Maybe PTE can supply us with duty cycle vs flow rate for the different injectors and you can work your math magic on it.

What you need is pulsewidth versus fuel delivered for different fuel pressures. The Delphi 50s do not follow the typical equation for fuel delivery versus pressure increases.

I have the pulsewidth versus fuel delivered data for the 50s, John I'll get that to you sooner or later.

The offset is about typical for these injectors, the ones to really worry about for that are the 42.5lb and if anyone is running low impedance injectors.

Brian Green

 

So when i switch to my 42lb svo injectors how do i figure out the table for my fuel pressure rise with boost or should i just eleiviate the signal for FP increase so it stays at a constant(58psi)?

Also, where is the FP limit to keep a safe duty cycle for svo injectors (ex: 42lb @58psi static = 80% vs the manufactor recomended limit of X ?

Great thread Jeremy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">So when i switch to my 42lb svo injectors how do i figure out the table for my fuel pressure rise with boost or should i just eleiviate the signal for FP increase so it stays at a constant(58psi)?

Also, where is the FP limit to keep a safe duty cycle for svo injectors (ex: 42lb @58psi static = 80% vs the manufactor recomended limit of X ?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The generally accepted theory is that if you're using a fuel pressure regulator that rises 1:1 (fuel psi. to boost psi.) that the injector flow does not change. The additional pressure from the boost effectively lower the flow rate of the injetors and rising the fuel psi in the line essentially counteracts that it to a 0 delta.

For duty cycle, I would stick to around 90% to be safe. On the drag strip you can get away with 100% in short bursts, and in a open road race you should come down to 80%. 90% is a safe compromise for a street car that sees a few gears worth of boost.

-Jeremy

 

Bgreene what do you mean about the 42.5 injectors? I have Lucas 42.5# and they SEEm much harder to tune for than the 36/38# I had. Please elaborate

 

Alright, I hate to jump in the middle here with a stupid question, but all this stuff is getting over my head...

I'm putting either SVO 30# or 36# injectors in my '98. Fuel pressure will remain constant. Do I just use the correction factor in Godspeed's table?

<small>[ March 29, 2002, 06:30 AM: Message edited by: GeorgeC ]</small>

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Alright, I hate to jump in the middle here with a stupid question, but all this stuff is getting over my head...

I'm putting either SVO 30# or 36# injectors in my '98. Fuel pressure will remain constant. Do I just use the correction factor in Godspeed's table?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">How about this

SVO 30's

4.61 4.64 4.66 4.70 4.72 4.75 4.78 4.80 4.84 4.85 4.89 4.92 4.94 4.97 4.99 5.03 5.04

SVO 36's

5.53 5.56 5.59 5.64 5.67 5.70 5.73 5.76 5.81 5.82 5.87 5.90 5.93 5.96 5.99 6.04 6.05

SVO 42's

6.45 6.49 6.52 6.58 6.61 6.65 6.69 6.72 6.77 6.79 6.85 6.88 6.92 6.95 6.99 7.04 7.06

<small>[ March 29, 2002, 08:56 AM: Message edited by: Godspeed ]</small>

 

That'll work... Thanks Godspeed.

I wonder if the 42#'s would be way too big for my application. I know where I can get a brand new set right now for a pretty good price...

 

TTT for Big Tex <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

Bgreene what do you mean about the 42.5 injectors? I have Lucas 42.5# and they SEEm much harder to tune for than the 36/38# I had. Please elaborate

Sorry for the late response.

I have some injector data (hard copy only for now, sorry - working on getting it all scanned) that shows the 42.5lb/hr have a bit of a different offset than the 30/50/55lb/hr injectors. They are difficult to tune for, as they deliver a *lot* of fuel at low pulsewidths, then seem to taper off. They deliver more fuel at 1-3ms than 55lb/hr injectors do. Because of those non-linear characteristics, I don't like to use them.

Brian Green
Which 36/38# injectors were you using?

 

links don't work anymore any updated info on these?

 

I have the following injectors:
Delphi / Lucas, 37 lb / hr
Part Number Delphi D3165BA (Lucas old 5203002, Lucas New 621037)
Static Flow Rate: 37.27 lb/hr @ 43.5PSI (300kPa) or 282gm/min
Dynamic Flow Rate: 8.42 gm/pulse - 2.5ms pulse width and 10ms repetition rate
Coil Resistance: 15.9 Ohms / High Impedance / High-Z (No ECM driver modifications required)

98 PCM with stock regulator and lines but a Walbro 340 pump and racetronix harness.

What values should I change, Where are these values stored and what should the values be set at?