Date: Wed, 15 Mar 2006 15:30:45 EST
Reply-To: FrankGRUN@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Grunthaner <FrankGRUN@AOL.COM>
Subject: Re: Update: permanent fuel pressure gauge - Source!
Content-Type: text/plain; charset="ISO-8859-1"
In a message dated 3/15/06 11:14:07 AM, jfarrugi@umich.edu writes:
> Frank
>
> i was looking at speedhuts website and it doesn't appear that they sell
> senders is that correct? are you sourcing your senders from autometer?
> also i would be interested to hear your comments on gene bergs assertation
> that most oil temp senders provide inaccurate data.
>
> jonathan
> Johnathan,
As far as I know, Speedhut sells senders with gauges or gauges alone.
Specifically, for the EGT gauge for my TDi install, I bought the Speedhut gauge
without sender and had a custom thermocouple probe made for the EGR port with
adequate length to go to the front of the van. For purposes of this thread,
Autometer makes pressure senders compatible with gasoline or diesel.
On oil temperature data quality, I would say that correct thermal measurement
with a thermocouple (high temperatures) or PRT and thermistor for oil and
water temperatures can easily make measurements with 0.1 degree precision even
under the limitations of 12V automotive electronics. Unfortunately the accuracy
of the measurement (relationship to the real oil temp) depends on placement
and flow. The key question is what temperature you want to know ... the average
temperature of the sump, the bottom 1 cm thick oil layer in the sump next to
the base of the sump, the temperature of the oil at the main bearings, the temp
at the valve galley, before or after the filter, heat exchanger ..... it is a
significant problem. In my case, I insert the sensor into a full flow galley.
In particular, I use two sensors. One at the inlet yo the oil filter, since
it is closest to the oil temperature as picked up in the sump, and one at the
outlet of the filter since this is the oil going to the main galley and
represents an indirect measure of the critical film strength parameter at the main
bearings. But its a bit more complicated. I actually use the dual oil filter and
external oil cooler adapter from the Audi 5000T. This is used with dual
filters and prior to each filter, I have the high capacity PD oil-to-water heat
exchangers in a configuration similar to the regular vanagon/golf/jetta I4 setup.
The Audi adapter thermostatically controls oil flow to the external
air-to-oil heat exchanger (cooler) and the temperature monitor point I use (called from
filter above) corresponds to this point. Therefore, I monitor the inlet sump
temperature as well as oil galley inlet temperature, and can follow the
effectiveness of the oil cooler system as well. Finally, in the spirit of aircraft
gauge overkill, I monitor oil pressure at these points as well to see changes
in the oil pressure drop over the filter indicating clogging, and anything
untoward regarding the cooler circuit.
Frank Grunthaner
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