Aerodynamic tests and modifications on the MR-2 Spyder

[Autobahnschleicher]

Yea, you got the car right.
It's a pre-facelift MR2 Spyder from '00.
That roof in the video is what I was refering to when talking about a Kammback. (Or ar they called fastbacks?)
Anyway, cooling air flows from the sidescoops into the engine bay and out of bottom or rear bumper.
That grille only realy helps reducing heat soak while after shutting the car down and there is even a panel below it, so not realy much happening there.

Main issue with such a top is that it is a lot of work with fiberglass and styrofoam while the vortex generators where 10€ shipped.
Don't get me wrong, I'll probably build something like that eventualy, but first I'll need to do a few mockups and make more tufts and find the time for it.
That's a larger project for a later point.
But if I can build molds from it and fabricate good hardtops, maybe I can recoup my investments by selling them.
OEM hardtops are drying up and where never sold in some markets...

[AeroMcAeroFace]

I saw this once on google maps, don't do this.

[Autobahnschleicher]

Well, that's one way of getting the engine bay temps down..
But that wing placement is just absolutely dumb.
Not only is it sitting right in the turbulence behind the roof, wich is probably worse due to the softtop, it is also sitting WAY too close to the cars body.
That thing just adds way too much pointless drag and likely produces 0 downforce.

Unrelated:
Raised my tire pressures further from 2,0/2,2 bar to 3,5/4,0 bar. (0,5 above sidewall pressure)
Rolling resistance decreased noticeably, I can now coast down parts in neutral where I had to stay on the throttle before.

[Autobahnschleicher]

I performed another wool tuft test to see if the airflow on top of the roof is flowing inline with the car.
This had to be done to ensure proper placement of the VGs at a 15° angle
As we can see, the airflow ontop of the roof is flowing straight, so I can install the VGs with a simple template.
First location will be 5cm upstream of the rear window, spaced 100 mm at 15°.
If that doesn't work, I'll place them 5cm downstream of the front edge of the hardtop.

[Autobahnschleicher]

Ended up mounting them a little forward and had to change the spacing ever so slightly because of trim lines.
Wool tufts are sticked on as well now, will test tomorrow because it's dark now.

[Autobahnschleicher]

I just performed the test.
Airflow is mostly attached to the rear window now, but it's still not as attached as it should be.
Will run that setup for a while and maybe try smaller but more vortex generators further rear.

[freebeard]

If you tuft the deck lid, you may find there is re-attachment aft of a bubble.

[Cd]

Completely agree with Freebeard.
From the look of the photos, the tuft that you can see on the decklid appears to be attached, but I can't tell very well with just the one tuft showing.

Where can we see the video of the tests ?

[Autobahnschleicher]

I will have to run more tuft tests, but I agree with both of you, the flow should reattach to the engine bay.
I haven't uploaded the videos anywhere yet, but will perform a tuft test on the engine bay tomorrow.
Still, there is significant room for improvement.

[Autobahnschleicher]

I noticed something interesting:
When driving through rain, the rear window now stays completely dry.
Also I feel like it coasts slightly longer now and wind noises have been reduced.
Will probably mock up a kammback/fastback from depron soon.