 Outside air flow or fan cooling?, Which does a better job? |
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| bandjoey |
 Jun 28 2013, 12:31 PM
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#1
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bandjoey  Group: Members Posts: 4,926 Joined: 26-September 07 From: Bedford Tx Member No.: 8,156 Region Association: Southwest Region  |
Every day I drive 30 miles to work. Every freeway in Fort Worth is under construction that'll last another 2 years. Now the air temperature is hitting 102.
My speed is 50 mph most of the time. Will the motor run cooler by shifting up a gear with rpm at 2200 and depend on outside air flow over the motor?? Or will the fan provide better cooling than outside air flow by downshifting to maintain 3000 rpm? Anyone who knows or can test this who has a cyl temp gauge? 4 cyl 2.0 Thanks all |
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| yeahmag |
Jun 28 2013, 01:00 PM
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#2
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Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California 
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Heat is based on load and RPM. Try to keep the motor closer to 3000 RPM and you are close to the "fat part of the curve" for cooling. The best CHT for the money is the Micro 1000 sold at Aircraft Spruce.
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| SirAndy |
Jun 28 2013, 01:23 PM
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#3
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Resident German Group: Admin Posts: 41,640 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(bandjoey @ Jun 28 2013, 11:31 AM)  downshifting to maintain 3000 rpm (IMG:style_emoticons/default/thumb3d.gif) |
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| tomeric914 |
Jun 28 2013, 02:47 PM
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#4
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One Lap of America in a 914! Group: Members Posts: 1,259 Joined: 25-May 08 From: Syracuse, NY Member No.: 9,101 Region Association: North East States
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I experimented with this years ago in another air cooled vehicle where I have both oil temp and dual cylinder head temp.
Relatively speaking with respect to gear choice: - In 4th gear, the cylinder head temp is higher and the oil temp is lower. - In 3rd gear, the cylinder head temp is lower and the oil temp is higher. All depends on what you want. Do you know what your head temps are at? Is it worth possibly overheating the oil? Any pinging? One of the worst "modifications" made is an 009 distributor. If you have vacuum available, use a vacuum advance distributor which will keep your engine cooler at steady state speeds. |
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| Bob L. |
Jun 28 2013, 03:02 PM
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#5
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Senior Member Group: Members Posts: 847 Joined: 7-August 11 From: Austin TX Member No.: 13,411 Region Association: Southwest Region |
QUOTE(tomeric914 @ Jun 28 2013, 03:47 PM) One of the worst "modifications" made is an 009 distributor. If you have vacuum available, use a vacuum advance distributor which will keep your engine cooler and steady state speeds. Since you bring it up... What if you have a '76 2.0 where the vacuum advance is intentionally left unconnected? I have an "011" |
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| tomeric914 |
Jun 28 2013, 03:35 PM
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#6
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One Lap of America in a 914! Group: Members Posts: 1,259 Joined: 25-May 08 From: Syracuse, NY Member No.: 9,101 Region Association: North East States
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QUOTE(Bob L. @ Jun 28 2013, 05:02 PM) What if you have a '76 2.0 where the vacuum advance is intentionally left unconnected? I have an "011" Keep in mind that the mid 70's were a bizarre era where vehicle manufacturers were trying to keep emissions down to meet federal standards. Porsche was intentionally raising operating temperatures to meet these standards. It wasn't just '76 that had the advance lines intentionally left disconnected. Look at '74 where the retard was connected and the advance left to atmosphere! Roughly '75-'77 were the thermal reactor and 5-blade fan years for 911. Just an ugly time IMHO. So back to your '76... If the advance line isn't connected, connect it! Follow Jeff Bowlsby's drawing for a '74 2.0. This will help your engine run cooler. (IMG:http://www.914world.com/bbs2/uploads_offsite/bowlsby.net-9101-1372455358.1.jpg) |
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| michael7810 |
Jun 28 2013, 04:20 PM
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#7
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Senior Member Group: Members Posts: 1,081 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region
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Living in Phoenix I watch my oil and cylinder head temps and have noticed that the heads are cooler and oil is hotter at high RPM, and vice versa as long as I'm not really loading the engine. My rule of thumb going thru the mountains is if I can't accelerate in a particular gear I downshift. Of course I'm driving a barely-more-than-stock 1.7 with carbs.
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| bandjoey |
Jun 28 2013, 11:20 PM
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#8
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bandjoey Group: Members Posts: 4,926 Joined: 26-September 07 From: Bedford Tx Member No.: 8,156 Region Association: Southwest Region |
Not having any problem. Pinging or otherwise. Car runs good but worried about 105 degrees today and a hot summer ahead. All I want is a long life motor
Keeping the 3000rpms up. |
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