MKIII aerodynamics question

[CRE]

Hey guys, I'm curious about something for a bit of an experiment. On the pre89 MKIII is the upper grill area a high pressure zone? Is the lower grill area higher pressure than the upper?

I suspect that the bumper may create a considerable amount of turbulence, enough to disrupt the flow of incoming air through the upper grill, can anyone confirm this?

This is for an intake duct, so a low turbulence, high pressure area is essential.

 

[bigaaron]

This may be something you will need to test yourself. Maybe a sensitive pressure gauge, with a small funnel placed in several places, going to a hose run into the car would do it. I would be interested to hear the findings.

 

[CRE]

That's what I'm thinking too. I figured that someone may already have a good idea... If not I'll rig something up for testing.

 

[ma71supraturbo]

Both are high pressure areas, being at the front of the car (& therefore at first contact with stationary air).

While I don't know from experimentation, my meager fluid dynamics experience would lead me to believe that the lower grill area should be higher in pressure than the upper (but also more turbulent). My reasoning is that a good portion of the higher pressure air above the bumper is able to escape over & around the small lip in front of the hood. The air under the bumper has no where else to go (since it is forced between the ground and the much deeper lip below the bumper).

Here is one of my awesome MSpaint drawings to help you visualize:

 

[johnathan1]

I believe they are both high pressure zones.

I have an old japanese article where they use the HKS speed cut defenser on a white 87...and it hits around 150MPH...and you can literally see the front header panel lifting up two inches in the center from the pressure.

If you guys wanna see it, I'll scan it in.

 

[CRE]

I'd like to see it! Thanks for the info guys. I figured it'd be high pressure, but in some cases the air displaced by the bumper can create an umbrella type effect which drastically reduces the pressure further in the vent opening.

 

[SupraOfDoom]

I wanna see it.

 

[suprageezer]

I'd love to see that also. I think everyone would love to see some of the wind tunnel tests results Toyota Did during the design of the MkIII sure wish we could get our hands on that Secret Data useless to them today.

 

[screaminglemon]

someone did do pressure tests in the past but he focused more on the hood. looking for the highest negative pressure to find the best place for a vent. i cant remember if he took any numbers on the front. hell i cant even remember his name as hes not around anymore.

 

[ViR2]

does anyone know cW (drag coficiant) for supra?
Did facelift made any effect to aerodynamics or not?

I would really love to see some aerodynamic upgrade possibilities to supra which are not only for show, but have real purpose

 

[SupraOfDoom]

I think that was Shawndude.

 

[swaq]

does anyone know cW (drag coficiant) for supra?
Did facelift made any effect to aerodynamics or not?

Pre-89 was 0.34 Cd without spoiler, and 0.33 with it. (Motor Trend, Nov. 1986) I'm not sure what the numbers are for the 89+.

 

[SupraJDS]

does anyone know cW (drag coficiant) for supra?
Did facelift made any effect to aerodynamics or not?

I would really love to see some aerodynamic upgrade possibilities to supra which are not only for show, but have real purpose

Same here

 

[figgie]

I would really love to see some aerodynamic upgrade possibilities to supra which are not only for show, but have real purpose

not going to happen

that requires wind tunnel testing and that is not cheap. You could run simulation software but that is not cheap either.

 

[CRE]

IIRC, there was only a difference of .01 Cw between the wingless pre89 and 89+. One of the wings reduced Cw by .02 and I'm pretty sure it was the pre89... whichever it was the other reduced Cw by .01.

 

[Poodles]

I believe the wings actually caused more drag (but reduced lift at speed)

can't seem to find that damn link in my bookmarks, had a link with a ton of cars and their Cw...

 

[CRE]

The spoilers reduce drag. From what I recall (found a wealth of info on the spoiler vs wing a long time ago) the pre89 wing provided more down force than the 89+ spoiler, but neither produces any appreciable amount.

 

[ViR2]

thats a lot of drag for supra, my lexus IS220d (Europe version of IS350) only has 0.27cW.
Supra's spoiler is more of a show then go

BTW, I've heard that some Japan aftermarket body parts manufacturers actually test their products in wind tunnel... Ware Greddy testing their bumpers?

 

[Poodles]

for it's time, the drag isn't that bad, it's about the same as the the good F-bodies of that time (T/A, camaro has aweful drag), and I think it's around the same as the vette...

 

[Supracentral]

I was digging through some of the old data on the Supracentral server and I found this in a text file:

0.37 - 0.39 Cd for the MKII
0.33 - 0.34 Cd for the MKIII 88-
0.32 - 0.33 Cd for the MKIII 89+
0.31 - 0.32 Cd for the MKIV

No sources cited and I can't for the life of me remember where the data came from, but I'll bet it's accurate, or damned close to it.