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It's official: Nissan GTR moved to SCCA Solo Super Street in 2015 (with a catch)

5K views 32 replies 5 participants last post by  AutoXGTR 
#1 · (Edited by Moderator)
For now, only the 2009 - 2011 are eligible to compete in Super Street. 2012+ remains on the exclusion list.

http://www.solomatte..._moves_for_2015

Woohoo....so I guess the GTR will see much more autox next year and the Evo may be for sale.

Quite interesting that I just wrote a letter a couple of weeks ago and came home to find this today. Thank god, all these years of resisting to modify the car is all worth it now.
 
#2 · (Edited by Moderator)
Nice to hear about this.

Using a 2009-2011 Stock GTR for Super Street Class SCCA autocross-

The OEM runflats are OK and better than many other non runflat tires, of the options, the OEM Dunlop SP Sport Maxx GT 600 DSST CTT is the fastest (on track) and can be mounted on both front and rear OEM wheels using stock suspension which I would think is the best option. However in 285/35-20 there are three versions, each with slightly different tread depth and tread designs:
Year Front Size Rear Size
255/40RF20 (97Y) 285/35RF20 (100Y)
2013 8/32" 9/32"
2014 7/32" 7/32"
2014 NR1 6/32" 7/32"

For standard version for 2009-2013 MY GTR in 9/32" tread depth tirerack.com has it listed for $516 each, 39 lbs, 200 treadwear for all 3 versions
For 2014 GTRs or later in 7/32" tread depth, $549 each, 38 lbs
For Nismo GTR (NR1 version) in 7/32" tread depth, $583 each, 38 lbs, (front tire size is 6/32" tread depth)

You can also use the Bridgestone Potenza RE-070R or RE-070R 2 in 285/35-20, 140 treadwear, they cost less and also have different tread depths, 8/32" for the R2 (40 lbs, $467 each) and different tread design. RE070R is $485 each, 39 lbs, 9/32" tread depth, tread pattern is less aggressive.

For better wear you can use Dunlop SP Sport 7010 A/S DSST (ultra high performance All season tire), 240 treadwear , 10/32" tread depth, 40 lbs in 285/35-20 $520 each. The tread design is not for performance/track type driving so grip will be less but durability will be better and will last on street longer than the runflat summer tires.

Expect the runflats with 7/32" tread depth or less to perform better for track or autocross but when combined with street use they may wear quickly.

For Non runflats you can again use 285/35-20 front and rear, this will help a little to reduce understeer from providing more front grip.

Extreme Summer tires:
BFG g-Force Rival $305 each, 4 rib tread design, 30 lbs, 200 treadwear
Hankook Ventus R-S3 version 2 $298 each, 31 lbs, 200 treadwear
Goodyear Eagle F1 Supercar G:2 about $244 each, asymmetric directional tread pattern, 29 lbs, 220 treadwear, tires different for Right and Left sides of car.

Additionally, the GTR may be eligible for Super Street R class (use race tires)
For R compound tires in that size-
Toyo Proxes R888
285/35-20 on front wheel, $378 each, 31 lbs, 100 treadwear
315/30-20 on rear wheel, $418 each, 33 lbs.
Or
Nitto NT-01 Road course track tire, comes in three sizes, 100 treadwear
255/40-20
285/35-20
315/30-20
All are OK for the GTR.
 
#3 ·
Also legal for Super Street class in SCCA-

DOT Street tires of treadwear of 140 or greater, after 1/1/2015 treadwear 200 or greater
Any one swaybar mod- you can try the thinnest rear swaybar that is adjustable and see if that alone can reduce understeer without increasing oversteer.
Any drop in air filter
Any Cat back exhaust- titanium exhaust would drop weight, make sure noise level is less than 100 dBA at WOT
Any engine oil
Silicone hoses in OEM sizes and locations
Any wheels of OEM size and diameter with offset of + or - 6mm and wheel diameter can be increased or decreased by 1". Custom lightweight rims are costly but legal. Aftermarket 19x9.5" fronts and 19x10.5 in the rear could work. Use tires 285/35-19 on both front and rear wheels. BFG Rival, Kumho XS and Bridgestone RE-11 come in that size, 26.8" tire diameter is very low but will work. Wheel gap will be large but it's OK. 99 load rating is low but OK for autocross and one person.
Any aggressive alignment using OEM suspension parts to adjust toe (zero in front) and give max negative camber in front, adjust rear camber to about -1.6 degrees, rear toe zero to slight toe in. Note that aggressive front negative camber will wear front inner tire treads FAST.
Roll cage/bar is legal, not required
Racing harness is legal, not required
Accessory/additional gauges are legal
Data logging instruments are legal
Any shift knob
Any video cam
Any brake lining
Any lightweight 12V car battery

