RolexNJ

I remember Danno tried using this for calculations. I called the company about 2 years ago because something didn't seem right, and I spent time with a techician on the phone and he aggeed it was off too. I wouldn't use this calculator, but I'm sure there are more on the Net.

HansB

It is correct physics that a relation exists between fuel consumption and HP.

The "trick" would be in the assumption of how much fuel is used to produce 1 HP,
For our cars a value of 0.5 concurs with my own measured values:

- Almost maxed out at 290HP(crank) on stock injectors at 43,5 psi
- 80% duty cycle at 350HP (crank) on 55lbs/h injectors at 43,5 psi

Lorax

I ran stock injectors to 300+ with 3.0bar and didn't encounter a lean condition or anything.

TurboCab

Is not how much HP support an specific injector size, but what Air Fuel Ratio and duty cycle you will be operating.

DrZ1

I am curious as well. I have a AFM, K27/6, 3 inch test pipe and catback, 3 bar regulator, I would like to run 16 psi of boost. I plan to use for the track, until I finish my project. I like the idea of stock injectors since I use as daily driver and want to get the best gas milage. Any one noticed drop in milage going from stock to 55lb injectors?????


I am about to start tuning the Vitesse chips with the Piggy Back, I am sure I will learn more from this.

Steve

blown 944

everybody needs to remember to add the boost pressure to the equation ie; 43.2 + 15 psi or whatever. Imo the stockers are maxxed just at 300hp running a little higher FP.

I have also heard that the stock injectors are more like 42# ers. I tend to believe this a little b/c I have ran 36# ford injectors in my car and have had to turn down the FP to get the same AFR when going back to the 951 units.

RPHARRIS

If you're willing to run risky AFR's, high duty cycles, and ridiculous fuel pressure, they can support 300hp. RKD managed 400rwhp with 48lbs. I personally couldn't get anywhere near that out of mine though, but my fuel pump had seen better days so that's not a fair measure.

V2Rocket

this is very good, very good to know. thanks for the information so far.

sid, once again (as always) you prove to be an invaluable resource of information...is there anything about 944s that you DONT know? lol.

is there any way we can settle once and for all how much stock 951 injectors really flow? any method of testing?

spoolin51

I dont think that injector size is an issue when it comes to gas mileage. Although the injector is bigger, it will only spray the appropiate amount of fuel it's programmed to.

333pg333

Is this question purely for a theoretical value or do you plan on maxing out stockers? If that's the case wouldn't it just be worth the few dollars to buy a bigger set than risk blowing your motor? Not trying to be a ********, but seems like it's not worth the risk.
btw Sid, we have ordered a set of those new injs. 1650ccs *****. Hope they do the trick! Looks like all going well, it's on the dyno next week.

spoolin51

Patrick, you're already hitting up the dyno! Thats awesome. What hp goals are you shooting for?

V2Rocket

definitely hoping not to max out the stockers just yet...951 injectors should be perfect (read, more than enough) for the power levels i would like to achieve..

im gathering all the necessary information for my (very long-awaited) upcoming project...this includes fuel injector sizing..

a big box labeled 'eaton' will be at my door on tuesday...

333pg333

Waqqas I was hoping to be on the dyno a week or two ago but one thing and another gets in the way and creates delays. As for goals, well it depends on what fuel type you're talking...but this is not my thread so I'll leave it to another day when I have some numbers.

Sorry for the OT.

333pg333

Hehe, i was wondering what those candy coloured screws in your avatar were about, but won't that still require a fair bit of fuel? Guess you're intending to run high c/r ~ lowish boost and therefore no need for too much fuel?

Raceboy

With boosted cars, the fuel pressure will be higher with boost but this is offseted by the same boost in the intake and that means the fuel injector flow rate remains the same.

At 3 bar, stock 951 injectors are good for around 280-300 flywheel hp and that is a stretch. I wouldn't use them anywhere else than street car. 951 engine with 8v head doesn't have very good BSFC, 16v is much better (more efficient).
For example: on my turbocharged euro 924 I had 440cc injectors (same as 951 ones at 3 bar) and at 250 flywheel hp (1 bar of boost, talk about crappy flowing head, huh) , injecors were at 70% duty. Lambda was 0.83-0.84.