Aero resistance

The ´flap´ under the front I mentioned as a functional aero mod yes. I fitted one and noticed a difference at highway speeds.

Venting the bonnet could be felt, seen and ´measured´ by me.

Adding the lip behind the rear deck edge gave a difference observed  by both gfs.

Ok, not changing the car, perhaps marginal changes for some but then so is fitting a lightweight seat. The aero mods above were more noticeable than lightweight seats...

I have read at  two owners mentioning side wind instabilty being markedly less with the ducktail. Ditto passing trucks.  Maybe ist was a placebo effect but both theory and practice backs it up.

As to racing use, Spirit used a large rear wing and 3D wings were used by all the SuperGT teams. Same thing splitters/airdams/diffusers. 

Aero mods/gadets dó have effects. See the flap behind/between the seats and the mongos. With your smaller mirrors you will find that the effect of the mongos will be different.

Aero works for a surprisingly low speed.  Why remove a few kilos because it sheds weight and not add aero mods that have at least as large effects.

All in all this thread illustrates the title.

Posted by: @petrus

 

The MR2 Spyder is rather bad aerodynamically. It has a lot of lift and a lot of drag from turbulence at the rear. This turbulences also cause instability.

Secondly it is a lightweight car, meaning that aero forces have a relatively large effect.

There is no opinion involved in the above. It is well prooven science. Again; bícycles have been increasingly aero since the seventies!! Today hobby cyclist pay through the nose for aero bikes and the advantages are réal.We all get why the time trailists are tricked out slick for pedalling at 50-60 km/h.

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It is the WÓRSE for cars as those are inverted air foils; the drag creating lift!!

So what is it with the aero-resistance among Spyder owners??!! I mean; we all experience that this pop up mini flap behind the seat is aeffective in reducing back flow: A very small flap in an area of detached, slow turbulent air!
Ditto the effect of mongos.
Why the discarding of all other aero add ons?

  Lets get back to the crux of the discussion.   

 Granted the Spyder isn't the most aerodynamic vehicle but it isn't poorly  designed where aero is an issue.  In regards to having a lot of lift, drag and so on it's the first time I have heard this argument.  I have driven cars that I felt were bad aero wise like a Ferrari Testarossa when I taken it at speeds above 60mph and tried to take a corner with it and it lifted awkwardly. I have also felt the drag of cars like my Sisters G wagon when you let off the gas.   The Spyder never really had an issue that I'm aware of and it was designed well without any aero quirks that some cars are known for where it is clearly obvious.  Those that drive their Spyders fast that I have seen never felt the need for aero improvements and if there was an edge to be had it would have been adapted years ago and has for those that race on the edge to be competitive with a high large rear wing being the only aero mod that was adopted but it's not  necessary for street use or even all track events.   

 Im sure there can be improvements if we were to have a team of engineers add stuff  strategically but how much more improvement can be achieved if the car has no obvious aero issues to begin with. Maybe a marginal difference.   It would be a costly endeavor to find out beyond anecdotal accounts which can be very misleading.  

 A lot of times what is felt as lift uneasiness  can be traced back to shot or bad damper design if the valving is off.  I have experienced that when I first bought my Spyder and compared it to a relatively  new one.  

From what i observe, a lot of spyders that see track time generally see autocross time. aero isn't really that effectual at those speeds. However, an off-the shelf splitter plus an off-the shelf carbon wing made be a reputable company will be beneficial on tracks where the speeds are higher.

I doubt that TPS designed their rear wing in house. it's just a part they bought with the right width and adjustment for their purposes. their front splitter/lip area is quite exaggerated and i'm sure that helps to balance the aero forces.

I use a duck tail myself, but it's a stylistic choice in my case.

The duck tail may be a style choice for you but it does have are effects. 

The Spyder not having issues applies to the weight balance, geometry, suspension, engine at all to. It does not mean that there are no gains to be made. See the TRD optimo kit per example. Or the TTE Turbo. Or other Toyota blessed mods, including the off factory aero mod under the front bumper.

Just about ány aspect of the Spyder is subject to modding/improving, Take the bracing. One can go over the top there, add braces that only add weight yet also add stiffness without weiging the thing down. Heck TRD supllied a front brace!  Dev´s door spacer is a perfect example too; it works! even though the Spyder has no issue and quite a few drivers do not notice anything.

* even the most marginal of aero mods are is effective as taking a handfull of kilos off. The latter is applauded, the former... not. That I don´t get, sorry.

My opening observation about aero is that it ÍS a bit of the black sheep of mods among enthusiasts and I wonder why. I still do as I don´t get the rejection* but I do have an answer. So thanks for you time.

Most modern era cars produced in the last 20 years will generally get the aero right including mass produced passenger cars however mistakes can happen from poor engineering mistakes  but it doesn't mean all cars have gaping holes as they are designed well enough where aero should not pose a problem at street driven speeds under triple digits.  Aero usually becomes a problem at much higher speeds and most cars are speed limited either by a governor or just by being underpowered like ours.   Im sure what you do it in regard to the stylistic choices do make a difference like my carbon fiber  mirrors that probably reduce drag but it's so marginal  that the most I will probably get is a little better gas millage if anything but I certainly don't feel any faster.  The best I can hope for is the weight reduction of the mirrors  that adds up incrementally to where it can be felt as a global strategy of weight reduction, but adding more of something  like wings and things will negate that so it's a trade off and you have to come to some sensible conclusions of what is more important for the maximum gains.  The good news is if you decide on stylistic choices it doesn't really harm the car either and make it unstable because not all aero from manufactures that just copy stuff thats on other cars without actually tested it would be beneficial and could actually have disastrous consequences but that is never the case.   

 If I felt the car was lifting at speed or aerodynamically having some kind of instability I would currently entertain aero or just sell the car  but when the car hugs the road with great suspension and tires It leaves little room to entertain aero.   

In regard to the bracing it can make a difference but it's mostly a perceptive  one.  I use to think it reduces camber change and it might to some degree but it doesn't make the car grip any better. I think it makes the car feel better.  Same with my door bushings where it was tested by some members that autoX and on a few that have taken it to the track. The feedback I got was it did not change their times or gave them an edge which I suspected from my own testing but what it does is give you is feeling of increased body integrity which was felt universally.  I felt that it did more at lower speeds just driving around than it did at high speed.  Not everything needs to work or feel good at high speeds, sometimes just driving around with a solid feeling car can give you a sense of satisfaction.   

I hope I haven't turned you off with my counterpoints as Im just expressing my opinion and Im sure it is subject to be picked apart but these were my observations and the general view of most for almost 20 years since the Spyder was in production.  Im just expressing the general consensus over the many years and it should always  be challenged.

The TRD door stabilizers were met with all kinds of people that dismissed their effectiveness with various explanations that they couldn't do much of anything  but it didn't stop me from trying to prove their effectiveness.  It was so bad at one point that I was ridiculed harshly by a rude member but it certainly didn't age well in the end. 

For mé the most important thing of car behaviour is predictability. Second that it gives me feedback. Those two give me the confidence to push it to the limits of the combination of my skills and the car´s possibilities.

Concerning the latter I desire compliance to the surface. That enevelopes a world of difference circumstance: road race track and competition both have nóthing in common with having fun driving spiritedly on the public roads. The latter is, after four decades of cicuit racing, road racing, enduro and rallye, now my play ground. Now even thére. on the public roads, there are two almost opposing worlds; the highways & provincial roads vs the B- & local roads through the mountains.

The latter dictate at least OEM ground clearance, the former higher speed stability. If I need compromis, the mountains win.  The OEM  ground clearance / soft suspension / chassis compliance is a both  véry demanding and restricting framework.  Oh and lastly, I potter around in charming company. Although the ladies are very accomodating and tolerant; I do need to take their limits into account. Take brakes; those need to lack initial bíte, whatever I might prefer 😉  

And thanks for expressing it, but don´t worry about putting me off.  I´ve been pushing my limits on rubber since the mid seventies and know that my skills, experience, preferences, idiocrisies are mine; personal. I like to study an aspect, read other experiences, learn other opinions and those álways affect my next choices. It is progressing insight. So thanks!

Back to my idiocracies, preferences. You aero/arrow connction is só apt: When Japanese motorbikes entered my racing, it aided my riding to enter corners with a trailing brake; it stabelised the bikes. That came and went depending on the bikes and era and with the MR Spyder it is back. No, not the actual braking; you need to have that done before peeling off, but me wanting an ´arrow effect´. I lóath understeer so as an unavoidable consequence I have shifted the balance of my car slightly towards oversteer. Ok, I do like that but reducing yaw momentum* when entering the corner ... mwah, that I would like. Maybe a rear wing can. The resistance against aero has motivated me delving deeper into the subject which will aid me in setting it up. Agaín thanks.

* when peeling  off into a corner, the change of direction = a change in air flow direction and a rear wing can have an arrow feather effect. When a driver mentions that the rear feels more planted with a rear wing despite it not being reflected by G-forces registered, it is probably thát; a perceived improved stabilty at the rear.

Ah, your door spacers. As I use my car on the road there is no way to establish whether they make the car faster nor does it have ány impotance. The crux is that it make mé perceive more feedback from the car. As such they give me just that bit, however marginally, more control over the safety margins. 

Aero Resistance, sounds like a British punk rock band.