engine air intake temperatures

[simple]

On my journey from Auckland to Palmerston North last week, I logged the
ambient temperature, and the engine air intake temperature (every minute, and
about 0.3degree resolution). Apart from occasional towns & roadworks,
almost the entire journey was at 105kph. Shame on me for breaking the law :-
)

I haven't done extensive analysis of results yet (and probably never will,
because I don't really care), but this is what I found:

=========================
Time, Ambient temp, Intake temp, Locality

11:45am, 15 deg, 27 deg, Auckland
2:30pm, 13 deg, 27 deg, Tirau
4:00pm, 9 deg, 24 deg, Taupo
5:45pm, 2 deg, 4 deg, Desert Rd
6:15pm, 4 deg, 6 deg, Taihape
8:00pm, 6 deg, 8 deg, Fielding
=========================

The most interesting thing, to me, is the big difference in Intake vs Ambient
temperature between day & night. Sunset was about 5:30pm - before that,
intake temp is about 12-15deg higher than ambient. After sunset, the
difference is about 2 degrees.

I guess that sunlight heating the bonnet is the cause. This is only one test
run, so the results are not conclusive, but it will be interesting to do tests in
summer, when the bonnet will presumably get somewhat hotter.


(Note1: the ambient temperature sensor was in the mouth of the car, a couple
of inches in front of the radiator, and a couple of inches below the bonnet
catch. The air intake temperature sensor was a couple of inches in front of
the air intake itself. My car engine is stock 1.6l, with aircon not in use at the
time)

(Note2: when I stopped for lunch in Bombay, and shopping in Tirau, engine
bay temperature rose to about 38 deg)

(Note3: yes, graphs would be nice, but I don't currently have a host for my web
page & have no immediate plans to resolve this)

(Note4: I've got GPS coordinates and roadspeed logged for every 30 seconds
of the trip - I've not correlated the data yet, but I don't think it will reveal
anything much useful that I don't already know)

(Note5: trip was almost entirely fine weather - very occasional light rain - I
don't think it was enough to noticeably affect bonnet temperature for significant
duration)

(Note6: I've seen some MX5s here in Palmy, but they've had the roof up, or a
hard top. I snobbed them.)

(Note7: yes, I have too much time on my hands)


Karl.

[jeff]

hey Karl - what equipment are you using to measure the temps and is your intake just the standard snorkle ?

This could explain why I enjoy driving at night so much

Jeff
Karl Mowatt-Wilson <simple@free.net.nz> wrote: On my journey from Auckland to Palmerston North last week, I logged the
ambient temperature, and the engine air intake temperature (every minute, and
about 0.3degree resolution). Apart from occasional towns & roadworks,
almost the entire journey was at 105kph. Shame on me for breaking the law :-
)

I haven't done extensive analysis of results yet (and probably never will,
because I don't really care), but this is what I found:

=========================
Time, Ambient temp, Intake temp, Locality

11:45am, 15 deg, 27 deg, Auckland
2:30pm, 13 deg, 27 deg, Tirau
4:00pm, 9 deg, 24 deg, Taupo
5:45pm, 2 deg, 4 deg, Desert Rd
6:15pm, 4 deg, 6 deg, Taihape
8:00pm, 6 deg, 8 deg, Fielding
=========================

The most interesting thing, to me, is the big difference in Intake vs Ambient
temperature between day & night. Sunset was about 5:30pm - before that,
intake temp is about 12-15deg higher than ambient. After sunset, the
difference is about 2 degrees.

I guess that sunlight heating the bonnet is the cause. This is only one test
run, so the results are not conclusive, but it will be interesting to do tests in
summer, when the bonnet will presumably get somewhat hotter.


(Note1: the ambient temperature sensor was in the mouth of the car, a couple
of inches in front of the radiator, and a couple of inches below the bonnet
catch. The air intake temperature sensor was a couple of inches in front of
the air intake itself. My car engine is stock 1.6l, with aircon not in use at the
time)

(Note2: when I stopped for lunch in Bombay, and shopping in Tirau, engine
bay temperature rose to about 38 deg)

(Note3: yes, graphs would be nice, but I don't currently have a host for my web
page & have no immediate plans to resolve this)

(Note4: I've got GPS coordinates and roadspeed logged for every 30 seconds
of the trip - I've not correlated the data yet, but I don't think it will reveal
anything much useful that I don't already know)

(Note5: trip was almost entirely fine weather - very occasional light rain - I
don't think it was enough to noticeably affect bonnet temperature for significant
duration)

(Note6: I've seen some MX5s here in Palmy, but they've had the roof up, or a
hard top. I snobbed them.)

(Note7: yes, I have too much time on my hands)


Karl.

[simple]

what equipment are you using to measure the temps

An 'Escort Junior' thermal logger, from Escort Data Logging Systems (or some
name like that) - the company used to be called Tech Innovators, and they're
based in Auckland.

The logger has 8k memory - enough for 7040 individual readings if I just use
one sensor, or 3520 sets of internal + external. The internal sensor is well...
internal... to the case of the thing (a white plastic disc 75mm across and
18mm deep). The external sensor is in a stainless probe about 70mm long
and 4mm diameter.

Resolution is dependent on temperature, but is generally something like 0.3
degrees C. I don't know what the accuracy is, but I assume it is about the
same. Internal sensor spans from -40degrees C to +40deg. External is -
20deg to +60deg. I don't know the sensor time constants, but estimate
internal to be on the order of 1 minute, external about 5 minutes. Minimum
sampling interval is 1 minute.

The logger is intended for applications like monitoring temperatures of chilled
goods shipments, to be certain things haven't got too warm.

Right now, it's logging temperatures in the lounge & outdoors, here where I'm
staying Palmerston North. It's currently 8.9deg outside, and 11.4deg inside.

There - more than you ever really wanted to know

and is your intake just the standard snorkle ?

Yep.

This could explain why I enjoy driving at night so much
Jeff

Yep.

Karl.


[...]

[SG & NA Fisk]

Hi Karl any chance of making contact while U are in Palmy - say tomorrow
nite come round for a coffee
Steve 02199405