When looking for donor parts, sticking with one from a similar displacement engine is usually recommended because you'd expect the throttle butterfly diameter to be properly metered. Sharkey runs a TB from a 5.0 Mustang so I'm nearly at maximum volumetric flow at around half throttle (if you *just* look at the numbers -- it's actually closer to about 2/3 throttle). I've tailored my accelerator pedal movement so that approximately 1/2 pedal movement equals about 1/3 butterfly movement, but I couldn't get it perfect so I still have this feeling that the last bit of "oomph" on the pedal doesn't really get me going any faster. A TB from a 2.3L Ford might have been better, but you also have to consider the shape and style of the TB. The Mustang TB has an incorporated mounting point for a pulse-width modulated IAC solenoid, which is a simpler way of controlling the air bypassing the butterfly when idling. Others use stepper motors, which are more complicated to control and Megasquirt may or may not work with them (I know this used to be an issue years ago with Megasquirt and some other aftermarket engine management systems, but it may have changed since then -- long story short: if current Megasquirt systems cannot handle stepper motor IACs, then you'll need donor parts from a system that uses a pulse-width modulated IAC). It's really nice to be able to get into a cold car with an aftermarket EFI system, not touch the gas, crank the starter, and have the engine rev up and sit at a preprogrammed RPM, knowing that it is *your* programming -- working in conjunction with one or two sensors monitoring engine temp -- that sets that RPM and slowly lowers it as the engine warms up.
And if you're going with a custom TB set-up, you'll have to figure out how to make the throttle cable work. I ended up using a Morse cable, which is the same type that rail owners run. They have an outer sheath that can be rigidly attached at each end (much like brake cables on a bicycle). _______________________________________________ vintagvw site list [email protected] http://lists.sjsu.edu/mailman/listinfo/vintagvw
