Aerodynamism R&D

[GEN 3 SHO FAN]

This car with his 0.30 cx, is an exemplar of aerodynamism surpassing many sport cars until today but when I look under it, I'm not impressed...

I'm thinking for some time now since I saw the car jacked last time if the rear bumper cover is acting like a parachute. Lot of air circulating under the car may be kept by this big opening pointing at the front of vehicule...

I'm wondering if I put some kind of plastic splash guard (like the one of the front) to close this hole between spare tire well and bumper cover cannot help against a potential parachute effect. My project is to put a spare front splash guard on to the rear as it have already the round shape (but I will need to cut it for exhaust). How it will be held is not clear from now.

Anyone have tryed something there ?

Images are for exemple as they are for an other car and it's a near perfect system.

Some say on the net that it's help the car stick on the road at high speeds and the most important part in that system is the rear one.
At least, if I can save MPG, I will be happy.

 

[98SF19]

Interesting . . .
I saw in another Gen 1/2 thread they had a group buy proposal for carbon fiber rear diffuser, but I expect that wouldn't apply to Gen 3.
I don't think the rear bumper geometry has the effect you describe. A parachute is wide, and it's bulbous shape is what really provides the drag. Our cars' rear end geometry is fairly streamlined. Also, at higher speeds, the air trapped in this rear area stagnates to an extent and begins to develop a fluid boundary layer over which higher velocity air can pass with little friction. The diffuser not only reduces the volume behind the bumper, but also creates a solid boundary layer (and more of it) which aids in allowing more laminar flow at lower speeds. But I don't think a Gen 3 diffuser exists.

As for the mid-body and underneath the tranny, unless you're competing at a high level (not a reality with the Gen 3 IMO) and you've already maxed out all other upgrades, I think those would only create problems. IE the cats get hot and need the air flow. You already have the shield under the radiator which actually helps with it's cooling as well as tranny and PS fluids' coolers.

Having said all that . . . the pleasure a creative-minded hobbyist gets at pursuing novel ideas cannot be overstated.

 

[GEN 3 SHO FAN]

Thanks ! As the gas price always rising, I try to think about to save some money. What about a 8 speeds transmission ?

Seriously, I just want to put something more linear on the rear. The front have no big "holes" and become very hot and I rode somewhere it's a "bottom breather".

I will keep you informed if I found something, thanks for the infos by the way.

 

[GEN 3 SHO FAN]

Surfing on the web and onto this link interesting link to calculate (rapidely) the coeficient of aerodynamism of a car.
http://hpwizard.com/aerodynamics.html

I tryed it and it seems that what I found on cars guides from 96-99 was good (our car have a 0.30 aerodynamism coefficient, Cx) which is really good for that time and even today. Many sports cars and super cars don't have an areodynamism as good as this. Ford put a lot of money in R&D to reach that spec. Taurus was the figurehead of the company at this time. Thanks to Jack Telnack and his revolutionnary look. Sadly, his look was not popular and Mr Telnack takes his retirement from Ford as soon as 1997...

Today, in our square SUVs world (69% of vehicules in Canada in 2017 are pick ups, SUVs or minivans...!), this look remains very futuristic (like a "rolling saucer"). Probably because of the popularity of SUVs and other trucks, today car guides don't evaluate aerodynamism anymore... (at least, in those I checked). My old SLO with an OHV motor, can make 32 mpg and I suppose that this good spec help to reach such results.

I will put some others 1998 cars infos from car guides to compare later. (Don't forget that the smaller the car is, the better is the aerodynamism too. Also, 2 doors cars have a better spec than 4 doors.)

GM EV1 1996 : 0.195 (!) (first real electric car on a large production)
Tesla model 3 2017 : 0.21
Toyota Prius 2016 : 0.24
Mazda 3 2012 : 0.26 (!)
Nissan GT-R 2011 : 0.26
Hyundai Genesis 2009 : 0.27 (for Mr Nimz)
Infinity G35 2 doors 2003 : 0.27
Nissan GT-R 2007 : 0.27
Mazda 6 2008 : 0.27
Ford Fusion 2013 : 0.275
Porsche Boxster 2005 : 0.28
Porsche 918 2010 : 0.28
Corvette 98 : 0.28
Lexus LS400 98 : 0.28
Audi A6 98 : 0.28
GM Volt : 0.285
Audi A4 98 : 0.29
Toyota Prius/Yaris/Echo : 0.29
Lexus ES300 98 : 0.29
Mercedes E320/E420 98 : 0.29
Eagle Talon 98 : 0.29 (same for Eclipse)
Lamborghini Diablo 98 : 0.30
Taurus 96-99 : 0.30 (wagon : 0.34)
BMW 318i 98 : 0.30
BMW 528i 98 : 0.30
Porsche Boxter 98 : 0.31
Mercedes CLK 98 : 0.31
Contour/Mystique 98 : 0.31 (same for SVT)
Civic 98 (2 doors) : 0.31
Aston Martin DB7 98 : 0.31
BMW 740 98 : 0.31
Concorde/Vision 98 : 0.31
Cirrus/Stratus 98 : 0.31
Firebird 98 : 0.32
Aurora 98 : 0.32 (which was the direct competitor of SHO)
Accord 98 (2 doors) : 0.32 (4 doors : 0.33)
Taurus 92-95 : 0.32
Sable 96-99 : 0.32
Continental 98 : 0.32
BMW M3 98 : 0.32
Camaro 98 : 0.32
Ferrari F355 98 : 0.32
Porsche 911 98 : 0.33
Ferrari Maranello 98 : 0.33
Mustang 98 : 0.33
Ferrari 456 GT 98 : 0.34
Mark VIII : 0.34 (surprisingly)
Dodge Viper 98 : 0.35
Caravan 98 : 0.35
Windstar 98 : 0.35
Jaguar XK8 98 : 0.35
Mustang Cobra 98 : 0.36
Sunfire 98 : 0.38 (worst than a minivan !)

For the top of our car, a simple man can't do anything to ameliorate this spec. But under, I don't know.

 

[zak]

Did the 96-99 cars come with a lower engine cover? If not maybe adapt one from a 2000-2007 Taurus?

 

[GEN 3 SHO FAN]

I'm not sure what is the lower engine cover ...? The black plastic part under the motor ?

 

[zak]

Correct. Using one will decrease drag significantly

 

[GEN 3 SHO FAN]

They have one under the rads but it doesn't go under the motor.

 

[zak]

The later Tauri (2000 and up) have a lower cover. I know the 2001 subframe that I adapted to my 1995 has the little welded on nut plates to secure such a cover.

 

[GEN 3 SHO FAN]

I will try to watch this thing the next time at the scrapyard. Maybe the 2000+ is taller than 96-99 ?

 

[gamefanatic]

Maybe without going all in try something like this Plaskolite or might even be able to zip up some card board boxes. Just for testing at least.