No coilover sleeves or lowering springs
No aftermarket ECU Map
No aftermarket suspension bushings to adjust negative camber
No changes to the OEM engine unless specified in rules
 
#4 · (Edited by Moderator)
Thanks for listing out all of these. For some reason, I have always thought the Dunlop runflat has 140 tread rating, but boy, at 500 a piece, that's like running A6s. Still would like to know if it is truly faster than the Rivals. Apparently, BFG is planning to have a version 2 of the Rivals soon. They were testing them right after the Nationals.

Before you go out to stock up on the Dunlop runflats, there are a few caveats which I think make these tires not eligible for Super Street (that is if you want to compete in the Nationals, for local events, you will likely be ok). I am quoting these from the rule book:
13.3 B2 says:
"Tires must be equally available to all competitors. Tires that are in short supply do not specifically violate Section 13.3. Extensive shortage may result in tire being placed on the exclusion list until supply is replenished. Tire variations differing from standard specification, delivered only on a limited basis, or only to selected competitors may not be used."

13.3 B3 says:
"Tire models must have tires available in at least 4 rim diameters and in at least 6 sizes which meet these requirements."

Also, the rule book does not mention about tire diameter, so I am not entirely sure that we can run a shorter tire by going to 19 inch wheel.

As for exhaust, does the stock midpipe have a secondary cat? I think it's just a resonator, if so, then I think we can run an aftermarket midpipe plus the rear section.
 
#5 ·
It's hard to say which 20" street tire will be the fastest, it may depend on how you drive, what tire size you choose front to back and what surface your events have.

I would think that the Dunlop Sport Maxx 600 in almost any form would be the quickest. Using the 2009-2013 version would give you the most tread depth for wear but initially may be a little slower.

It's hard to say which of the Extreme Summer tires will be best for autocross, you just have to try them out. With contingencies influencing which tires we see at Nationals, you have to do some head to head testing which I thought Grassroots Motorsports did with the Rival when it came out. My feeling is that the Rival is easier to drive for most and that the times are pretty close, in that case, choice of tire size and price is a factor.

The other problem is who else is in Super Sport Street and even with the best DOT street tires, will the GTR be able to keep up in "stock form". The answer is no, which is why SEB should have allowed the GTR into SS long ago. The Lotus Elise or a recent Corvette will have a better chance to do well in SS or SSR. But on the local level it will depend more on driver skill than the car.

To be at it's best the GTR needs to dial out understeer and maximize grip to the tires, usually by means of suspension upgrades, full coilovers, adjustable swaybars front and back, and more negative camber in front via Whiteline control arm adjustable bushings or an adjustable front control arm. Add wider than stock front wheels, wide rear wheels and very wide tires that still fit under the fenders or even use a wide fender kit for clearance. Short of those things, other power mods are not as big a factor. A simple midpipe mod with any ECU MAP tune, plus or minus cat back exhaust or large air intake will work, no need to go all out on power unless your autocross course runs top speeds of 70+ or you do prosolo, then up the power.

For tires, I don't think tires that work for the GTR will fall into the exclusion list, even if in short supply, they usually come back into stock in a reasonable time. Tire diameter is not an issue for non runflats, even the Bridgestone RE-11A has 4 diameters, most have 5 or 6. But you are right, many of the exotics come with tires that only come in very limited sizes and diameters. Using the OEM Dunlops there are only 20" tire sizes. That's a problem on the national level but probably not on the local level. Someone should ask SEB what gives?

