Spittybug
03-06-2012, 07:28 PM
Does anyone have dyno outputs for a stock setup? What I'm trying to look at is the spark advance at various engine loads and RPMs. I'm fine tuning my tables in megasquirt and while I think I'm mimicking the stock distributor setup, I'd like to be sure.
Since the switch on the throttle blocks the vacuum advance at idle (via the solenoid), the idle advance is ~13*. As soon as you step on the gas the full impact of vacuum advance kicks in, another 20* of advance. Likewise, when you decelerate down to idle from high revs, you immediately drop from high vacuum, high RPM advance down to ~13* very quickly from what may be as high as ~53*. Looks really odd on a table, so I wanted to see if that is what really happens in the "real world".
The good thing about all of this is that a couple of keystrokes on the laptop and I can immediately test the changes. The challenge is converting years of analog and mechanical feedback control to digital! The transitions are the most challenging. At any given engine load and RPM there is an optimal fueling and timing value to use. It is the "stomping" on the gas or the rapid deceleration without starving the engine that are the fine tunings that must be done. The more of us doing it with Megasquirt the better!
Since the switch on the throttle blocks the vacuum advance at idle (via the solenoid), the idle advance is ~13*. As soon as you step on the gas the full impact of vacuum advance kicks in, another 20* of advance. Likewise, when you decelerate down to idle from high revs, you immediately drop from high vacuum, high RPM advance down to ~13* very quickly from what may be as high as ~53*. Looks really odd on a table, so I wanted to see if that is what really happens in the "real world".
The good thing about all of this is that a couple of keystrokes on the laptop and I can immediately test the changes. The challenge is converting years of analog and mechanical feedback control to digital! The transitions are the most challenging. At any given engine load and RPM there is an optimal fueling and timing value to use. It is the "stomping" on the gas or the rapid deceleration without starving the engine that are the fine tunings that must be done. The more of us doing it with Megasquirt the better!