Braineack

iTrader: (62)

apparently. i dunno, i still wouldn't use stock injectors on that system if i was running 10psi. at 6psi, as shipped, sure. But that thing is too efficent of a setup apparently.

18psi

iTrader: (76)

So you agree with corky, that tapering torque increases the fuel system overhead and nets you more power?



k

Braineack

iTrader: (62)

here's how to test that: increase timing until boom! note the AFRs.

18psi

iTrader: (76)

I mean if he's gonna claim that the stock fuel system can go beyond the injector duty cycle limits because the pump is strong, and that you can keep going with injectors never closing until you run out of fuel pressure, I think I would have to agree with that. At least based on what they've provem already with the AO kit.

Most of us would agree that is very dangerous, but appears possible.

nitrodann

I agree that torque=pulse width.

You still don't understand thats pulsewidth at a given duty cycle changes with rpm.
That baffles me.

18psi

iTrader: (76)

pulsewidth at given rpm changes the duty cycle

potato pohtahtoe

can you unwad your panties so we can move on and discuss the actual interesting topic of this thread is drifting to, which is the oem miata fuel system "real" limit?

nitrodann

Calculate it.

I did.

240 crank, at 12.5:1afr, 10psi, 60psi flat pressure in the rail.

18psi

iTrader: (76)

omg, are you on 28kb connection or something? did you not see the last few posts? We know its possible, because it was already done. And backed up.

and it's not 60psi flat on an nb returnless system. but that doesn't matter, because BEGi already proved that its still possible, even with a tapering rail pressure.

Braineack

iTrader: (62)

ill give you some tapering rail pressure.

sixshooter

iTrader: (12)

Savington

iTrader: (31)

omfg, this thread is painful to read.

Someone with a Dynojet plot of their car and a datalog of a WOT pull please post the following four traces on the same plot:

1. horsepower (SAE corrected)
2. torque (SAE corrected)
3. ECU-commanded pulsewidth
4. ECU-calculated injector duty cycle

Savington

iTrader: (31)

BTW, before that chart is posted, here's what I think it will show:

-injector pulsewidth correlates to torque, but not as closely as Corky thinks
-injector duty cycle correlates to power, but not as closely as anyone thinks
-both of these are true because BSFC (fuel mass required to make X horsepower for X hours) goes up as engine speed increases

Here's a cool chart to show why this is true:

3OugEDm.png

[/thread]

nitrodann

Yep. Along with the fuel system variables etc

williams805

iTrader: (2)

I am very curious to see pulse width at peak torque and there after.

Also Sav, forgive my stupidity but I've never seen a graph like that. Can you explain what I'm looking at here? Are the camel back lines the torque curves at different load percentages? And what is the pink line? Also not sure why looks like horspower lines are going down while rpms are going up.
Or just point me at some reading materials so I can read up on this.

18psi

iTrader: (76)

I didn't have a PW log of the above tune (different car).

Here's one I dug up from years ago of my gt3076 miata on e85




You were saying?

williams805

iTrader: (2)

Is it safe to say that peak torque is at 4600ish? Looks like pw is still going up until MAF begins to fall. So if 100% dc is hit at peak torque that would be bad news. AFR would have to fall at that point.

18psi

iTrader: (76)

here's an even better one with MAP falling toward redline

pw still goes up



if someone has better examples post up.

18psi

iTrader: (76)

last one cause now I'm getting bored


pw maximum at peak is 15.1, and minimum at the end is 14.4

Savington

iTrader: (31)

Lots of little things contribute to the consistent rise in PW/IDC that everyone sees in reality. Things like the lack of mixture homogeneity that comes as the injectors are forced to open while the intake valve is open (ideally the entire fuel pulse would be delivered to a closed valve). Increasing BSFC is a big contributor, though - if BSFC goes up by 10%, fuel requirements go up by the exact same amount for the same power/torque being produced.

Savington

iTrader: (31)

"Camel lines" are torque curves, yep. The colored areas are BSFC. Google "brake specific fuel consumption"

Horsepower lines are going down because torque goes down as you move down the Y axis. If you multiply RPM and torque anywhere on that chart, you get a horsepower number, and those are shown graphically on the chart by curving lines.

I'm not 100% certain on the pink line, but I believe it is a peak efficiency line from idle to redline.