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Old 05-05-2009, 04:34 AM   #15 (permalink)
roflwaffle
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Quote:
Originally Posted by diesel_john View Post
I'd like to just take out two pistons once i get up to cruising speed, but i haven't figured out how to do that yet.
Unless you have a significant downhill/low load drive, or have basjoosed your VW, taking out two pistons won't do much. Even then, the stock tires are so small that increasing wheel/tire diameter can cut engine speed a good ~30%, even if you have a trans that already has the engine turning at ~2100rpm at 55mph.

In terms of FE word is that the biggest pump side gains come from fiddling with the dynamic timing advance, since the static timing range isn't wide enough to help much. Before doing this you also need to check internal pump pressure since a drop will retard the dynamic timing mechanism, which means worse mileage. In fact, since the diesel today has much lower viscosity than the diesel of the 1980s, even if the pump was in tip top shape we would still need to at least reset the internal pump pressure. Anyway, fiddling w/ dyamic timing ]ain't too bad, just different springs/smaller shims.

You can also get a turbo pump/turbo, and use something to cut off the boost pressure connected to the LDA on the turbo pump to get super lean or stock fueling on demand from in the cab. Supposedly a stock VNT turbo from a TDI offers a small efficiency/great power improvement with an IC and appropriate boost.
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