Under bed air movement / vents

[Guardm16]

OK, so here is the question:

Is the air in the bed just in front of the tailgate, High pressure of Low pressure?

I have a NASCAR truck style wing on the tailgate and vents in the bed above the tank to vent the transmission cooler. Should the transmission cooler be pushing air up into the space (Low Pressure) or pulling air down onto the cooler (High Pressure)?

Short of putting pieces of yarn (Ford Vs. Ferrari style) I thought one of you brilliant minds out there would have a good answer.

205693
205694
This is not my, but it has the same NASCAR wing.
205695

I don't want to fight the air pressure that is already there.

[J R Jones]

There may be existing data in this forum, but given inherent complexities, you should do research.
Adding to the complexity is the air pressure delta that exhists above and below your deck vents.
The numbers will be the result of air turbulance below your truck and the low pressure envelope behind your cab.

I have used hand held digital pressure guages in the 1-30 PSI range (very low) to measure pressures on the fly and in wind tunnels. An alternative to that expence are (water) monometers that you can fabricate with clear recipe hose and a back-board. With two monometers you can read static pressure above and below your vents simultaneously.

Standard spoiler experience is high pressure on the front and low pressure behind. Because of the turbulance behind your cab, I expect minimal spoiler effect. Consider it cosmetic.
In the end I expect you will need a fan to move air through your coolers and pullers are more efficient than pushers.
jim

[Guardm16]

There may be existing data in this forum, but given inherent complexities, you should do research.
Adding to the complexity is the air pressure delta that exhists above and below your deck vents.
The numbers will be the result of air turbulance below your truck and the low pressure envelope behind your cab.

Standard spoiler experience is high pressure on the front and low pressure behind. Because of the turbulance behind your cab, I expect minimal spoiler effect. Consider it cosmetic.
In the end I expect you will need a fan to move air through your coolers and pullers are more efficient than pushers.
jim

Yes, the spoiler/wing is for looks, not for effect, (I just like it that way) I have a fan on the transmission cooler, I can mount on the front or rear of the cooler, depending on which way the natural flow of air would be (exiting the vents or entering) I agree that the under vehicle turbulence could also play a huge roll in which direction the air would naturally move. It may even be a speed sensitive situation i.e., below a set MPH air moves into the the area but above that MPH air exits. Will have to play with the parameters.

[edwardb]

Strikes me that it would be easy to overthink this topic. With a thermostatically control fan, and the cooling fins in the under chassis airflow, it's going to do the job. Unless you're pushing things to the limit, e.g. track or whatever. I put a Derale unit under the rear bed on my truck build. I don't recall the direction I had the fan running (it's been a couple years) but a season of driving and just under 1,000 miles, the transmission was always easily within operating limits. The stock exhaust was relatively loud, so wasn't able to tell when the fan was running. But I could monitor the temp via an app into the HGM controller. I don't have a lot on my build thread. But this FWIW: https://thefactoryfiveforum.com/showthread.php?37287-EdwardB%92s-35-Hot-Rod-Truck-Build&p=464368&viewfull=1#post464368

[Guardm16]

Strikes me that it would be easy to overthink this topic. With a thermostatically control fan, and the cooling fins in the under chassis airflow, [/url]

And there is the rub, my cooler is mounted vertically just in front of the tank and slightly on the drivers side. I thought this might be an area of stagnant or higher pressure air... hence the bed vents.
205700
205701

[J R Jones]

The most efficient way to cool the transmission is oil to water in the radiator tank. I assume you do not have a cooling device in your radiator tank.
I have used that configuration to cool engine oil on a high performance rotary engine. That thermal load was way higher than a transmission.
My local race shop had a cooler device. I modified the one pass Griffin cross flow into a two pass and welded the cooler into the transfer tank.
jim

[Guardm16]

The most efficient way to cool the transmission is oil to water in the radiator tank. I assume you do not have a cooling device in your radiator tank.
I have used that configuration to cool engine oil on a high performance rotary engine. That thermal load was way higher than a transmission.
My local race shop had a cooler device. I modified the one pass Griffin cross flow into a two pass and welded the cooler into the transfer tank.
jim

The standard radiator supplied does not have the Trans cooler lines, and I wanted to keep the nose of the car as clean as possible (always visible) but, this works and I I thought if I can use and clear some higher pressure under the vehicle so be it.