ked

Due to thermal - metallurgical constraints of building very high performance air cooled IC engines, precision & exotic solutions demanded that costs (thus your price) would go ballistic. Thus, "having your cake & eating it too" in Porsche's case (to supply a cost-effective, high performance, quiet, low emissions power source) has lead to a water-cooled solution. We need a CFD-smart engine designer to tell us if air or water cooled is THEORETICALLY superior, & then look at applications requirements in differing regimes. I think Porsche knows alot about making HP both ways.

Don't blame "the Jane Fonda crowd" for everything bad in the world, sometimes physics has a role.

I hope we continue this thread so we can get to THREE pages (a rennlist record?) of replies. The important thing is that a) Paul Kinder gat a car he wanted and b) we finally got Ed Bighi & Roland Kunz going on neat topic, always insightful.

Ed Ruiz

Let's not forget that with few exceptions, many of Porsche's top race cars were cooled in some way with water. The 917 with water cooled heads is a classic example. The same is true of the 956, and 962. Even the GT1 had a water cooled power-plant.

Lastly, the quintessential and most rare and most expensive 911 ever made, the 959, had water cooled heads. YMMV.

Ed Bighi

No, no. The 917 was never water cooled. Always air cooled. Including the 917/30 rated at way over 1,000 hp. And I might add, Porsche had a air-cooled, normally aspirated flat-16 rated at around 755hp in case the 917/30 became obsolete. They figured a normally aspirated 755hp ought to do it. And if not, in turbocharged form it could easily achieve over 1,500hp. Yes the can/am years were great. But those great years ended when they banned the 917/30. I guess Mark Donahue really achieved the unfair advantage with that beast. Now the 962's had water cooled heads and air cooled pistons, with the exception of the early IMSA versions because of the rules. Those ran modified 935 air-cooled plants that sometimes rivaled the rivaled the regular 962's. You can recognize those by the big opening on the top of the engine cowling like Al Holbert's Lowenbrau car. The true limits of air cooling are when 4 valves are used due to cooling. But 4 valves aren't as much of a necessity when the engine is turbocharged. Neither is displacement which is evidenced by the 4 cylinder Brabham BMW F1 engine. And if I remember correctly, the air cooled focke wulf 190 of WW2 put out around 1550hp. The reason they used an air cooled plant instead of water cooled was they felt there was no cooling system to go bad. And since most air battles ended up at low altitude anyway, they felt an air cooled engine would put out more power at a lower altitude. And speaking of airplanes, mostly all small aircraft are air cooled since there is less to go wrong. Putting out hp is secondary to reliability when dealing with aircraft. Air cooling has the edge on that. Again the only weakness with air cooling is increased noise, less control of the cooling, but not necessarily less cooling and more emmissions from actually having the pistons running colder than they should. In today's world, the pistons have to be hotter to reduce emmissions. I go racing a lot and have seen many air cooled Porsches run hot. But have never seen one just overheat massively. I can't say that about water cooled engines. I have owned 911s for years and have never overheated to a point of having to pull off the road. But I have done it countless numbers of times in other cars. From thermostats going bad, hoses that popped, radiators that were holed, bubles in the system, etc... Just the other day I overheated my mom's 500sl due to a faulty radiator cap. Of course, these incidents were partly caused due to ignorance. But with an air cooled engine, one can almost be ignorant with the exception of the fan belt. Don't get me wrong. They can and will run hot, but overheating in the official sense is rare. Having owned almost a 911 alongside a 944 turbo for a while, I always checked out my 944 closely before a long trip accross the desert. With my 911, I just threw an extra fan belt in the trunk, and left. Don't get me wrong, I like water cooling, but I prefer it on front engine cars.

Carlos

Looks like we've come quite a distance from "air good, water bad." These are my favorite kind of threads (cause a lot of thought). My personal opinion on why aircraft are air cooled is 1.weight and 2.and abundance of free air from the propeller and 3.reliability. Works great on a plane. The one thing that you can't overcome in an air cooled auto engine is noise. No way to kill the resonance from the fins.

Roland Kunz

Hello

A other way to cool down engines was to cool them with injectet fuel. This was done by most american made charged engines. the Chrysler Shelby needed twice as much fuel to keep up with a n.a. 944.

Now this will not help economic nor the enviroment. Also it will not help to win a race but Porsche had used the same trick to cool down the 917 turbo and the funny thing is they still didn´t more fuel then a Can Am V8 as they had far less WOT demand.

The aircooled engines had been on ther limit. Porsche would have to enlarge the volume again for the n.a engines to get more power while meeting all new emmisions and don´t forget the future will bring more then c.a.f.e. ( didn´t Bush stoped that ? ).

So Porsche would have to make a new engine case anyhow and they made one from the most sophisticatet engeniered units witch has enough flesh for the future.

If they had made a aircooled engine out off it they wouldn´t have enough power to satisfy all those power fucused and g-force hungry car nuts while staying in the laws or they should have made a outlaw engine only to sale in the 10% restmarked ( Africa, middle east ) as on all other staates inclucding germany they wouldn´t had passed the emissions.

One part of the Porsche history is allways to have to utmost enovirment friendly engine and car in production as the weissach engenieering needed the rolling evidence to proof there mastership and in fact nearly every car manufactorer uses Porsche to help there engines into the new epocs.

Porsche allways tryes to make new landmarks and every Porsche reflect this but the 928 was one from the boldest machines in car history. They even considered to make it full alluminium but the industrie didn´t followed and Porsche didn´t find a partner to share the risk. Can you imagen the 928 beeing some 10-15% lighter hiting on the marked in that time. This was to risky to bear for a small company but still today the 928 is one from the lightest GT´s.

