Did a CFD Analysis on the MKI - Interesting - Page 6 - MR2 Owners Club Message Board
 1Likes
 
LinkBack Thread Tools
post #101 of 178 (permalink) Old December 5th, 2007, 03:19
Lifetime Gold
 
bentheswift's Avatar
 
Join Date: Mar 2004
Location: OR
Posts: 10,238
OldTrader Rating: (22)
https://mr2oc.com/showthread.php?t=22...=bernoulli%27s

Resources:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
's
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
's
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
bentheswift is offline  
Sponsored Links
Advertisement
 
post #102 of 178 (permalink) Old December 5th, 2007, 03:21
Lifetime Gold
 
bentheswift's Avatar
 
Join Date: Mar 2004
Location: OR
Posts: 10,238
OldTrader Rating: (22)
A scoop is good for routing cold air into wherever you want it to go. It is not good for increasing the pressure in the intake manifold.

Resources:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
's
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
's
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
bentheswift is offline  
post #103 of 178 (permalink) Old December 6th, 2007, 09:54
Pretty Darn Nice Guy!
 
The Money Pit's Avatar
 
Join Date: Feb 2005
Location: Millbrook - Heart-O-Dixie - Alabama
Age: 71
Posts: 479
OldTrader Rating: (30)
Garage
Quote:
Originally Posted by MosquitoXR13
So what about a Tom's style C-pillar scoop
I have no degrees ... All OJT and some of that was crisis Fast Trak ... so this is worth just exactly what it cost, nothing ... if it helps, great ... I do keep meticulous records and know how to research ... I used a TOM's style scoop (made by Ken Schultz of KD Garage) and ducted it to the air filter housing ... (see pictures toward the bottom of the "Cars" page on my Web Site - Ken's MR2 Parts ... I closed off the bottom of the scoop, allowing for water drainage and installed a plastic nipple for the 3 inch hose, which fit the air intake of the filter perfectly ... the car is a 1986 NA auto daily driver ... fuel economy went from 33 mpg at 70 mph (consistently over 240 miles) to 36 mpg under the identical conditions ... I extrapolate that the fuel economy increase is due to thermal efficiency increase and therefore it can be assumed there is a power increase due to the same improvement ... one thing I am absolutely sure of, was it sounded great at higher rpm under load ...

as stated, I have no degrees; please feel free to correct any errors I have made ... my skin is thick from years of Toyota Service Management ... and my senses dulled from same ...
The Money Pit is offline  
Sponsored Links
Advertisement
 
post #104 of 178 (permalink) Old December 6th, 2007, 21:02
Registered User
 
Join Date: Dec 2005
Location: Metro St Louis Area MK1 2ZZ-GE w/ 6spd
Age: 41
Posts: 640
OldTrader Rating: (9)
Quote:
Originally Posted by The Money Pit
... one thing I am absolutely sure of, was it sounded great at higher rpm under load ...
This is a bit off topic here. But, thought I would add this bit of information. I modded the driver's side adding a sidevent. I made a fiberglass "scoop" (for lack of better terms) similar to Deno's. Sound increased tremendously. Went from "sounded great" to ear piercing when the valves open on the second set of lobes.

My theory... I, like you, now have a fiberglass megaphone

Looks cool. Gives fresh, cool air. Not sucking air from next to header any longer. But is damned loud.

Sorry to jack the thread.
blown59 is offline  
post #105 of 178 (permalink) Old December 6th, 2007, 23:38 Thread Starter
Lifetime Gold
 
Join Date: Apr 2006
Age: 36
Posts: 2,106
OldTrader Rating: (10)
Quote:
Originally Posted by choi0706
the filter is attached to the ITBs surrounded by a airbox.. I need a duct to feed the box some cool air..
Are you using a 20v setup? Do your ITBs already have filters on them?
superpilun is offline  
post #106 of 178 (permalink) Old December 7th, 2007, 00:28
Registered User
 
Join Date: Nov 2005
Location: Houston, Texas
Age: 39
Posts: 1,614
OldTrader Rating: (19)
yes, not at the moment..
choi0706 is offline  
post #107 of 178 (permalink) Old December 7th, 2007, 19:07 Thread Starter
Lifetime Gold
 
Join Date: Apr 2006
Age: 36
Posts: 2,106
OldTrader Rating: (10)
Then this is so easy, like I said just get an intake pipe that bends down. The filter sits behind the transmission. Like I said, I've logged IATs in Megatune with this setup and the temps are SOLID ambient.
superpilun is offline  
post #108 of 178 (permalink) Old December 28th, 2007, 14:17
Registered User
 
filonin_2's Avatar
 
Join Date: Nov 2005
Location: North Highlands, CA
Age: 33
Posts: 8,745
OldTrader Rating: (11)
I don't know if your model of air flowing through the engine bay is that accurate. At 100mph, my engine lid axctually lifts up to a 45 degree angle from all of the air going through there, must be more 2-3mph.
filonin_2 is offline  
post #109 of 178 (permalink) Old December 28th, 2007, 15:05
Registered User
 
