Question about a Prius Boattail Implementation

[Rishar]

This is something I want to do but I have a question about the current Prius design. Would this require a rework of the entire rear end? Or will a continuation of the current slope work? For reference.



Using the tool to overlap the template this is what I ended up with. Not sure if it's correct though. If it is, despite the looks, the Prius is not quite shaped right.



Thoughts?

[NeilBlanchard]

It looks like you have applied the template correctly - but to do it with the higher line on the window is going to be a lot harder, than keeping the existing line. Here's what I'd do: tuft test your car and see what the actual air flow on the back looks like. If you can just extend the existing surfaces (sides as well as the top) then that makes building it much easier.

You should also consider a full belly pan before moving to a boattail, as that would help make the boattail better, and you'd benefit from it whether or not you build a boattail.

[basjoos]

I think a better match would be if you slid the template forward until you lined up the part of the template where the template's upper slope lines up with the Prius' rear upper slope and then see how it looks going back from there. If Toyota did its homework right, there should be attached flow all of the way back to the rear spoiler, but it wouldn't hurt to tuft-test to confirm it.

[Rishar]

Originally Posted by NeilBlanchard

You should also consider a full belly pan before moving to a boattail, as that would help make the boattail better, and you'd benefit from it whether or not you build a boattail.

The Prius has a pretty good belly pan right off the line. At least the Gen 3, not sure about previous ones. I do need to do a little cleanup for the exhaust. No idea how I'd even begin to tackle the rear suspension though.

Originally Posted by basjoos

I think a better match would be if you slid the template forward until you lined up the part of the template where the template's upper slope lines up with the Prius' rear upper slope and then see how it looks going back from there. If Toyota did its homework right, there should be attached flow all of the way back to the rear spoiler, but it wouldn't hurt to tuft-test to confirm it.

Moving the template as suggested does show a much better attachment. I suppose the only way to be sure is a tuft test. I'll have to get on that. It is a rather nice day today too.

[Cobb]

Is it me or does it look like the front and rear are towed out?

[Rishar]

Originally Posted by Cobb

Is it me or does it look like the front and rear are towed out?

Haha, yeah, I guess the camera the guy used sorta fish-eyed the pictures. Otherwise, I don't think this car would move very far. :P

[basjoos]

Originally Posted by Rishar

The Prius has a pretty good belly pan right off the line. At least the Gen 3, not sure about previous ones. I do need to do a little cleanup for the exhaust. No idea how I'd even begin to tackle the rear suspension though..

Even though the Prius underside is smoother than that of the average car, there is still a lot of room for aerodynamic improvement since it is nowhere near as smooth as the top or sides of the car.

Coroplast is flexible, so if you use it for building your underpanelling, you can install it over some of the movable parts of the suspension and the coroplast can cover and move up and down with the suspension. I did this when covering up some of the suspension arms on the aerocivic.

[serialk11r]

I don't have a lift so I wasn't able to do this, but an idea I had was to use the vinyl sheet (or something kind of similar) that you line say dinner tables with. At 1 dollar per foot from OSH the cost is negligible, and the stuff is quite tough. I used it to block the grill. You could wrap it around the (roll?) bar, and stretch it all the way back to the bumper, and then for the suspension arms wrap all of them together.

[basjoos]

Would this table cover vinyl sheet be stiff enough not to flap and flutter in the wind? Once a surface starts fluttering, its surface drag goes way up (think of when you hold a fluttering flag up to the wind compared with holding the same size rigid sheet to the same wind).

[Rishar]

Did some tuft testing. Looks like Toyota knew what they were doing after all. Seems to have kept good attachment and it was smooth. So when I do the boattail, it'll be a continuation of the current slope. Prius comes with good attach points too, that blade on the back has 5 bolts that hold it. Remove it, and there are 5 mount points on top ^^. Going to remove a tail light later on and see how many mount points I'll have there. See if I can get away without any extra holes.