I logged Inj. Duty Cycle today and it was 110-126% from 5000+. Am I losing quite a bit of power from my injectors being maxed out? Also, are 42lbs ideal for a big cam/stock heads/full bolton car? I ran 89mph in the 1/8 before cam and intake and I'm still running the same now. I'm hoping its fuel related.
Originally Posted by jpolser
You're definitely out of injector, which is not safe. Ideally stay 80% or so, no more than 90% is ideal.
It only affects performance if you are leaning out due to running out of fuel, but even if the A/F is not trailing off it is a bit dangerous to run that way.
Jody
On a car with 100% duty at 5500rpm, when we changed from 28lb to 36lb the car only made more peak power ie the same curve but to a higher peak.
Joe
LS1 LS2 LS7 tuner, L98, LT1 & Haltec
In fact you cannot get over 100%.
Since the stock tune is pig rich, a 10% shortfall in
available duty cycle on a stock car might actually
be better (performance wise) than more injector.
But presumably by the time you get to flowing the
air it takes to max stockers out, you're more than
ready to do it right, tune for proper commanded
fueling and true up the fuel delivery and airflow
so what you say is what you get.
Bolt-ons car could probably get by with SVO 30#
or Delphi 32, 36 but soince they all cost the same
and aren't much different in the tuning effort, may
as well go for the 42#ers; lots of them in use and
folks around who have already bedded theirs in,
for tune examples.
I have heads and cam, with SVO 30's and im already back up to 105% duty cycle at 6K+ at 13.0:1 A:F Moral of the story is: Go bigger.
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If a guy was using a 42 lbers what do u set Injector offset table to?? Or would u just leave table stock??
Most are leaving the Offset table alone. You would need the values from a similar vehicle with the same injectors to be sure.
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never have saw one that is suppose to be correct!!!!!
The only in-car way I can see, is to set up the IFR table
properly and then work the injector offset table to get
back to the same hot idle LTFT+STFT value you saw
right before the swap (idle being the shortest pulse width
and most affected). Then you would be back to the same
quality of model that you had before (for whatever that's
worth).
From what little dynamic flow data I've acquired, there
is a fair bit of variability in the offset - anywhere from
0.5 to 0.8mS - even within "family". Not to mention that
said data comes with no info on system voltage, a prime
actor. So leaving it alone, is as much of a guess as
guessing blind. Unless you got lucky and picked a type
that happened to be similar to stock in its offset profile.
I've been accumulating the gear for an injector flow bench
to do fine injector pulsed testing (I made one before but
the electronics are too sloppy for anything more than
group matching). Have to find the time to cobble up an
accurate pulse driver, I'm all set for the plumbing and
the variable power supply is on the brown truck.
My first test will be to extract data from a stock injector
set and compare that to the stock table at center and
corners. If that comes out to anything worth believing
then I'll be doing my Delphi 32# and after that, requests.
I multiplied my offset table by 0.7 for the FMS 42#ers
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Jimmy,
You going to be using Stoddard fluid or ??? for testing.
Stoddard is supposed to be close to gasoline with out the fire hazard. I need to read up a bit more on the fluid end of things.
EC
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