Exhaust header wrapping(keep it cool)

[sleepdoc]

My 3.2l 914 runs pretty hot. Hot in the engine bay, in the cab where the
oil cooler lines run, hot in the front at the cooler, and hot along the body
where the oil tank is located. I haven't callibrated the oil temp sender yet but
I am guessing 240. If I leave her idling in the shop for an hour I would guess 250 maybe more. The front cooler is big, but not big enough to keep the oil cool at prolonged idle. I'll probably install some forced air through the cooler. In following the "keep it cool threads" I have only seen one reference to exhaust wrapping by Bill
Verberg. This seems like a good place to capture a signifigant amount of heat and spit it out the back. The heat generator affords it's own highly efficient pump, the more energy being converted to heat the more robust the output flow. The cost of exhaust system wrap is small compared to say another oil cooler and lines. Does anyone have experience with header wrapping? Are there downsides that need to be weighed? Does anyone really know of any badness for porsche engines from this? Bill suggests that the exhaust system may deteriorate faster with a wrap, how fast anyone?, hmmm how long do you thing my pipes will last anyway here in Hawaii. If I get two yeas out of my steel headers I will be pleased, and actually suprised. Maybe the wrap would protect them. Any experience, tales, voodoo, history?

best Mark

[cim]

exhaust systems headers, downpipes, etc. are often ceramic coated to increase thermal efficiency....wrapping will be less expensive but effective nevertheless...and slightly expensive....exhausts always oxidize (rust,rot) from the inside out...wrapping should not cause rust....try it...i want to know where i can get some....p.s. how are cars there...do they often rust everywhere....

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www.angelfire.com/va3/vw

[Clark Griswald]

Header wraps wont do much to help the heat problems you describe. The wrap is to keep the exhaust hot, not cool the engine.

I've been told wrapped headers last 1 year or less. The problem is the get very hot under the wrap, and the extreme expansion and contraction makes them fail fast.

apperently the reason for keeping the exhaust hot is to increase the velocity, thereby improving scavenging. On turbos, it has added benefit.

Your description sounds like you have problem, perhaps a non-functional thermostat. you have two thermostats. Or maybe you are running too lean. debris on your cooling fins. broken fan belt....

I don't know what kind of mods you have or the type of external cooler, but No way you should be seeing 250 at idle.

[Joe Bob]

Wrapped headers will last six months...ask me how I know....

Use a ceramic coating. I used Jet Hot.

[911pcars]

I'd suggest not wrapping the headers as this tends to trap too much heat and shortens material life. In addition, unless the wrap is sealed to the outside elements, moisture can condense inside and create further corrosion. A better solution is to add a thermal coating (inside and outside) to the pipes. Jet Hot and SwainTech are two suppiers of this service (there are many more). They require removal and sending to them where they will prep the headers (sandblast) prior to coating. The cost is a few hundred I believe.

In regards to your oil cooling situation, forcing add'l air through the cooler via a fan(s) and ducts may be an effective solution, especially at idle and low vehicle speeds. You have an air-to-air cooler which works best with ..... cool air to transfer heat.

Heat transfer to the interior can be minimized by adding some insulation material designed for this purpose. Even a piece of sheet metal positioned in the space between a hot object and a cooler surface provides an effective insulation layer. There are high tech materials for this, but a certain brand of silver attic insulation works well. The factory shields around the catalytic converter and exhaust pipes are examples of metal heat insulators.

If I may add a commercial plug, I have a couple of products that may assist as well.

Regards,
Sherwood Lee
http://www.seinesystems.com

[Formerly Steve Wilkinson]

Clark Griswald is correct. Any lowering of engine-compartment temperatures is only a minor byproduct of exhaust wrapping, and its purpose is to keep the gases hot and increase the extraction effect. As for exhaust-pipe deterioration, I wrapped the entire exhaust system of my aircraft (a Falco) and had it in place for about nine years. Removed and replaced it with new tape at every annual (which I did myself), because the exhaust system needs to be checked for cracks. There never were any, nor the slightest deterioration of the exhaust system. Anybody who experiences deterioration under exhaust tape can attribute it to the poor(er) quality of the steel. It should only be used on the highest-quality stainless, which of course an aircraft system would have. And keep in mind that an airplane runs hour after hour at vastly higher power settings than a road-going 911 ever experiences for more than a few seconds: takeoff and climbout at 100-percent power, cruise typically at 75 percent.

