MKII CFD Aerodynamics Analysis - Page 3 - MR2 Owners Club Message Board
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post #41 of 345 (permalink) Old January 21st, 2011, 03:53
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If it wan't there to draw air up, then why make it not flat? Having it flow upwards will provide some airflow up into the engine bay. Be like saying diffusers aren't functional because nothing sticks down to grab air and push it up...
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post #42 of 345 (permalink) Old January 21st, 2011, 04:03
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Originally Posted by Caprandom
Something I noticed when looking through is that the plastic under body scoop isn't incorporated into the models. The one for the engine bay. I know engine bay air flow has been a hot topic for some and I find it weird that nobody remembers theres is an air scoop under there that feeds into the engine bay.
I make sure I have that plastic part fitted on all my MR2s. It directs air over the down pipe and cat as they are the hottest parts in the engine bay.

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post #43 of 345 (permalink) Old January 21st, 2011, 07:49
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Be like saying diffusers aren't functional because nothing sticks down to grab air and push it up...
It's nothing like this as a diffuser and a scoop are completely different...
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post #44 of 345 (permalink) Old January 21st, 2011, 09:27 Thread Starter
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Actually, the little underbody scoop is something I have been planning on on adding to my models, just hadn't gotten around to it yet.

If you look at it it almost has an NACA duct sort of design, with a recesed area in front of it, and then the curved "scoop" at the back. If one were to close off the engine bay adding a couple of real NACA ducts would probably be a good idea...


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post #45 of 345 (permalink) Old January 21st, 2011, 18:40
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Actually, the little underbody scoop is something I have been planning on on adding to my models, just hadn't gotten around to it yet.

If you look at it it almost has an NACA duct sort of design, with a recesed area in front of it, and then the curved "scoop" at the back. If one were to close off the engine bay adding a couple of real NACA ducts would probably be a good idea...
If the stock under engine scoop is naca based in design then it likely has a low effect on how the air flows beneath the engine bay.

On the note of racing in ssm autox everytime I get inspected all they really go into detail on is making sure all the safety equipment is good to go, that and wheel spacers, they always check those without fail. As far as being competitive I have a 800hp supercharged viper to face down, a tricked up exige and a couple of miatas that put my times to shame regularly.
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post #46 of 345 (permalink) Old January 21st, 2011, 23:58
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Originally Posted by Levi
It's nothing like this as a diffuser and a scoop are completely different...
I know it's not a scoop in the sense of reaching down to direct air up. I just can't seem to come up with a better term to describe it.

Still, I think it has a purpose being the shape it is otherwise toyota would have saved themselves the money and just made it flat.

EDIT: googled NACA duct and it reminded me of something I was going to mention but couldn't figure out how. I noticed several of those NACA ducts on the underbody panel for the engine of my mom's '07 vovlo v70. Behind a couple of them were air ramps to direct air upward's. They can't have THAT little of an effect if after 20+ years auto makers are still putting the money and design effort to making them a part of cars. It's quite obvious just looking at the thing it would save volvo considerable money to not have the ducts and make it a solid, flat piece of plastic.
Reason I had wanted to mention it was because nothing sits lower than the underside of the panel. All of the airflow into it would be created from air following it's shape up into the duct then being pushed into the engine bay. A similar idea to the one under the mr2.

Edit 2: Alex, what version of SW are you running those flowsim's on? Would you mind me sending your files? I'm still self teaching myself SW until I take a class on it and would love to play around with the models in flowsim .

Last edited by Caprandom; January 22nd, 2011 at 00:11.
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post #47 of 345 (permalink) Old January 22nd, 2011, 19:06
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Very interesting thread. As I too am still learning and trying to figure things out, I made this rear diffuser this past fall. It acts a scoop for the cooler and a diffuser to help push down. I just finished adding the turn buckles and since its winter (boooo-hissssss) I have idea how this works yet... The exahust is almost done and very cleverly positioned where it won't effect any cooling. should be cool


Last edited by Raising Arizona; January 22nd, 2011 at 19:09.
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post #48 of 345 (permalink) Old January 23rd, 2011, 19:21
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bet the cops love following you lol
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post #49 of 345 (permalink) Old January 23rd, 2011, 20:11
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Originally Posted by Eversor
bet the cops love following you lol
What? to low?

its 4" from the ground. I measured the Elise Sector III diffuser and its about 4", the NSX diff my friend has is 3" from the ground. I may trim another inch, we'll see

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post #50 of 345 (permalink) Old January 23rd, 2011, 22:37
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The diffuser looks cool, any more photos?
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post #51 of 345 (permalink) Old January 24th, 2011, 04:57
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Originally Posted by Blurvision
The diffuser looks cool, any more photos?
sure. let me pull some off PB. stay tuned
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post #52 of 345 (permalink) Old January 24th, 2011, 14:58
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What? to low?

its 4" from the ground. I measured the Elise Sector III diffuser and its about 4", the NSX diff my friend has is 3" from the ground. I may trim another inch, we'll see
its not that its too low, its because a intercooler and diffuser wide open on the back is high profile.

