Aero Belly Pan and cooling
 

So obviously the purpose of the belly pan is to reduce drag... but is that at a cost to sucking air out of the engine bay?
And to clarify, I'm not talking about the plastic undertray.
This is the aluminum part that starts behind the cross member.
I have a turbo swapped vert with A/C and a FMIC in Houston so I'm defiantly more worried about cooling and the A/C working than a little drag.
This is the vert compatible belly pan I'm looking at:
RX7 Convertible Aero Belly Pan |

Thanks!

Those parts are made by a forum member(Landon) he's a great guy I'm sure he'd answer any questions you have, I'm not sure how much direct feedback you can get at this point he has not been producing these parts for too long but everything seems to be well thought out and very well produced, in my opinion the belly pans (especially combined with ducting)help to direct air flow properly as much as reduce drag
GL Rikk

i would leave the aero panels off, they do hinder cooling system efficiency to a small degree but add to the aerodynamics at that cost.

I agree with you Ben merely adding panels is not going to help the cooling process, Landon and I spoke about the probability of incorporating a front splitter into the panel(s) in order to move air beyond the radiator,IC,oil coolers,etc. "In theory" Id like to try to force as much air thru ducting/ventilation beyond the motor/turbo system out and under the rear if possible?

i have an insight that i mod a little here and there but the theories and applications are completely backwards from the FC almost ironically. i put a full bellypan under the engine and the aerodynamics rose slightly while the water temps also creeped up just a little bit.

in all honesty the FC doesn't really need much in the way of aerodynamics beyond the stock body shape. if you make power then the aerodynamics are a bit moot. if you're doing it for economy on a stock car that can sacrifice a little temperature then it has some validity.

the aerodynamics at the rear underside of the car could likely greatly be improved without much sacrifice.

Hey guys-

I have the panel on my personal vert, an '88 w/ a street ported T2, running a T04B hybrid & megasquirt, also a FMIC car. I am only running the stock gauge for water temps, with a big aluminum radiator, and am in central FL. I did not notice any changes in temps on the stock gauge, which isn't saying much obviously. The real test, and what I did on a miata with MS3, would be to drive around for a long enough period of time to record water temp data, both with & without the pan. If it's a deal breaker, I'm happy to do it, I think it's good information to have for you, I, and future customers, and shows a lot better feedback of the product, in my opinion.

Thanks!

Since this thread has been started and we are talking about aero and cooling panels, I too have a question.

Jack and I recently replaced the drier in my s5 vert, and I have neglected putting the passenger side panel that covers the drier back on.

What are the purpose of those panels under the relays and coolant overflow? The reason I ask is because the hood has a gasket there so I would "think" that air flowing to the radiator wouldn't be able to escape. It also seems removing those panels would allow more air to reach the condensor and radiator but please if Landon or Ben could explain.

it keeps the force inducted air moving through the radiator while you are moving and the fan becomes obsolete. same reasoning why we use radiator upper panels to block off that opening.

On the driver side the panel also allows the airbox snorkel to breathe air from outside the bay.

Right, but that snorkel is still gasketed away from the engine bay, panels removed or not.

the hood simply extends/encloses the duct from the plastic tray to the snorkel.

I would think its purpose is to keep it air flowing more smoothly, as it enters the bumper it is kind of a < shape going from front bumper to the radiator, with the oem paneling

vs if it just went from bumper to a space between bottom tray and hood its more of a square area, which may create more turbulence or swirling of air?

That's kind of what I was thinking. Smoother airflow = less air being sucked out

I like that idea, as long as it does not hang low enough to get torn off

I have a street vert. the least aerodynamic 7 ever.. I'm not going for either top speed or .5mpg increase... I was just having trouble keeping it cool.

That would be interesting, if your MS controls the efan, to be able to datalog the coolant temps on the highway (fan off) with the pan on and pan off.

I suspect that the pan either does nothing, or like lyger said will slow the air from escaping the engine bay.
I'll probably still get a upper radiator cover from you to replace the plastic parts and hide my janky relay wiring.

Isn't that pan (at least on the non-verts) there in part to make sure airflow from the grill/chin actually hits the rad and oil coolers? Otherwise, the air would tend to be deflected down and under the car - bad for aero and for cooling.

There are two different panels. One is the stock panel that you are referring to. It goes from the bumper back to roughly the bottom of the radiator, maybe the subframe(its been awhile since I put one on or off).

The aero panel being discussed is another panel that encloses part of the engine bay further back. This panel was not standard equipment. It was part of an Aero option package. It reduces drag, but also reduces air flow exiting, thus the discussion.

So I've been researching radiator ducting for quite a while now trying to improve the cooling of my '86 GXL when doing track days. I would say the purpose of the panels, jjwalker, is to create a diverging nozzle right before the radiator. Air tends to want to flow from high pressure to low pressure. So by slowing the air down in front of the radiator you thereby increase the pressure which leads to more air wanting to flow through the radiator. This is only true if you can seal the air to make sure it cannot escape around the radiator without going through the fins.

Ideally you would use a front splitter to help get as much air in the nose as possible, have ducting that starts about 1/3 to 1/2 the surface area of the radiator, then diverges to the same surface area of the radiator and is sealed which slows the air down, then have converging ducting or sometimes just as large of ducting as you can get after the radiator that either goes out through an opening in the hood or is ducted down to return to the air stream beneath the car (generally only feasible in an airplane). Going out the hood is a much easier choice. You should also try to use some diverging ducting in front of the oil cooler but don't worry about any ducting on the back side as it will then just flow through the radiator. It also helps to have an e-fan because then you have more flexibility with your post-radiator ducting since you don't have any shafts attached to the engine.

If you incorporated this kind of ducting and then also used the aero undertray piece this thread was started for, you would both increase your cooling efficiency and increase your aerodynamics. Win win!

I plan to fab up some cardboard pieces and then converting those to aluminum to build the radiator and oil cooler ducting. Also will use 1/4" or maybe 1/2" plywood coated with fiberglass resin and then mount it to the chassis to use as a front splitter. I will try to take pictures of everything as I go but there is not a planned date on when I will start this work... Hopefully before winter.

That'll show those Mazda engineers a thing or two!


Plywood splitter FTW!!!:lol:

Think lavitz is smoking crack
This thread was supposed to be about the aluminum belly pan that a copy of the stock aero option. Not the plastic radiator under tray that should be on every car anyway.

Interesting response since none of my post had anything to do with removing the plastic under tray unless you want to replace it with a front splitter that covers the same area as well as sticking out the front a bit. I was merely adding to the discussion since previous posts had talked about worrying about reducing cooling efficiency when adding the aero belly pan, which is the whole point of this thread, but really the problem isn't the belly pan it's how the incoming and outgoing air and pressures are handled.

If you are just driving the car on the street and want to add the aero belly pan you are not going to see any aero benefits. The real gains would be seen on the track. In my experience when doing track days with a stock car, oil and water temps on my '86 GXL get pretty high on the stock setup after 20 minutes hard. Hence my previous post about solutions to both incorporate the aero belly pan as well as increase the cooling efficiency of the radiator/oil cooler package. Redirecting the air and controlling the pressures across the radiator are the key.

If you don't find this information useful then I apologize for creating such a long post but I personally find this information to be quite relevant to the subject matter.