Quote:
Originally Posted by Kodename47
Interested on the DI cycle. I run far more DI than the stock setup, my S/C runs about 5.8ms on the ECUtek logs at the higher RPM, compared to ~3.5ms for stock. Is there any way to calculate this at all?
You can log the PI duty on ECUtek although I currently don't....
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You have to start thinking in terms of crank angle degrees and injection window. On PFI, the fuel can build up on a closed intake valve or spray into an open intake valve. For open valve injection, we can say you've got the full 720 degrees to inject PFI fuel. That's 100% duty cycle. The start and end of injection don't matter at that point.
For DI it's different. In one sense, pulsewidth doesn't matter as much assuming a fixed rail pressure. You're limited by your injection timing window. For max injector flow you can't spray when the exhaust valve is open, or rather you can but it will go right out of the cylinder and be useless. You've got from the start of injection time until a maximum of when the spark plug fires. So if my SOI is 320 BTDC, and my spark is 20 BTDC, I've got 300 degrees window (oversimplifying a bit). The number of corresponding milliseconds varies with the engine speed.
For DI: log your SOI, log your milliseconds duration, calculate your crank angle duration from that, and then calculate your end of injection. The closer your SOI gets to 360 BTDC (top dead center Intake), the more you are hosing down the piston and/or cylinder wall, getting oil dilution, smoke, and other kinds of problems. The same applies to the EOI: the closer your EOI gets to 0 degrees (top dead center Firing), the more you are hitting the piston and/or diluting the oil.
But even if you don't give a crap about hosing down the cylinder and the piston, you still can't throw fuel out the exhaust valve. So your DI will never get anywhere close to 100% duty, because my exhaust valve is open for 200+ crank angle degrees. From what I've seen typical stock tunes don't run more than 200 degrees injection duration on DI due to concerns about smoke and oil dilution, but as I said that can be stretched.
Quote:
Originally Posted by P@ul
Ford called this the Bobcat. I recall having a conversation with a coworker that some turboed v8 prototype motor was making 1000 lb ft on a dyno. It was supposed to be an alternative to large diesels, avoiding the costs and packaging of SCR and Urea Injection (IE Scorpion).
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whatever the final technical merit ended up being, basically government subsidies for ethanol and fuel economy credits are being cut so there was no economic incentive to go forward with it.