Pele

iTrader: (28)

Looking to maximize the mileage I get out of my 1986 GXL... Part of that indluces reducing drag.

Firstly, which factory spoiler was included in the factory aero package?

The little duckbill (Sport):




Or the Wrap Around (GTU/Turbo) one:





Are there aftermarket spoilers that may be even better?


Secondly, what all do I need to complete the factory Aero package?

Anyone have pics of the tray mentioned in this thread: (It's old, the pics aren't working any more.)
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/aluminum-underbelly-pan-whats-point-242363/

Tray, Spoiler, Side skirts that fit in front of the rear wheels, Front bumper lip, Aero Mirrors... Is that it?

cmanns

I think the duckbill was S4 and the wrap around was S5...

The aero mirrors I think were S5 (with the hole) and the S4 aero was similar but without a hole?

glhs0867

On my 88 S4 GTU. I have the full wraparound rear fin, my mirrors are the Aero type with holes, and I also have 2 under engine air trays. One is a forward metal tray, and a smaller rear one. You also have small air deflector in front of rear wheels and front wheels..

SirCygnus

iTrader: (1)

yah. there is an aluminum under tray, and then there is the duckbill wing. there are also little rubber fins before each wheel mounted on the wheel well.

texFCturboII

iTrader: (17)

the s4 Aeros mirrors were a little more "orthagonal" the s5's were a little more rounded out.

glhs0867

Got any pictures that show the difference your talking about?

ericgrau

iTrader: (1)

The factory aero spoiler is smaller than all of those. Anything bigger is liable to increase drag if anything. It provides a small amount of downforce to match the downforce in front and back to keep handling balanced at higher speeds. Not sure if it actually decreases drag; I think only the other pieces underneath do that.

Mirrors account for around 3% of drag so you'd have to totally eliminate them just to get 0.01 lower drag coefficient. There are aero mirros but I don't think they're included in the aero package.

texFCturboII

iTrader: (17)

Not readily available. But a quick look at some s4 t2's versus s5 t2 will show ya. I do, however have backup:

From forum member: Metal

Quote:
Originally Posted by widowmaker88
what are the differences between the s4 and s5 mirrors?

S4 aero mirrors have more of a square hard edged cut through them opposed to the sleeker S5 aero mirrors.

ATRON3000

Want to decrease drag?

Then get rid of the spoiler altogether, and the rear windshield wiper as well.
Get rid of the side view mirrors and put in cameras if you need to see behind you.

daviddeep

iTrader: (4)

If you add all the factory "Aero" stuff to your GXL, I'll be interested to hear if it actually makes a measurable improvement in your fuel mileage. Honestly, I think back when the FC was launched in the summer of '85 aerodynamic drag coefficients were sort of the horsepower race of the day. There seemed to be competition amongst the automakers to see who could claim the lowest. I believe someone once demonstrated that the early S4 "duckbill" spoiler actually decreased drag while the '88 GTU/TII/S5 rear wing-type spoiler increased downforce while slightly increasing drag; for minimum drag, get the duckbill. While reducing your drag certainly helps some, I'm guessing the aero add-ons aren't going to have a significant impact on your real world mileage.

By the way, many of the suggestions you've gotten are good ones if you really want to be a rotary hypermiler: eliminate the rear wiper, shave the mirrors and replace with cameras, remove your front wiper arms and replace with Rain-X (though probably not street legal, but this is a hypothetical discussion). Of course you'll want to reduce weight too. And to get as low a coefficient of drag as possible, you'll want to go with as narrow a tire as possible; this will also decrease rolling resistance and boost your fuel mileage.

Per glhs0967's request, here are some photos of the different "Aero" mirrors that I posted in another thread a couple days ago. S4 style is on the left, S5 on the right:

jdm_emperor

iTrader: (6)

the black car with the sport wing is sexy,

cmanns

Any pics?

I didn't know there was more under trays and deflectors infront of the wheels

glhs0867

I will post up some pictures, when I get back home.

Thank you for the pics of the mirrors..I like my squared ones best..

ericgrau

iTrader: (1)

The great majority of drag is not to be had by eliminating little bits and pieces. It comes from the wheels, the radiator and the undercarriage. The mirrors are minor, though eliminating them entirely would help a little. The body form is major but much harder to change than the other 3 major things; you'd have to give your car a long tail like an airplane wing profile or something crazy like that. The factory aero pieces go in front of the wheels to redirect flow away from them. That's because if you're driving 100mph, the top of your tire is moving at 200mph creating tremendous drag. Smoothing out the under-carriage and the air flow around and behind the radiator would be the next logical steps. To some extent Mazda already did this, but you might be able to do more. The key is to give the air a place to go without creating voids in the wake of anything; so usually you focus on the back side of things more than the front.

As for gas mileage, aerodynamics affect high speed freeway mileage more than anything, with little or no effect on city mileage. So dropping the drag coefficient from 0.31 to 0.29 using the aero package would give less than 2 mpg at best, and probably 1 mpg or less. i.e., if you somehow managed to get 29mpg freeway from other changes and somehow installed frictionless tires, then dropping from 0.31 to 0.29 would ideally boost your mileage from 29 to 31 mpg.

daviddeep

iTrader: (4)

Please excuse the lousy quality of these photos at it is raining now, but they give you the general idea if you haven't seen these pieces.

