Before you begin digging in to this post, get some popcorn, a drink and do a quick trip to the bathroom. It's gonna be a bit of a read.
One or two of you may recall my intro thread titled "Eco-Unfriendly" (see
http://ecomodder.com/forum/showthrea...dly-17772.html) in which I discussed running 200 MPH in my 2009 Mazdaspeed 3.
Unfortunately, due to limitations of the vehicle, drivetrain and powerplant, I've since deemed it infeasible and have abandoned the platform as the tool to reach my goal of joining the 200 club.
All is not lost, however, and the dream continues with a new vehicle; a 2-door 1965 Ford Falcon Wagon. Originally, I was going to chop and channel a pre 1967 Karmann-Ghia, but I couldn't find one that didn't need over a month worth of body work before the modifications could be done. I drummed up the above on Craigslist (which was listed for an AMAZING price considering the rarity of the vehicle in question), and body work has been ongoing.
I'm getting to within a month of being ready to chop the top on this thing, and that brings me to the point of this thread.
Ya see, the aero on this thing is pretty terrible; the Cd is listed as being 0.58 from the factory, which is terrible compared to my daily driver (2009 Mazdaspeed 3) @ 0.32. I figure if I can get the Cd down to 0.4 I should be in pretty good shape for 200 MPH in a standing mile event; the only issue is I don't know how much I can expect to get out of the modifications I already plan to do to the car (and this is where you folks come in).
Starting out, I've got a short list of comparative aero statistics between my Mazda and various levels of modification done to the Falcon; the ultimate goal here is to get as close to if not better stats than what my Mazda already has:
MAZDA FACTORY:
Curb weight: 3153
Width: 69.1 in
Height: 57.7 in??
Cd: 0.32
Frontal Area: ~22.427 ft
CdA: 7.176
FALCON FACTORY:
Curb weight: 2815 lbs
Width: 71.6 in
Height: 60 in??
Cd: 0.58
Frontal Area: ~24.165 ft
CdA: 14.0157
FALCON CURRENT:
Curb weight: ~1800 lbs
Width: 71.6 in
Height: 50.5 in Front, 52 in Rear
Cd: 0.58
Frontal Area: ~20.943
CdA: 12.146
FALCON CHOPPED & GUTTED:
Curb weight: ~1500 lbs
Width: 71.6 in
Height: 47.5 in Front, 49 in Rear
Cd: 0.58
Frontal Area: ~19.734
CdA: 11.44
FALCON FINISHED (hopefully):
Curb weight: ~3200-3500 lbs (or better)
Width: 71.6 in
Height: 47 (before ride height adjustment)
Cd: 0.40 (or better)
Frontal Area: ~19.734
CdA: 7.893
With those references in mind, I present to you the following is a list of tweaks I plan on doing to the car already (aero wise), with the goal of getting the 0.58 Cd down to .4 or lower:
Planned:
MASSIVE frontal area reduction (via chop top and lowering)
Slight windshield angle change
Side mirror delete
Door handle delete
Radio antenna delete
Badge delete
Rain gutter delete
Custom front bumper (rolled?)
90% front grill block (leaving enough for brake ducting/engine air intake)
Full aluminum undertray
1 piece front body clip (two body seams total; the "hood" will actually be a tilt front end)
These are the things I'm not too sure about doing or could use a little tiny bit more info (and yes I've already been through the master aero list a couple of times); items are numbered with my
questions to follow:
Uncertainties:
1. Tire Spats
If I do add these, I'd probably try to channel the deflected air to under the car, which might add a touch of downforce at speed. Considering I intend on having the car extremely low to the ground (within 3 inches) during the high speed pulls, will I even need spats? Might interfere with ride height adjustments or bottom out on bumps. My Mazda has these from the factory, so I can look at them for reference if needed.
2. Rear tire boat tails
I could see how these could help a bit, but I'm not sure how much of an improvement they will really be. Also, might interfere with ride height adjustments or bottoming out on bumps.
3. Radius front wheel arches
The result from doing this would have to be pretty significant for me to consider it. Any anecdotal evidence/science to go along with this mod? I didn't find any (though I didn't look too hard either).
4. Partial kammback or spoiler(s)
This mod I *know* would have real gains on this car, however, I'm questioning if it would provide more than just doing the sharp edge airflow separation/airflow trip. Any input on this?
5. Front air dam vs splitter
If I understand these two correctly, having a really low ride height means I may not really require a full air dam and might be able to get away with just a splitter, correct?
6. Rear airflow trip/separation
As you will see from the images below, there are areas that could use some improvement as far as unsticking the air goes. My question is, should this be done around the entire outside edge of the vehicle, or are there just specific points that would be needed to reach a level of effectiveness approaching diminishing returns? I'm also wondering how much of the factory body lines I should mess with at the rear of the vehicle.
7. Rear diffuser
I know these work, or they wouldn't be on supercars. I also know that some vehicles route the exhaust into them to help with scavenge; what I'm not certain of is how large they should be, sweep angles, and the like. Would an off the shelf one work, or should it be done custom with specific requirements (which I'm not certain about)?
Your thoughts/criticisms are appreciated.
On to pictures of the car!
(Click for big)
Next to the Mazda:
Lowered:
Rear modification reference images:
There's other misc images in the library.
Below are some other modifications I plan on doing to the vehicle which will help improve efficiency (and as a side effect, mileage); they don't really have any bearing on the focus of this thread, but some may find my plans interesting.
Misc Mileage:
Lean burn (maybe)
Variable displacement (maybe)
Fully polished/cryo-treated six speed manual transmission
REALLY low cruising RPM from gear ratio
Mild camshaft (tuned for turbocharging; low lift high duration)
Carbon fiber drive shaft
Lightweight engine internals/flywheel
Under-driven crank pulley (10-15%)
Dual electric water pumps
Multiple electric fans
Well, that's pretty much it until the discussion starts. Thanks for reading this far and for your input as a community.