Running Hot
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Burning Brakes
Joined: Jul 2001
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From: Atlanta, GA
Running Hot
During normal driving, even in Atlanta summer, my 3.0l '77S runs about 200 degs. However, on the track, I can only get 2 to 3 laps before the temp reaches 250. I have to back down too cool off and I feel like I loose half of my quality track time.
I installed a carrera cooler and opened a hole (about 3x6) in the stock spoiler, but I still get these temps.
I do need to seal off around the cooler better, and am considering "boxing in" the hole to create a true duct.
Would a carrera fan help or hurt on the track, or should I add an additional cooler. I'm really not interested in a Ruf style cooler and spoiler up front, from both cost and aesthetic viewpoints.
Any advice is greatly appreciated.
I installed a carrera cooler and opened a hole (about 3x6) in the stock spoiler, but I still get these temps.
I do need to seal off around the cooler better, and am considering "boxing in" the hole to create a true duct.
Would a carrera fan help or hurt on the track, or should I add an additional cooler. I'm really not interested in a Ruf style cooler and spoiler up front, from both cost and aesthetic viewpoints.
Any advice is greatly appreciated.
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Mark,
I went through the whole range of cooling options. You've probably already looked at the article on the tech.rennlist.com site about 911 engine cooling.
First, you're sure the engine is in a good state of tune, ie., not running lean. Next, you're sure you have no obstructions in the normal air cooling to the pistons or engine mounted oil cooler. Here's an odd one - when I replaced my alternator I found that someone had removed one of the air duct fins on the piece behind the alternator. I put another in, and it helps keeps things cool at lower temps. You also checked that the brass lines to the front cooler aren't squished.
Other things to try - add a fan. I used an SPAL fan mounted in front, which made a considerable difference. Fit the gravel guard from the Carrera's. Less concerned about gravel hitting the cooler than taking advantage of airflow from the tire helping to pull air through the cooler. Also focuses air to the cooler as the only exit. You could also cut a whole behind the right lamp and remove it for the track (I've seen people do this, but I didn't want to be removing the headlamp for each event). I'm not sure the plastic scoop from Pelican and others is worth it on the track, but it's another option to get air in there.
I know one person that did box his radiator-style cooler completely in, which worked for him.
On my 81, even with the radiator style cooler, a fan in front of it, and holes in the valance, I had to go to a front-mounted valance/cooler, which fixed the overheating problems.
I went through the whole range of cooling options. You've probably already looked at the article on the tech.rennlist.com site about 911 engine cooling.
First, you're sure the engine is in a good state of tune, ie., not running lean. Next, you're sure you have no obstructions in the normal air cooling to the pistons or engine mounted oil cooler. Here's an odd one - when I replaced my alternator I found that someone had removed one of the air duct fins on the piece behind the alternator. I put another in, and it helps keeps things cool at lower temps. You also checked that the brass lines to the front cooler aren't squished.
Other things to try - add a fan. I used an SPAL fan mounted in front, which made a considerable difference. Fit the gravel guard from the Carrera's. Less concerned about gravel hitting the cooler than taking advantage of airflow from the tire helping to pull air through the cooler. Also focuses air to the cooler as the only exit. You could also cut a whole behind the right lamp and remove it for the track (I've seen people do this, but I didn't want to be removing the headlamp for each event). I'm not sure the plastic scoop from Pelican and others is worth it on the track, but it's another option to get air in there.
I know one person that did box his radiator-style cooler completely in, which worked for him.
On my 81, even with the radiator style cooler, a fan in front of it, and holes in the valance, I had to go to a front-mounted valance/cooler, which fixed the overheating problems.
Thread Starter
Burning Brakes
Joined: Jul 2001
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From: Atlanta, GA
Bill, thanks for the info.
I do have the stone guard in place, and have checked the lines.
What is a SPAL fan and who carries them? Is this better thatn using the stock carrera fan?
Thanks.
I do have the stone guard in place, and have checked the lines.
What is a SPAL fan and who carries them? Is this better thatn using the stock carrera fan?
Thanks.
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Joined: Jun 2001
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From: Africa
Hello Mark,
Bill G has given you most answers. I had a similar problem, and we do get some hot weather here!
Have the thermostat on the engine checked. If it doesn't open fully, the engine mounted cooler will be useless.
I drove my car for a long time, and the temp was fine on the open road, even on a hot day. On track - 3 laps and the needle was climbing.
You'll struggle to get to the thermostat but it is easy to check if its working. Replacing mine solved the problem.
