donour

Ladies and Gents

In the spirit of class build threads that I have started on other forums, lets start the discussion of options for the V6 GC in SCCA D Stock.

* 2012 Solo Rules*: The Sports Car Club of America - Solo

For those new to stock class autocrossing, here's a general ranking about the importance of the available allowances.

1) Tires /wheels
2) Shocks
3) Power
4) Weight

This is different from most other forms of motorsports because the weight and power rules are so restrictive.

Tires: I suppose it goes without saying that top folks will be running Hoosier A6s. Sizes?

Wheels: What's the lightest we can find in OE size and offset.

Power: Is there anything to gain from drop in air filters and catbacks on the v6? What's the difference between 85 octane colorado gas and 93 or 100?

Weight: The catback and wheels are the best bet for saving a few lbs, but the gains will be small.


*Setup*

Alignment: I have my car aligned as follows:

Camber: -1.9 F / -1.0 R
Toe: 0 F / 0 R
Caster: ~+7.2

The car still pushes on street tires, but that's not a very good indication of how it will do fully prepped.

Sway bars: Bigger front or bigger rear bar?

Tire pressures: TBD.




,
donour

donour

[reserved for future posts]

donour

Reference threads:

alignment settings: http://www.gencoupe.com/suspension/6...r-setting.html
Koni shocks: http://www.gencoupe.com/suspension/8...ml#post1012240

ABQautoxer

Background: I'm an experienced autocrosser/track guy, with thousands of autox and track miles, etc. But, I'm no national champion so take any of my comments with that in mind. I've won and trophied at National Tours, trophied at Pro Solos and the National Championship.

Today I finally got a chance to drive my GC 3.8 Track on an autocross after having done a dozen plus runs teaching a PCA school. My car is bone stock other than tires as I wanted to have a basis and before throwing on the 29mm sway bar and camber bolts. Tires are 245/35/19f 245/40/19r. Temps were mid 40s and the course was mostly 30-40mph (no more than 45mph in the fastest car I drove today) as it was slow for novices.

This car really has a hard time putting power down, it will need the front sway bar IMO to fix this more than a rear bar as with my understeer doomed stock alignment balance wasn't nearly as bad as expected at low speed. Even with the LSD, it just had a hard time powering out in low traction situations. I don't see it getting better as the weight transfer is worse with more grip.

The ABS system isn't all that great. While the car is capable of good stopping, it was VERY easy to invoke ice mode in 1st gear situations, much easier than in a C5 vette IMO which is notorious for this problem in autox. This car really wants a two stage braking modulation much like the Z06 or even stock class Miatas where too hard of an initial stab after a full acceleration causes problems. I find braking 80% at first and then quickly going to full braking made it stop a lot shorter and didnt upset the electronics.

Power steering also I find to be an issue but this could be isolated to my car. I was able to get way ahead of the system in a tight slalom and lose most of the assist. This by itself isnt terrible but it was inconsistent so one gate you wouldn't have assist and the next you might. My PS fluid looked pretty terrible but I dont know if the OEM fluid has that coloration by default. When I got home I sucked out as much as I could and replaced it with some synpower stuff to dilute the old fluid and then did a bled on the system. We'll see how much this helps my car.

Balance on the car is pretty good in the sense it responds how I would expect and was much more nimble in transitions than I expected with the stock front sway bar and stock shocks. I think with good shocks things would only get better. Unfortunately I won't get a chance to do typical nationals sized courses until next month but I'm teaching another autox school next weekend in hopefully warmer weather and slightly faster course to get more feedback. I'll also try to string up the car for an alignment and install the front sway bar by then thanks to daylight savings.

Tom R

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Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport

GTIGuy

I appreciate someone posting "here's my experience level" so the reader can weigh the input accordingly.

I'm light on AutoX experience, heavy on road course. Before the season ended, I had one course and one AutoX on the car. Glad the grass is greening now and I'm just 6 weeks away from getting back on track.

Stock, I agree it takes some patience / throttle control to keep the rear hooked up and not oversteering ... it def likes to display its 'drift' handling slant. To the OP, a bigger front bar will help more overall since it's easier to oversteer this car than understeer.

I did feel a bit of understeer when I AutoX'd it, but I think that was poor driving on my part combined with rain. I'm more comfortable on road course and there I could feel no understeer at all ... I really loved the handling, and that was without extra camber, so looking forward to that improvement.

ABQautoxer ... Yep, there was an occassional "dead spot" in the power steering keeping up on fast left right work. Not isolated to your car. I guess we tell ourselves to expect it so we're not surprised. Holler if super fluid works.

ABS / 1st Gear? In my non representative experience I've never used 1st gear in AutoX ... are you running super tight tracks, or is there a technique / application I'm missing?

OP ... Hopefully others can contribute more to the D Stock knowledge base per your other questions. There's bits and pieces of this info, will be good to consolidate.

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donour

Thanks GTIGuy. Some of my questions are rhetorical, to get conversation started.

