Vortec 350 L31 Duty cycles

[hog]

What are you guys seeing for duty cycles on the stock poppets, or even the MPFI conversions?

Can you please include a brief description of mods.

I'm wondering if we have to stick to the "80% DC" rule like with conventional injectors? Esp for minimal amount of time these spiders are actually at WOT, and because they are immersed in fuel?


http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/spidercomparo.jpg
http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/injectordebris.jpg

I know that 330rwhp/381rwtq has been fueled using the stock pump, stock poppets, stock intake on a ported Vortec head 383/LT4 hotcam kit 97 ecab 2wd.

Then there is a user here, who did a 350HO crate install, which is a stock Vortec 350 longblock with a 212º/222º 0.435"/.460" flat tappet cam, and was seeing almost 100% IDC and then cranked the poppets to 82 psi to keep IDC's around 80%.

IDC% is a calculated number, and represents an injector which is held open statically. But the correct IFR has to be inputted. I know of some guys who have spiked 125% IDC.

Thanks guys

peace
Hog

[joecar]

IDC above 80% but under 100% might be ok as log as you don't see a lean condition (i.e. where the PCM has to add additional fuel)...

the 80% rule is to allow the PCM the space to add more fuel if something inadvertently causes a lean condition (or for that matter, if extra fuel is required as for cat protection mode, or piston protection mode).


Yes, the usual IDC is a calculated value based on the time elapsed during 1 complete cycle (4 stokes, 2 revolutions), so 100% represents the injector being held open (not being closed);

IDC above 100% means the injector is not flowing any more fuel compared to 100% (at 100% it was already held constant open).

The above is true if the injectors are sequentially fired;

if they are batch fired (all injectors in each bank are fired twice per cycle (i.e. on each revolution)), then anything over 50% means the injectors are held open.

[Mikz86ta]

What peramiter number is that listed under in Tune Tool?

I have 2003 s10 4.3L (has the updated mini injectors not poppets) and was going to check to see where mine was at for reference.
For info, my rated 19lb injectors but are listed as 22.13lb in B4001 flow rate

[joecar]

Hi Mik,

There is no IDC parameter/table in the tune...

IDC is calculated based on injector pulse width and RPM...

the CALC.INJDCn pids are calculated by the scantool from GM.IBPWn and SAE.RPM.

[EagleMark]

IDC above 80% but under 100% might be ok as log as you don't see a lean condition (i.e. where the PCM has to add additional fuel)...

the 80% rule is to allow the PCM the space to add more fuel if something inadvertently causes a lean condition (or for that matter, if extra fuel is required as for cat protection mode, or piston protection mode).


Yes, the usual IDC is a calculated value based on the time elapsed during 1 complete cycle (4 stokes, 2 revolutions), so 100% represents the injector being held open (not being closed);

IDC above 100% means the injector is not flowing any more fuel compared to 100% (at 100% it was already held constant open).

The above is true if the injectors are sequentially fired;

if they are batch fired (all injectors in each bank are fired twice per cycle (i.e. on each revolution)), then anything over 50% means the injectors are held open.

For injector duty cycle in percent.

Where X is BPW and Y is Engine RPM

Sequential or Batch( X * Y)/1200
Bank ( X * 2 * Y)/1200
TBI Alternating ( X * 4 * Y)/1200

hog, I've got a stock Vortec I'll get a baseline for you next time I log. MPFI with 0411 RoadRunner PCM now. Also doing a 1997 next week that is supposed to still have poppets in it.

HTH!

[hog]

What peramiter number is that listed under in Tune Tool?

I have 2003 s10 4.3L (has the updated mini injectors not poppets) and was going to check to see where mine was at for reference.
For info, my rated 19lb injectors but are listed as 22.13lb in B4001 flow rate

The poppets(CSFI) and Multec-2 mini-injectors(CSFI to MPFI conversion spiders) flow 23.1 lb/hr at 63 psi of fuel pressure.
19.17 lb/hr at 43.5(3BAR) of fuel pressure
22.15 lb/hr at 58 psi(4BAR) of fuel pressure

Delphi states that its CSFI and MPFI spider have their FPR's set at 435 kPa(63 psi). This makes sense since most repair books have the KOEO(Key On Engine Off) pressure being between 62-66psi. Then the manifold vacuum causes the FPR to lower the fuel pressure when at KOER(Key On Engine Running).
The CSFI spiders require fuel pressure to open their poppets and most wont open down at 43.5 psi.

peace
Hog

[hog]

Thanks Mark, that'll be cool.

peace
Hog

[hog]

For injector duty cycle in percent.

Where X is BPW and Y is Engine RPM

Sequential or Batch( X * Y)/1200
Bank ( X * 2 * Y)/1200
TBI Alternating ( X * 4 * Y)/1200

hog, I've got a stock Vortec I'll get a baseline for you next time I log. MPFI with 0411 RoadRunner PCM now. Also doing a 1997 next week that is supposed to still have poppets in it.

HTH!

