Did a CFD Analysis on the MKI - Interesting - Page 9 - MR2 Owners Club Message Board
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post #161 of 178 (permalink) Old January 26th, 2009, 16:36
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I have a question.. Did we ever do a simulation with and without the rear roof spoiler? and with or without the rear trunk spoiler? on a MK1?

Last edited by quadzjr; January 26th, 2009 at 16:39.
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post #162 of 178 (permalink) Old May 10th, 2009, 15:29
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post #163 of 178 (permalink) Old May 11th, 2009, 10:37
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Is someone willing to run another MKI CFD, with some 'custom' parameters?

This would be for an autocross car (thread in AX forum) that is constrained by a rule book.

PM me?

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post #164 of 178 (permalink) Old May 13th, 2009, 02:53
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I <3 this thread.
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post #165 of 178 (permalink) Old May 14th, 2009, 23:35
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Quote:
Originally Posted by mtbmr2
Is someone willing to run another MKI CFD, with some 'custom' parameters?

This would be for an autocross car (thread in AX forum) that is constrained by a rule book.

PM me?
I can't see aero being a huge deal in autocrosses, at least the ones in parking lots where 60mph is top speed. Now on a track, even short ones, aero would
could play a bigger part and not just weigh the car down more rather than helping the car planted to the ground.
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post #166 of 178 (permalink) Old May 15th, 2009, 01:31
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Quote:
Originally Posted by bitbycarbug
I can't see aero being a huge deal in autocrosses, at least the ones in parking lots where 60mph is top speed. Now on a track, even short ones, aero would
could play a bigger part and not just weigh the car down more rather than helping the car planted to the ground.
He is constrained by a rule book and might just be curious about what aero mods might actually hurt at those speeds. Then again, autox cars are usually driven to the course so he might just be thinking about a gas mileage boost or hindrance that a certain part might have. Honestly, if I'm right on all my assumptions , I am building my autox/street monster and have some of those same questions.
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post #167 of 178 (permalink) Old May 20th, 2009, 13:14
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Quote:
Originally Posted by MosquitoXR13
He is constrained by a rule book and might just be curious about what aero mods might actually hurt at those speeds. Then again, autox cars are usually driven to the course so he might just be thinking about a gas mileage boost or hindrance that a certain part might have. Honestly, if I'm right on all my assumptions , I am building my autox/street monster and have some of those same questions.
Close-ish.
My car isn't street legal, so it is riding on a trailer, towed behind my SUV.

In September 2007 I remember I had a discussion with, this guy: http://www.alexjobracing.com/team_fordahl.htm
Regarding the splitter and rear deck spoiler on the his (former) 914-6: http://gulick.us/projects.html.
IIRC he indicated the spoiler made a difference of ~45lbs of downforce at 45mph. He wouldn't talk about the splitter.

The car I drove that year, a 1974ish Datsun 240Z added a rear spoiler last year. There was some data that indicated the car could carry extra speed through a 6 cone 60 ft slalom.

SCCA D-Prepared MR2's have a minimum weight of about 1750lbs, and they can fit 20" diameter, 9.5" wide cantilevered slicks, on the 13x7" rims. Which means we don't brake a lot, even on an autocross course.

SO, I'm curious to see if the aero components I'm limited to, are at least positioned in an area of air flow to produce some downforce. All the CFD's in this thread had a rear wing.

I want to see MKI CFD's:
1) without OEM rear wing
2) without the OEM rear wing and add the roof visor.
3) without the OEM rear wing, add roof visor, and 10" SCCA legal decklid spoiler.
4) 3) + an SCCA legal splitter.

Last edited by mtbmr2; May 20th, 2009 at 13:36.
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post #168 of 178 (permalink) Old June 7th, 2009, 13:16
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Very interesting thread ... am also interested in seeing some informatin on the MK2
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post #169 of 178 (permalink) Old July 31st, 2009, 20:50
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I finally followed up on my vortex generator ideas- unfortunately I don't have pictures of my oil traces. The results were not what I expected.

My baseline stock traces showed laminar flow at the front of the roof, beginning to separate in the middle of the sunroof, and completely separated at the back of the roof. There was almost no flow on the trunk, just barely enough to push my oil back 1/2" and my drops on the wing flowed downhill to collect on the bottom front edge.

I made 5 vortex generators, 2"long at the base .125" tall up to 1.5" tall at the back, triangular shaped, and taped them on the windshield with the front at the bottom line of the window tint at top.

I had no laminar flow across the entirety of the roof, and my trunk traces actually flowed forwards towards the engine bay- bad news!

I then moved the generators to the front of the roof

Laminar flow across the whole top of the roof, no flow whatsoever on the trunk, wing traces obeyed gravity with no signs of airflow.

I'm going to leave the generators up there for a while and compare my mileage, I think that the air is flowing straight back along the roof, and killing the large bulb of low pressure over the bonnet might result in gains, as I do about 70% of my driving above 65mph. I'll post whether it is conclusively good, bad, or inconclusive.
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post #170 of 178 (permalink) Old August 1st, 2009, 09:18
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give them a try at the rear of the roof as well.

youll never get the stock wing to work effectively because of the giant void in front of it. any effective wing on a mk1 either needs a screen in front of it to fill in the engine bay void, or needs to be raised substantially higher to inline with the roofline.
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post #171 of 178 (permalink) Old August 2nd, 2009, 13:24
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ill give that a try after im done testing @ the front, no further results yet
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post #172 of 178 (permalink) Old August 4th, 2009, 09:11
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I thought the rear wing may not create down force but reduces the aero drag on the car.
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post #173 of 178 (permalink) Old September 8th, 2009, 00:19
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successful experiment, negative results. across 2 tanks of gas, no change in normal driving, showed a 1.5-2 mpg decrease with the vortex generators. I havent gotten around to testing them at the back of the roof, I wanted to do an A-B-A test
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post #174 of 178 (permalink) Old February 12th, 2010, 12:27
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drvr5 -- did you ever get a chance to finish up this experiment?

I am surprised this thread has gone quiet. I thought for sure there would be countless tests to see what changes could positively effect the aero.
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post #175 of 178 (permalink) Old February 24th, 2010, 08:17
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i am to, i was wondering what the flow would be like in the engine compartment if you sealed the bottom of the engine bay opened the rear trunk compartment up pulled air down with fans through the hood, and opened the rear open where that plate normally goes and attach a fan there, maybe a good place to mount a intercooler, or attach a small scoop on the bottom of the engine compartment and then have a draw in from the bottom and top exiting at the rear of the car
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post #176 of 178 (permalink) Old February 24th, 2010, 08:46
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I never saw this thread before, but its incredible!!!!! Two thumbs up for your guy's work!

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post #177 of 178 (permalink) Old March 1st, 2010, 10:52
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Quote:
Originally Posted by The Money Pit
Great Illustrations of your question ... my opinion (and everybody has their own) the issue is what will improve what we're starting with? ... I forget the Japanese word, but the philosophy is constant improvement ... see an area that can use help and make it better ... thanks so much for your work ... and I'm wondering, does the rear window sunvisor make a difference? ...
The word is KAIZEN

Great thread.
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post #178 of 178 (permalink) Old March 1st, 2010, 22:46
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This is an incredible thread. Glad it was stickied.

Found out that we have SolidWorks at school. I wonder if they have the FloWorks add-on... It would be great to be able to test and optimize ideas before actually going through with them. I have some 3D modeling and CAD experience, which should help.
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