I agree with Tom that a large front bar is a good place to start. There's a lot of front, lateral weight transfer and the front camber curves are ... um ... undesirable. I have heard rumors of a 30+mm unit from whiteline, but I can't find it online. Getting good turn in and good exit is going to be the challenge.

About me: I've autocrossed for about 8 years, done pretty well at some national tours. I'm a midpack filler at nationals. I work for a large professional race team, have advanced engineering degrees, and used to teach at university. I like numbers.

donour

ABQautoxer

1. It was better today but I was only able to dilute the original fluid maybe 30-40%. I'll get some redline power steering fluid this week to see how much this helps. It's really only a big deal on a very tight slalom.

2. Tight courses can have you doing 1st gear from full acceleration to full braking power, even at a Nationals level if your 1st gear is tall enough and the course has a slow enough section. This is typically a regional problem depending on the site.

3. The OP knows more than most about car setup/dynamics, I think he is just leaving the topic open for discussion rather than cloud it as he probably hasn't had much time to test. This is due to the fact he works for a major professional racing team you have heard of and they have a near year long schedule where most of us are amateurs.

Feedback today, I ran my GC again in about 55F temps on roughly the same course and then ran my BS prepped Boxster on RS3 on the same course in about 60F weather and much warmer pavement. I was about 1.4 seconds slower in raw time, and if the conditions had been similar I think it would be about 1 second on a 37 second course which is about .5 seconds slower according to 2012 PAX. Not too shabby considering the course favored transitions and was tight (read as almost completely 1st gear) which the Boxster does best being somewhat narrow, mid-engined, and a 16" shorter wheelbase. On top of that the GC is stock. Hopefully more feedback in a week or two. I'm debating what to do about struts/shocks (OEM track, Bilstein Sports, or AST 41xx).

__________________
Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport

AutocroSSer

Video from today : course was a cooperative effort between Josh Salvage (trophied at Nationals in FP in 2010) and Heyward Wagner (multiple Nationals trophies mostly in ST_ and HS, works for SCCA National Office, "Mr SoloMatters").

Ed Runnion, SFR SCCA Rd2, Run4 (Fastest),, 47.511, 34 DS, 2012 Hyundai Genesis Coupe V6 R-Spec - YouTube

265/35R19 A6 all around, G35 Rays Wheels, Eibach 29mm bar on stiffest setting, stock shocks. For what it's worth, Alex Muresan (former DS National Champ in his Type-R) ran a 46.415 on the same course, also on his last run.

Tire pressures : 43F, 38R. STILL need to get it actually aligned, but "as much camber as I could get" up front (ballpark -2.0 degrees). Stock brakepads (for now), CNT Racing Catback, K&N Filter in stock airbox, CA 91 Octane.

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Ed Runnion -- San Jose CA
2012 Hyundai Genesis Coupe R-Spec, 3.8L V6, Daily Driver and Autocross Toy
1996 Chevy Impala SS, not stock (engine, manual trans swap, suspension, etc etc etc)
2006 GMC Sierra 2500 HD, Duramax/Allison, Tow Rig, not stock either

ABQautoxer

Thanks for sharing again Ed. Did you set the camber bolts to max neg but not check the toe yet (so its probably very toe'd out)? Just curious to hear the before and after. I'm installing my camber bolts after work today and doing the alignment tonight or tomorrow after work (strings/camber gauge). I'd be curious what rear toe you are running. I'm going to start around 1/16" rear toe-in per side on the 19s and zero toe up front.

__________________
Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport

AutocroSSer

No check yet, maybe middle of the week (Mon, Tues AND Thurs days and nights are shot already). Need to kick the Impala SS out of the garage and throw the GenCoupe in for a few days...more involved than you'd think due to how you have to jockey things around in my driveway (about 60 ft long but only about a foot wider than my car trailer!).

That said, for street driving I'm guessing it isn't as toe'd out as one might first guess (stock alignment fairly toe'd in??) due to the non-wandering nature of the car on the street as set now.

Do have the Longacre Toe plates and Camber gauge (along with an adapter I made out of some bar stock to make the camber gauge work with the G35 wheels center hub).

__________________
Ed Runnion -- San Jose CA
2012 Hyundai Genesis Coupe R-Spec, 3.8L V6, Daily Driver and Autocross Toy
1996 Chevy Impala SS, not stock (engine, manual trans swap, suspension, etc etc etc)
2006 GMC Sierra 2500 HD, Duramax/Allison, Tow Rig, not stock either

ernibal1musicman

So I went to my first event a few weeks back, and had no idea what class I was supposed to be in. The guys there said I was in ESP (i have a CAI and Quaife LSD) but is that correct? I know the 2.0's I went with were in DSP, and it seems the title of this thread make me think the op runs his 3.8 in D stock? if so shouldn't I be in DSP?

Also, If i ditched the CAI, could I run in stock class even though I have an aftermarket LSD? Its stock type (gear/helical) so I thought maybe I could? Thanks

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Current Car: Genesis Coupe 3.8 Base 6MT Nordschleife Gray

Previous Car: 1992 Camaro RS

AutocroSSer

Just a guess (but "sounds right"), the 2.0t would goto DSP and the 3.8 would goto ESP. That said, with those mods you're likely a lot more competitively classed (assuming on street tires with treadwear > 140) in STX.

