Good thread. What have you found on under car aero and rear diffusers. It seems like it could be an area.to make fairly large gains on a track car.

 

New episode of MythBusters has some cool car stuff in it that related to this discussion.

 

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New episode of MythBusters has some cool car stuff in it that related to this discussion.

What were their findings? I saw an episode where they attempted a gas mileage test between two trucks and their test design was a complete joke. I don't know if they ran out of time or just didn't care but in the end they claimed to have "busted" a myth.


A flat bottom has a dual benefit of reducing drag and if low enough creating downforce but it's a difficult and/or expensive option. Combine a flat bottom with a little forward rake and you can create a diffuser effect. You can also screw up your engine cooling airflow if you don't know what you're doing. Any under car maintenance becomes a royal pain in the butt too.

A rear diffuser has to be very low to the ground and have pretty clean airflow to it (flat bottom) to be effective. You'd need a very low, very stiff suspension to run one.

 

A very interesting video :

http://www.youtube.com/watch?v=uMEYeQMvzLc

 

Very cool video, thanks for posting Wangan. I'm glad to see the high speed airflow along the side of the car tends to dive down below the window openings suggesting that the rear wing is getting good airflow even when running windows down.

The rolling tire sim is cool too and again I see why Honda installed the tire deflectors under the nose.

This video also indicates the center 1/3 of the rear wing isn't getting any clean air on its underside so I'm not going to bother with installing an extended deck lid spoiler. The outside 2/3 of the wing was getting good airflow underneath coming from the side of the car.

Definitely worth a watch

 

Thanks for posting this. Very interesting.

Rob, I'm not sure of the rules for the height of your wing. I'm sure you noticed that the wing in this sim is very low. A cab high or higher wing obviously will have much more effective center section. Also I thing that the shape of the roof, IE using a mugen or a Spoon style Hard top will also have a positive effect on the center section effectiveness.

If you can't go high go wide

 

http://mandm-honda.com/product_ap1_a...atbottom_.html

http://ameblo.jp/mandm-honda/entry-11414364949.html

M&M honda has a flat bottom diffuser, and the maintenance isn't going to be an issue. but it's insane expensive for few pieces of aluminum.

 

Even without major "downforce" from a rear diffuser, I imagine there is some benefit to reducing the parachute effect of the rear bumper, whether for drag or reduced lift. I doubt it is as effective as a wing, though, especially with no rear fender liners, making it difficult to know what the air is doing down there to begin with.

 

I don't understand the ducting on the flat bottom. If it works there should be a low pressure area under the car so air wouldn't flow into the ducts. And yea, if the price is in Yen then that's about $2000 before shipping.

 

initially, i thought 2 of them are used for cooling rear brakes, but i realized that i was wrong. those 3 ducts near rear wheels are built for cooling differential.

the piece under the front bumper is almost an exact copy of NSX NA2 Type R. its shape and style is just the same except the circle in the middle, so there is no doubt about it. honda already engineered that part.