Join Date: Oct 2005
Location: northern NJ
Age: 30
Posts: 1,051
OldTrader Rating: (25)
Quote:
Originally Posted by filonin_2
I don't know if your model of air flowing through the engine bay is that accurate. At 100mph, my engine lid axctually lifts up to a 45 degree angle from all of the air going through there, must be more 2-3mph.
It's very possible that thats got more to do with a low pressure area above the lid, and a slight positive pressure area in the bay.
backspace is offline  
post #110 of 178 (permalink) Old December 28th, 2007, 15:18
Registered User
 
filonin_2's Avatar
 
Join Date: Nov 2005
Location: North Highlands, CA
Age: 33
Posts: 8,745
OldTrader Rating: (11)
That's what I'm saying. The negative pressure is sucking a lot of air from below, you are just looking at it from the other way. If the negative pressure from above is enough to lift the engine lid like that, what do you thinnk it is doing to the air underneath it? The air underneath has to have higher pressure or it wouldn't lift, and air moves from high pressure to low pressure, so there must be a lot of pressure under and a lot of vacuum above.
filonin_2 is offline  
post #111 of 178 (permalink) Old December 30th, 2007, 06:02
Registered User
 
Join Date: Feb 2007
Location: England
Age: 34
Posts: 1,434
OldTrader Rating: (0)
still air is of a higher pressure than moving air though, so id say it does more to prove that air in the engine bay hardly moves at all. there is massive seperation behind the roofline giving low pressure, and stagnation in the engine bay giving high pressure. the lid lifts up and air naturally wants to flow from the high pressure area to the low pressure area, but only as much air can flow as there is present in the first place, and as much as can fit through the restrictions in place. with the engine lid left open, im sure there is probably a faster flow, but id say not significantly so. with the engine lid closed and with standard vents, there is probably hardly any flow at all. less than in a front engined layout id say. all youre getting is a lift force acting on the large flat surface that is the engine lid. this lift needs to be reduced (or ideally turned into downforce) to improve rear end stability at speed
Jim2109 is offline  
post #112 of 178 (permalink) Old December 30th, 2007, 20:08
MR2OC Founder
 
Bill Strong's Avatar
 
Join Date: Sep 1999
Location: Lovingston, Va
Age: 56
Posts: 42,296
OldTrader Rating: (122)
I agree. That lift force can be reduced by making a lid the runs from the roof to the trunk. The angle is critical so that the boundary layer does not separate from it. I think that this would do a huge job at increasing top speed, or at least reducing the amount of power it takes to get to a given speed.

Making a complete flat bottom would also decrease cd. Use side vents with a vent exhaust between the tail lights to remove engine heat.

Bill Strong
Marketing Director
On-Air Host
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

ChampCar Endurance Series


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Bill Strong is offline  
post #113 of 178 (permalink) Old December 30th, 2007, 22:38
i overtake on roundabouts
 
feral4mr2's Avatar
 
Join Date: Mar 2004
Location: Queensland
Age: 47
Posts: 3,775
OldTrader Rating: (0)
so the feral's rear end isnt too bad then? well apart from the drop down behind the window....

it'll have a complete flat bottom by this time next year too.

yes i still have a handful of aw11's.
feral4mr2 is offline  
post #114 of 178 (permalink) Old December 30th, 2007, 23:29
Registered User
 
Join Date: Mar 2004
Location: Houston, TX
Age: 37
Posts: 3,069
OldTrader Rating: (7)
I haven't read the whole thread, but has anyone tried modeling the Mk1 and Mk2 with vortex generators (ala Evo8 MR) on the back edge of the roof?
kbrew8991 is offline  
post #115 of 178 (permalink) Old December 31st, 2007, 01:57
Registered User
 
Join Date: Nov 2005
Location: Houston, Texas
Age: 39
Posts: 1,614
OldTrader Rating: (19)
Quote:
Originally Posted by superpilun
Then this is so easy, like I said just get an intake pipe that bends down. The filter sits behind the transmission. Like I said, I've logged IATs in Megatune with this setup and the temps are SOLID ambient.

the way my airbox is being setup, it needs some "ram air" dryer hose style ducting to a solid airbox, stacks covered in foam filter..

also any worries about water?
choi0706 is offline  
post #116 of 178 (permalink) Old February 6th, 2008, 18:03 Thread Starter
Lifetime Gold
 
Join Date: Apr 2006
Age: 36
Posts: 2,106
OldTrader Rating: (10)
Those vortex generators allow the boundary layer to stay attached to the rear window for a greater distance, resulting in a reduction in pressure drag. The problem is, it only works for rear windows that slope down gradually. They would do nothing on the mr2 because of its flat rear window. The general problem with the mr2 is that it is designed to have a low pressure area behind the rear window to aid movement, however slow, of air through the engine bay. This sort of passive pressure delta to cool the engine compartment is more economical than doing it the right way. The right way to do it is how Ferrari did it on their F40. My boss has one and I've been able to look at it in person. All those aggressive NACA style ducts tearing into the side of the car are functional. They are ducted to various locations in the engine bay, including the dual intercoolers. Look at the rear "window" of a F40, it's vented but slopes down very gradually so you don't have a huge low pressure area there. The combination of active ducting and a vented rear window allows them to cool the engine bay without adding too much drag to the car. One way to accomplish something like this would be to put a similar vented plastic sheet from the roof to the back of the trunk, cut holes in the stock engine lid for large fans, or take it out completely and find some way to duct air from the side of the car to the engine bay.

