EFI Madness

[Two Lane Blacktop]

Re: EFI Madness

( My old buddy Bruce Plecan would have loved to participate in this thread. )


Check out the 2 vids at the top of this thread:

http://www.bigblockdart.com/index.php?PHPSESSID=0e2349297040598ce95cc88a270552d3&topic=25622.0

[CTX-SLPR]

Re: EFI Madness

If you don't mind me asking, where did you know Bruce from? He was a friend of mine too from the Dayton area Turbo Buick community.

[427]

Re: EFI Madness

You and I are not getting the same thoughts together. My timing of injector close is in direct relation to valve close, this is what helps us with power. The timing would not need to be changed in a math mode, like you are thinking. I am talking about fuel flowing out of the injector when the valve shuts/intake air stops. Somewhere in that cycle the engine gets more powerful if I take the time to manipulate the injector timing versus rpm. I was not clear when I said it would not fire at anytime when the valve was shut. I am talking about our testing for power related to injector timing.

Kurt

In our engines, when the injector does not fire, the coil for that cylinder also does not fire. If you just kill spark as we did in the past, you load the ex with fuel. The raw fuel has caused a few problems that made it desirable not to do that.


You won't fire the injector after the valve is shut if your injector sizing/timing is right, unless you want to or your engine speed is very high.


Kurt

I also had the best luck with fuel & spark cut when I set up rev limiters...


Howwever, unless you are making your peak power on less than 15% duty cycle (?), aren't the injectors still open when the intake valves are shutting? I understand the phasing on the BS3 and MoTec (have used them both), but I am not sure how to make a standard pressure EFI injector (non direct injection) fire enough fuel in such a short amount of time as the intake valve opening sequence... feel free to educate me, I may be entirely off base!! it's happened before,

-scott

[dieselgeek]

Re: EFI Madness

You and I are not getting the same thoughts together. My timing of injector close is in direct relation to valve close, this is what helps us with power. The timing would not need to be changed in a math mode, like you are thinking. I am talking about fuel flowing out of the injector when the valve shuts/intake air stops. Somewhere in that cycle the engine gets more powerful if I take the time to manipulate the injector timing versus rpm. I was not clear when I said it would not fire at anytime when the valve was shut. I am talking about our testing for power related to injector timing.

Kurt

In our engines, when the injector does not fire, the coil for that cylinder also does not fire. If you just kill spark as we did in the past, you load the ex with fuel. The raw fuel has caused a few problems that made it desirable not to do that.


You won't fire the injector after the valve is shut if your injector sizing/timing is right, unless you want to or your engine speed is very high.


Kurt

I also had the best luck with fuel & spark cut when I set up rev limiters...


Howwever, unless you are making your peak power on less than 15% duty cycle (?), aren't the injectors still open when the intake valves are shutting? I understand the phasing on the BS3 and MoTec (have used them both), but I am not sure how to make a standard pressure EFI injector (non direct injection) fire enough fuel in such a short amount of time as the intake valve opening sequence... feel free to educate me, I may be entirely off base!! it's happened before,

-scott

OK, for some reason your method sunk in this time!!! You played with phase angle and found a power increase, or safety margin. Your phasing is such that the closing time of the injector, not the opening time, is sync'd with the intake valve event. I understand that will vary with injector duty cycle but I'd suspect the important phasing happens at WOT under full power. NOW it makes sense, and that is awesome! thanks for taking the time to clarify that.

[427]

Re: EFI Madness

Geek,
I am not very good at writing, but sometimes I can get the basic info across. Most of my testing was done on my pick-up engine when it was new, although the casper engine seen some abuse also. I would steady state the engine on low boost and change the injector timing looking for power. Some rpm points picked up 15hp (500hp truck engine), and the sweep runs after the mapping was done showed a 7hp average gain. We have also seen a gain in spool time for big turbo cars, but they all seem to be a little different timing for best result.

Kurt

[Dynoroom]

Re: EFI Madness

That's why I always try to never say never.......