T4 Engine tin: thermal design Options

[914werke]

So seeing a product recently got me thinking about the result of its application & my own observations of how well (or not) the T4 handles air flow, Engine block cooling & resulting oil temperatures. (IMG:style_emoticons/default/smile.gif)

Its somewhat well known that ...in the 914.. the T4 suffers from less than optimal cooling from the front mounted impeller/fan particularly to the #3 Cylinder
& that it is vitally important to seal the tins multiple openings to contain as much laminar air flow front to back over the finned cylinders.
In a gross approach, the goal was to seal the engine compartment "intake" air on top from the eng. heated "cooling" air below the tins.
When a motor is new and all its components serviced & refreshed, the design does, or did, a pretty good job.
After years of use (neglect), elements (oil dirt mice ext) conspire to restrict that air flow.
As well as eng. heat causing hardening of rubber pieces that are intended to help contain that cooling air below.
Now almost 50 yrs on I see fewer & fewer "STOCK" engine configurations which you can guess usually means more heat to deal with.
Jake addressed the cooling air via his(?) DTM solution, but IMO its not very practical for stock or near stock motors (& expensive)

The go-to response to eliminate that heat is usually an additional or a remote oil cooler which comes with its own set of challenges. (IMG:style_emoticons/default/confused24.gif)
How about KISS (IMG:style_emoticons/default/biggrin.gif) Has anyone used any of the Fiberglass based stick-on reflective heat shielding products on the engine-sides of the tin?
Idea being rather than allow heat absorption to all the those steel pieces reflect it back to carried away by the cooling air?

BTW Im not a Porsche engineer...but I did stay in a Holiday Inn last night (IMG:style_emoticons/default/happy11.gif)

[914werke]

Now almost 50 yrs on I see fewer & fewer "STOCK" engine configurations which you can guess usually means more heat to deal with.

perhaps in a hi-po version with increased capacity it gets dicey, but not in stock form.

(IMG:style_emoticons/default/rolleyes.gif)

[wonkipop]

Now almost 50 yrs on I see fewer & fewer "STOCK" engine configurations which you can guess usually means more heat to deal with.

perhaps in a hi-po version with increased capacity it gets dicey, but not in stock form.

(IMG:style_emoticons/default/rolleyes.gif)

i guess if you think tinware material is contributing to the problem or could improve cooling you would roll your eyes. (IMG:style_emoticons/default/biggrin.gif)

for me, like i said - an interesting conversation going down in this topic.

of relevance is something i have always noticed, which is the tinware and the magnesium fan casting are actually reasonably cool to the touch when the engine is running.
particularly the fan casting which does not seem to get hot at all. probably not surprising given the amount of air moving through it.

they certainly get very hot after shut down. particularly the fan casting.

i've always thought the mid engined application of the standard VW engine ran a bit against the grain of the air path in the rear engine cars. particularly the way the tin curves back around at the opposite end to the fan in the rear engined cars. its a real full seal that sends the air back along the underside of the engine so it can be drawn out of the car at the low pressure point at the underside of the tail. the 914 has a bit of a problem in that respect as its trying to send air flow in a counter direction.
sure there are underside air guides and plastic deflectors to assist but its a kind of an inbuilt problem with turning the engine around. i'm not sure VW or porsche got it entirely correct. its probably the only way they could do it without a major redesign of the engine tin but that would have defeated the purpose of using as many standard components as they could to keep it economically viable.

i suspect a lot of the heat shedding issues with higher performance engines might be along the underside of the cylinders and heads rather than the upper surfaces that are in the initial air flow?

it would be interesting to know if the same engine in the 912E ran slightly cooler.

PS
of interest in this regard was some special tin that was developed for the type 3 engine for hot climates (like australia). all the early engines did not have it. and overheated.
its a piece of tinware that wraps around the cylinders on the underside and is similar in some ways to the small deflectors in the type 4 that are up between the cylinders.
its more extensive a deflector in the type 3 hot climate spec engines. the problem was definitely on the underside of the cylinders with these particular cars. the beetles here did not have that deflector. ran cool enough without them. the twin carbies also helped the engine run that tiny bit cooler.