TBI High Pressure Injectors

I reviewed some of the factory GM injectors listed here:

http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

I was looking at the "17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph" injector and curious how GM used these injectors in the 7.4 road vehicles and 5.7 on marine applications? What was done differently with the injectors which allowed GM to use the same injector at the same pressure to be used on 2 different size engines?

Steve

Quote:

---

Originally Posted by sfara002

I reviewed some of the factory GM injectors listed here:

http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

I was looking at the "17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph" injector and curious how GM used these injectors in the 7.4 road vehicles and 5.7 on marine applications? What was done differently with the injectors which allowed GM to use the same injector at the same pressure to be used on 2 different size engines?

Steve

---

It is all in the tuning. Also keep in mind the Marine 350 makes more HP than the road going 454 did.

Quote:

---

Originally Posted by Fast355

It is all in the tuning. Also keep in mind the Marine 350 makes more HP than the road going 454 did.

---

Was that due to a much larger heat sink available (in the form of the large container of water it operated on)?

I didn't know the marine engines ran such high HP numbers!

Where these 17104288 injectors any special design from the original 13 psi injectors or were they simply regular TBI injectors with the pressure amped up to 30 PSI? Would this allow for safe operation of any GM TBI injector to be operated at these higher pressures?

Steve

Quote:

---

Originally Posted by sfara002

I didn't the marine engines ran such high HP numbers!

Where these 17104288 injectors any special design from the original 13 psi injectors or were they simply regular TBI injectors with the pressure amped up to 30 PSI? Would this allow for safe operation of any GM TBI injector to be operated at these higher pressures?

Steve

---

They were essentially a 4.3 injector ran at a higher pressure, if you do the math , the 45 pph 4.3 injector @ 13 psi would be around 70 pph @ 32 psi , GM's thought was it would fight vapor lock by using a higher fuel pressure , aside from designing a new injector , what they already had was used and the pressure increased to fuel a BBC . Anyone who has dabbled with a TBI BBC though finds out quick enough that the injectors at that pressure were marginal for fueling at the factory settings , one of the first things I did to the stock 454 in my '94 Dually when I bought it was to revert to the earlier injectors (5235231) and ran them around 15 psi , woke the otherwise stock engine up .

If you are going to be raising pressures , especially on the BBC injectors , I would stay with the 5235231 platform , these are much more tolerant of higher pressures than the 17104288 injectors .

I as well as many others have run the 5235231 injectors upwards of 70+ PSI with no adverse effects on cone shape nor spray pattern.

TOM

Awesome, thanks for the info Tom. 70+ PSI, that's so much higher than the original 13 PSI as designed. So are they just relabeled 4.3 injectors? Any changes in spray pattern between the two? I assume a 4.3 at 28-32 PSI would accomplish the exact same results?

I was thinking of running the 17104288 injectors in my mild 350 truck. I was seeking better atomization and cleaner burn through higher pressures. I had concerns about being able to get the fuel psi with the injector set right with a pressure regulator spring for a 350; as well as, minimum pulse width optimized from a 7427 PCM for low enough for idle/fueling conditions on the 350 vs the 454. I already have a pump capable of 30 PSI and Spring on hand but I don't have the injectors yet.

Remember, when you change the injectors and/or the fuel pressure, you change the base pulse width needed and should make accommodations for it in the .bin.

Buddrow

Right, just to confirm for the $0D mask, the BPW function is a mater of setting the injector flow rate in lb/hr. and the cylinder volume. In the case of the 17104288 at 30 PSI, should be set to 74lb/hr. I am assuming the 7427 PCM will be able to compensate enough at idle going from 61 lb/hr from the stock set up to 74 lb/hr with the 17104288 at 30 PSI. If not I would have to reduce fuel pressure from the 30 PSI on those injectors.