Wind direction affect oil temperature?

Jake Raby · Posted: Mon Jul 27, 2009 4:49 pm Post subject:

Use a video camera and small 2-3" pieces of party streamers taped all inside the engine bay to see the flow of air inside the bay.

You'll be suprised.
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Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

LeeVW · Samba Member Joined: June 14, 2006 Posts: 1016

I agree that the next logical step is to verify the actual oil temperature.

I have ALL the stock tinware (German original) except the front and rear breast plates (don't need them in a buggy). I fabricated my own pieces to fill in where the heat exchangers go. I did this to direct airflow as well as keep flying rocks from damaging the pushrod tubes. I highly recommend this to everyone.

My CHT gauge tells me when I am pushing the engine too hard. When it starts to creep up out of its normal range I take my foot out of it. It takes a lot to get my stock 1600 to get too hot in most cases, but climbing a steep grade into a headwind with the roof rack fully loaded when it's 100+ degrees out is one way to do it. A lot of times I just have to sit there in the slow lane doing 45 MPH in third gear and wait until my CHT and Oil Pressure gauges tell me it's ok to go faster. This is one of the realities of driving an antique air cooled vehicle long distances.

Jake is THE MAN when it comes to things like this. I am very tempted to go with his DTM shroud in the future. I have a feeling I would be able to spend a lot more time in fourth gear with that setup. Smile

Lee

ellobo · Posted: Mon Jul 27, 2009 10:12 pm Post subject: Bunch of Wndgineers..

Have any of you ever been to Lake Havasu in the middle of Summer? If you had...You'd notice that your A.C. unit is blowing 90 degrees when it's 115 outside. It's normal to think that things aren't normal. So, why you put a stoopid gauge on your dash when it's totally not nessary?

I'm not trying to create arguement. I'm just saying that all of this is relevent to conditions and circumstance.

Jake Raby · Posted: Mon Jul 27, 2009 10:38 pm Post subject:

ellobo · Posted: Mon Jul 27, 2009 11:05 pm Post subject:

Hi Jake... I'm not trying to stir the Pot. It's not an aircraft. If it were. the gauges and their positions would be certified. Right?

Abrasive, No... Certain conditions (stoopid gauges) can create mis-conceptions when improperly mounted that can be mis-interpreteded by the driver and the actual situtaion...(No offense to you Vincent)

I'm enjoying the information that this thread has lended in an
informative way to remedy an over heating issue.

So, Let it go Forward....

Jake Raby · Posted: Mon Jul 27, 2009 11:13 pm Post subject:

Its not the fault of the instrument if the driver misinterprets the information that it is providing... Bad information is better than none at all.

I live by instrumentation and feedback from the engine...

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_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

lostinbaja · Posted: Tue Jul 28, 2009 3:56 am Post subject:

Even if Vincent's oil temp gauge is inaccurate it still shows a trend. If the oil temp typically never exceeds 240 deg but now it's at 260 deg you know you have an issue.
I'm all for gauges.
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Jake Raby · Posted: Tue Jul 28, 2009 6:19 am Post subject:

Trend data is exactly what instruments are for... Even if the gauge value is not accurate, but suddenly changes you know there is a problem.
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

vincent9993 · Posted: Tue Jul 28, 2009 6:40 am Post subject:

Jake Raby · Posted: Tue Jul 28, 2009 6:45 am Post subject:

Buy a Westach CHT gauge... The ONLY place to install the sender is under one of the spark plugs, preferably #3

The temperature of the head has a huge differential as you travel further from the core of the chamber into the fin area... All my data has been captured under the plug, for very good reason.
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

vincent9993 · Posted: Tue Jul 28, 2009 6:53 am Post subject:

CrashedAgain · Posted: Tue Jul 28, 2009 7:52 am Post subject:

[quote="vincent9993"]

wythac · Samba Member Joined: August 02, 2004 Posts: 2791

I had some info from my drive this evening that I thought might be a good addition to Vincent's thread;

My buggy has access to the battery thru the floor of the package tray. I haven't finished the cover for the access hole, and had just been leaving it off when I drove. I threw the cover over the hole tonight to see if it reduced engine noise while I drove....when I got up to about 50(80kph for you, Vincent) it kited off the hole aned landed behind the front passenger seat. That drew my attention to the hole, so the next time I got up to that speed(and then up to about 70 for a half hour) I put my hand over the hole, and, no surprise, a lot of air was rushing upwards thru the hole, indicating a surplus of air pressure in that area.

I guess I share this in an effort to answer the question about whether or not there is a negative pressure zone in the area in front of the engine cooling fan and behind the package tray that is stealing wind from the fan and causing the engine to work harder. My experience seems to indicate that there is "+" pressure there.

For what its worth, temps in my part of the world today were about 52F...oil temp at 70mph was about 160-170F. I have a 1776 with dual Weber 42 DCNF carbs, mild cam grind, 7:1 compression, Pertronix distributor. I am using a stock doghouse oil cooler as part of a full flow system with an externally mounted filter bracket using a WIX 51515(PH8A size) filter. This gives me about 4 quarts of oil capacity.

CrashedAgain · Posted: Sun Oct 04, 2009 12:53 pm Post subject:

wythac · Samba Member Joined: August 02, 2004 Posts: 2791

Hadn't put that much thought into it, but what you say makes sense...it could be evidence only of a differential pressure when overall pressure on BOTH sides of the package tray could be below normal atmopheric pressure.

Warmer today, in the mid-60's. Took a drive at 70 MPH for just less than 1 hour. Windy enough to blow the car around a bit, but oil temps pretty consistent right at about 170F. Put about 10 lbs on top of the lid over my battery case and it was still blown off by the pressure from underneath. I was just going to tack it down with velcro, but I'm clearly going to have revisit that idea.

CrashedAgain · Posted: Sun Oct 04, 2009 9:37 pm Post subject:

....and I was going to try to vent my battery case to the engine compartment area on the theory that the acidic fumes in the battery area might damage the seat cushion which currently serves as the 'top' for the battery box.

Clearly that isn't going to work!


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