Thanks Mark, that'll be cool. If someone who installed a simple 350HO crate and is seeing just under 100% IDC, just imagine what a ported Vortec 383/hotcam setup was seeing?

peace
Hog

[joecar]

For injector duty cycle in percent.

Where X is BPW and Y is Engine RPM

Sequential or Batch( X * Y)/1200
Bank ( X * 2 * Y)/1200
TBI Alternating ( X * 4 * Y)/1200

hog, I've got a stock Vortec I'll get a baseline for you next time I log. MPFI with 0411 RoadRunner PCM now. Also doing a 1997 next week that is supposed to still have poppets in it.

HTH!Correct.

The INJDC calc pid provided by the EFILive scantool implements the first calculation (sequential).

[hog]

IDC above 80% but under 100% might be ok as log as you don't see a lean condition (i.e. where the PCM has to add additional fuel)...

the 80% rule is to allow the PCM the space to add more fuel if something inadvertently causes a lean condition (or for that matter, if extra fuel is required as for cat protection mode, or piston protection mode).


Yes, the usual IDC is a calculated value based on the time elapsed during 1 complete cycle (4 stokes, 2 revolutions), so 100% represents the injector being held open (not being closed);

IDC above 100% means the injector is not flowing any more fuel compared to 100% (at 100% it was already held constant open).

The above is true if the injectors are sequentially fired;

if they are batch fired (all injectors in each bank are fired twice per cycle (i.e. on each revolution)), then anything over 50% means the injectors are held open.

Thanks Joecar, remember those 1992-1995 CPI Vortec 4.3's in the S-10 SS and the ZR2 Highrider? Those CPI injectors fired 3 times per rev, or 3 times a cycle. Kinda weird.

That makes sense about avoiding a lean situation. I thought it was to avoid injector overheating.

Thanks

peace
Hog

[joecar]

I do recall something about earlier injectors overheating maybe... but they do have cold fuel going thru them... I'll have to dig up some old GM books/documents.

[Mikz86ta]

The poppets(CSFI) and Multec-2 mini-injectors(CSFI to MPFI conversion spiders) flow 23.1 lb/hr at 63 psi of fuel pressure.
19.17 lb/hr at 43.5(3BAR) of fuel pressure
22.15 lb/hr at 58 psi(4BAR) of fuel pressure

Delphi states that its CSFI and MPFI spider have their FPR's set at 435 kPa(63 psi). This makes sense since most repair books have the KOEO(Key On Engine Off) pressure being between 62-66psi. Then the manifold vacuum causes the FPR to lower the fuel pressure when at KOER(Key On Engine Running).
The CSFI spiders require fuel pressure to open their poppets and most wont open down at 43.5 psi.

peace
Hog
Thx for that info!
Yea my 4.3 on the gauge seems to run up to 58psi max. I never recall seeing it over that if the gauges were accurate.
I have a racetronix FP wire upgrade relay kit installed. A racetronix upgraded injector kit is sitting here waiting for the day the stocker takes a dump :) Not sure if that will net a higher psi but time we will see I guess.
I wish there was a def way to read the actual FP to know for sure

[Mikz86ta]

Thanks Joecar, remember those 1992-1995 CPI Vortec 4.3's in the S-10 SS and the ZR2 Highrider? Those CPI injectors fired 3 times per rev, or 3 times a cycle. Kinda weird.

That makes sense about avoiding a lean situation. I thought it was to avoid injector overheating.

Thanks

peace
Hog
Didnt all the 'poppet' style ones do that? Before the Multec swap was done

[hog]

Didnt all the 'poppet' style ones do that? Before the Multec swap was done
No only the CPI V6's did that.
The CSFI 1996-2001 CSFI poppets are operated by fuel pressure in a sequential fashion, the fuel is allowed down the spideres legs by "injectors" located in teh fuel distribution block "centrally located" in the middle of the manifold..
The MPFI 2002-2013 L35/LU3 use the upgraded Multec-2 mini-injectors on the end of the spiders legs.

Only the CPI 1992-1995 GM 4.3 VIN “W” fired 3 times per engine rev or 3 times for every cycle

CPI intake http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/cpiintake.jpg

CPI 1992-1995 VIN "W" Central Port Injection
http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/cpispider-1.jpg

CSFI spider top (1996-00)/MPFI (2002-13) spider bottom
CSFI=Central Sequential Fuel Injection MPFI=Multi Port Fuel Injection
http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/spidercomparo.jpg



This pic is of a marine intake next to an L30/31 inatke(I couldnt delete this pic)http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/marineL31endtoend.jpg

peace
Hog

[EagleMark]

Thanks Mark, that'll be cool.

peace
HogFound this again and realized I forgot about you? Sorry Hog!

Have a couple WOT runs to 4800 where my stock 5.7 Vortec shifts, has the upgraded spider and 76% is my max Injector Duty Cycle.

[hog]

The guy from Bakersfield Cali with the Hotcam, ported L31 heads, headers on a 383 with the stock Vortec injection must have been on the edge, if not over it with a chassis dyno of 330rwhp/381 rwtq.

thanks

peace
Hog