Engine Tin

Need some input on this subject. I recently purchased a 57 speedster. It has no tin on the bottom of the engine bay. My present mechanic says it is better that way, as it will get more air.
Yet, every speedster I have seen has tin on bottom. Also I had a inside covering under the engine lid grill, and he removed that for more air. What is the story on this senario? Rich
getrichqk@aol.com

Your mechanic is incorrect. The tin on the bottom of the engine bay is there specifically to separate the hot air from the bottom of the engine (exhaust, etc.) from the cooler air on top. The upper air is used for engine cooling as well as intake. Without the separation, you're just recycling the hotter air from under the car. This is probably more of an issue in slow moving traffic than when moving at speed. Dune buggies escape this problem because they are completely open.

The inside cover on the decklid is the panel just beneath the vent grill, right? I think that's there to keep the rain off of things. Again, it should be there.

Go to this link: http://shoptalkforums.com/viewtopic.php?f=11&t=128494 - after you view the upper left video there will be a series of short "next" viewable choices. Surf through these for a clue as to the parts involved. (I've had relatives out in the desert for 40 years-I know HOT); if you have a 4-cyl VW/Porsche engine without engine tin in the Coachella valley you will, repeat will, be buying a new engine. Besides "tin", get a good external oil cooler. This will require some investment (fairly modest), so do your research here. Ask a lot of questions. A great local (fairly local) source is in Ontario: his name is Larry Jowdy, highly respected experienced mechanically oriented guy, member of this forum. There are many others as well. LARRY JOWDY-this man needs your assistance!
Add-by the way, your present mechanic has NEVER laid hands on an air-cooled vehicle (dune buggy excepted) OR you've been flashing too many large $$$ bills around. Quietly lose him for VW work.

Post some pictures of engine bay. Look in the CMC buildmanual in the library - there are some other fiberglass pieces for sealing the engine bay too (back upper/lower and partial side pieces). The upper lid piece is mainly for rain protection but also adds strength - on CMC the hinges mount to it.

Hey Guys, Thanks for the input, I am going to pursue your suggestions.
I wonder if there is anybody out there that subscribes to the no Tin senario, I would like to hear from them. My mechanic says he has a report or instruction paper that says he is right, (I am waiting to see it), and will report back. I am so happy I found this site, I just wish I had found it before I purchased my car. Regards, Rich

Unless its for a VW powered airplane - I doubt you'll see his evidence. It's probably on his list of how to make money in these hard times - #1 Push engine oil additives, #2 Push flushing engine systems, #3 don't need no stinking OEM air cooled tins, #4 pay extra for nitrogen in the tires.

The tin serves several purposes - from getting the engine warmed up quickly (thermostat and shroud flaps), keeping it from being over heated, and circulating same cooling to all cylinders equally (so #3 valves don't go first and destroy engine). Car manufacturers rarely add unseen parts and cost to vehicle if it isn't needed.

An even more important reason that it is there is to prevent exhaust gas from getting into the engine fan which blows directly through the heat exchangers into the passenger compartment! If you don't have heat, or don't use it, it's not a big deal, but if you use the heat without the tin you are risking CO poisoning!

Nitrogen in your tires? I paid a premium to have Helium put in my tires. The car weighs less now. I'm thinking Hydrogen next time!

Has anyne tried "chassis magnets"? You put them on the bottom of your chassis, align them for your locale, and they resist the pull of earths gravity - presto - your car is lighter. Or reverse the polarity and you increase traction.

I am very interested to hear the "mechanic's" evidence to not use a complete engine tin with good seal.

The chassis of the Hoopty is close in design to a sand rail, so you'd think I'd have been able to avoid making a full set of tins. The Wrench took a few temperature readings when we first drove the car in November of 2006 and determined that tins would be a good idea.
Some of the surround aluminum that came from Jake were used, and we made some other pieces to close it up -- and the same measurements taken afterward showed a thirty-odd degree difference in the engine compartment.
Jimmy used a laser/infrared temperature meter and aimed it at the heads, the carbs and the fan shroud for his ballpark figures. The bottom rain-catching fiberglass on my decklid has been cut away, and the meter was held through the decklid with the grille removed to meter the carbs and shroud with the engine running. The head temps were taken from below the fenders, aiming upward.
The top of the fan shroud had the biggest difference. I don't know if that helps any.
It also keeps he engine from getting clobbered with road dust and grime. I love that added bonus.