SSpeeDEMONSS

i have a '94 Ford F-350 with the 7.5L(460ci)V8. I have heard that it has a speed density type fuel injection. how does this work and what are some positive or negative things about it? also, can it be upgraded at all? thanks for the help.

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DIE YOUNG

if it's fun it's probably illegal

my truck hauls like one of those big aussie road train things

LunaticSVT

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.

cheahman

(cool)