The left picture is the air deflector for the front wheel shown from the wheelwell side. The middle picture is a front view of this piece and the adjoining tiny front lip. The right picture is the rear wheel deflector. These pieces were molded from a dense flexible foam rubber, I'm guessing the same material as the 86-87 duckbill spoiler. Many cars that originally had them have lost particularly the front ones due to unintended contact with curbs, concrete parking backstops, etc. People also remove them to be replaced with more modern-looking front spoilers or ground effects.

For '89 these parts were discontinued and replaced on the TII with side skirts and a larger front chin spoiler/lip. I think by '89 the drag coefficient craze had died down and was no longer a hot-button marketing point. Most prefer the looks of the S5-style parts, but I like the quirkier S4 stuff, especially since it is actually functional, even if it has a negligible effect in the real world.

daviddeep

iTrader: (4)

I'm torn myself. When I owned an S5 I found the mirrors were pretty functional, especially the right-hand one. I now have the S4 aero mirrors and I feel they verge on being useless. I usually turn my head before doing a lane change now. I don't know if they changed the curvature of the right hand mirror glass between the series, or if it was just that they were a tiny bit larger.

However, I agree that the more squared S4-style aero mirrors better fit the lines of the car.

Evil Aviator

If gas mileage is your goal, you would be better off reducing weight, installing the skinniest tires that you still feel are safe for your driving conditions, and driving at slower speeds and accelerating more slowly. In other words, you should not drive a sports car.

Parasite drag increases with the square of speed, so reducing drag isn't going to affect your gas mileage by any significant amount at city driving speeds as mentioned earlier by ericgrau. Driving 55mph or less on the highway will help gas mileage there. If your goal is to have better gas mileage at high speeds (150-200mph), then you will want wheel covers, a good custom front air dam, TII or similar side skirts, and a regular TII type rear spoiler will probably work fine or you could install a wing if you think more downforce is needed. You would definitely need upgraded suspension for these speeds.

You are correct, it was the Sport duckbill type.
http://www.aaroncake.net/RX-7/brochu....asp?Number=23

Probably not for reducing drag. Most aftermarket spoilers are either for looks and have basically neutral aerodynamics, or they are made for more downforce which will increase drag.

Sport spoiler, front and side air deflectors.

glhs0867

Are u saying the other fin styles are not standard issue?

Pele

iTrader: (28)

My friend Jason (Tofuball on here) claims to have gotten ~28 MPG in an S5 vert on a stock ECU, averaging around 70-75 on the Highway.

Stock touring tires on factory BBS wheels, Freeflowing exhaust (RB true duals), Cone filter intake, and ignition upgrades...

I'd say that'd be a good goal for me, considering the lower weight of the S4 GXL, but also the lower compression ratio.

Then I'm gonna pitch the stock ECU and gut the stock AFM and run a Megasquirt. I figure with the lower compression ratio, I can run eithe rmore advanced ignition or a leaner mixture.

It's not the ultimate goal, but more of a personal challenge.

daviddeep

iTrader: (4)

In 1986 and 1987, the factory "aero" package included the duckbill spoiler. By adding the full "aero" package to a 1986-1987 car, Mazda claimed the coefficient of drag was lowered from 0.31 to 0.29.

For 1988, Mazda discontinued the duckbill spoiler and replaced it with what is sometimes called the "GTU-style" wing because it was standard on the '88 GTU and the '88 TII. It could be added by the dealer to an SE or GXL by ordering it from the Mazda Finish Line catalog. Since these cars (GTU and TII) also had the aluminum undertray extension and the rubber wheel deflectors, you could say the GTU-style wing was part of the factory "aero" package in 1988, though I'm not sure Mazda called it that anymore. Also I believe by 1988, Mazda no longer made any claims about the "aero" package lowering the coefficient of drag, probably because the new wing was intended mostly to enhance the styling.

In 1989, the so-called "GTU-style" wing became standard on all coupes and the wheel deflectors disappeared. On the TII there was a new front lip and new side skirts. However, Mazda did not claim that these parts lowered drag in any way.

So to answer your question, yes the other wing is factory OEM, but it was not marketed by Mazda to be for the purpose of lowering drag.

Pele

iTrader: (28)

Besides, it's a moot point anyhow.

I like the GTU/Turbo/Wrap Around style spoiler.

Never was a big fan of the FC. I always thought it was too big and heavy and the styling was boxy and just kinda ugly...

Driving around this clean *** white 1988 GTU has kinda made the FC grow on me. If the wing is color matched to the body, it makes it look really nice. (Side moldings were painted to match the body as well. White with a blue/orange pearl effect in it.)

I'm gonna put the wrap around one on my GXL regardless.

ericgrau

iTrader: (1)

Better mpg w/o lost performance: follow scheduled maintenance, limit braking by keeping a good distance between yourself and the guy in front of you, coast long before a red light, keep a fairly constant throttle when cruising, tune lean (but leave a good safety margin to avoid popping your engine), reduce weight, Royal Purple oil (minor), avoid long idling or excessively low speeds (<30 mph)

Better mpg w/ lost performance: keep your speed down (as in mph, see myths), shift when the shift light says to shift, install a convertible (tall) final drive ratio in the differential

Myths: light acceleration helps mpg, cruise control hurts mpg

Proper maintenance, a lean tune and a convertible final drive ratio will do the most.

Evil Aviator

See the above post by daviddeep.

Just to clarify the above statement, aggressive driving sucks the most gas. Light acceleration at part throttle isn't all that efficient but beats the heck out of aggressive driving. The best method to save gas is to try to maintain your speed so that you do not need to accelerate very often. For those of you reading this who think it is confusing, which it probably is, see a test here:
http://www.edmunds.com/advice/fuelec...cle.html#test1