On Jan 31, 3:44 pm, wrote:
what is the usual CHT of a 1300
sustaining 40hp on a standard day
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I don't know.
The only quantified engine parameters provided by Volkswagen were for
their industrial engines and then only for OT & OP... and only for
color-coded gauges. By comparing the VW gauges to standard gauges
allowed me to define the limits of the arcs. I've posted that
information somewhere (probably on the AirVW Group).

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(or any day, that you might have
measured)?

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VDO offered a dealer-installed instrumentation package but the
readings couldn't be trusted due either to improper installation or
depredation of the installation over time. VW issued a couple of
Service Notes pointing out that after-market instrumentation should
not be used for diagnostics unless they had been calibrated.

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That would give a nice reference point to the max temps
given by pratt & whitney.

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With 50W oil and forged heads (vs cast) I don't think such a
comparison would be very wise.

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Now check this related stuff out from a supplier's website:

Continuous HP, 3400 RPM 80 (note this is 6.6 gph, no?)
Bore (mm) 92
Stroke (mm) 82
Displacement (cc) 2180
Compression Ratio 8.0:1
Idle RPM 700-900
Cruise RPM 3200 +/- 200
Maximum RPM 4000
CHT @ Cruise 350-375 degrees F
CHT @ Climb (5 min) 420 degrees F
CHT Max 450 degrees F

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There's nothing wrong with the numbers. Dig around the AirVW Group
archives you should find dyno pulls posted by myself and others.
Indeed, the figures are fairly typical for a VW hot-rod engine. Which
of course is the problem.

What's missing are a host of apparently unimportant details, such as
how certain things are measured. By simply locating the CHT sensor to
a cooler location on the head you can 'prove' the engine runs cool.
Ditto for oil temp. A lot of flying VW's are actually measuring the
temperature of the crankcase rather than the oil inside of it. (VW
measured CHT at various locations, depending on the purpose. For
engines converted to flight the best location is the threaded boss
adjacent to the exhaust flange, as provided on a particular model of
cylinder head, which I've shown in several articles. Oil temperature
was measured at the inlet to the oil pump.)

But as I've said before, this is Old News. This ground has been
tilled many times before.

-R.S.Hoover