Fat 911 T4 Cooling .. datalogger results

[Sandeep]

Thanks for the info Wally, I'll take the measurement this weekend. Just got word that my Hall Effect sensors arrived , should have the RWS and RPM circuits running on the weekend.

Hopefully I'll have everything ready for the next BoxerAutoGruppe meeting, and I'll take the long way there to get about 50 mins of data. This is a nice trip, about 140kph for about 20 mins on the highway and then some in town driving.

I built this logger for my track days in 2005 so I'll post any data I accumulate before the car hits storage for the winter.

Sandeep

[Bill K.]

Kuhl project. How are you going to aquire oil temp data?

[Sandeep]

I will get the oil temp data by taking the vdo oil temp sender (thermister) in the sump location and remove the thermister and modify it for a thermocouple (thermowell).

I can drive the oil temp gauge with a D/A converter as well as the CHT gauge by modifying my program to feed the signal from the highest cht of the 4 to the cht gauge so it will always read the highest temp from the 4 cht thermocouples.

I'm not worried at all about oil temp right now because my cooler/ducting system never goes over 200F while driving at extended rpms for a long amount of time.

Sandeep

[Bill K.]

I'm interested in datalogging too, so your experience is very helpful.

Why are you converting the thermistor to a thermocouple? Are you using thermocouples for ambient and fan inlet temps too? Why?

The auto max-reading gauge is very kuhl. Will you know what cylinder is being read while driving?

[Sandeep]

I'm converting to a thermocouple for oil temp because the IC's I use to read the TC's have an error of 0.5 F and their output is linear. No need to calculate or extrapolate the temp from graphs that are provided for a particular thermistor, whose output in not linear with temp.

For AAT and FIT, I'm also using IC's with a linear output but the IC tells the temp accurate to 0.5 F, no TC's here and the IC is the size of a pencil eraser ... very small. FIT and AAT won't get above 50 C and the IC's are very accurate in this range.

The auto-max gauge concept is for me to tell if the heads are too hot when I am racing ... I can always tell which cylinder was too hot when I look at the graphs after the run.

I could have used an LCD on the dash to give me the required information, but I like the look of the gauges ... and I don't want my dash to look high-tech ... I want it to look like VW could have built it in '74

Sandeep

[Massive Type IV]

Sandeep,
Head temps are normally not a huge concern in road racing except on the straights.

In the infield you are working in the upper RPM and in a lower gear which removes load from the engine..

Your datalogger will show this very well..

[Bill K.]

Sandeep, are you sticking with a 1 Hz sample rate? How did you decide what was enough but not too much data?

[Sandeep]

New columns added for run 2, check it out here. Its true that during the warm up stage the temps are uneven .. but later in the run they seem to stabilize. I'm using stock T4 under cylinder tins and a BAS 21152 header with dynomax super turbo 2 1/4" muffler.

I've got the rpm and rws sensors hooked up and hope to do some hard runs this weekend. There is some snow on the ground now but it is supposed to be gone for the weekend.

Sandeep

[Wally]

Originally Posted by Sandeep

Its true that during the warm up stage the temps are uneven ..
Sandeep

and that may even be an engine/tuning issue...who knows?

Thanks for the update and good luck on the run. Keep the car (and youself) in one piece!

Walter