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Autocross- SCCA EV-X Class vs. SS
- Thread starter RacerChris
- Start date
Supercharger ~25 minutes away at Del Lago casino. I get to Seneca at ~93% after charging up to 100%.When? Dunno. I don't have a car yet... Where would you charge near there?
after I get it, I have to do a few events down in Jersey to see if I gel with the 3. If i want to go into debt again, mebbie I will do a full EVX build. Jury is still out...
I have my old 10 tire tag along trailer with hardtop mount from my A Stock S2000 days. I wonder if I can set it up with my Honda Generator, along with all the stuff needed for a multiple day/weekend event... Hmmm...
I was debating EV-X but I got an offer to co-drive in a STU 350z for this year so I jumped in that
We do have on site camping! Or Sampson State Park is across the street
We have a two day pay out event this year too! We are about to post the MSR events.
Got another weekend playing with the M3P. Bit of a mixed bag, but it doesn't completely suck 
Me: National Champion Autocrosser, 19yrs in the game
Mods: MPP Sport coilovers, 265 RE71 (1 year old, 10k street miles)
MPP standard rates are great for the street but the car is still pretty floppy. Definitely need more than that ~1.3deg I have. I think some camber and swaybars will be a happy medium for street car and occasional autox.
The biggest issue, this car critically needs an LSD. Because it cant transfer power, when any wheel slips it can only reduce power globally. The bias seems to work well as a tool to shift power rate forward or backward. If the rear seems to step out more then more front bias will allow more throttle and power to the end with grip and less to the other.
Compared to my evo with "magic" diffs, the car is just so reliant on all tires maintaining grip. I can drive around it, but it would be faster if it could put power down earlier.
Me: National Champion Autocrosser, 19yrs in the game
Mods: MPP Sport coilovers, 265 RE71 (1 year old, 10k street miles)
MPP standard rates are great for the street but the car is still pretty floppy. Definitely need more than that ~1.3deg I have. I think some camber and swaybars will be a happy medium for street car and occasional autox.
The biggest issue, this car critically needs an LSD. Because it cant transfer power, when any wheel slips it can only reduce power globally. The bias seems to work well as a tool to shift power rate forward or backward. If the rear seems to step out more then more front bias will allow more throttle and power to the end with grip and less to the other.
Compared to my evo with "magic" diffs, the car is just so reliant on all tires maintaining grip. I can drive around it, but it would be faster if it could put power down earlier.
Yeah, but look at the reverse- this is a stock 4 door car that is best classed with SS cars, and CAN actually keep one axle powered while the other backs off, unlike most stock AWD cars. It's absolute magic in low traction conditions. Sure, it's not a gutted, winged, Hoosier'd SM car, but it's damn fast for what it is, and can be comfortably driven to work in exactly the same config as you AutoX it in.
When you say the car backs off power globally- do you mean that the driver has to as one wheel slips? Are you running -10 on the stability control in track mode? I can do 4 wheel power slides (not fast for sure, but possible)- I don't tend to notice a power back off. Not even sure what logic the car would use to decide to back off power when you have SC/TC basically turned off.
Ironically, this weekend I beat a national champion in his C7 Grand Sport on Hoosier A7's, and I was on MPS4's. His main comment on watching me: Holy cow that car corners flat, and handles way better than it has any right to. Also ironically, my car is faster on MPS4's than one year old RE71's. Those things heat cycle out, and the rear end gets real tail happy when you're in sweepers and are asking for a lot of power. Not sure you'd feel the same about the power backoff if you were on the Hoosiers you are used to and the tires could absorb the power a bit better.
More camber in the front really makes a big difference. I actually got rid of my front Eibach swaybar and got faster.
I run a bit less pressure in the rear than the front FYI. Check your tire temps after a run and the back is doing less work, and a bit less pressure helps get some more grip back there.
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For sure, I'm not knocking the car, just looking critically at what it needs most. I design and sell suspension for my side business and been in Street Mod for almost the entire time I've autocrossed, its just in my nature to keep hunting for the next most important item.
