Belly Pan

Comp2, you should be interested in my upcoming article in the July POCA News, on Larry 'Downforce' Stock's street/track Pantera. Larry finished (today!) a very extensive under-car aero remod' that starts at the air dam and ends at a rear diffuser ala F-1. He'll be running it for the first time at the Reno-Fernley Open track event this weekend as part of the Fun Rally, to see what the overall effect is, and hopes for great things. Before, his 425 bhp car on DOT tires beat some machines that had 200 bhp more and were running gumball slicks. Should be fun to watch.

Nice dude! Not many go to that effort. Get ya mirrors ready for shows. I have lots of shots of mine if you need any, but looks like you have it down excellent. See a couple photos in my DOES 200 album : http://www.poca.com/index.php/gallery/?g2_itemId=1585

This mod rates pretty high on my to-do list. I have to get a rotisserie first though, and a bigger garage, and a welder, and ....... Excellent start you have there. I may have to finally get off my lazy a$$ and send in my POCA form. Thats an article I dont want to miss.

Blaine

Thanks Does, I will check out the photos. Let me know if you need any help framing up a roto Blane.

I just got off 8 straight days of flying. All I have had a chance to do is make the main center portion from aluminum. I rolled a couple bends in it with the die roller.

When I made repairs in the under channel and a few other spots I welded in nuts. I need to make a few more nut plates but these make it easy to bolt stuff too:

Can't really show how it ties to the aluminum airdam as the air dam will not fit while on the roto. The aluminum air dam was built with a bottom and it rolls up the back side to close off all air. All air out through the radiator exits the hood. No air goes out the bottom. This is all closed up.

I am considering putting a belly pan on 5481. Does anyone have any experience using them at high speeds 150+.

Mark 5461
5481

Curved corners to weld,
Back half to build,
dozen or so more mounting tabs to add:

By the way Does200, I looked at yours and it's a lot better looking job then what I am doing here. This is .050 aluminum.

quote:

Originally posted by comp2:
By the way Does200, I looked at yours and it's a lot better looking job then what I am doing here. This is .050 aluminum.

I don't know about that, yours is looking exactly the same. The guy I got it from said it was powder coated, but I am not sure about that. I am not sure about what material mine is. Aluminum will be nice and light. He he, now you will need to be careful where you jack it up when done! And watch da speed bumps too, don't want to scratch that puppy up now.

Well there is not much special about it other then knowing the bolt hole locations. Getting the first one made as a template is the hard part. Once it is off the roto that job will be 10 fold harder.

Questions out of curiosity, given my recent problem with corrosion post ...

I noticed that you cut away chasis panels and treated the interior. As well, you welded on nuts to the removed panels.

How much rust did you find in the boxed in sections that you opened up?

Certainly welded nuts are a strong way of attaching bolts to a panel. Did you consider installing Rivnuts?

Interested to know

Surprisingly not that much rust. The plates were mostly beat up from people jacking on them. At that points welding in nuts were as easy as anything. The rest will be nut tabs.



I added a support piece to the channel, cut groves for drainage and even added drain holes.



The replacement plate is heavier plate.



The last step before beginning final body work on the car is to spray the inside of every channel.

FWIW Larry Stock shaped and blended the underside of his '72 race car for the recent Fun Rally event. He then had to raise the rear ride height by an inch as the additional downforce was causing the rear to scrape all the way around the track.

This was his confirmation that there is a lot to be gained from a belly pan/underside aero mods and diffusers

Julian

Interesting. I figured do it now while on a roto or not at all.

The 3 aluminum sheets welded together and side pieces on front welded on.

Nut plates added. Pan will be bolted on in 34 locations. Should be snug.

Looking good Gary!

It's not great but it's done. I need to clean the edges here and there but I won't need to crawl under the car to do so now. It's ready to bolt up. I can set it aside and move forward now.

Looking great! You going to powdercoat it before bolting on? That is what the proior owner said he did to my Group 4, although I am not sure if it is or not. Seems it would last longer that way, no?

This all looks interesting? But like the Racing Drag Boats that have flat bottoms, sometimes when they catch some air they seem to want to take flight! And that would wreck your day!

Nice work Gary! Keep the pics coming.

This is something I've been thinking about for a few years. I've seen Jan's partial treatment, but always thought that a pure flat bottom would not improve handling and as Cuvee points out, be quite dangerous at high speeds.

But a well planned ducted flat bottom leading to a rear diffuser could be a great improvement - even when not at race speeds. Joules, do you have any pics of Larry Stock's setup?

Does 200, I am not sure what I will do for finish. Might just paint it flat black so it disappears. I need to work on the bends some but having it done while the car was upside down was invaluable. If I had to make it with the car on it's wheels it wasn't going to happen.

Aerodynamics? No one knows for sure. That's what testing is for. My car has a number of things different. For one all air going through the air dam and front of the car exits the hood. All air underneath is blocked off. That alone will change a few things. Smoothing the air may actually help prevent lift in that dirty air turning under the car will back up creating more pressure. Smoother air will have a chance to evacuate.

As far as diffusers and such, one step at a time.

Will it help, hurt? I am certainly making no claims. We'll see how it does.

Comp 2, I added a couple more underbelly photos on my Group 4 below showing cooling lines. From your photos it looks like yours may be going up under the pan? If so, how would you get to them?

http://www.poca.com/index.php/...ery/?g2_itemId=10206

Excellent photos thank you. That is one clean looking underbelly!

My pan is removable. It is held on by 34bolts and goes all the way to the front of the car.

Comp-2, when you start testing, be sure to include brake rotor temperatures. One midwest track-Pantera owner that blocked off most underbody airflow with a deep airdam found that the rotors then got no cooling air and he ate pads 3X as fast as before.
There's no free lunch with Mother Nature'