At what temps does your front oil cooler get hot?
Keep cool, Tom
Bill G has given you most answers. I had a similar problem, and we do get some hot weather here!
Have the thermostat on the engine checked. If it doesn't open fully, the engine mounted cooler will be useless.
I drove my car for a long time, and the temp was fine on the open road, even on a hot day. On track - 3 laps and the needle was climbing.
You'll struggle to get to the thermostat but it is easy to check if its working. Replacing mine solved the problem.
At what temps does your front oil cooler get hot?
Keep cool, Tom
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SPAL is the company that makes a fan that comes in a variety of sizes and capacities. I did an internet search, found the best price, and bought it from Racers Part Wholesale who matched the price. Here's the web link:
http://www.racerpartswholesale.com/fan.htm
I think I went with the 6.5" fan - I can check if you want. It was the absolute largest I could squeeze in there. Less expensive than the factory fan and a choice of sizes/capacities. You do have to make your own mounting brackets, which is easy to do with some 1/2-3/4" wide metal bar stock from Home Depot. Since I had removed the fog lights, I used that switch to turn the fan on/off.
http://www.racerpartswholesale.com/fan.htm
I think I went with the 6.5" fan - I can check if you want. It was the absolute largest I could squeeze in there. Less expensive than the factory fan and a choice of sizes/capacities. You do have to make your own mounting brackets, which is easy to do with some 1/2-3/4" wide metal bar stock from Home Depot. Since I had removed the fog lights, I used that switch to turn the fan on/off.
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From: Virginia
Mark,
Bill and Tom have passed on some good advice for additional engine cooling. You did not mention the type of oil you are running in your car. With oil temps approaching 250 degrees, I would also suggest running a good synthetic oil...like Mobil 1. Technical data has shown that Mobil 1 handles high oil temps very well, plus it's on Porsche's list of approved oils.
Regards, Bruce
Bill and Tom have passed on some good advice for additional engine cooling. You did not mention the type of oil you are running in your car. With oil temps approaching 250 degrees, I would also suggest running a good synthetic oil...like Mobil 1. Technical data has shown that Mobil 1 handles high oil temps very well, plus it's on Porsche's list of approved oils.
Regards, Bruce
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Burning Brakes
Joined: Jul 2001
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From: Atlanta, GA
Bill, The link was perfect. I'll try anything for 60 bucks.
Did you buy a Relay or relay wiring kit? And what should I tap into for power? (I still have my Fog lights.)
BER - I switched to Mobil 1 a couple of weeks ago specificaly for this problem. Although the temp didn't improve, I did not use any oil! On a hot track weekend, I was using 1 to 1 1/2 qts with dino, this time I used Nothing. That made me feel good about the changeover.
Did you buy a Relay or relay wiring kit? And what should I tap into for power? (I still have my Fog lights.)
BER - I switched to Mobil 1 a couple of weeks ago specificaly for this problem. Although the temp didn't improve, I did not use any oil! On a hot track weekend, I was using 1 to 1 1/2 qts with dino, this time I used Nothing. That made me feel good about the changeover.
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From: TX
I looked up which SPAL fan I used - it was the 7.5" push fan (SPAL-0393). Before you order it, however, make sure you have room to fit it. One other person had to use the next size down, as the fit is somewhat dependant on how your fan is mounted. If you need to hook up a switch, as opposed to a factory thermostat to turn it on, there's a cutout in the dash, as I recall, between the instrument clusters. Feel the vinyl and you'll find the indentation/cutout which can house a switch.
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From: Los Angeles
For me, on the track, ducting made a huge difference. I cut two holes in the spoiler in the approximate location of fog lamps. Then my mechanic created ABS ducts to make sure that all the air drawn in would have to go through the coolers (I have one in each fender, since I have a swapped 3.6). When it's really hot, I take the headlights out, where I have two holes cut for additional cooling. I re-cover the holes when the headlights are in, since I don't want to cook my lights.
Aluminum or ABS ducting is a must, though. You need to make sure that the air that's scooped in only has one place to go -- through the cooler(s). On the track, my car looks a little bit odd, but it went the whole day at LVMS in 109 degree heat and never got above 235.
Aluminum or ABS ducting is a must, though. You need to make sure that the air that's scooped in only has one place to go -- through the cooler(s). On the track, my car looks a little bit odd, but it went the whole day at LVMS in 109 degree heat and never got above 235.
