[silver_pilate]

Just a little FYI on converters. A converter uses fluid dynamics to couple the flywheel to the tranny in the same way that the friction plates on a clutch does. At lower speeds, the converter can "slip," meaning that the engine and tranny aren't directly coupled. It's analogous to feathering/slipping the clutch and it allows the engine to rev faster, in essence, almost free-reving until the resistance of the tranny fluid against the stators is enough to overcome the resistance of turning the transmission/driveshaft/axles/wheels. This occurs over a continuum, with the converter coupling more and more with increasing rpm. Eventually, the fluid dynamics creates a resistance enough to basically lock the converter into one solid peice, thus directly coupling the engine and transmission as long as that rpm or higher is attained. This, in very rough terms, is considered the "stall" speed of a converter: the point at which the converter no longer slips.

When I bought my converter, I decided to go with a non-lockup. This means that the converter slips in all gears up to its stall speed. A lock-up converter will directly couple the tranny to the engine (ie. not slip) in third and fourth gears. Looking back, I should have gone with a lock-up converter. For one, anytime the converter is slipping, it's creating heat (the number one enemy of AOD's). This means that a non-lockup cruising at 65 mph is still slipping some (~2000 rpm @ 60 mph vs. a stall speed of 2800 rpm) and thus is creating extra heat. A lock-up converter, on the other hand, will directly couple the engine to the transmission in third and fourth. This means a little bit of performance loss at low speeds in thrid gear, but not much. And when you think about it, when racing, you will be going all out and shifting at a fairly high rpm. When the tranny shifts, the rpms will not drop below say 3500-4000 rpm (which is higher than the 2800 rpm stall speed of the converter). This means that a non-lockup converter is not slipping anyway.

So, after all that verbage, a lock-up converter will give you better gas mileage while cruising in third and fourth gears and the same performance off the line in first and second gear as a non-lockup. Also, with a converter that locks up in third and fourth, you decrease the amount of heat created. When I send my PI back for reconditioning (had some junk from a blown tranny wash through the converter and it's not working right anymore), I'm going to have them convert it to a lock-up and raise my stall speed to around 3200. This won't effect my highway cruising, as the converter will lock-up in fourth gear anyway, but will drastically improve my launches (while maybe costing me a couple mpg in town).

Unfortunately, because my converter is malfunctioning, I can't really give you an estimate of what my gas mileage is. I can tell you that with any higher stalling converter, you will burn quite a bit more gas when just cruising around town. Thus the reason that Ford chose a 1500 rpm stall. However, if you're cruising on the highway for your commutes, a lock-up converter will likely give you better fuel economy to the tune of 2-3 mpg.

As for shift kits. The Transgo kit comes with a video for install. Basically, you just swap out a few valves in the valve body and a number of springs. This will allow higher fluid pressures in the transmission and thus firmer/faster shifts. Also, you have to drill or enlarge a few holes in the converter and seperation plate.

The Lentech valve body, on the other had, is reworked so as to change the shift pattern from the annoying 1-2/3-OD pattern that we all hate. This shift pattern means that you have to do the 1-D-1 shuffle to hold second gear, and shifts are often inconsistant as to when the tranny shifts in relation to when you tell it to. Mine would sometimes lag behind: I would throw the lever at the same point every time, but sometimes the tranny would hold the gear for a while longer and bounce the rev limiter before shifting. The Lentech valve body changes the pattern to 1-2-3/electric OD. This means you can completely control the tranny with manual shifting, and OD is accessed with the flip of a rocker switch. Shifts are fast (all the time), hard (when at full throttle), and superbly consistant (all the time).

Sooo...after that little mini-novel, maybe you can make some decisions. Let me know if you have any other questions/concerns.

--nathan