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negatively pressurizing the cab?

1016 Views 2 Replies 2 Participants Last post by  robiewp
Anyone ever thought of negatively pressurizing the cab?

I was at the local tofu market earlier today buying some soy products (just kidding, I was buying pork buns...). When I closed the refrigerator door, I heard a slight sucking sound which slowly faded out. After a little messing around, I figured out that this refrigerator was negatively pressurized to help make sure the seal at the door was good.

So, to my rolling Tofu Mobile. When I go above 60MPH I start to get air rushing sounds at my doors (I've adjusted both strikers, and hinges to the max, BTW). It starts at the driver's door and at higher speeds and winds I get whistling at both the passenger and driver door. Funny thing is, If I switch from fresh air to recirc, the noise goes away except in the worst gusts. I don't particularly like using recirc ever, and there are times you just cant (defrost...).

I know there are two pressure equalizing vents between the cab and bed (saw 'em when I had the bed off), so the cab air is already supposed to exhaust somewhere. My idea is this: Why not get a marine engine compartment blower motor (known on ebay as "electric superchargers" compatible with any car!), put it with the jack under the back seats, and vent it through one of the exhaust vents or something? Just run it all of the time, or wire it into the fan control so it steps up with the climate controls. This kind of thing might also improve the heat distribution in the cab. It could also be used with the car off to help keep the air fresh on overnights (I'm gasketing my cap to the cab).

The only downside I can see is if you had a leaky exhaust or seals between the cab and engine compartment you might be sucking in things you rather not. My BamZippy Products (Ltd.) T100 Carbon Monoxide Sensor should protect me from that... and I'm pretty sure I'm not gassing any noxious fumes in inappropriate places anyway (other than from the damn dog, who thinks he's a bull dog gastronomically

It's definitely beer o'clock.

P.S... You can see the right exhaust vent on the cab in this pic:
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You mean this ventilator? There should be two of them...left and right. ;)

The commercial fridges do that so there is less warm air to cool back down. Think vacuum...less air mass. This makes it more efficient on keeping the cool items cool. :D

I think in part that the sounds yer hearing are from the air hitting the gaps in the door. Air rushing over the door will create a low pressure area and it will try to pull the door out. If you seal that gap with some tape and go down the road will see how much that noise dissapears. The other item that can create that sound is the antenna and the mirrors. ;)
I also wonder if we... Cough Cough ... clogged the vents when painting the cab. I can't find 'em in my FSM, but I bet the bed has to come off to get them out. Damnit.

I bring the idea up though, because there is a definite correlation between the noise and the cabin pressure, as is demonstrated by it's disappearance in most situations with recirc instead of "fresh air". It also gets worse as fan speed is increased while on "fresh air".
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