Injector duty question..
06-04-2010, 02:41 PM
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Injector duty question.. I am currently maxxing my injectors @ 100% at about 6300 rpm. If you know the IPW at this point...can you work backwards to determine what injectors will get this down in the 80% range?
06-05-2010, 01:21 AM
#3
The number that the PCM comes up with is calculated and not actually measured to it may or may not be exact.
What injectors do you have? I've seen a heads/cam car that was hitting 100% around 4700 on stock 28s drop to around mid 50% max with some green top fords.
What injectors do you have? I've seen a heads/cam car that was hitting 100% around 4700 on stock 28s drop to around mid 50% max with some green top fords.
06-05-2010, 11:52 AM
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I currently am running SVO 30's, which scale between 36 and 40#. If you do the injector flow calculation based on 450 rwhp (~575 bhp) it comes in around 39# at 80% duty. So I should be ok? I was getting ready to put some green tops on, but I have read where you can have some tuning issues with too big of an injector rating. The SVO 42's scale in the 52 to 57 # range would be maybe too big?
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06-05-2010, 12:04 PM
#8
I currently am running SVO 30's, which scale between 36 and 40#. If you do the injector flow calculation based on 450 rwhp (~575 bhp) it comes in around 39# at 80% duty. So I should be ok? I was getting ready to put some green tops on, but I have read where you can have some tuning issues with too big of an injector rating. The SVO 42's scale in the 52 to 57 # range would be maybe too big?
The green tops are around 52 at 58psi and the reds are 36. If you're keeping your desired AFR inline than you should be alright for now on the reds but if you move up I would at least go with the greens. Neither of these injector are considered too big. You have to think that Ford runs the greens on a smaller motor which would need less fuel at idle and part throttle than an LS1.
Plus the fact that the FORD injectors have all the data readily available for tuning makes them an easy choice for me.
06-05-2010, 12:21 PM
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Yes the 42's scale from 52 to 57 with the data I have, which does not line up with a standard 3bar calculation.... more like Fords rating at 39.15. Confusing. I thought I was running fine with injector duty and went to the dyno for WOT tuning and found I was running lean.... set the AFR to 12.2-12.5 and my ID went to 100% at 6200 rpm and the HP curve was at about a 45 deg slope at 430 rwhp and still rising... this cam wants to run higher and need to make that happen. I may be out of pump also.
Last edited by BLUEBYU; 06-05-2010 at 12:37 PM.
06-05-2010, 01:29 PM
#10
Yes the 42's scale from 52 to 57 with the data I have, which does not line up with a standard 3bar calculation.... more like Fords rating at 39.15. Confusing. I thought I was running fine with injector duty and went to the dyno for WOT tuning and found I was running lean.... set the AFR to 12.2-12.5 and my ID went to 100% at 6200 rpm and the HP curve was at about a 45 deg slope at 430 rwhp and still rising... this cam wants to run higher and need to make that happen. I may be out of pump also.
If you are actually going lean on the dyno (not just from bad tuning) then I would look at the pump first. I've seen injectors go to 120% by the PCM and still keep up with my commanded AFR.
36lbs/hr injectors should be able to run 450rwhp all day long, if they are in good working order.
06-05-2010, 03:48 PM
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You even stated " should work if the injectors is in good working order " That is the point of staying @ or below 80%. I am not an injectors expert but you are misleading anyone reading this post by saying 120% injector can keep up with your desired AFR- Safely.
06-05-2010, 05:48 PM
#12
How is it a Calculated value? 20ms Pulse width @ 6000 rpm = wide open injector 100% cycle. Just because your AFRs keep up doesn't mean the injector isnt over its duty cycle.
You even stated " should work if the injectors is in good working order " That is the point of staying @ or below 80%. I am not an injectors expert but you are misleading anyone reading this post by saying 120% injector can keep up with your desired AFR- Safely.
You even stated " should work if the injectors is in good working order " That is the point of staying @ or below 80%. I am not an injectors expert but you are misleading anyone reading this post by saying 120% injector can keep up with your desired AFR- Safely.
The safety margin is there for safety. As with everything you can run it over the margin and you may not ever have trouble. You are would be over working.
And I said that red tops should be enough for 450 rwhp and a safety margin. Of course, every car and setup is different, but he should check the pump. If it's not pumping enough then the injector will have stay open longer for the same amount of fuel or it will just go lean.
06-05-2010, 05:58 PM
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Yes. I think the pump is the issue, because when I do VE tuning my LTFT histogram log data when pasted into the VE table keeps pushing the numbers higher than they should be (115-124).... What is my best option on the pump swap?
06-06-2010, 07:15 PM
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The ford 42 pound injector are a very good injector with a lot of head room and are easy to control----
the % data is a calculated guess of the injector flow rate table-been caught out to many times thinking i need a bigger injector....
if really unsure log the afr to see if you have control vs your fuel pressure- vs your commanded
the % data is a calculated guess of the injector flow rate table-been caught out to many times thinking i need a bigger injector....
if really unsure log the afr to see if you have control vs your fuel pressure- vs your commanded
