Date:         Sat, 15 Jan 2000 21:34:06 +0000
Reply-To:     Mark Keller <kelphoto@ISLANDNET.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mark Keller <kelphoto@ISLANDNET.COM>
Subject:      Poor Milage and Automatic Torque Converter
Comments: To: Candmhok@AOL.COM
Content-Type: text/plain; charset=us-ascii; x-mac-type="54455854";
              x-mac-creator="4D4F5353"

Hi Charles,

With a torque converter there are a couple of things to clarify.  Vanagons do
not have a "lock up" torque converter.  This device is found on most passenger
cars.  It's main advantage is to lock the engine and xsmn together, usually at
speeds above 40-45 mph.

Torque converter function similarly to a boat propeller.  The engine spins
chamber with fluid and some fancy vanes, while the  "propeller" sitting in this
fluid is connected to the xsmn.  So at lower RPMs like idle the slippage is
total.  Depending on the engineering torque converters can be made to achieve
their greatest lock up at various RPMs. The rate of slippage is less that 3% at
full lock up.

Now for the vanagon, the engineers created a lock up RPM that matches the
engines maximum torque RPM.  3200.  This works particular well IMHO.  The down
side is that if you spend a lot of you time at less than 3200 RPM, 45 mph + or
-,  then slippage is greater that 3%. Not by coincidence, the aerodynamic drag
begins to take effect at this speed too.

So if you've notice that your engine RPM tends to stay around 3200 while your
climbing a hill, and you'll see the speed bleed off to about 40-50 mph.  The
engine is profiled perfectly, at max torque, and the aerodynamic drag is
reduced.

Hope this helps.

Sincerely,

Mark Keller

Charles Hokanson wrote:

> Thanks to all who responded to my 14 mpg problem.
>
> It looks like I may have done something right (but I do not know what), I
> filled up last night and found I got around 17 mpg on the last tank.
>
> Here is what I have done:
>
> new top end on motor (about 2000 miles)
> New AFM
> patch harness for AFM (for bucking problem I had)
> new cat. converter
> new S&S exhaust system
> new o2 sensor
> four wheel alignment ( and new tires),
> new injector hoses (old ones cracked)
>
> hours of messing with stuff,   adjustments at local vw shop (who did not know
> about the available patch to deal with the bucking) when I felt like I wasn't
> doing any good my self and more knowledge was required.  He said he checked
> the temp sensor and that it was okay.
>
>  SO there it is.  Oh yeah, the nose sits a  little higher when unloaded, but
> my guess is that it more lthan levels out with people in it.  Most driving is
> around town with my (very small) wife driving my 5, 3, and 1 year olds. when
> I drive on the freeway, I keep at or below 4000 rpms.
> any help appreciated.
>
> Oh yeah two more things:  mark replied that the torque converter only locks
> up at 3200  (I think that is what he said), can that be changed.
>
> Second, Is there a method for normal tuning of timing and air fuel mixture
> without the special tools called for in Bentley?
>
> thanks very much.
> Charlie.