For the exhaust, cat back exhaust is allowed. Cats are found on the OEM down pipes and on the midpipe. In theory, you need to leave both DP and midpipe alone and mod only after that. You're not supposed to use a midpipe with no cat, and or a high flow cat. The OEM downpipe has a resonator but you don't have to keep that. I think on the local level you could get by with modding the midpipe and or the cat back exhaust but on the national level you can hear the loudness of the exhaust and an inspection will reveal what you have from below.

So my initial impression is great, allow the GTR into SS class. This gets people in the events instead of watching from the sidelines. Once they try autocrossing they will either love it and think about modding or they will be frustrated. I don't think it is that easy to drive a stock GTR well. You have to be wary of the weight and manage it and avoid understeer when possible.

Here is a video in three views of my last event-


The run was good for 2nd on raw time out of 101 drivers, I lost by 0.1 second on a 48 second course, and 2nd on Pax overall, lost by 0.09 seconds. I am on Kumho V710 315/35-18 tires and 18x10" wheels square. You can hear the tires on hard turns (3 U turns) and slight understeer briefly occurs.
 
#6 · (Edited by Moderator)
For the exhaust, cat back exhaust is allowed. Cats are found on the OEM down pipes and on the midpipe. In theory, you need to leave both DP and midpipe alone and mod only after that. You're not supposed to use a midpipe with no cat, and or a high flow cat. The OEM downpipe has a resonator but you don't have to keep that. I think on the local level you could get by with modding the midpipe and or the cat back exhaust but on the national level you can hear the loudness of the exhaust and an inspection will reveal what you have from below.
If I recall correctly, if the car comes with cat in two stages, you can remove the secondary one (the one that is not attached to any O2 sensor).......I guess I have to check this, I'd rather not go back to the stock midpipe.

As for whether it be competitive or not, hard to say, if we are forced to all run on similar street tires, I feel the GTR may have a traction advantage and the Vettes/Porsche may not be able to put down the power as well. The Lotus will be tough to beat though......I guess I will find out how my car fair next year and decide. Will try to get some hot shoe to co-drive for the season.
 
#7 ·
Not sure that it would be legal to remove both OEM cats for Street class GTR.
see
http://www.sccaforums.com/forums/aft/35330
last post on page 1

or see post from PZ
http://www.mazda3forums.com/archive/index.php/t-233952.html

So for Street class you cannot modify or remove emission control devices. Further if you do replace the midpipe you need OEM cats. I guess you could put a straight pipe after the secondary cats and forget the mufflers. Might be louder than 100 dBA.

Getting back to the question of Dunlop 600 runflats coming only in one tire size, by virtue of those tires being OEM for the GTR I think that is why they are allowed for Street Class.

For the GTR in SS the biggest problem is weight. You have to move around a heavy car, 1800 lbs more than the Lotus. That's like stacking a lotus on top of another one. Agility is another thing, the Lotus can turn on a dime, the GTR requires some planning to drive the right line and get rotated around sharp turns.

Again an outside video of my last event, of the first three runs the 3rd was fastest, the 4th run was another 0.5 sec faster but did not come out.

If you watch how close the GTR can turn left around the cones it's not bad.
 
#8 ·
Getting back to the question of Dunlop 600 runflats coming only in one tire size, by virtue of those tires being OEM for the GTR I think that is why they are allowed for Street Class.
Thanks for the links. I guess the midpipe is a no go. I will try to find some loop hole around this.....lol

But on the tire, I think the keys are the part I posted in red fonts.
1) The OE Dunlop is made specifically for the GTR, so it is not available to all competitors.
2) This tire only comes in two sizes and one rim diameter.

Furthermore, Section 13.3.C.1 says:
"Any tire which is OE on a car eligible for Street Category may be used on that car in Regional Solo events. OE tires must meet all requirements of Section 13.3 to be eligible for National Solo events."

The point is that just because it's an OEM tire doesn't mean it is eligible for the Street class, so you can't go by "logic" when trying to understand SCCA rules. It's like when they used to call Stock classes, but we know they are not truly "stock" in a sense that it is completely out of the showroom.

Again, maybe you are thinking about local/regional events, but don't count on the runflats being eligible if you plan to do any National Tour or ProSolo.
 
#10 ·
Very steep uphill battle indeed. I agree.

