[Vwdiesel] So many variables, so little time

hwy9fergs at comcast.net hwy9fergs at comcast.net
Tue Dec 13 15:14:33 EST 2005

Bob said
Set it up by the book, and it will probably run, 
but it will run a lot better if you take the time to adjust each aspect to personal 
standards attained over a lifetime. Granted, this takes more time.

Svend said, 
TIME her and then take her here and I will TUNE 
it   free
of charge----then marvel at the difference,.------If that does not  convince you
  ---    have a nice day.

Guys, I'm all ears.  Bob, I still have your post about your timing numbers, but you mention "each aspect" of tuning. Can you be more specific? Svend, I'm glad you mentioned in your recent post about still needing to get back to me on your actual specs (what the specs ended up after you "tuned" bunny bondo). Because, I am still curious.  I hear people talking about getting 50 mpg or better with these 1.6 IDI vw's, but my real world experience, driving my 91 ECO turbo Jetta, (AC, power steering) has me getting around 42 on my work commute (mixed driving, some mountain road, some freeway).  I get about 37 MPG on a long trip at 75 MPH. I think that's pretty damn good. Can it be better?  Well------you tell me.  People throw out mpg numbers alot of times, but don't get very specific about the conditions. Sure, I don't doubt my car could get 50 mpg or better just the way it's set up (tuned by the book). All I need to do is drive at 48 mph with a 25 mph tailwind, and I wouldn't be surprised. Hell on a long downhill, I'd probably get 70 mpg.   Unfortunately, in my world I have to be realistic.  How many things can you effectively "tune".  OK, pump timing you can play with. If your pump is a little weak, you can bump the working pressure up a bit from what I recall in an earlier post (Hagar's) Any one ever play with their cam timing?  I've heard that if you retard the cam timing, you will pick up some horsepower (at the expense of low end grunt) and if you advance the cam timing you improve the low end torque (and lose a little HP). I don't have any information on how many degrees of timing you would play with on that, or how it might affect mileage. My cam is set at stock spec.  Over all, what I have concluded is that, once you get one of these engines properly bolted together, there aren't really that many things you can play with other than---injection pump working pressure/timing, cam timing, and maybe valve clearance on the mechanical engines. I know you can adjust turbo pop off and waste gate stuff, but I'm not talking about full throttle stuff right now. So at this point, what I would like to know is, assuming you have a starting point at factory specs, what do you consider adjusting and which direction to you go in your adjustments to improve mileage?  Maybe go from 1.00mm to 1.05mm on the timing?  My engine sounds awfully marbley when cold as it is.  Wouldn't advancing the timing make that worse?  If you retard the timing, doesn't that quiet the marbles down at the expense of mileage?  I haven't ever checked my working pressure in my pump, but I'm considering trying to put the bits together to be able to accomplish that.  OK guys, the ball is in your court.  How many of these variables have you acually played with in your "tuning"?  How about "real world" mileage specifics.  I'm keeping an open mind.  Flyboy Doug.   

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