Join Date: Feb 2001
Location: The Sticks of Central TX
Re: speed density
Speed density is great realistically a lot simpler than Mass-Air, but terribly inflexible. After you radically change/improve VE of the engine, the speed density system will tellyou to bugger off because the load/fuel mixture tables are chiseled in stone. They are buried in the processor, so when you exceed these parameters the system can no longer effectively compute injector pulsewidth "f/a ratio" and timing. The net result is loss of driveability. In extreme cases, engine failure due to detonation caused by lean mixtures and/or over-advanced timing.
You can burn a chip....if you have access to a chip burner and a dyno with A/F monitoring equipment, but do you want to reburned every time you make another mod or change to your system? Yes you can change the air/fuel/timing parameters in the speed density system, but the inherent inflexibility that is designed in to the system you can not get rid of.
You can do a Mass Air conversion. I know there are kits out there for that, but I do not have info on them for a 7.5L 460ci. I have seen them for other engines throughout the Ford lineup.