Can't run stock class with an aftermarket LSD. Also has to be a configuration that theoretically COULD be bought from the manufacturer (so, for instance, can't throw the Brembos/19s/Torsen on a 2.0t Base unless you do EVERYTHING to convert it to a 2.0t R-Spec of the same model year).

Put another way, to run DS in your car you'd have to convert it to something that could be bought from Hyundai. I THINK you can get away with this on a 3.8 base by converting to an R-spec in terms of suspension, brakes, wheels sizes, Torsen, swaybars, etc but to be honest I haven't studied in-depth what the 3.8 base came with.

__________________
Ed Runnion -- San Jose CA
2012 Hyundai Genesis Coupe R-Spec, 3.8L V6, Daily Driver and Autocross Toy
1996 Chevy Impala SS, not stock (engine, manual trans swap, suspension, etc etc etc)
2006 GMC Sierra 2500 HD, Duramax/Allison, Tow Rig, not stock either

ABQautoxer

Also, a stock class designation doesn't mean its the same letter for the street prepared. So DS does not by default go to DSP. It's all about relative performance and the spirit of the class. My 2012 rulebook copy says ESP for all Genesis (09-12) all on the same line. If the Coupe falls into that line, you could swap a V8 in if you can do it within the limits of SP, I never noticed that before. If the Coupe doesn't fall into the line, there is a Hyundai catch-all in FSP - wouldn't that be nice but probably it goes in ESP.

Just got done in the garage. Camber bolts are in as is the 29mm Eibach front sway bar on the stiffer hole. Also the following alignment:

Front
-2.1
0 Toe

Rear
-1.3
3/32" Total Rear toe-in

Rear toe is a bit less than I planned to try at first but since it was perfectly even at that setting, I left it so I could at least try that first. FWIW Ed my toe setting once I maxed out the bolts was 5/16" of toe out, which I consider a lot. The car did not pull one side or the other, its actually a lot more nervous to follow ruts/grooves now that its at zero.

Running this just around a default lap in an unpopulated area of my neighborhood, it feels very different as it can put power down MUCH better and the front end doesn't seem to wash out as easily unless well overdriven into the corner. We'll see how it feels on course hopefully on Saturday.

Also I read the 2011 sway bar front endlinks part superceeds the 2010. Can anyone confirm this and what the change was? I want to swap for them if its an improvement if I can't find an adjustable endlink to put on the car instead.

__________________
Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport

GTIGuy

Great thread, subscribed.

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Track Pro Advisor. Visit and sign up at www.trackproadvisors.com, your safe source for track day tips & tricks, and a great place to hang out with those who share your passion! 3.8 R Spec

donour

I think the biggest gotcha with this would be interior bits and sunroof -- they have to match the trim you're going for.

This seems in line with what i've seen. I've actually never driven my car with stock settings as I wouldn't take delivery until the dealer installed the camber bolts and realigned. Your alignment settings are exactly what I would target for autocross. Mine has slightly less rear camber, but I'm still running staggered tire widths. I need to get off my butt and get some real tires.

It might be easier to just make your own endlinks. I did this for the evo and it was immediately copied by a bunch of folks at nationals. It's also cheaper than the off-the-shelf stuff.

donour

ABQautoxer

I'm pretty sure the rest could fall under Comfort and Convenience since they all potentially would provide "worse" performance.



I remember this I think. What did you use? The endlinks are roughly 8" long so not quite as long as SW20 MR2 endlinks but longer than most.

__________________
Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport

donour

www.cs.unm.edu/~donour/cars/evo_endlinks/

It should be pretty easy to adapt to any car with straight endlinks.

donour

donour

13.5D allows for the replacement of bumpstops for aftermarket shocks. It explicitly forbids increasing travel before stop contact. What is people's take on going the other way (e.g. extending the bump stop in order reduce travel before stop contact)?

donour

dsurzyshyn

I've noticed the power steering problem as well. it's very easy to get ahead of the PS, and if you lose the back end I'm often making a correction essentially without power steering. Is this a fluid issue? cheap PS pump?

Damon

ABQautoxer

No, that's an attempt to gain spring rate and would be illegal. Also I believe there was a ruling on bumpstop modification that the answer is you can't change them at all.

Awesome, this is my next project though I'm trying to be lazy and see if RMR wants to sell them.
It's actually not that uncommon. I had it so badly in my 99 Miata that I eventually did the swap to a manual rack which was an option that year. My C5Z06 had it but bleeding/better fluid fixed it. Last night I swapped out .5 qt of fluid with Redline power steering fluid and I had replaced .3-4qts on Saturday night. The fluid is looking much less murky already. I'll probably wait another day or two of commuting and then do the swap again. I'll be able to test it on Saturday when I teach another autox school and plan to use my car for ride-alongs. I think it will be better, just never entirely go away.

__________________
Tom

2013 Subaru BRZ Limited
2006 Lexus IS350 Sport