I dont have that and I get followed all the time, so I imagine it must be worse for you
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post #53 of 345 (permalink) Old January 24th, 2011, 15:19
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Originally Posted by Eversor
its not that its too low, its because a intercooler and diffuser wide open on the back is high profile.

I dont have that and I get followed all the time, so I imagine it must be worse for you
I think he was just saying it draws a lot of attention...like you'd be likely to street-race or speed.
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post #54 of 345 (permalink) Old January 24th, 2011, 15:48
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Originally Posted by Eversor
its not that its too low, its because a intercooler and diffuser wide open on the back is high profile.

I dont have that and I get followed all the time, so I imagine it must be worse for you

its not to low, but its get'n there. The IC hang'n down gets alot of attention. It does help confirm that its a read mid engine car though, to those who don't know-LOL! I don't street race ever and just try to blend in. We'll see how it works. can't wait!

I may raise the Diffy some and slant the IC... just an idea, which I have alot of. Its nice to have access to a full machine shop w/ materials at my disposal.

Last edited by Raising Arizona; January 24th, 2011 at 15:51.
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post #55 of 345 (permalink) Old January 24th, 2011, 19:54
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Originally Posted by Raising Arizona
Its nice to have access to a full machine shop w/ materials at my disposal.

you been holdin out on me?

a side question to the discussion though- does anyone know the frontal area of the mk2?
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post #56 of 345 (permalink) Old January 24th, 2011, 20:07
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Originally Posted by scarecrowX
you been holdin out on me?

a side question to the discussion though- does anyone know the frontal area of the mk2?
You know where the shop is..

Last edited by Raising Arizona; January 25th, 2011 at 05:36.
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post #57 of 345 (permalink) Old January 24th, 2011, 20:51
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On the previos page reagding rear end flow dynamics. Would the rear spoiler from a 98 version achive some of desired the flow seperation on the rear end as compared to the ealier versions?

Would be nice to see some of the model comparisons such as for front lips (as shown above) and rear spoilers. There is a common understanding that the spoilers are for show only.

I have a similar set-up to the IC diffuser shown above but direct the air into the HE for an A2W IC. I 'scoop' the air into the box and direct through the rear vent. I mention this as I have experimented with the sccop lip to help draw air though and your flow analysis may be helpful in determining optinum position. Pics below of what I'm referencing. From the temps I monitor it works pretty well.







jim

Last edited by benckj; January 24th, 2011 at 21:15.
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post #58 of 345 (permalink) Old January 31st, 2011, 20:50
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I've heard that placing a mesh such as 1/2" squares chicken wire helps reduce drag, by encouraging some flow around the concave surface.
It's probably nowhere near enough to cause overheating, but it would be interesting to see how effective it is.

Probably be ugly as sin, however.
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post #59 of 345 (permalink) Old February 1st, 2011, 06:54
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Originally Posted by Smurfcrusher
I've heard that placing a mesh such as 1/2" squares chicken wire helps reduce drag, by encouraging some flow around the concave surface.
It's probably nowhere near enough to cause overheating, but it would be interesting to see how effective it is.

Probably be ugly as sin, however.

I've seen that on race cars, especially rear mid's... Not sure what it'll do. Obviously the V8 Ferrari's have it for ventilation, etc.

As I watched the Rolex 24 this past weekend all the DP (prototype) cars had the square'd off backends as discussed above. Very unfinished, very racey looking, which I like. Looking at the GT2 and GT3 cars, there stock and round (RX-8, F430, 911, etc. and appear to run the track just fine. There's nothing square about a 911.
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post #60 of 345 (permalink) Old February 1st, 2011, 09:56
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Originally Posted by Smurfcrusher
I've heard that placing a mesh such as 1/2" squares chicken wire helps reduce drag, by encouraging some flow around the concave surface.
It's probably nowhere near enough to cause overheating, but it would be interesting to see how effective it is.

Probably be ugly as sin, however.
Its the most simplistic vortex generator money can buy. The idea is you are creating turbulance to reduce greater turbulance, depending on where you are putting your vg's effects the purpose they are serving.
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