I dunno, just what I read on GW about theirs.

Velma 82 1.9L AAZ TD Westy
On Jul 30, 2014 12:02 PM, "mark drillock" <mdrillock@cox.net> wrote:

> The speedos are the same so I assume you mean the tachs. The gas tach gets
> pulses from the ignition coil and diesels don't have ignition coils. The
> diesel tachs from the Vanagon era use a much different signal from the
> alternator "W" lead.
>
> Mark
>
>
> Ralph Meyermann wrote:
>
>> I think the diesel one hooks up different or the pod is somehow
>> different. I went from a 185/75/14 to a 215/75/15, just by
>> guessing/eyeballing I'm about 5 faster than Speedo shows. I would like
>> to keep up on my mpg while tuning my fuel/boost for happy oomph, temp
>> and fuel economy without over taxing my Power Plant. My phone doesn't
>> have good enough signal to use its gps
>>
>> Velma 82 1.9L AAZ TD Westy
>>
>> On Jul 30, 2014 7:33 AM, "mark drillock" <mdrillock@cox.net
>> <mailto:mdrillock@cox.net>> wrote:
>>
>>     The "W" factor has to do with the tachometer, not the speedo. The
>> speedo
>>     and odometer are driven by a cable that does not know or care what
>>     engine the vehicle has or even that it has an engine.
>>
>>     Mark
>>
>>
>>