% more than rated in the LT1 fuel system, because it has a higher operating pressure than the SVO's are rated at. The SVO's are a Bosch "pintle style" injector, and will accept the elevated operating pressures for dry nitrous systems and blower motors using an FMU. The stock RP's are not real happy with high fuel pressures.

Downside of the SVO's is an occaisional problem with the length and getting the spring clip retainers to seat properly.

Beyond 42# sizes, you typically need to go to a low impedance, peak-and-hold injector, and the stock PCM need a "piggyback" black box to handle low impedance units. All of the aftermarket ECU's will handle them fine. Bosch seems to be very popular, but at that level, you will find people often prefer Lucas or Siemans, depending on their personal experience.

You will find that most injectors, no matter what the brand are made by the companies mentioned above... if its a pintle style injector, it is made by Bosch, or by Denso in Japan under license to Bosch. Ball and seat design are RP (now know as Delphi), discs are Lucas.

What kind of HP are you looking to support?

[MOMO96Z]

Looking for #36

I was told by pcmforless to use #36 injectors for a supercharger on a stock lt1 motor, to get rid of the FMU.

[Rob]

MSD/Delphi 50# injectors and brand new Seimens 57# injectors are about as high as you can go without changing the drivers.

I'm running 50# in the TA.

[Injuneer]

Re: Looking for #36

Originally posted by MOMO96Z
I was told by pcmforless to use #36 injectors for a supercharger on a stock lt1 motor, to get rid of the FMU.

I'd follow his recommendation. The 36's will be good for up to 500HP, when you consider that a blower motor has a higher brake specific fuel consumption, and when you try to keep the duty cycle no higher than 85%. Any of the manufacturers I mentioned will make a satisfactory injector. pcmforless will need to know the exact injector, and your fuel system operating pressure, so he can program the PCM with the correct injector flow constant and offsets. I used the Bosch/Denso "Ford" injectors for my old dry nitrous kit/bolt-on motor, and they seemed to work fine.

[Joe 1320]

Originally posted by Rob
MSD/Delphi 50# injectors and brand new Seimens 57# injectors are about as high as you can go without changing the drivers.

I'm running 50# in the TA.

I am ready to ditch my #40s with a #40 7th, for the 50s. How do you like them? I'm running lubrant chips with the 40s and am pretty happy, I just don't like having to run a 7th for the additional fuel at WOT.... It's not easy to dial in correctly and when it is, it usually doesn't stay.

[Rob]

Originally posted by Joe 1320
I am ready to ditch my #40s with a #40 7th, for the 50s. How do you like them? I'm running lubrant chips with the 40s and am pretty happy, I just don't like having to run a 7th for the additional fuel at WOT.... It's not easy to dial in correctly and when it is, it usually doesn't stay.

They are great. Very linear, just like stock. I ran a JL93 chip and sailed right through emissions with no changes to the car. I was running a Thrasher that was modified. Basically a stock injector chip with the injector constant change. Other than running really fat down low, that was a nice chip.

I'm now trying a TurboTweak chip from Eric Marshall. This is turning out to be a real nice chip also. I have to tell him to make some minor adjustments and that'll be perfect. I also had a Jim Testa chip that wasn't too bad. It just didn't like the alcohol from my SMC kit.

Hope that helps. Sorry to hi-jack the thread.