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MG MGB GT V8 Factory Originals Technical - Question for you hood scoop guys ...

Is it OK for the motor to draw in water through the air cleaner when it rains?

Will Symonds

If you're in Seattle, you should be able to tell us.<G>
The main problem would be the saturation of your filter element, causing the car to run richer. If you always drive far enough to get the engine temperature up and stabilized, there should be no other serious consequences,IMO.
George B.
George B.

I try not to drive my MGB V8 in the rain unless caught out by accident. I did however get caught in a severe thunderstorm (top down I might add) shortly after completing my project and needed to drive about 1/2 mile in the down pour before tucking under an overpass for about 45 minutes until it let up. I did not notice much water getting in through the scoop, but I didn't press my luck. My scoop has a mesh grating covering the opening (same one that is used to cover as an option the air intake just in front of the center of the windshield) but this would not be enough to stop a heavy rain for many miles.
Michael S. Domanowski

A few drops or a mist would probably not hurt, more than that will create problems. Take a look at some of the hood scoop installations on the factory muscle cars from the late 60's early 70's, Mustang, Chevelle, 'Cuda, Challenger. All of them had a way to allow water to drain. Also consider the scoop facing backward using the low pressure area in front of the windshield (Chevelle). It eliminates the scoop from picking up other debris that you may find yourself driving through.

Good Luck, Bill Martin
Bill Martin

Bill, how'd the American muscle cars drain water? I was looking at an incredibly cool Mopar the other day -- I believe they called this model a "shaker" hood -- with a couple of intake flaps above the hood, and I was wondering about this exact issue.

water injection is used to allow increased spark advance and or boost for supercharged engines. Get an MSD ignition with adjustable timing and move the timing ahead in a rain storm and pick up an extra ten hp. You may have trouble getting all that extra hp connected to the wet road, but that's another problem.
Barry Parkinson


Many of them had the air filter base modified so that there was a seperate opening that matched the hood scoop opening when the hood was closed. The water would collect in the opening of the filter and drain through a hose. Air would be directed to the carb. These were cool as there was also a mechanical flap which worked on vacumn. During normal operation the carb drew air from inside, during acceleration the vacumn dropped opening the flap and allowing air induction!
Others used a baffle which allowed the air to run over the top and the water would collect at the bottom. Some scoops of the "shaker" design simply were made so that the air inlet of the carb sat higher than the air inlet of the scoop.
By the way, water injection consists of a jet that mists the water as it is injected into the carb, not to be confused with pouring water down the throat of the carb.

Bill Martin

Bill I was trying to add some humor. Thanks for your good tech info.
Barry Parkinson

I have used two different types of hood scoops on my car.From 1983 to 1999 I had,(still have but not on the car) a cowl induction style that was open at the rear. It was very effective at venting under hood heat out at speeds slower than 35mph or while the engine was off.(hot soak) At speeds faster than 35 mph high pressure at the base of the windshield and under hood air pressures were about the same. Rain water intrusion ( I live in rainy Western Washington too)! was minimal. From 1999 to present I am using a 67 GTO scoop which is a closed type. Hot air is now vented through RV8 exhaust manifold holes.
bill jacobson

This thread was discussed between 01/12/2000 and 04/12/2000

MG MGB GT V8 Factory Originals Technical index

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