Arjan B.

Hello,

Here I am again, now with real data.....

We talk all the time about the big heat between the undertray and engine but have no dat.

This morning I did a test with a so called 'heat gun'.
Here are the data, I hope we can discuss it.

Outside temp. 25 degr. Celc.
20 km road use
Thermostat opened at normal level/temp.

Temp. measured at Block, cilinder, oil tank.

Measuring directly after trip,

Oil tank: 80 degr. Celc.
Engine block, near oil drain stop: 98 Degr. Celc.
Cilinder head [the first best accesable: 125 degr. Celc.
Valve head covers: 100 degr. Celc.

After running the engine in idle for 1/2 hour.

Oil tank : 105 degr. Celc./ 95 degr. Celc. after fan stops running.
Engine block: 130 dgr. Celc.
Cilinder Head: 150 degr. Celc.
Valve head covers: 125 degr. Celc.

Oil pressure after 1/2 hour running in idle
is 1.3 Bar, oil temp gaug 9.30 H. Oil: Mobil 1 0W40

So, now let somebody say, is this the so called "to high temperature" ??

Have fun,

Arjan
964 C2C 1992 Black

Note: Measuring was done WITH undertray installed.

John Boggiano

Arjan,

Great work!



Any chance of a follow-up set of results without the tray?

Arjan B.

The measuring without tray is a part I hope is doing by somebody who has also a heat gun, and wants to tell his side of the story.

Have fun, and...thanks for loading up the pics on the 'off topic forum' John.

Arjan
964 C2C 1992 Black

John Boggiano

Someone please step forward...

O/T

Take a quick look at Arjans's garage in This Thread, everyone!
It's near the bottom of the first page.

Dave R.

Arjan,

I think the comparison would be most valid if you performed the no-tray test also, thereby minimizing variables; same car, same heat gun, same ambient thermometer, same measuring technique, etc.

This is a worthy project.

How about if we put together an incentive package for you? Perhaps take up a collection for post-experiment refreshments, and/or send momentos or tokens of appreciation from different places around the world?

I'm about to go the US Virgin Islands for a few days, I could pick up something modest but interesting (send me a private email today), or perhaps pick up something from the Smithsonian Air & Space Museum in Washington DC when I return. Any requests?

Any pledges, folks?

-Dave
'90 C2

Wikkid911

Good idea Dave R.
Arjan,
I'll let you have a quick once over with my Zymol when you are passing by Manchester.
Dave
'90 C2

Arjan B.

O.k. I did the test without the tray on request just now after my work was finished.

Amazing is to see that the temp. is just a fraction lower then with tray.
I made my measurements on a car-lift with 2m bottem clearance.


Outside temp 37 Degr. Celc.
Car drove 18 Km without tray.

Measure directly after driving inn:

Oil tank 90 Degr Celc.
Cilinder head 123 Degr. Celc
Engine block 101 Degr. Celc.
Valve head covers 102 Degr. Celc.

Idle for 20 Min. [fan blows]

Oil tank 108 Degr. Celc.[96 after fan stops running]
Cilinder head 146 Degr. Celc.
Engine Block 127 Degr. Celc.
Valve hed cover 121 Degr. celc.

Same oil pressure as this morning.

So, it made a small difference, thats tru, but I think the big cooling coms from driving the car, cool air has more acces then before.
In idle the difference is not so much, cause of no cooling air.

Tell me, is this the big temp. difference we expected???

Now I need a cool down myslef ppfffftttt.......

Nice day,

Arjan
964 C2C 1992 Black

John Boggiano

Arjan, you are a star!

Some real data for everyone to argue about!

Remarkably small differences.

Now you just need to do it again at the same air temp to keep everyone happy!

Burston

And if you do you are allowed two ppfffftttt....... ppfffftttt....... afterwards.
Good work.

Richard

TMH

Arjan,

Thank you for your time and efforts spent, and for sharing with us on the board.

Tom

Cupcar

Arjan-

Good work.

The difference in ambient temperature is huge between the two experiments. Is it correct that the studies were done at ambient temperatures of 25 degrees C. (77 degrees Fahrenheit) with tray and 37 degrees C. (99 degrees Fahrenheit) without the tray? If correct it would influence your data.

If true, and the car is still cooler after a 20 minute idle after a run without the tray in hotter weather, it seems to me reasonable evidence the car probably runs cooler without the tray at any given ambient temperature. It's for sure good evidence it cools down faster at idle after a run without the tray.

Dave R.

Arjan,

Are the ambient/outside temperatures of 25C (tray on) and 37C (tray off) correct, no typographical errors? [Edit: I see Cupcar beat me to the question...]

-Dave

Adrian

Dear Arjan,
Whilst your tests are non scientific they clearly show from your prespective something I truly respect. Somebody who is prepared to stand up and do experiments and not just talk about things. Your figures clearly show that with the engine cover removed the engine runs slightly cooler but I notice the engine only ran 20 minutes at idle without the cover fitted. However what is clear to me is that the differences in your measure engine temperatures is not the difference with which anyone could possibly argue that would cause "premature valve guide wear". I expected much wider gaps to be quite honest. Air cooled engine temperatures do not vary that much in value just time taken to get there so I would not expect to see many extra differences with matching ambient temperatures.
Thanks sincerely for your efforts. You deserve a few drinks and I will have a beer for you right now.
Ciao,
Adrian
964C4

Arjan B.

Yes guys, we had a hot day today, it is 25 and 37 deg. Celc. No errors in the test results.

I think that the data on a tracktest will be much different, cause of the big performance and heat production.

Sorry, that is not in my range to do.

Have fun,

Arjan
964 C2C 1992 Black

91C2wrencher

Wow Arjan, where do you find the time for all this? The very fact that you did this little experiment makes you a true 964 junkie in my book. Wow again! I would comment that with the large ambeint temperature difference and the fact the indicated temps were still lower show that perhaps removing the undertray does provide a value in additional cooling, my point all along. I have no clue how this effects valve wear and quite frankly don't care, A cooler running engine just generally performs better and lasts longer. If anybody needs a tray you can have mine for cost of shipping....