Rain Tray or Not? Options

[VWTortuga336]

When I bought my car, it did not have a rain tray installed on the engine bay cover. I was going to buy one, but now I'm building a 2366 and want to do everything I can to keep it cool. Are there any cooling benefits to not having a rain tray? If I don't add one, how do I stop water from getting in the engine?

[r_towle]

A few tests were done years ago by a member, I recall there was not a enough difference to take it out and then deal with all the rainfall.

[era vulgaris]

A few tests were done years ago by a member, I recall there was not a enough difference to take it out and then deal with all the rainfall.

I actually tried this this past summer, just to see for myself. I've got a 4 channel digital CHT gauge in my car with sensors under each spark plug so that I can monitor all 4 head temps in real time. There was no difference in temps whatsoever between running with or without the rain tray.

I keep it on. I don't drive in the rain, but there's a surprising amount of stuff out there (leaves, bugs, etc) that'll fall into your engine bay without it. What annoys me are the little side vents on either side of the engine lid, neither of which have a rain tray. So water gets all over the battery on one side. It baffles me why Porsche would place the battery in a spot where it would come into direct contact with water. It's literally right behind the rain gutter on the roof, so at speed you'd be just pouring water right into that open vent and onto the battery. It seems like a poor design to me...really the only thing about the 914 that I don't like. No other air-cooled Porsche or VW has the battery in a spot where water would get dumped right on it. It makes washing the car kind of annoying. Does anyone know why they put it there?

[914_teener]

A few tests were done years ago by a member, I recall there was not a enough difference to take it out and then deal with all the rainfall.

I actually tried this this past summer, just to see for myself. I've got a 4 channel digital CHT gauge in my car with sensors under each spark plug so that I can monitor all 4 head temps in real time. There was no difference in temps whatsoever between running with or without the rain tray.

I keep it on. I don't drive in the rain, but there's a surprising amount of stuff out there (leaves, bugs, etc) that'll fall into your engine bay without it. What annoys me are the little side vents on either side of the engine lid, neither of which have a rain tray. So water gets all over the battery on one side. It baffles me why Porsche would place the battery in a spot where it would come into direct contact with water. It's literally right behind the rain gutter on the roof, so at speed you'd be just pouring water right into that open vent and onto the battery. It seems like a poor design to me...really the only thing about the 914 that I don't like. No other air-cooled Porsche or VW has the battery in a spot where water would get dumped right on it. It makes washing the car kind of annoying. Does anyone know why they put it there?

Just curious what engine config that you tested and what was the ambient temp?



I run without it during the Summer. It does.t rain here but where you are.......might need an Ark right now forget the teener.

[era vulgaris]

Just curious what engine config that you tested and what was the ambient temp?

I run without it during the Summer. It does.t rain here but where you are.......might need an Ark right now forget the teener.

2270 with dual Dell DRLA40's. External oil cooler. Ambient temps were anywhere from the 80's to the high 90's, with high Raleigh, NC humidity.

I ran with the rain tray on all year through the end of July. I took it off in August to do some tuning work on the Dells, and left it off for the rest of the month to see if my temps would be any different out of curiosity. They weren't so I put it back on. I always ran in the low 300's while cruising, and mid 300's on hills (for CH #3).
It makes zero difference to run with or without it, whether you're cruising backroads or sitting in traffic. At least on my car.

I also find that ambient temps make no difference to my head temps, except for the amount of time it takes for my engine to get to operating temp. Whether it's the dead heat of summer or the bone chill of winter, the operating temps are always the same.

The only thing that matters is knowing how to drive an air-cooled car, and how to use your rpm speed to keep the engine cool. Keep the revs between 3K and 4K when cruising, downshift when you hit a hill, and you'll be fine every time. I will say, I highly recommend that everyone who drives an air-cooled car get a digital CHT gauge. I've learned more about how to drive these engines in the last 10 months that I've owned this car, than in the many years I previously spent driving air-cooled cars.

BTW, this is the CHT gauge I have: http://www.mglavionics.com/TC2.pdf