Stephan

[jabb]

Mark:

Did you remove the rain tray from the engine cover ? This is a must with the 914/6 conversion. This allows more cool air into the engine compartment. Another thing you can do is fabricate a GT engine cover lid .
Also ducting air accross the oil cooler would help. Ideling the car for an hour in the shop is to long and will lead to hotter temps. What are the temps on the open road when driving the car ....

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• Joe A.
• 84 911 Targa
• 75 914/6 3.0

[Clark Griswald]

Mark,

Since you swapped the 3.2 into your 914, I am curious if you put in place the sheet metal that surrounds the engine and seals it against the engine compartment. And is it an effective seal.

Without that, you are re-circulating hot air around the engine and back into the fan. It will run hotter, especially when sitting in your garage.

[Superman]

Most of the performance 914s I know here have a ceramic coating on the inside of the exhaust. This is effective at controlling engine heat. I suspect that wrapping would have the opposite effect.

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'83 SC

[Evans, Marv]

Jet Hot quoted me a price of $195 to coat my headers inside & out. Once you take away the cost of the wraping material & figure in the supposed reduced life of your headers, if you wrap them, I think the difference in cost should be worth it. That is, considering your headers are in good condition.

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Marv Evans
'72 911E

[tobluforu]

If you want to try anything try jet hot. Heard nothing but good things about this process. Saw a program on how they do it and the differences in temps. before and after. Quite a difference.

[Jack Olsen]

My biggest cooling gains came from ducting. The fallow air in the fenders impaired the capabilities of even a pair of good oil coolers.

A high-volume fan (like the 964 2-speed fan, set at the higher speed), and even a later-style cooler from a 964 or 993 (if you can find the room) is a good idea. David Griswold has had good success with these.

But ducting -- a clear path in, no way for the air to go but through the cooler, and then a clear path out -- makes the difference at speed.

No amount of air is too great:




I consider my car to be a cool-air vacuum with an engine attached.

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Jack Olsen
My Rennlist page • My Pelican Gallery page • My Porsche Owners Gallery page

[This message has been edited by JackOlsen (edited 10-18-2001).]

[Rufblackbird]

Cim,
Only on the wet sides of the island do these cars rust (if ungalvinized or no care was taken). On the dry sides of the island cars are less likly to rust. But then again, we've got salt in the air so yeah, cars rust pretty much everywhere here.

BTW, nice website. I just bought a '86 GTi as a daily driver.

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Jeff
1976 911S Coupe

[sleepdoc]

I of course live on the North Shore, maybe the most beautiful place on the planet, but those lovely trade winds eat through new cars ( and I do mean through and through) in under two years. Those who live on the leeward side of the island only come out here to surf, and they just think the cars here look like they do because we are poor,
drugged out and haven't bothered to wash our cars this century. Wrong, those are new cars the rice makers won't pay on the warranty claims. Somehow living "on the ocean" in this context means a "5 year no rust" claim for through holes at two years are is not covered!

I went into the porsche dealership (only one in state) and asked about an 82-84 SC. They responded sorry, no used porsches available, but they could get me a new porsche to see in a few weeks. Ie you want a porsche, you pay and wait for delivery.
Ahh the price of paradise.

Thanks for all the great info and ideas on wrapping I think I am convinced to pass. I will report about the quest for lower temps as I make discoveries.

best Mark

[Rufblackbird]

Mark,
I beg to differ. Over the last couple of weeks I have seen about 5 different SC's up for sale, though not necessarily '82-'83, as there was none in '84. Currently there is a turbo bodied '84 Carrera Cabrio slantnose in the Advertiser. Car is out in Waimanalo, and is beautiful, for $12K. Only thing *wrong* with it is that it's got a salvage title. If you don't mind the salvage title you should give the guy a call (name's Marshall), and grab a Carrera for a SC price.

Did you know if you buy a new VW they have a 10 year corrosion warranty?

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Jeff
1976 911S Coupe