However the first step is to be legal and listed as eligible, we didn't even have that option until now.

If that will mean more GTRs will come out to autocross as least regionally, then so be it.

Perhaps the other benefit is that if GTRs do autocross we can get more feedback about which non runflat Extreme Summer tires work.
 
#12 · (Edited by Moderator)
Should be about 35mph. Why you ask? You thinking about running a shorter tire?
 
#14 ·
Correction. 1st gear @ 6400 should be about 35mph (using a final drive of 3.7).

Nissan website lists:
Front final drive ratio: 2.937
Rear final drive ratio: 3.7

What does the 2.937 stand for?
 
#16 ·
For understeer-
http://www.drivingfast.net/car-control/understeer.htm


Whether to change any swaybar will depend on your wheels/tires and suspension mods if any-

For mods to reduce understeer the one biggest change would be larger 285/35-20 tires on the OEM front wheels.

Now that the 2015 Nismo GTR has 20x10" OEM front wheels, can SS class GTRs use 20x10" in the front too?

As for gearing, I run 315/35-18 tires which have tire diameter of 26.4" vs OEM 28". I shift out of 1st into 2nd as soon as possible usually within the first 3 seconds of the course, I never max out 2nd gear and will often hit max speeds of 60+. I suppose if the max speed were 70 I'd think of 3rd. I never downshift. I don't use 1st gear because it's too low and there is enough torque at low rpms for the GTR to use 2nd gear ASAP.

For which street tire to use may depend on tire company support and contingencies at Nationals. I'd start with BFG Rival then Hankook RS3 but have not used either yet.
 
#17 ·
Now that the 2015 Nismo GTR has 20x10" OEM front wheels, can SS class GTRs use 20x10" in the front too?
Going by the rule book, Section 13:
"Option package conversions may be performed between specific vehicles of a particular make and model, but only between configurations from within a particular model year. Such conversions must be totally complete and the resultant car must meet all requirements of this Section."

So, no, you cannot do that. In the hypothetical scenario that the 2015 GTR is allowed in SS, you still need Nissan to offer the Nismo wheels as a stand-alone option for the regular 2015 GTR for you to be able to swap those wheels.
 
#19 ·
Well, I had my second event on the Rivals this weekend, and I can understand why everyone flocks over to RS3 now. Now, I haven't driven on the RS3 yet, so my comment is strictly on the Rivals at this point.

Goods:
Crisp turn-in
Good margin of slip angle before it breaks totally loose
Shoulder takes up the beating by the GTR weight amazingly

Bads:
Needs lots of temperature for the tires to work. Think throw away your first run and possibly 2nd.
Steady state cornering grip is definitely lower than the OEM runflats (and I am only comparing my very old first gen Bridgestone)
Very loud (makes you think you are killing the tires all the time)

Overall, it's still a good tire. It needs to provide grip at a lower temperature and perhaps a even stiffer sidewall to work for the GTR. I had to bump up the pressure to 38-40 before the fronts start holding for me at turn-in. Not sure how the RS3 will work on the GTR, but it will be something that I should find out next season unless BFG releases their new compound for the Rivals before the NJ Tour in May.

For reference, my time this past weekend was about 1.3 off of a 991 Carerra S running on RS3. The car was driven by a pair of very good drivers in the NJ/NY region, so this gives me a bit of comfort that the car may just have a very tiny shot at being competitive in the class.

My first thing for next season will likley be trying out the following:
Alignment (will play with toe)
Tire/wheel (offset and RS3)
Front sway bar

If the above can bring the car within 0.5s of the 991, then I may think about shocks.
 
#20 ·
Not sure why you are eager to change the front bar.... Stiffening the front bar alone is going to make the car push more....everwhere

I would recommend wider tires first, followed by shocks and then determine which bar if any you want to play with. Also are you staggering your pressures front to rear? assuming a square setup, rear trye should be at least 4 if not 6 psi lower. Another simple and easy thing to experiement with is to just disconnect you rear bar for a session, the rear bar is so wimpy it wont make a huge differnence but can give you some feedback wihout having to buy anything. My guess though is if you get everythin gelse right corner exit will cease to be a problem and you can instead focus your efforst on fixing other important things
 
#21 ·
I have been wondering when you would start chiming in


To your points,
1) Tires - Remember I am not in the unlimited budget SM class, so I am already running the widest tire available in the street tire class (285 all around). I have already looked at both 19/20 inch options, although RS3 has a 305 option in 19 inch which I could run in the rears, but there is no workable sizes for the fronts because the fronts are limited by the 9.5 inch wheel as well as no correct overall diameter to match the 305 (the 305 in 19 is a bit taller than the OE size).