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From: Solana Beach, CA
If you have a fender mounted cooler, have the back of the headlight buck cut off. When you go to the track, remove the front headlight, add a screen to keep out debris, and away you go. When you leave the track, duct tape the bucket back in place, or use wing nuts, or cosmic glue?
If you really want to do the job right, the 934 front valance cooler will do the job to your satisfaction. I have an article in Pelican Auto Parts Technical Section that explains my quest for the ultimate oil cooling solution.
The 934 front valance is available in good quality from Better Bodies Motorsports in San Diego for less than $300, the cooler from B&B in Phoenix for about $800. This is the best fix available. Bill Gregory will probably agree. Anything else is a compromise, IMHO, of course.
Martin
If you really want to do the job right, the 934 front valance cooler will do the job to your satisfaction. I have an article in Pelican Auto Parts Technical Section that explains my quest for the ultimate oil cooling solution.
The 934 front valance is available in good quality from Better Bodies Motorsports in San Diego for less than $300, the cooler from B&B in Phoenix for about $800. This is the best fix available. Bill Gregory will probably agree. Anything else is a compromise, IMHO, of course.
Martin
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Now, Martin, how'd you guess I'd agree 
I ended up with a RUF front valance and a RUF valance-mounted oil cooler. Of course, with the front valance I had to put a spoiler on to balance the aerodynamic effects. The RUF cooler is one of the few, maybe only, made of polyurethane which gives when it scrapes on the ground. It doesn't shatter like fiberglass. On my very lowered 911SC riding around the cragy, angled roads in Connecticut, the PU construction was the right choice. There's at least one other vendor that uses material that will give a bit (name escapes me at the moment). The RUF oil cooler is nice as the oil flows the length of it, giving it maximum exposure to cooling air. More expensive than the solution Martin described. Temps usually run in the 190 degree range, and on the track in hot weather can go up to 205-210.
One person told me they had problems with their daily driver/track 911 having the back of their headlamp bucket cut out when it rained. Seems the H4's would short out due to water coming in.
I ended up with a RUF front valance and a RUF valance-mounted oil cooler. Of course, with the front valance I had to put a spoiler on to balance the aerodynamic effects. The RUF cooler is one of the few, maybe only, made of polyurethane which gives when it scrapes on the ground. It doesn't shatter like fiberglass. On my very lowered 911SC riding around the cragy, angled roads in Connecticut, the PU construction was the right choice. There's at least one other vendor that uses material that will give a bit (name escapes me at the moment). The RUF oil cooler is nice as the oil flows the length of it, giving it maximum exposure to cooling air. More expensive than the solution Martin described. Temps usually run in the 190 degree range, and on the track in hot weather can go up to 205-210. One person told me they had problems with their daily driver/track 911 having the back of their headlamp bucket cut out when it rained. Seems the H4's would short out due to water coming in.
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I had cut-outs done in the back of my buckets, but I had two bolts welded in on each side. When I'm not on the track, a plate with two holes gets bolted over thehole on each side. It keeps the rain out, and reduces the heat the lights are exposed to, also.
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I dont know about a 934 valance, I like Ruf. but do agree that the B&B spoiler mount(in the valance/bumper of you choosing) will cure all cooler induced heat problems. My Carrera 3.0 with 3.6 runs 80-90C under any conditions.
The original 3 liter ran ~100C max with a Turbotrol cooler ducted so that all of the air flow from the front went through it. A handy material to seal the sides of the cooler is pu pipe insulation, it is easy to work with, flexible, cheap, stands up to the temp, and will not absorb water. There were several Carrera coolers early was a multitube design later was a radiator style either should be sufficient(later radiator is better though). Are both thermostats working? Are the brass lines to the front true(uncrimped)? Is the engine mount cooler clean/clear of debris?
Fans are crutches for additional air flow in traffic jams and as such under track conditions will only impede air flow. The rush of 100mph air out cfms any 10 amp fan.
The original 3 liter ran ~100C max with a Turbotrol cooler ducted so that all of the air flow from the front went through it. A handy material to seal the sides of the cooler is pu pipe insulation, it is easy to work with, flexible, cheap, stands up to the temp, and will not absorb water. There were several Carrera coolers early was a multitube design later was a radiator style either should be sufficient(later radiator is better though). Are both thermostats working? Are the brass lines to the front true(uncrimped)? Is the engine mount cooler clean/clear of debris?
Fans are crutches for additional air flow in traffic jams and as such under track conditions will only impede air flow. The rush of 100mph air out cfms any 10 amp fan.