Very informative post kmook. Its interesting that the articel says teh TA Ram Air is not a diverging nozzle. It is not an ideal diverging nozzle, but I believe it is a diverging nozzle. It appears that the area at the MAF is smaller than the area at the throttle body, I didnt take measurements though. Although this doesnt really help any because it is after the restrictions from the rain baffles. See:

http://cjcfo.fbody.com/members/injun...B/N2ONozzl.jpg

This is a step in the right direction anyways, although I bet it is just a coincedence and not engineered that way. Another interesting thought is that there is a stagnation point in the middle of the nose of the car; lowest (approx 0) velocity, but highest pressure. It would be interesting to see if a intake system taking air just off to either side of the nose would have any benefits. Kind of envisioning a snakes nose. Of course this would increase pipe distance and would not be a straight through design on an F-body, but Im talking theoretical. I believe this, coupled with a well designed diverging nozzle for the particular engine, is how the motorcycles are able to see measureable gains at high speeds.

 

"Nope id take cold air over it in a second"

Then you would be taking a less effective (hoter) induction over a more effective (colder) induction. CAI, like Moroso, K&N, etc experiences more heat soak from the engine bay than RA, because it has more piping, thus increasing its surface area therefore increasing the heat transfer from convection it experiences. The RA will experience less heat transfer from convection, so it is already providing colder air. Next, the CAI takes air from only a few inches off the ground, which will be hotter, due to heat transfer from the asphalt. I am sure you have seen heat waves somewhere on TV. The RA setup takes air from 2 feet or so off the ground, in which the nise of the car is a barrier to the ashpalt, again dcreasing intake temps over CAI. The one downfall to the RA is heat transfer by conduction from the hood. However, a fiberglass hood will reduce this heat transfer, because fiberglass has a MUCH lower thermal conductivity. Fiberglass is around 0.036 (W/m-K) at 300K and steel (not sure what the steel of our hoods is, so heres a range) is between 38.0 - 58.0 (W/m-K) at 400K. I didnt have any values at 300K, but thermal conductivity decrease with increasing temp. So, the heat transfer rate is DRASTICALLY larger with a steel hood.

Some rough calcs:

Rth=L/(k*Ac)
where, Rth=thermal resistance
k=thermal conductivity
Ac=cross sectional area, assumed 1m^2
L=length or thickness in this case
(assumed 0.5 cm)
Q=changeT/Rth
where, Q=heat transfer rate

Assuming a temperature difference of 75degC, just picked a number. Increasing this temp difference only acsentuates the results.

Steel hood= 750,000 J/s
Fiberglass hood= 540 J/s

This does not take into effect convection on either surface or radiation effects, so it is very rough, but you get the idea.

Ahh, Ignorance is Bliss!

 

was that in reference to my suggestion of the SLP RA hood?

I concider it an ideal route to go (if ya dont mind the look). Previous posts explain the technical reasons why i feel its a logical hood so no need to repeat. Just thought it would be an interesting option for the thread starter to check out.

 

There goes the engineering talk! Ram air all the way! had both and stayed with the ram air and sold the moroso. -Michael

 

just wanted to post some of my personal
experiences with this topic.

I de-baffled my ram air hood ( ws6), cut 80 percent of the baffles away, and if you look close in the ram air nose it is straight shot to the air fliter, but the front of the air filter box acts as a baffle as well, what I can see is that even though i removed the baffles for a straight shot , my air box is blocking about 70 percent of the clear opening,.

i've had no problems in the rain yet.
zoso

 

Which baffles did you cut? I have been considering this, but am worried about driving in the rain...

 

********************************

I cut both of them it doesn't do any good to just cut one.

as long as you don't cut away the front of your air box, you should be ok in the rain,

the front part of the air box acts as a baffle to..........
zoso