Injector Timing? Reference Periods? refereencing what?

[DrLoch]

I don't see there being huge power gains if any by adjusting these values however it will greatly increase driveability and tame alot of bucking and fuel smell.

Which is worth the effort in some cases.

[MikeGyver]

Once you get past a certain rpm it doesn't really matter when it's injected ... however it will greatly increase driveability and tame alot of bucking and fuel smell.

Which is worth the effort in some cases.

You both sound as if you have experience adjusting these tables to have the injectors fire after the exhaust valve closes.

[LSxpwrdZ]

I've not experimented going further than where I'm at. Right now my pulse ends at the .050" exhaust valve closing point which is 375*. I kept adding small increments to the table until I got a smooth ride and haven't experimented going further or back the other way. I can say that I left the colder portions of the table stock and believe I am going to have to play with them some because fueling is good on cold start but it just acts ignorant til it's at least 150*. I don't get to play with my own stuff often and it being cold doesn't help. I may go out this weekend and play around with it a little! Mine is a good case to try to smooth out being a larger overlap large duration cam.

[SargeZ06]

I've not experimented going further than where I'm at. Right now my pulse ends at the .050" exhaust valve closing point which is 375*. I kept adding small increments to the table until I got a smooth ride and haven't experimented going further or back the other way. I can say that I left the colder portions of the table stock and believe I am going to have to play with them some because fueling is good on cold start but it just acts ignorant til it's at least 150*. I don't get to play with my own stuff often and it being cold doesn't help. I may go out this weekend and play around with it a little! Mine is a good case to try to smooth out being a larger overlap large duration cam.

So Soundengineer is basing his on the intake event and you are working from the exhaust closing event?

[S2H]

I'm not basing it on either yet....
I havent had any time to play with it to try it out one way or the other.
but it does make sense to me that we would need to add to the table for a larger cam
and thats about as far as I have gotten

[SargeZ06]

I'm not basing it on either yet....
I havent had any time to play with it to try it out one way or the other.
but it does make sense to me that we would need to add to the table for a larger cam
and thats about as far as I have gotten

So is "adding" actually subtracting say .31 from 5.55?

[S2H]

no... adding is adding... I dont talk in "no means yes" secret code terms

[SargeZ06]

no... adding is adding... I dont talk in "no means yes" secret code terms

This is why I thought that is what you meant.

so would it be safe to say that you could just do some backwards math and move injectors back that far?

like old cam/new cam Intake valve opening difference...
lets say stock ls1 = opens at [email protected]
my current cam = opens at [email protected]
Difference of 26* (26/90=0.29 rounded)
move back the injector timing using the "Normal" table by 0.29
so it makes it 5.26 instead of 5.55
move the Makeup table by the same amount?

safe starting place to guess at still spraying the back of the valve like GM does from the factory?

IVO = 351 + 9 = 360

So my LS6 cam ivo is 379 so that a difference of 28*. 28/90 = .31

So I should add .31 to 5.55.

[WS6FirebirdTA00]

Yeah I worded that wrong earlier about starting the pulse after the exhaust valve closes. That is too late. Finding the sweet spot in that overlap is key because the overlap acts like a vacuum on the exhaust side with all the exhaust gasses speeding out the header. So catching the tail end of that velocity is key..

What other indicators are there of this though? I have yet to mess with any of this to see any changes.

[WS6FirebirdTA00]

Scott was saying a starting point my be delaying the the EOIT by the change in exhaust closing from the stock to new cam. By doing this, in theory, you are delaying the injection so it will not start until the exhaust valve is closed about the same about.

The hope is by this point you are drawing more air in the cylinder than bypassing to the exhaust, and hoping you are still getting good vaporization of the fuel. The question is though at this point are about above or below the target point that prevents fresh gas from being drawn through the exhaust.

[S2H]

so today on my drive into Reba Rehearsals.. I tried a little experiment.
I calculated my Exhaust Valve Closing, and I moved EIOT over to line up with that.

what I noticed was a noticeably better part throttle response, better Idle, and a quieter LS1 sewing machine....the engine being quieter was the biggest surprise to me, I wasnt even expecting that.

I was some traffic with some brief periods where I just put my foot down to accelerate...in 6th gear lugging it felt better than it used to.. and the car seemed to have more power in the low rpm's in 5th and 6th gear..

this was just my morning observation... I'll drive the long way home tonight and see how it feels to test more.

[WS6FirebirdTA00]

Cool. Can you give a little more detail or does this line up with what you explained earlier?

I was going to throw the WB back in my car this weekend and do some testing myself. I kind of question the cold start running a little leaner if later injection would help that out as well. Maybe it is WAY too early with a lot of overlap. I think our cams are fairly close in valve events as well.

[S2H]

My Cam Events are
9/57/51/7
its a 240/244 113LSA +2


though I will soon be going to a cam I call "Cock of Thor"
mid 250's and big lift

[WS6FirebirdTA00]

How much did you add to the injector tables? I am going to run my numbers right now and probably try some out tomorrow

[Wnts2Go10O]

How much did you add to the injector tables? I am going to run my numbers right now and probably try some out tomorrow

i think the starting point is: (new EVC- old EVC)/90)+Normal or Makeup = new injector timing starting point.

thats the reoccurring theme ive seen in the thread anyways.
then to check the work... take the new value, plug it into: 784 - ((Boundary + Normal) * 90) and youll have the point in the whole cycle where the injector firing is finished.

[S2H]

heres a confusing worksheet..LOL

shows Original EOIT value based on values in the tune
computes new value posibilities based on shifting it with cam differences
or moving to match actual events...



on my vehicle,in my morning experiment. I went with Actual Exhaust Valve Close as my EOIT

[Wnts2Go10O]

heres a confusing worksheet..LOL

shows Original EOIT value based on values in the tune
computes new value posibilities based on shifting it with cam differences
or moving to match actual events...



on my vehicle,in my morning experiment. I went with Actual Exhaust Valve Close as my EOIT

with your worksheets new value plugged into cats formula we get (based on my cam specs):

((6.5+6.22)x 90)-784=360.8* this catches the VERY tail end of the overlap. if we add a few hundreths to bring it to 6.25, it moves the end of injection to 363.5 which maybe better considering the overlap. even more delay may be needed depending how it runs. maybe changing it up to account for overlap a bit?

using the IVO value we get:
(((6.5+6.14)x 90)-784= 353.6* this means the injection is finished before the intake valve even opens

[WS6FirebirdTA00]

Anyone have any luck trying to find the stock cam specs at 0.006"?

[WS6FirebirdTA00]

Maybe I am burning my brain from over thinking, but "300.5º ATDC compression stroke" is the stock value.

I am confusing myself on the "ATDC compression stroke". Can anyone elaborate?

[SargeZ06]

never mind it's in your spreadsheet. Duh... Thx Sound...


.006 for LS6?

Intake Valve opens - IVO 15 BTDC
Intake Valve closes - IVC 75 ABDC
Exhaust Valve Opens - EVO 73.5 BBDC
Exhaust Valve Closes - EVC 23.5 ATDC