less redneck air deflector

[MasterofDisaster]

A couple years ago I installed a plastic panel as an air defector under my 08 GT. It did give me maybe .1mpg better, and the hood fluttered less, but it was less than ideal. Attaching it with zip ties to the K-member looked pretty amateur. My sister-in-law's fiance has a lift that he offered if I wanted to change the oil. That was easy and quick enough.

When I was done, I asked his opinion about installing some 24" wide aluminum flashing running from the radiator support to the lower chassis brace. I said I'd like to run it further aft, but I didn't see any way to support it. I also thought that I'd interfere with the cats, and he more or less agreed. Then he said, wait a minute, let me see.

He came back with a flat aluminum panel. It had been a sheet from which Chevy was going to make 67 Camaro test fender skirts. Anyway, it was thicker than flashing, and it was wider too.

It took a lot of trimming and punching and hammering, but it connects to the radiator support with fender bolts and nuts. At the rear, the simplest thing was to attach it with the chassis brace bolts and nuts.

The final product looks nice and reasonably professional. [There's an extra hole at the front b/c we were a little brain dead yesterday. Doesn't matter b/c the oem air deflector covers that area.] It took a couple hours on Fri and almost three this morning.

If you can't find an aluminum sheet, flashing is not a bad idea. You can get a roll of 24" wide flashing for about $2.50 a linear foot at home improvement stores. HD keeps it by the roofing materials.

 

[Dino Dino Bambino]

I can see where you got the inspiration to do it. The only minor problem I see is that you'll have to remove the whole custom under tray each time you do an engine oil & filter change. Nice job though.

 

[MasterofDisaster]

I can see where you got the inspiration to do it. The only minor problem I see is that you'll have to remove the whole custom under tray each time you do an engine oil & filter change. Nice job though.

Thanks, Dino. We had discussed cutting out a rectangle so I could reach the filter. The problem was that it would probably induce some turbulence under the car.

The bolts on the chassis brace are only long enough for the stock nuts. You might be able to get one thread from another nut on there, but you'll ever tighten them. Maybe next year I will use longer M10 1.5 bolts so I don't have to mess with the brace?

There are enough nuts, bolts, and screws underneath that fitting the panel may be a two-man job. Maybe next year I will use studs and nut to attach the panel? That would definitely make alignment easier.

 

[GriffX]

I lowered the connection at the radiator support by 2 inch to get a flat undertray to the k-member. The resulting height difference from front to K is around 2 cm now

 

[Pentalab]

How do u get hot air from the eng bay down on each side of the eng block...when it's now blocked off ??

 

[Dino Dino Bambino]

How do u get hot air from the eng bay down on each side of the eng block...when it's now blocked off ??

That won't cause a problem since the hotter air goes upwards and sits under the hood. If you want to vent hot air, correctly placed '13 GT500 style hood vents (near front of hood above the space between the fan and engine) are the solution.

 

[Pentalab]

That won't cause a problem since the hotter air goes upwards and sits under the hood. If you want to vent hot air, correctly placed '13 GT500 style hood vents (near front of hood above the space between the fan and engine) are the solution.

U would have to use 13' GT-500 hood vents. Without em, their would be no airflow through the myriad of radiators.

 

[GriffX]

How do u get hot air from the eng bay down on each side of the eng block...when it's now blocked off ??

I thought about that too and made a log drive afterwards with nothing unusual recorded. And, every car I know has a sealed engine undertray and no overheat problems, and there is a lot of free space to the front suspension.
The better measurement than temperature would be a pressure drop measurement behind the radiator. My guess is that the ventilator will start some minutes earlier than before.

 

[Pentalab]

I thought about that too and made a log drive afterwards with nothing unusual recorded. And, every car I know has a sealed engine undertray and no overheat problems, and there is a lot of free space to the front suspension.
The better measurement than temperature would be a pressure drop measurement behind the radiator. My guess is that the ventilator will start some minutes earlier than before.

on my 2010 gt, it comes with the plastic cover....to improve aero..... BUT it only extends back to the front of eng. IE: must be removed when up on the lift, to get the oil filter out. The hot air flows to the grnd via each side of the eng block. In my case, I tossed the oem upper grille ( which blocks 80% of the air)..... which of course also deletes the upper foglamps. Eng bay now dropped 40 degs F ( measured). It also eliminated the 2 x 90 deg bends from front grille to intake of the oem 'snorkel ' that feeds the oem airbox. IE: replaced oem upper grille with the 7 bar grille. On the 05-09 cars, it's a 9 bar grille.

 

[crjackson]

IE: replaced oem upper grille with the 7 bar grille. On the 05-09 cars, it's a 9 bar grille.

I did this (GT500 hood, Roush upper grill, Roush lower grill & fogs) to my 2014 and it made a huge difference.

 

[Autokyrios]

The stock belly shield is IMO fine if the car is stock, and I actually ran for years without it. If you start adding things to consume airspace up front and/or make heat, it's more useful. My hood has ram and vents but without a belly pan the coolers up front see less airflow as the air just pushes around them rather than through. I have done some of my own paneling and am in the process of making new ones now that I have access to a plasma cutter, so I'll probably post the 'refined' versions of those. Ultimately the goal is entirely to make air go through the radiators and then get rid of it. You don't want to hold it to the body. Ideally once the air has passed through the last radiator, it should go away completely (as far as the engine is concerned). Don't trap heat in places it shouldn't be (like around the starter or headers). Also, if you have a significant surface area of flat metal, you might want to consider either adding some dimensional supports or adding some shaping to the metal, otherwise it can make noise waffling about as wind goes over it. My first custom pan I made a box and cross with some strips of aluminum riveted to it and that solved any rattling, waffling noises. Later versions I've used some rolling and creasing to firm up the shapes.