Every single one of my tunes is set to peak at about 3000 psi of ICP. I'm running a bone stock HPOP, and it supplies more than enough oil to maintain that pressure on my highest hp tune.

Granted my highest HP tune only allows a max 2.3 ms of pulse width. Since hybrids use less oil, the HPOP can keep up with the narrow PW. My tow tune, which is typically also my daily driver (or the wife tune), will hit right about 1.9 ms, which is a little under 180cc's. A stage I injector at 4 ms is still only giving 160cc's. So you can see the difference real quick there. More fuel at half the time.

As for how much ICP an injector can handle..... that's up for debate. Personally - and this is based on my own experience with my truck - I don't think they last very long. For several years I ran stock injectors with a twin HPOP setup, and ICP would peak at 3800 PSI. By the time I swapped in the hybrids and went back to a stock HPOP, I had already replaced one injector that went south, and another was on its way out. IIRC I think I had around 140,000 miles on the motor when I put the hybrids in. Truck just turned 200,000 a few weeks ago.

Not sure what mods or injectors you are running, but take stock injectors for example. Start going above 3.5ms of PW, and the stock HPOP won't be able to keep up. For some trucks, it's less. If you're dropping ICP, that will contribute to EGT issues. I have seen tow tunes (not naming names of tuners) with 4ms or more of PW on stock sticks.

But if you are holding a good ICP and still having heat issues, it's a matter of either airflow or fueling.

 

Oh... you mean this tow tune while pulling heavy on a grade... forcing the driver to cycle the throttle to control EGTs?

 

And that perfectly demonstrates exactly what I was talking about. I couldn't have drawn that better with crayon.

 

Curtis, what turbo are you running? My PW idles at 2.2 with stock AB injectors in 60E tune. I'm set on 200/100 injectors when I change. I just liked Robins set up and he said he wished he had gone to 100 noozles and none hybrid injectors. I'd like to give that a try.

 

I've seen that for 160/100's and 250/100% injectors as well from two different places...and like you...not putting any names out there.

 

all i know is i wish i had a long bed instead of a shortbed for towing!

 

38R

Idle is different. You're only around 500 psi of ICP, so there's far less fuel coming out. Splits also have a longer idle PW than singles.

Mine idles at around 1.4 ms.

 

So here I sit about 90% convinced 160's stock nozzle...new from PIS....is what I had settled on. Then Pocket comes in and lays down some pretty clear thinking on 250/200's. I don't think that's for me though.

Now I'm considering 160/30 to 160/80. The "problem" in a new AC's and then the over sized nozzle is $$$. $1850 for the new AC's....then like $450 more for nozzles.

I really don't have much stomach for a new turbo...and if I did, it simply couldn't be the 38R...the noise would drive me insane.

Damn you all

 

Make damn sure you have a person capable of tuning in your area (live tuning would be best) if you decide on ANYTHING with nozzles larger than 80-100% or you will not be happy.

 

Thanks Cody....and therein lies the issue. I'm not aware of somebody within a couple hundred miles of Mpls that does live tuning, so that is one reason I'm shying away from even 100% nozzles. I really, really don't have the desire to chase a tuner around the country.

 

Very informative guys never really linked the IH AC 160's in terms of engineered design and longevity.....

What is the consensus with a 175/80% injector with Borg Warner T4 S366 and .91 A/R, T500 HPOP and supporting mods? This is what I'm currently lining up for a DD and tow in '97 sig truck. Thinking I'll use the stock turbo with 1.0 maybe with a WWII short term, then do an engine rebuild (pending compression check, funds bla bla) then move to S366. Looking for usable power below 2800 rpm and quick spool say 1400-1500 rpm.
Thanks for sharing....
jrc

 

Both engines make peak HP around 2750 RPM.
Both engines make peak TQ around 1600 RPM.

 

[QUOTE=Shake-N-Bake;13965581]Both engines make peak HP around 2750 RPM.
Both engines make peak TQ around 1600 RPM.[/QUOTE

I'm not saying your wrong because I would have to look it up again but you would have to be special tuned for the 7.3L to make peak TQ at 1600 RPM's.
Haven't seen 800 FT.LBS, at 1600 RPM's on a 7.3L. And it would smoke pretty bad if it did.

 

This has been a very informative thread. Thanks to everyone for your input.

This is why I'll probably go with p.i.s 175/80's. You'd think with the rocky mountains in denvers back yard their would be a tuner in the area.

 

^^^^^^ WHS

As I mentioned in another post in this thread... big nozzles aren't for everyone, and small nozzles aren't for everyone. Much will depend on tuning. It's going to take time to get a truck with larger injectors and nozzles running the way you want it to run.

I know first hand that larger injectors/nozzles CAN work very well, but I also know that at the same time it can be difficult to get it to that point.

And there's nothing wrong with smaller injectors/nozzles too, just understand the limitations of that setup and don't try pushing beyond what they are capable of (which happens far far far far far too often).