So given this, I am going to minimize (max out depending on how you see it) the front wheel offset (since we have +/- 7mm to work with in Super Street) to get a wider front track and hope that will change the balance a little bit to help with turn-in, while keeping the rear offset at the OE spec.

2) Tire pressure - at the last event, I ended up with staggered tire pressure (38 f and 34 r) which seemed to work OK for the Rivals.

3) Sway bars - I know the front bar will likely induce more push, but I was thinking it may help to reduce body roll and plant the rear a little bit at corner exit. But you are right, I should probably try disconnecting the stock rear bar to see if it does anything or not. To be honest, when I was running the OE runflats, I didn't really think I would need to touch the sway bars, but since the Eibach front bar is "cheap" enough, I thought maybe worth some testing. Otherwise, the next thing will be money shocks.
 
#23 ·
Eric,

Which model JRZ coilovers and what spring rates front and rear? I might be interested since I am still on stock shocks with Swift springs.

I have Whiteline Front swaybar set for softest (2 holes) and rear 18mm bar set to medium stiff on one side and full stiff on the other (3 holes). With race tires this setup gives me mild understeer and controllable oversteer at limit. With OEM runflats it's moderate but controllable understeer. Whiteline also has a 20mm rear bar with 3 holes on each side.
 
#24 ·
I've got a set of double and a set of triples, not sure yet which one I will part with if either. As for springs, I have a wide variety between 600 and 1700 lbs and will tailor it as needed.

Forged makes the best rear bar (as in the one with the greatest improvement over stock) IMHO.

Protip of the day, if you haven't done so recently go get lube your bar. A bound bar is no ones friend.

Eric
 
#30 ·
Hi all, I am in the process getting a 14 BE. One main reason I want to get a GTR is to come back AutoX. Been absent for many years I am trying to come back slowly. Family and work occupy me too much of weekend time.

I exchange email with AutoXGTR a few times and he gave me a lot of feedback. Looking forward to join you guys soon.

Hung
 
#31 ·
Hung,

You can start simple with as few changes to your BE GTR, just get to know the car first. Having a plan for any mods is always good, check the rules for what's legal in your class.

Let us know how you do, post it on the Autocross results thread.
 
#32 ·
AutoXGTR. I finally got the deal done for a 14 BE. I was trying to get a TE but the dealer is very firm on the pricing so I took the BE. Will pick up the car about a month from now since the dealer is not local to me.
Look forward to it. I will try to run stock car first and see what needs to be improved. I am not planning to modify a lot. I think tires will be the first thing I want to do. I don't want ruin those expensive OEM tires.
 
#33 ·
You can try to keep the OEM runflats and wheels for street use. That means you can use 18" or 19" wheels or even 20" wheels with either non runflat Extreme Summer tires or R compound tires. Durable R compound tires like Toyo R888 or Nitto NT01 can be driven to the track or autocross event so that you can swap the wheels at home. TPMS does not seem to be bothered much by a wheel swap.

What do you drive now? What past autocross or track experience do you have? Initially the GTR is not that hard to drive, especially if you have a more high speed autocross course. If you see a short course with tighter slaloms or turns then it will be more critical to slow down enough to drive a good clean line and be patient for the higher speed areas. Corner exit is the strength of the GTR. I find that it can be easily overdriven, especially on street tires which don't have quite enough grip for all out driving. Knowing that, just be a little careful and think before you pounce on the throttle. Brakes are very strong so use them, don't baby them but avoid braking too late (you'll overshoot your turn apex and delay corner exit).

Have you been out to your local autocross events? What else is driving in SSP or SM classes? Those are your SCCA eligible classes.
 
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