The 928 was also a show off to promote the weissach engenieering branch and I remeber japanese crowding the cars and have that strange look as you kicked there rear ends

OK back then the japanese startet into the higher engenieering deegrees and needed evry input to jump into more modern car generations but they still needed some years to make a Lexus or puting IRS into the ZX.

I hope Porsche will make a similar gap with the coming GT again and i don´t care to much about the cooling as long the engenieering is typical Porsche. The 996 is a to carefull step in my eyes and the car tried to keep the Porsche traditionalists inhouse but people still compare the 911 to the 996 while noone compares the 356 to the 911.

In my eyes Porsche is a pure special spirit filled into different bootles. Every bootle has a other design and have differen´t colored and tasting fluids but all are delicius and make in a special way druken and maybe you never can live without some of that drug. Now it is like with the wine as you have good and bad years and some wine needs time to develop while others will taste fresh the best way.

Other vinerys also fill wine but some off them have no taste and no spirit even comimg from a sunny valley. It is they way how you produce wine to get quality and cheap whine is not selectet and all the wooden stuff goes in ther and to make it drinkable they add sugar and other stuff. This is the wine that will give you the hangover and doesn´t wake the spirits in your body and head.

Sorry thats the only way to descripe it for me.

Grüsse


On the way to new frontiers, maybe some others can join in ? many things to discuss and show from different views.

ked

One can dampen the resonance of fans, it just isn't cheap or easy, it can weigh more, too. You can muffle the soundfield of a fan, but it also has cost & lightweight solution.

Perhaps we should distinguish normative judgements (air = good / water = bad) from empirical ones (air = light / water = heavy).

Enough labor today, it is time to generate some driving data.

86Coupe

Air cooled contributes greatly to superior appeal of the 911, not for rational reasons like "air weighs less than water" or any of that but because the rational negative of "too much noise" is actually an emotionally appealing "sound" on the 911. The last 89 911 sounded exactly like the first 911 I heard in the 60s when I was a small child and first fell in love with the 911.

Ed Bighi

Man, I love that air cooled sound. When I was a kid, whenever I heard that sound, I always knew what it was without even looking. I remember when I was dating my wife at the age of 21 when one day in her backyard I heard a 911 going down the street. We couldn't see it of course. That moment she said, "sounds like a 911." She was no expert in cars, but she knew that sound. It is just as recognizable as its shape. It sounded special and still does. I have owned a 911 in some form or another for a long time, and that air cooled whoosh mixed with valves and chain sound still gives me a smile every morning. I love these cars will own an air-cooled 911 in some form or another for the rest of my life.

Roland Kunz

Hello

When automotive history starte air cooling was the safest way to the costumer. Ferdinand Porsche made water cooled cars and also watercooled racecars. He chosed air cooling for the Volkswagen as it made the car more bullet proof and lighter.

Over the years Porsche became the master in aircooling and managed to have a more efficint engine becourse the power drag for aircooling devices wheer similar to Watercooled but he saved the additional wight.

As creature comfort shiftet more into focus the wight benefit startet to get eaten up by the added devices to hat and cool.

However race cars could dump the added devices and benefit from it.

Porsche was never focused onto a typicak solution, they always chose the best solution.

The next step from WC is swifting to overpressurized luiquids mostly based on silicone mies. This was testet at Porsche in the late 80´s ( It hapend that I know the engenieer who developed it ) also Reeves Callaway testet it and used it on the last TWR Jaguar engines at Le mans.
Don´t ask me with what the actuall F1 are cooling. I heard they run a 5 bar pressure.

Back then the used Porsche 928 engines had hand made cilinderheads with tousends of fine luiquid passages and I think even today the technology isn´t steped into handling a casting from such a special head and a competive price.

But stay tuned the 928 only used 20% off the usuall liquid wight and the cooler had the size from a typical oilcooler.

Not to forget no mechanical water pump was draining power or could leak.

Automotive progress is a like driving with a bike uphill. If you have not enough pwer for the straight up you have to make a long winding up. Now Porsche was long enough making only slide degree and it is time to make it upper again.

Grüsse

bds1

Simple get the 911 (this is a 911 forum). Also is the 928 a PORSCHE? engine in front? engine cooled with water...doesn't sound like a Porsche.

Like some-one else said: air good, water bad

Carlos

check the badge on the hood. It's a dead give away. Oh yeah I forgot 911's only get the rear view.

snakepitt1

Back in high school (many, many moons ago) my best friends Dad had a new 928. We pushed it out of the garage one night and went joy riding. We took turns driving the car that "girly man" Tom Cruse would later drop into a lake. It was fun, but not too exciting. Not too many people knew it was a Porsche, until they got behind us and read it on the car. I now own a 1973 911T. Absolutely know one mistakes this car for anything other than what it is.. A Porsche. When I drive my car my grin is so wide that my wife says she couldn't fit in the car. Now if I could just get a decent stereo.

bds1

Hey snakepitt1.

You are 100% correct, It is just plain the greatest thing to do. Put a good CD in, top off and drive and GRIN.

I have tried and tried to get my wife to drive the car and have the ultimate experience, but she is just not interested.
Well I guess stubborn, women never do what they are told!

GRIN-ON

Carlos

How's your A/C Ha Ha Ha.

Steve, 914 guy

Carlos, Porsche sure won alot of races in the 928
HA HA HA HA