Contour Enthusiasts Group Archives Forums Modifications Forced Induction Rev. Po'Jay dyno

Jason,

Without seeing the A/F curve we have no way of knowing if the injectors went to 100%. If they did they would go static open and the A/F curve would actually go rich and then lean out rather fast...I have a good example somewhere.

Seawulf:
Sorry man but the BSFC of our engines does not follow those old estimates. Our engines for whatever reason are way more efficient than that. 19# injectors are dyno proven to provide 240 wHP on our engines without being maxed out.
I had a duty cycle of 69% at 7000 rpm with over 210 wheel HP on 24# injectors.
By the way, the SVT contours with return style fuel system run 45psi idle and 55 psi wide open throttle. The ford injectors are rated at 39 psi and a certain duty cycle that I forget. Doing the conversions means that 19# injectors act just like 21# injectors at 39 psi.

You can quote the "Rules of thumb" all you want and so did we last year until dyno after dyno proved it wrong, along with all the driveability issues people were having.

Just remember that I am running rich right now, pushing 350 wheel horsepower on 8.5#'s of boost (Yes I know whats in my sig is OLD) with 36# injectors and a Walbro 255LPH fuel pump. IT is too rich since I tuned the car with the stock pump and it was running out of steam above 6K rpm. With the new pump A/F was much richer and steady all the way to 7K.
Say what you will but proof is proof.

So this 69% duty cycle, was it done naturally aspirated or boosted? Cause if it was naturally aspirated the chart numbers work out ok. And who did that 240whp figure on 19s? What fuel psi was that run on, NA or FI?

I'd still like to know what kind of fuel psi the rest of you are running. I need to get me a guage before I head back out to StreetFlight.

That fuel ratio was 11.9:1 and 12.5:1 on two different dynos, both N/A. The measurements weren't taken at that time but later on after more exhaust modifications so the power was expected to go up.
Also, I should clarify that those were the absolute highest I had seen and most of the duty cycles on full throttle runs were in the low 60's. It probably had variation due to temperature and altitude since the power numbers were correted.
Therefore the information I gave you is useless other than to say that at no time did I ever record my 24's to exceed 69% and that was only for an instant at 7000+ rpm's.

Second, I don't know the pressure for the 19's on 240 wHP, but that was DavidZ's old engine.

I made 217 on 19#'rs with 11.5-11.9 A/f ratio and stock fuel pressure.

Bottom line like anything is you need to test this stuff but you can go off of experience from us or you can go off of what you want.

Well, so far the the numbers you posted still fall within the specs the fuel injector table says they should. And I know the calculator is correct when it comes to the Zetec engine.

I'll believe the differences in calculator vs real world examples is the question of just what are ford injectors rated at and at what fuel psi.

I give up, Po'Jay nice numbers, just get bigger injectors as soon as you can.

OT but, got picks of the Franken Fuel rail? I need to make a similar beast.

I will see what I can do. Remember that it is more like a Picasso than an Ansel Adams. Functions beats fashion hands down!

I heard that. You should see my engine bay. Keith said he'd never seen more plumbing supplies in an engine bay before.

Got your Home Depot sponsorship, huh?

Dude, I got two 3" rubber plumbing connetors. The nearest pro shop is 50mi away, lay off me!

I am very interested in your guys' injector picks. I have MSD 50lb injectors soon to go to 72lb in the spring on my nissan. Reason being is I want to stick with a 3bar fuel pressure instead of running my 50lb injectors at 4bar fuel pressure and hitting the 90percentile duty cycles. I would imagine that 42lbers would be the way to go on your cars.

Brent