Weird 3.0 turbo Fuel pressure/ ghetto fuel setup math

[Ondonti]

I was messing around with come calculations.

With the basic idea that 19# stock 3.0 injectors can support 190hp (crank or at the wheels???)

I run 30# injectors @ 31psi which is about 22# equivalent.

If I theoretically ran 90psi under peak boost (highest boost) then the injectors would be ~ 39# injectors.

39# injectors are double 19# so

190hp doubled is 380hp.........

so does that math really work??? I had always done the math a little differently because I was not taking into account that under boost my fuel pressure will be MUCH higher then stock with a rising rate regulator. So even with stock injectors I cold support more then 190hp. (260hp @ 90psi)

I had always just said "well 19# injectors support 190hp so 30# injectors support 300" but I guess this is only correct if fuel pressure stays the same (which it doesnt with rising rate regulator).

so 380 crank or 380 @ the wheels??????

[mwinkle353]

Brent, you need a performance calculator. I've got one here. Let me know if you'd like to use it. If you want, PM me with your email and I'll send it to you.

[Ondonti]

I didnt fudge any of these numbers. Those are from the many calculators available online. I just needed the injector flow calculator on RC engineering (they make some of the best injectors that I cant afford )


But do they use crank or wheel hp.........im guessing crank cause whp is variable based on drivetrain loss.

[Shadow24V]

well, i looked at an injector and flow calculators (witchhunter calculator) and at 43.5 psi, to fuel 380 HP youd need 52lb/hr, but if you increase the pressure on a 39lb/hr to 90 and you hit a flow rate of 56lb/hr so it seems to work tor me *shrug*

[Ondonti]

Quote:

Originally Posted by Shadow24V well, i looked at an injector and flow calculators (witchhunter calculator) and at 43.5 psi, to fuel 380 HP youd need 52lb/hr, but if you increase the pressure on a 39lb/hr to 90 and you hit a flow rate of 56lb/hr so it seems to work tor me *shrug*

Thats not right. I dont think anybody read my post either. The only injectors mentioned were 19# and 30# injectors

I dont use the incorrect BSFC numbers on those calculators because they flat out are not right.
Mines below .5 so those "supercharge/turbocharge" are BS. Nobody builds turbocharged engines with horrible BSFC's like that. Those are BS calculations from 50 years ago with carburators. Reeves 10 second omni does something like .43. Mines higher because of lower compression but its not anything from those calcs.


Stock 19# injectors can? make 190hp @ 48psi (stock pressure or is that at 43.5 they are flowed?)
260hp @ 90psi

Or 190hp @ 43.5psi
270 @ 90psi

30# injectors can make 300hp @ 48psi
410ish hp @ 90psi

or
30# injectors can make 300hp @ 43.5psi
430 @ 90psi

[Ondonti]

Quote:

Originally Posted by Shadow24V well, i looked at an injector and flow calculators (witchhunter calculator) and at 43.5 psi, to fuel 380 HP youd need 52lb/hr, but if you increase the pressure on a 39lb/hr to 90 and you hit a flow rate of 56lb/hr so it seems to work tor me *shrug*

Thats not right at all. See above post.

If you needed 56lb/hr to make 380hp (um)
Then our stock 19# injectors would only support 130 crankhp.
Thats obviously not right.

6 cylinders need about 1# for each fuel injector per 10 hp

140hp=14# injectors minimum.

This is assuming our ECU goes to around .8-.85 injector duty cycle (which I have no idea on). If it goes higher that means we have even more room for fueling

[c2xejk]

In talking to a calibrator he said that they generally target 80-85% max duty cycle, but can go higher... He didn't think that our controller would have a %limit. But he was involved with GM vehicles...

[Shadow24V]

ok, in light of my apparently off the wall wrong post, what is it you are tying to figure out? the max sustainable HP of your 30lb injectors?

[mwinkle353]

30# injectors
21 psi base fuel pressure
90 psi max fuel pressure
85% max duty cycle of injectors
0.55 BSFC

By my calculations, with these numbers, I see an estimated maximum 365 "CRANK" horsepower capablity from 6 30# injectors.


Of course, that's supposing that your fuel pump is up to the task of flowing that much fuel at 90 psi.

[Ondonti]

Quote:

Originally Posted by mwinkle353 30# injectors 21 psi base fuel pressure 90 psi max fuel pressure 85% max duty cycle of injectors 0.55 BSFC By my calculations, with these numbers, I see an estimated maximum 365 "CRANK" horsepower capablity from 6 30# injectors. Of course, that's supposing that your fuel pump is up to the task of flowing that much fuel at 90 psi.

I really dont think that math is right.
90psi on 30# injectors will flow more then 365crankhp worth of fuel.
43.5psi should be enough for 300 crank hp on 30# injectors.

Walbro 255 high pressure so 120psi is no problem....just have to worry about the fact that pumps push less fuel at higher pressures...and fuel pressure over 90 is worthless for increasing flow. If stock pump can even flow 90psi before pressure safety opens....It probably flows nothing there.

I dont have a BSFC of .55 either. Maybe if I was TBI over a single plane v8 intake....but I'm not.

[Ondonti]

The dark brown line is a test from a different person/magazine.
As you can see 12v @ 90 psi only provides about 100 liter/hr
Thats only good for about 300hp even with a walbro 255highpressure....because of the 90psi. I have no idea what my actual fuel pressure is though under my current boost. Means on ghetto fuel control I have to ere on the side of safety.

[Shadow24V]

i think you might be right brent. an auto manufacturer wouldnt go to the limits of a part. IIRC the 3000GT VR4 runs 360cc injectors (about 34ish lbs/hr) for 320hp, and i think you can take those to something like 400+ (dont quote me) so 30lbs/hr should be close

(unless im off the ball again lol :-p)

[Ondonti]

Quote:

Originally Posted by Shadow24V i think you might be right brent. an auto manufacturer wouldnt go to the limits of a part. IIRC the 3000GT VR4 runs 360cc injectors (about 34ish lbs/hr) for 320hp, and i think you can take those to something like 400+ (dont quote me) so 30lbs/hr should be close (unless im off the ball again lol :-p)

Well they can definitely do 300 at the wheels on stock injectors. They usually upgrade after that along with the pump. I think they cant do much more then that. Still, that number is at the wheels with only 42psi fuel pressure. That says something about what a 30# injector @ 90psi can do.

[Ondonti]

Quote:

Originally Posted by c2xejk In talking to a calibrator he said that they generally target 80-85% max duty cycle, but can go higher... He didn't think that our controller would have a %limit. But he was involved with GM vehicles...

I know those are normal targets (instead of limits)......Some of the TD cars like the TIII cars came stock very near 100% though.

They only have 4 33# injectors which should only be good for 220whp or so.....and of course they get a little more then that. they are 220hp from the factory and with a few simple mods can easily put that down on the dyno and more.

I just think that a lot of the talk I have seen over the years about fuel requirements was incorrect.

Technically you can turbocharge a 3.0 with stock fuel injectors..you just cant make more then 230whp (270 crank) and be safe.

And injectors that are more then 50% larger then stock (30# injectors) have no reason to not support 50% more HP then 230whp of stock....at least 340whp.


Im not saying these numbers are totally correct because i dont know what pressures our injectors were rated at and what my fords were rated at...but they differ greatly from what I had previously seen over the years.

Everyone always said "bigger injectors etc etc etc" but that only applies when you have used up what you already have.....anyone without a turbo or crazy mods certainly hasnt

[BAKES]

dont know if you have seen this web site
Stan Weiss' - Electronic Fuel Injector (EFI) Flow Data Table