or basically...when is aero a tool and not a band-aid?

ive been running this through my head for awhile, and even more since a few threads and minor discussions have started about splitters and such. we all know that the general public is safer with under steer, but this can be bad on track. last year in fact i watched a few students under steer right off the track at lime rock in turn 2. i have experienced the rear of my car hopping around and getting a tad loose, and it certainly can make you (me) very uncomfortable very quickly.

personally im after a car that is as neutral as possible (for now), one that gives you confidence but at the same time makes you remember that you can overcook it with a mistake. lately, i have also felt that having a car that is more planted/neutral may be better for a somewhat inexperienced as opposed to under steer, and definitely better than over steer. thoughts?

im currently running 340whp, with no intentions of turning it up until i get a lot more seat time. now with the new nasa classing this has come to the forefront even more for me at least, as the option to run TT3 with an aero penalty seems quite appealing.

so...that being said in the eyes of the more experienced guys around here, and i'd really like to hear form those of you who are instructors (what goes through your mind when an HPD1 car shows up with a big wing?), when is it time to add a well thought out wing and splitter combo?

lets use an example car:
3150lbs no driver
350whp
ohins/ast/etc 8k/10k coilovers
using one of the common tires (rs3/star spec/nto1/hoosier)

what would you do, and why?

 

LOL, those example specs are almost my exact specs, and I'll be in HPDE 1.

Sub'd.

 

I'm running basically the same as you also. Except 10k/12k (which helps by the way).
I have the most trouble in the 80mph+ corners. Which is right in Aero territory.

I'm building a lip / undertray in the 4" area right now. In the hopes that the front will feel a little more planted in the higher speed corners. Eg. diving turn at LRP, Turns 3 and 5 at WGI, and Spoon at Calabogie. Of course all but 3 at WG are high speed downhill corners.

 

what speeds have you carried on to the front stretch at LRP?

im confused...i definitely thought more people would jump in this discussion.

 

Anytime someone shows up in HPDE1 with a race car the instructor is going to be seriously cautious. They will be far harder on a new student with a high powered or heavily modified car than someone who shows up in a stock Miata. I experienced the same thing when I started as my car was already making nearly 400 whp.

An HPDE1 driver does not need aero, they need seat time. My coach when he was teaching me told me that the three worst things you can do when learning how to drive are learning on a car with A) Too much power, B) AWD, and C) a turbocharger. I learned with all three.

The "right time" to add aero, power, or tires is when they are slowing you down... when you are at the limit of what you can do or would experience a substantial improvement in your driving from adding it. I added aero on my car when I started noticing how much time I was losing in high speed corners and felt my skill could handle it... the result? I went off at nearly 115 mph. Fortunately I controlled the car and it resulted in no damage, but my advice is to focus on learning as much as you can before making major platform changes.

 

so in your case, sounds like you were watching data acquisition above just lap times to see where you were lacking?

ill be honest, lime rock exposes things more than some other tracks i feel and the rear end was just not as stable as i expected (0 toe, -1.5 camber). im adding coilovers this year, so this season will be my experiment with springs and alignment but i feel like that is going to help turn in/under steer on entry, but not necessarily exit? and wont really have any effect on stability this is all with me trying my best to follow the slow in fast out mantra.

ive also done all the reading on the rear diff mods and how everyone loves it etc, but to me personally i feel like that would be equivalently bad for a rookie-ish driver who may/may not have great right foot control.

ive almost managed to go off at 100mph as is, were all gonna have off's nature of the sport. i guess its hard to believably prove through the internet that your after stability and not high downforce levels to go nutso fast lol.

 

when you say the rear is not stable, how so? is it trying to step out mid corner, unstable under hard braking, etc.

 

There is alot to say about this but my short answer is this.

I think that you first need to make sure you are using what you have already to its full potential. IMO this means that you are at full pucker factor anytime you are on the brakes, turning or doing anything but going straight. At that point, adding aero will help you get a bit of that comfort zone back. Going fast is all about being comfortable!

 

its just a feeling of a nose heavy car or "light" rear end, not twitchy really. it was a feeling of the yaw of the car increasing to the point where i felt the need to lift for a second.

i wanna hear the long answer. my goal is for this to be informative to help others make decisions.

 

Never lift!

 

Playing with your setup to achieve a comfortable turn in, mid-corner point, and on throttle behavior is going to take YEARS. There are some recognized things which can help and that will make you happier and more comfortable for the car. What I've been told by professionals including multiple Audi R8 Rolex drivers is that AWD cars will always understeer or push in the corners, its just a fact of life. You can reduce that with your setup, but its one of the trade offs.

My first season my car's suspension was pretty crap. I was on stock KW V3s with their extremely crap light rear spring weight, had no aero, relatively mild camber, and a stock unmodded rear diff. Getting the car to turn in was impossible. It would understeer on turn in, then plow wide, and getting on throttle early was impossible as it just made the push worse. This did not make for a confidence inspiring drive. I had to do things like throttle off snap oversteer to get the car to turn into corners and wait very late to get on power. Not a good way to get fast and if you make those kind of corrections mid-corner you can easily crash. Lifting mid-corner = bad.

Going to stiffer springs helped tremendously, getting some of the front end weight, and adding a splitter/canards helped, and the rear differential was huge. The car is hardly perfect, and its going to need lots more tweaking to get it where I know it can be... but by the end of 2012 I was able to turn in without understeer, get on throttle early and get on-throttle oversteer so I could get on the power way earlier than I was used to.

So if you are going after changes to the car to make it more controllable and comfortable, then I would recommend the rear differential change, stiff springs, and an aggressive alignment first then a good wing/splitter combination. The rear diff isn't something that I feel only advanced drivers need, I feel like the CAR needs it period. Nobody who tracks their Evo should drive without a proper differential imo.

 

^^^i need to meet up with you at an event, i feel like we could have some awesome setup conversation.

when i say let out its not a full lift as i know thats a good way to get in trouble.

im working my way right down the list of the well known setup changes. the setup i listed in the first post is basically what ive come to see as the most common track setup. last year i was on gtworx springs/bilsteins zero toe, -1.7 front/-1.5 camber rear, whiteline front/rear bars.

this year i am adding ohlins 8k/10k, and will be doing -2.5 front/-1.5 rear camber, zero toe front and maybe a tad bit of toe in rear and i will have a splitter to test.

i have obviously also contemplated doing the rear diff and/or an ACD flash. it just seems it may be a quick way to get yourself in trouble with the heavy power on over steer. how controllable is it? i mean, how often are you throwing in oppo lock? lol. my biggest question i guess has always been how progressive is the lock?

 

If you're talking about the re-ordering the plates in the OEM diff, all I have to say is, DO IT! The change didn't add "heavy power oversteer" like you're wary of. It just helps get rid of the push and keeping you on your desired line when getting back on throttle after a turn.

 

Great information... now to decide on which rear diff mod to go with!

Do I reorder the stock plates or do I install a shep config?

 

stock plate "mod" is free (other than fresh diff oil and gasket maker) so I'd start with that first IMO. That said, I've never driven an evo on an aftermarket rear diff.