General theory question time, engine sheet metal?

lendaddy · 06-12-2002, 05:54 AM

What is it for? I mean I get the aethestics part but is it also an airflow thing? I took mine off last night and the engiine is just much more accesible without it, it seems. No, I am not considering leaving it off, I am just wondering what it's design purpose was. I am going to assume airflow blocking unless I hear different. Any thoughts?

ChrisBennet · ChrisBennet's Garage

It keeps the cooling fan from sucking hot air from under the car. It's pretty important.
-Chris

pnzr911 · 06-12-2002, 07:02 AM

It is VERY inportant to keep the sheetmetal on. Its a cooling thing. Why Porsche even went as far as sealing it all the way around with a rubber seal. Hot air bad. Cool air(from your decklid grill) good!

Early_S_Man · 06-12-2002, 07:26 AM

It kind of started with Ferdinand's Beetle ... keep the water and hot exhauted air out, and the cool air going where it is supposed to ...

And, the 'old' 111.905.449 VW spark plug air seals are a VERY important part of the equation too!

ChrisBennet · ChrisBennet's Garage

Warren,
Would a VW dealer be able to get those seals? An engine I purchased was missing them and I'd like to replace them. I don't see them listed as a seperate Porsche part.
-Chris

Early_S_Man · 06-12-2002, 07:57 AM

Chris,

No, VW updated them to an 'A' suffix part with reinforcement ribs that prevent them from working on a 911 engine!

Just go to a foreign car parts supplier or aftermarket VW specialist ... and they will have the 'proper' Mexican or Brazilian part without the ribs. Buy a couple of dozen ... and make sure they are soft and pliable, because the hardened ones won't work! I keep a couple of dozen sealed in a recycled tennis ball can (covered with self-sticking shelf liner paper) with a snap-on lid ... to keep out the ozone!

pwd72s · 06-12-2002, 10:20 AM

Once more, Warren comes up with a super tidbit of info. There will soon be a run on VW spark plug seals. At least in Oregon!

ChrisBennet · ChrisBennet's Garage

Thanks Warren! Are these the correct ones?
http://www.bughaus.com/spark10.htm
-Chris

speeder · speeder's Garage

Chris,

That would be them. Thanks for another common-sense tip, Warren!

Early_S_Man · 12:36 PM

Yes, notice the use of part of the VW part number ... and $1.95 for four is not a bad price! Although I have seen the whole Beetle park plug wire set go for $3.95 ... not a bad deal either ... even if you have to buy two sets to get six of the seals! I wouldn't recommend driving even 25 miies in the summer heat without functional air seals on a 911 engine!

Just like checking the oil level in your tank ... checking those air seals should be part of your routine at EVERY gasoline fill-up ... since full-service gas stations are a relic of the past!

Carrera Charlie · Carrera Charlie's Garage

Just want to add a note to the airflow discussion ...

The engine sheetmetal not only stops hot air entry, but dirt and debris as well. I have first hand experience with this from my '75 Toyota Landcruiser FJ40. The transmission cover had several rust perforations that I decided to repair, so I pulled the cover off and fixed them over a two day period. The cover separates the engine compartment from the passenger compartment and I soon discovered that hot air, sand, bugs and burger wrappers can be drawn through that small area with enough air flow at high speed. The solution was to close all windows which soon created a rolling sauna effect (lived in Savannah, GA at the time - 100 deg F with 100% humidity).

Since our AIR COOLED engines require airflow, keep the sheetmetal intact and avoid all the crap that could be ingested!

Regards,

john70t · 06-13-2002, 05:14 PM

This might sound strange, but has anyone added a water vapor mister to the fan cooling system?

A water jug feeding a tiny injector at the fan inlet, on a duty cycle so it mists every 5-10 seconds or so to lower the average engine temps (like a swamp cooler).
Heat cycling might be a factor, but running hard in 100+ temps can't be all that great for air cooled engine.

Jim Sims · 06-13-2002, 05:24 PM

It's been tried. A 911 fan moves a lot of air which would take a lot of water to cool by evaporation. Water is heavy; you don't want to carry a lot of it. Water used must be very pure as in distilled or it will leave mineral deposits on heat transfer surfaces (fins) which will diminish heat transfer to the air. Cheers, Jim

Doug E · 06-13-2002, 05:33 PM

Thanks Warren- great tip!

Two Oh · 06-13-2002, 06:58 PM

Quote:

Originally posted by lendaddy
What is it for? I mean I get the aethestics part but is it also an airflow thing? I took mine off last night and the engiine is just much more accesible without it, it seems. No, I am not considering leaving it off, I am just wondering what it's design purpose was. I am going to assume airflow blocking unless I hear different. Any thoughts?

291 posts from a Porsche owner and he asks a question like this!

Ever see those posts that are titled, "A dumb question"? They usually are not dumb at all, but this one sure is.

Hey Wayne, Give Lendaddy an award for asking the stupidest question regarding a 911 that I and many others have ever heard.

Lendaddy, Have you any Porsche books in your library?

Did you buy your 930 for prestige?

Jim Sims · 06-13-2002, 07:12 PM

Keep asking your questions Lendaddy. For each person brave enough to ask a question there are twenty lurkers who would like to know or need to know too and are too afraid to ask. Learning only comes through humility. Cheers, Jim

Doug Zielke · 06-13-2002, 07:18 PM

Quote:

Originally posted by Two Oh

Hey Wayne, Give Lendaddy an award for asking the stupidest question regarding a 911 that I and many others have ever heard.

Are you kidding? That's pretty harsh, considering most of us enjoy answering "stupid" questions for newcomers.
Your time may yet come.

expat · 06-13-2002, 07:27 PM

Geezus.....if that is your attitude TwoOh, my opinion is find another board.

Lendaddy, in my opinion take no offense to TwoOh's opinions.

Through your question we had others post some interesting information. That's EXACTLY what rocks this board.

Cheers
Mark

k9handler · 06-13-2002, 07:30 PM

Ditto to the previous two...your day will come!

Two Oh · 06-13-2002, 07:54 PM

Quote:

Originally posted by Doug Zielke

Are you kidding? That's pretty harsh, considering most of us enjoy answering "stupid" questions for newcomers.
Your time may yet come.

My time has come and gone a million times.

BTW, In the past I have come to this board with legitimate tech questions only to see them go unanswered or I was ridiculed.

And yes I was kidding, a little..........

But you have to admit, the question was somewhat elementry.