One of the primary reasons that a Type 4 with an auto is lacking in performance is the torque converter. The original torque converter was a dissaster. The engine spent almost all of its time below its ideal torque band, not good for a small air cooled. Later model Type 2's and maybe the last year or so for the Type 4's came with torque converter with a slightly higher stall, and then in 1980 (or there about) VW started using a torque converter with a 2700 rpm stall in front of the 2.0 liter. The Bentley manual recommends retro fitting the later torque converter into earlier 2 liter busses. It might be possible to do the retro swap as far back as the early 411's and 412's. If this could be done, it should noticably increase the off the line performance.
If you end up trying to swap an 003 into your 914, you might check into using a vanagon "Z" torque converter to gain back a little pep.
411/412 automatic transmission in porsche 914
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raygreenwood
- Posts: 11912
- Joined: Wed Jan 22, 2003 12:01 am
Wildthings is hitting on the right concept. The auto transmission in the type 4...is not the problem. The torque converter is not very good for the torque band of the engine. Its a little low.
Also, bearing in mind that few of us have ever aquired an auto tranny type 4 in "correct" tune.....thats a huge diffrence. They all need adjustment work by 50-70K miles...usually to the main pressure.
The positive thing for this...in a 914....is that the final drive ratio is nerly identical to the 411/412 4 speed. (3.67:1 for carbs and 3.91:1 for FI on the autobox....and 3.73:1 or 3.91:1 on the manual box)..and so is top gear...its 1:1. So the driving characteristics in top gear are almost identical. Its the missing two gears and having a slushy converter....whose stall speed is 1900-2100 rpm....that kills this thing.
Oh...that and the fact that it is heavier...and would have to have the differential flipped....which is an absolute impossibility...unless the entire differential section could be flipped on its four bolts...like several of us speculated a while back. I can't remember if anyone tried it or not...but I believe it was a converstaion with Searoy and Tom notch. It may be worth looking up. Ray
Also, bearing in mind that few of us have ever aquired an auto tranny type 4 in "correct" tune.....thats a huge diffrence. They all need adjustment work by 50-70K miles...usually to the main pressure.
The positive thing for this...in a 914....is that the final drive ratio is nerly identical to the 411/412 4 speed. (3.67:1 for carbs and 3.91:1 for FI on the autobox....and 3.73:1 or 3.91:1 on the manual box)..and so is top gear...its 1:1. So the driving characteristics in top gear are almost identical. Its the missing two gears and having a slushy converter....whose stall speed is 1900-2100 rpm....that kills this thing.
Oh...that and the fact that it is heavier...and would have to have the differential flipped....which is an absolute impossibility...unless the entire differential section could be flipped on its four bolts...like several of us speculated a while back. I can't remember if anyone tried it or not...but I believe it was a converstaion with Searoy and Tom notch. It may be worth looking up. Ray