Prius V Rear Diffuser

This afternoon's project, ventral diffuser fins for the 2012 Prius v Five.

Textured ABS, sized and angled to rear bumper contours, 12" long, from 2" to 4" deep fins, angled ~30 degrees outward from vertical. Uses factory 8mm push-rivet location at rear of wheel well liner/bumper cover and drilled for 8mm push-rivet on under-surface of bumper cover, with 3M VHT tape between bumper cover and fin mounting base

 

Why? Because scrap ABS sheet, design skills and mimicking Gen2/Gen3 rear aero treatment..

Haven't had it in the rain yet. Can't comment.

 

No plans. Hadn't considered it.

 

Thanks!

 

400 miles of very stable, higher than normal highway speed, half in rain, with higher than normal MPG, suggest this was a success.

Not to mention, don't believe I'll have to lift at the kink on the Mulsanne...

 

Apparently. (See above.)

 

Thanks. The rear of the ventral fins are canted a bit wide of fore-aft, creating a modest diffuser (and vortex generation). Full belly pan would reduce drag, but be difficult to achieve in practice. Most of what you see as aftermarket 'diffusers' reach only 8-12" ahead of bumper face and probably create more of a 'parachute effect' than pre-existed. Venting the rear bumper (cut outs where retro-reflectors are factory located or dimple die cuts in the bumper face) would solve most of the entrapment -- at the cost of a bumper.

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I looked at what was available and concluded a well-designed and engineered DIY would look better, mount more stably and less visibly, and actually be functional. So, no.

 

The photo perspective doesn't really describe what is going on, which is as you mention, both a wheel and undertray flow management device.

"Textured ABS, sized and angled to rear bumper contours, 12" long, from 2" to 4" deep fins, angled ~30 degrees outward from vertical."

In context, here, "bumper contour" (bottom) in the vertical plane slopes up, while the fins become deeper, and the outward fin angle creates a winglet-like strake that manages airflow around and behind the tire. Could have left these vertical (90 degrees, like the 2G) but the canting makes the fins more active as flow managers and vortex generators. The bumper bottom is well inboard of the outside of tire, so placing a vertical fin there makes it inactive from the perspective of flow alongside the tire and bumper.

"The rear of the ventral fins are canted a bit wide of fore-aft, creating a modest diffuser (and vortex generation)."

Again, in context, the "bumper contour" (side) in the horizontal plane narrows a bit, while the fins are canted outward a bit more than that, I believe wider than the 2G, creating a modest diffuser.

The 3G does, from your photo, have a full belly pan, but the v does not. Would be nice to have, but Toyota hasn't made it easy on the v. No obvious attachment points, for starters.

Within the "WAG" of desktop design parameters and unknown manufacturer baseline aero flow data, your idea works as well as mine.

So get to it, and report back!

 

Nicely done. Last photo looks like the rear diffuser undertray of a GTLM car.

Here's your class sticker.