Raceboy

Please email me your vemscfg, I'll take a look.

Porvair

I've been running VEMS logs and my stock (blueprinted) injectors (1988 turbo S with 3 bar fuel pressure regulator) are hitting 100% duty cycle at high boost (15 to 16psi, or a bit north of 210 kPa). Also seeing a spike in lambda so it looks like I am leaning out.

What are folks running as far as upgraded injectors? I've read through a lot of older (pre-VEMS) threads here and on Pelican but wondering what the current state of the art is for 951/VEMS.

Thanks
Sean

V2Rocket

ive got 2 sets of low-z larger injectors (55lb/hr and 72lb/hr) if you're interested. stock 951 is around 36 lb/hr.
$125 shipped either set.

they are the delphi fat-body type, physically interchangeable with the stock 944 injectors but have a better spray pattern.

VEMS can adapt to any kind of injector, just tell it the new flow rate and the injector type (low impedance vs high impedance firing patterns).

they look like this:

Porvair

Spencer - thanks for the reply. My intuition is that 72 lb/hr is overkill for me at 2x stock. 55 lb/hr should be adequate as those are 50% greater than stock and I'm not looking to do much more to the car as far as mods go.
I will shoot you a PM.

odonnell

Those are good injectors. If you want only slightly larger than stock, check out Ford "green giant" 42# injectors. They are plug and play as far as mechanical fitment and the deadtime/latency values are known.

darek_u

Spencer if Porvair won't take them I may be interested in. What model they are? Do they need any tweaking with resistance, latency etc? Sorry for the OT...

Porvair

I just installed a set of 55 lb/hr (which I believe calculates to 577.5 cc/min) injectors vs the stock 36 lb/hr (378 cc/min). Now I need to reset req fuel in VEMS. Basic req_fuel calculation:req_fuel = 6.49 * (D / N / I)
I injector flowrate (cc/min)
D engine displacement (cc)
N number of injectors (eg. 4 for a 4 cyl port injection)

So I would have expected a req fuel of 10.7 with the stock injectors (6.49*(2500/4/378)), however it was set at 9.6 from Peep, which I presume is correct. The calc with the larger injectors comes to 7.0 based on teh above formula, however I set it to 6.3, which is my original 9.6 setting *36 lb/hr/55lb/hr. That is yielding good lambda at idle (i.e., 1.0) so it seems Ok.

What am I missing with the calculations?

Porvair

And thank you Spencer for the new injectors.

V2Rocket

are you running @ 3bar or 2.5 bar fuel pressure?
they are 55# rated at 3 bar, less at 2.5 bar stock 951 pressure.

i remember having to set my reqfuel a little different than the equation would suggest too, didn't care to ask why.

Porvair

Running 3 bar. I'll drive it around and run some logs to see how those look. Just want to make sure that I'm not missing something obvious here.

odonnell

Make sure your dead time (injector latency) is set correctly. Hopefully you can find a datasheet online. Your low rev regions will be a lot smoother and easier to tune, with less AFR variance at idle.

Dave951

There are a bunch of "lag" time tables for a variety of injectors listed at http://injector-rehab.com/shop/lag.html

gpr8er

So I'm having an issue trying to get my tach in the dash working. I've checked with Peep and everything appears to be correct in the settings and also the harness. Hoping someone here can take a look at their settings and clue me in as to what might be wrong .

gpr8er

gpr8er

sorry for the discombobulated posting, trying to do it off the phone.