Oil coolers--What Berg says! m

I remember seeing a WW2 photo of a Kubelwagen (I think) and a couple of German soldiers around an engine with a head off? in the African desert, so they had their moments...

So, both here and on theSamba, discussions regarding cooling go round and round-- bouncing between the shroud/flaps, the oiling system, the engine design, and (in our case) air to the engine compartment. This is because cooling is probably the least well understood aspect of using an air-cooled engine reliably.

Every discussion starts with questions just like this, why indeed did stock VW engines work reliably in Kublewagens, etc. in the deserts of the world? I called the stock VW cooling and oiling system a "Rube Goldberg arrangement of compromises, which, when all the components are kept intact, usually works." Actually, it works very well with a stock engine.

A stock engine is small-displacement, has really, really thick cylinders, runs very low compression, and has modest power capibilities. There just isn't that much heat made- and when the engine gets hot, it tolerates it very well. The shroud and flaps (when new) do a good job of allowing the engine to come up to temperature, which is really important because a decent amount of heat is needed to heat up the single carb intake.

We're really dealing with four issues here, which is why the conversation bounces around a lot.

1) The engine itself. One of the first things to get modified on a Type 1 is the displacement. Unless we are running 92 mm thickwalls, the cylinders are thinner, and more prone to expand out of round in a high-heat application, so they are less able to tolerate heat to start with. More displacement and compression create more heat, which the cooling system has to get rid of. The bigger the displacement and the higher the compression, the more heat there is to deal with.

2) The cooling system for the heads and cylinders. This would be the shroud. Again, the stock shroud did a really nice job. The sled tins, thermostat, flap arrangement, etc. were all designed to cool the stock engine without overcooling it. Over the years there have been many, many attempts at improving it- how successfully will depend on who you ask. Cylinder head temp is very important, but very few people even monitor it, because there was no gauge in a stock cluster for it.

3) The oil cooling system. This is where things get murky, because this is something people DO have a gauge for, so they can see easily how bad the situation is getting. Cylinder head temperature and oil temperature do not have a linear relationship, but they are intertwined. I'll get argument on this, but the oil is picking up heat somewhere, and it isn't just in the oil-pump and bearings. The oil picks up heat from the heads to one degree or another. Doing fancier stuff (like using 911 oil squirters, or modifications to spray oil on the rockers) just ties oil temp more closely to CHT.

4) The aerodynamics of the car itself. These engines have an enormous appetite for air, and live in a very poor environment to be fed adequate amounts of it. A good amount of what we talk about and do by means of "extramechanical" improvement focuses on air. If we could just feed the engine more air, a lot of the hysterics we go to wouldn't need to be done.

Everything is interrelated, and so we bounce from one thing to the next. A comprehensive approach would probably be the best.

Everybody worries and argues about the shroud, but the way most of us use these cars (warm weather cruising), it's probably the least important of the 4 things to consider. An EMPI 36 HP doghouse shroud does a fine job in 95% of the applications we need to consider. IMHO, you might want to consider sled tins, but I wouldn't obsess about it.

The low-hanging fruit is probably getting more air to the engine to start with. If we don't do that, everything else is just a lot of investment with very little return.

The longblock is probably the next important factor. Build something with 94 mm cylinders, high compression, and a stroker crankshaft, and you better be ready to get serious about cooling. Build an 1835 with thickwall 92s and moderate compression, and you probably won't need to worry very much ever (I'm looking at you, Jim Ignacio)

... and then there's oil. Adding an oil cooler with a thermostatically controlled fan and a bypass thermostat is almost as obvious as getting more air to the engine. The stock cooler is fine for a 1200 cc singleport in a Beetle, but if you want your engine to live in a speedster- supplementing the little cooler is just a good idea. You can get as carried away with oiling systems as you want, but it's the cooler (not an extended sump, etc.) that is going to help. Getting one is just a good idea.

That's my take on the whole thing. You can go further and further down the rabbit hole if that's what turns your crank (it spins mine), but there's no need to spend a bizzion dollars and have a degree ion thermodynamics to make your Type 1 operable in the desert. Getting it to be operable in the desert and in the snow might be a bit more difficult, but is not outside the realm of possibility.

Regardless, living in fear of stuff is just silly. Just drive 'em.

MUBJIM Speedster philosophy;

1. Eliminate any angst about hypothetical Speedster problems (what's my head temp, what oil should I use, air-flow dynamics, etc, etc.) 

2. If the weather allows and the car starts, then off for a drive.

3. if something breaks, get it fixed.

Things to worry about;

1. A nuclear Iran

2. Addressing any personal health issues

3. Keeping a roof over my head and food on the table.

^GOOD ADVICE THERE JIMMY. NOW STOP WATCHING THAT VIDEO I SENT YOU. 

That's a good philosophy, Jim. 

I would add the coda that how you've speced (both) cars has helped your carefree attitude as well. A thick-wall 1835 with a remote oil cooler and freeway flier living in LA is pretty close to perfect. Your adherence to a pretty strict idea of what the car is (and isn't) makes you the smartest guy in the room a lot of times.

I posting these opus' for searches down the road. Trying to make a speedster "more" is where the real money gets spent. Ask me how I know. lots and lots of people want "more".

OTOH, my serpentine belted, DTM equipped, dry-sumped, twin-plugged 10.5:1 2276 has run like a watch this summer. Flawlessly. (Dare I say it?) almost perfectly.

I better tear it apart again and do something even sillier. 

All great stuff but I didn't see where anyone took a manometer reading from the hole in the firewall. Maybe I missed it.

My little 1904 runs cool, rarely beyond 180-185 no matter how I drive or what the temp. is outside. I have a 1 1/2 qt. sump, remote oil filter, 6" hole in the firewall, VW tins and stock oil cooler in the doghouse with proper tins, no remote oil cooler.  I also have the port holes in the fender walls but I haven't needed them opened up except to get at the front spark plugs and manifold bolts.

I have no deserts or really extreme high temperature areas to drive through so I don't really know if it would survive a high temp run. I was just wondering if the firewall hole makes the difference or if it was a waste of time.

Bruce's testing has shown that there is a difference in air pressure between the space behind the engine firewall and the engine compartment, so if there is a hole there I suspect that air can be drawn into the engine compartment.

This small hole may not be enough to lower the oil temperature, but it surely will be an added air source if and when the fan and carbs need more air.