superpilun is offline  
post #117 of 178 (permalink) Old February 12th, 2008, 03:14
Registered User
 
Join Date: May 2006
Location: Rochester, NY
Age: 35
Posts: 332
OldTrader Rating: (3)
Pardon the hijack but; OMG thanks for the new background!
MosquitoXR13 is offline  
post #118 of 178 (permalink) Old May 26th, 2008, 18:29
Registered User
 
Join Date: Mar 2008
Age: 29
Posts: 45
OldTrader Rating: (0)
This may be of use.



Awesome discovery, might need to get me this program.
SM-Design is offline  
post #119 of 178 (permalink) Old May 27th, 2008, 00:05
Registered User
 
Join Date: Jan 2005
Location: Monroe, NC
Age: 38
Posts: 1,593
OldTrader Rating: (6)
Garage
This is a super interesting thread... we've been road testing many of the ideas/theories stated here and modeled. We've had interesting results, and have really made some progress on adjusting the airflow on the rear of the mk2.

In regards specifically to the "dead area" on the rear decklid... most people would be shocked to see what happenes to the airflow over the engine lid when the sunroof is out of a sunroof mk1... wow, it really changes up airflow over the rear, my word!! It changes things up enough to cause a closed and gas-propped S/C fiberglass engine lid (with no latch) to fly up at 80 mph but when the sunroof is installed and closed the car will run on up much higher with no hood fly-up issues. The same thing happens with the sunroof popped up. In fact I can close my engine lid/open it at will based on MPH and sunroof position. If I want to open the engine lid at 80+ all I have to do is pop the sunroof up... to close the lid I simply close the sunroof. This causes me to question the computer's correctness in estimating the volume of air flowing upwards through the engine bay. Unless I'm completely wrong it must be missing something there. It just seems to be somewhat underestimating it in pretty much every chart I saw. Also our aw11 stage two kit that we are working on the design of now (the engine cover specifically) should take care of this "dead air area" over the stock engine lid that we don't seem to care for, while also allowing for proper engine cooling. Awesome work guys! Very interesting stuff.

Addendum... Ok, just read a few posts above, and I agree with the folks stating that airflow is actually underestimated... at least that's what our road testing determined on the mk2 when we rerouted air directly from the engine bay... (stick with me here, and remember that warm air rises anyway naturally, it requires substantial force to reverse nature and cause otherwise) and added a bomex style whale tail rear wing. Individually, the wing didn't make much of a change... until the very free flowing engine cover was added, then it was like night and day different. The rear of the car has a noticeable amount more downforce at speed+. As we figure it, the air flows directly from the engine lid across the trunk and spoiler. Can't prove any of this without putting the car in a wind tunnel, but I drove the car both ways and know how much of a differance changing the engine cover made. The engine cover came from Ed's 93, and when it was on his car, during the winter his engine temps were noticeably lower with the free flowing engine lid, but only at speed. This is only explainable due to noticeably increased air flow through the engine bay. Since he changed his lid back to stock, I believe his temps are now back to normal through the winter. This was a very interesting experiment with the mk2, however, this might be completely different with the mk1 as a different amout of air may likely be flowing through the engine bay, but I found it interesting anyway and relevant to the topic.

Also was going to note, Bill... what you described is basically what I'm having dad draw up for our stage two engine lid. I'm tweaking with the design of the top edge currently, and with the hinge setup, etc. Not sure which wing will work best with this setup so I'm building at least 3 additional different trunks with various spoilers to interchange and test. One will have no wing... one will have the modded wing, one stock, and one big ole functional aluminum race wing... oh and one of our own design too... dad has his mind set on building a custom one as well. I'm also looking at doing flat underbody panels for the mk1. I've got enough trunks sitting around now... and about 3 too many spoilers, so it is time to get to work on that soon. So many mk1 projects... must... get... customer's Rustang... out of shop...soon... akk!!! To top it all off I just picked up my 4th MR2 (6th between me and dad's cars) today... our 86 hardtop widebody project car!

Last edited by curvesrgood; May 27th, 2008 at 00:35.
curvesrgood is offline  
post #120 of 178 (permalink) Old May 27th, 2008, 00:17
Registered User
 
Join Date: Oct 2005
Location: northern NJ
Age: 30
Posts: 1,051
OldTrader Rating: (25)
Since this thread has picked back up a bit...in case anyones interested, my MK1 model is available courtesy of twobrutal here: http://dizzine.org.uk/filestore/aw11.zip .max format (must use max 8 or later) materials and renderer are set up for Vray, so you will probably have to switch those around.
backspace is offline  
Closed Thread

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the MR2 Owners Club Message Board forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: (0 members)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome