tfbmiata

Hi All - I recently added a turbo to my '02 LS. At a recent track day in ATL I went from peaking at 103mph to about 123mph. I run open top (because I'm cool) and have no aero at all. Anything medium high speed is starting to feel unstable at best and I started to think some rear downforce might be the trick. I like to have a fairly oversteery car, but also don't wanna feel like I'm barely keeping it on track at 70+mph turns. I'd prefer not to add a huge wing and as far as I can tell from research, seems that might not even be that helpful on a open top setup. Anyhow, I was hoping to get some insight from anyone who's had a similar setup. I suppose my next options are just to buy multiple different rear spoilers/wings to figure out what gives me a solid planted feeling in medium/high speed turns, but I thought I'd ask advice rather than just starting to blow cash!

highroller101

I have a gtc-250 rear wing for sale. It would solve your issue, but to maintain balance you’ll want to add either a front splitter and or an air damn

tfbmiata

I was hoping to find something a bit less wild as a solution hence the minimum. I appreciate the advice though now I know there's a definite solution with a big *** wing.

Fireindc

iTrader: (13)

The 9LR street wing is much smaller/lower, advertised to eliminate lift in the rear without any added drag and not need a crazy front splitter/dam setup. My car feels super dialed with it.

Probably not what you are looking for though, it's still pretty wild. heh.




You might wanna look into the blackbird fabworx spoiler on a spare trunk lid. Definitely calms down the rear, but it's a pretty high drag piece, as spoilers tend to be.

Gee Emm

First of all - put the bloody top up! Be fast, even if it looks uncool.

I was surprised at the added rear end stability/DF an MSM deck spoiler provided. This on an atmo car though, it would help tame the rear end lift problem and give more confidence in the fast corners.

A turbo car probably needs more, and it has the grunt to overcome the added drag of a wing. And the DF will make lap time. The wing will need a splitter/dam of some sort to balance that rear grip, or you will understeer off at the first corner.

Check out the aero section here, lots of detail/advice there.

sixshooter

iTrader: (12)

I have the rear spoiler that rivets to the trunk lid and it settled the rear of the car significantly over 130 mph. It kills lift. Put up the top to stop confusing the air and you might go faster too.

tfbmiata

I don't hate it! How easy would it be to remove between track days? I noticed in their installation pics, the instructions seem to only say to screw in through the trunk surround, but then the pics have 3 bolts on either side of the rear part of the trunk. are those actually necessary or are those just that dude's car?

Which one is that?


Thanks for the advice everyone else! To reiterate, I'm looking for the low point of entry (in crazy race looking *****) to create enough stability to inspire confidence. I'm not going for the best possible lap times around, just for the best I can do with what I have and do that with confidence I'm not going to end up in a wall. My setup is very oversteery so I'm not sure I'll hate having a little more understeer in my life tbh. As winter turns to summer, I might end up with the top up anyways just to keep out of the sun and so that might make a spoiler like the one mentioned by sixshooter a better option too.

rascal

If you have no aero now and your car is ‘very oversteery’ then I’d be fixing that via suspension and alignment before I’d use a rear spoiler ad a bandaid. Otherwise It will still over steer on the slower corners.
fwiw my nat asp car was very neutral through 125mph turn 1 at Phillip island with just the factory Tupperware kit.
now with rotrex and front splitter / rear wing it still feels neutral at 145mph in turn 1, just with more grip.

Gee Emm

Rascal's point is really important, and bears emphasising - get the mechanical handling right first.

If the car is mishandling in low speed stuff, fix that first.

Then look at the high speed handling, where aero can be a factor in contributing to both the problem and its solution. The NB is known to generate rear lift at high speed, a spoiler will settle that - as pointed out, that might just be a MSM spoiler (worked for me).. After that you can look at aero from the point of generating lap time, with confidence that you have a good mechanical package as your base.

sixshooter

iTrader: (12)

This is the spoiler https://www.rspeed.net/miata_trunk_s...p/na0-4622.htm


As mentioned above, working out the mechanical aspects first goes without saying. To that end, if your pinch weld heights are even front to rear you will benefit to changing that to one quarter inch of rake. That will make the car handle better in many cases and will settle the rear a bit at speed.

OptionXIII

As someone in a situation similar to OP, I am a bit surprised to see all the emphasis on suspension vs aero in the comments. Of course you need to get the suspension balance right and aero isn't the first tool you should turn to, but I like different behavior at different speeds. I like a neutral to loose car at lower speeds and am happy with my handling there, but as speeds increase I find my stock bodied car can feel a bit "nervous".

Adding more rear downforce (or reducing rear lift) would seem to give me exactly what I want, a car that goes more to understeer as speeds increase. Am I missing something?

Gee Emm

Yes you are - reducing lift/adding DF at the rear will make it more understeery as speeds increase. You want to do that at the front, if that is the end state you are looking for.

But are you SURE you want a twitchy car at high speed?

I'd go the other way, twitchy/highly responsive at low speed, more stable at high speed - but YMMV, that is only my preference.

OptionXIII

I think you misread my post. I want just what you're describing, a car that gets more stable at higher speed. That is why I'm interested in increasing rear downforce.

The problem I have is that it's pretty easy to find ways to cut both lift and drag in the front. It's the rear of the car that seems harder to add downforce to without committing to the racecar look. Hence my interest in a spoiler that is a bit more... aesthetically minded than say a Blackbird spoiler or 9LR Street ****.

Gee Emm

Yeah, I misread that, I read you wanted looser at high speed - duh.

You are tight, adding grip at the rear will move the balance towards understeer - I guess the question is how much that balance has to change. If you are having to regularly apply big steering inputs to control the rear, a modest spoiler may not do enough. If the control inputs are more subtle/modest, then maybe a small MSM-type spoiler would be enough. This may well be a case of suck-it-and-see, starting with a best guess solution, and working from there.

I can only add that the addition of an MSM spoiler to a bare NB bootlid transformed my otherwise well balanced atmo NB8A from twitchy bum-tightener through a particular 170-175kph corner to a confident take-a-deep-breath-and-send-it.

OptionXIII

Since this is a US centric site and this is from the UK, I doubt anyone here has tried it, but I'll ask anyways.

Anyone familiar with the Track Car Aero brand wing? It's pretty much in line with this thread... easily removed and no cutting to the trunk lid. It's small enough that I wouldn't mind running it on the street when I'm set up for the track.







The only info I can find is testimonials from random users. It'd be nice if there was any data I could find on the airfoil shape. I'll reach out to the manufacturer, but I figure I'll poll MT.net as well.

It's certainly not 9LR quality, but I can't get myself to install a wing that will make my car look like I'm trying to turn a Miata into a Plymouth Superbird.

tfbmiata

Thanks everyone. To those saying to fix the suspension, I actually love the low to medium speed oversteer attitude of the car, I don't want that gone. What I do want is what aero provides which is more stability at the higher mph. I'll be taking a look at that spoiler as it is probably just what the doctor ordered. If when I do it, I'll report back.

Fireindc

iTrader: (13)

I found them and made a thread here a few years ago seeing if anyone had any experience, but got minimal to no feedback. I agree that it's closer to what OP is looking for.

It's called the Thuperbird, TYVM!

flier129

iTrader: (7)

100%, put the top up before you even buy anything. That alone might net you an improvement.

The 9LR street **** was my brainchild. I saw Moti leaving the market on his BBFW spoiler and saw a need for a mild rear aero setup that's still affordable. It will certainly help to stabilize the car and the bolt holes are the same for it and the big **** so you can upgrade later on easily if you want.
Ok, now that official response is done. If you're cool running with the top down, I doubt you're worried about lap time. I'm in the camp of "non-aero cars are more fun to drive", so my personal $0.02 would be to keep driving as is and have fun

OptionXIII

The feedback I've gotten on a Trackable Miatas Facebook post is that the Track Car Aero wing is a copy of an OEM Mini wing, and the owner has no idea what profile it is. He just copies it. Johnny C also mentioned that at the height of that wing, a ducktail spoiler may actually work better.

As someone chasing the same thing as OP, at this point I'm leaning towards a spoiler like the Carbonmiata Longtail. It's not going to give me a multi second per lap improvement, but it's a step in the right direction. I've been looking for any other option because I have heard CM might take 6 months to get me something. The DCN Performance spoiler isn't bad looking, but a bit more "bolt-on" than I would like.

If I could handwave what I want into existence, I'd use a ducktail spoiler to hide the mounting location for wing uprights that bolt to the bodywork right next to the trunk lid, and install/remove the wing as needed. That would give me enough rear downforce to get a quick install/remove front splitter like the RGR setup to reduce both lift and drag, without creating a car that wants to kill me going into T10 at VIR.

tfbmiata

Personal lap time yes, but not to the last tenth or hundredth. I'm still too new to it and definitely don't have the time/effort ability to put towards really chasing something. What I was chasing is a little more fun with the turbo and now that it is in there, a little less "fun" with tail happy high speed activity.