On the reduction in power, my point was more that if you have X front power and Y rear power, without an LSD if a wheel is spinning on Y axle then Y power is reduced. So X+Y is total, but you're left with X+Y-slip because the slippage can be transferred to the other side or the front. Conversely, with LSDs or a Front/Rear connection I only need 1 wheel holding (hypothetically) to put down 100% of the power. Really of course its more like 1 wheel slipping is irrelevant and the diffs just dont let that happen.
For reference, I had the joy of spending an entire year chasing my tail in setup and we found the car had a 100% broken front diff, rear diff was worn to zero preload, and center diff clutches had some broken spline teeth from the extra work. The car would do very similar things to the tesla if you account for the effects of traction control stepping in.
With my old lame tires, I did find 60/40, -10, and 75% was more friendly to drive and get the front to get more power early in the corner than the rear. Certainly some fresh A052s would have changed that effect.
Definitely an interesting car. It might be AWD but the dynamics and electronics make it quite a bit different to manage. As far as rolley go, my Evo is stiff and all bushings are solid. So our point of reference is different than most. But even my wife feels its a bit to floppy but doesnt want to give up the nice ride for a street car. Cause its a great street car still.
Well, break out the checkbook and wrenches then!
unpluggedperformance.com
I'd love to see someone do that who actually knows how to drive and see if it makes a big difference. It would move you out of EV-X though.
Tesla Model 3 and Model Y - Limited Slip Differential (LSD)
Our LSD improves performance for Teslas on the race track or off road by putting more power to the ground without stability control.
unpluggedperformance.com
I'd love to see someone do that who actually knows how to drive and see if it makes a big difference. It would move you out of EV-X though.
Anyone run Nankang AR-1's?
Looking for a Tire that is quicker than the Falken RT660 but wears better than a Yoko A052 or Hoosier.
My club doesn't care about TW ratings, and I need something I can drive on the street 20 miles to/from the event.
I also need something that heats up fast as we run year round and some events are in the 40F range.
AR-1 looks like it might fit those needs and is cheaper than the other options also.
Looking for a Tire that is quicker than the Falken RT660 but wears better than a Yoko A052 or Hoosier.
My club doesn't care about TW ratings, and I need something I can drive on the street 20 miles to/from the event.
I also need something that heats up fast as we run year round and some events are in the 40F range.
AR-1 looks like it might fit those needs and is cheaper than the other options also.
Rodney!
Looking for a hot receptacle
So, MPP coilovers need more springrate? How is the rebound curve? If you up the rates, will they need a revalve? Or should we just go a different route?
*I spent a decade in SM, served on the SMAC, and then got bored and left after I created SMF, I went to go play in stock... I "retired" when stock became street.*
Rodney!
Looking for a hot receptacle
Noted on the supercharger, thanks!
Yeah, i don't camp...
I have family in Seneca, so I used to stay with them when I went up there.Yeah, that's why I am looking at the AR-1 not CR-1. Grassroots lists the AR-1 as an "A" for warm up just like the A052 and A7, and the CR-1 is a B like the RE-71 and RT660. Seems like a good overall mix, I'm guessing it just doesn't get used a lot due to the 100TW rating and people either going "street tires" or "full race" (as if an A052 is actually 200TW against an A7 40TW...)
Grassroots Motorsports ultimate track tire guide
What you need to know before choosing your next track tire.
grassrootsmotorsports.com
There's more than one set of MPP coilovers- the "sport" ones are KW V3's with some custom valving, but you still have the rebound/compression adjusters around that valving. MPP's suggestion for the compression/rebound is nowhere near the max settings.
The "comforts" are based on V1's and don't adjust.
I still don't think this car needs as much stiffness as other chassis' due to the lower CG. Lots of people are of the opinion of not running an upgraded front swaybar on the car for similar reasons.
MPP has the sports spring kit, but of course they aren't stating what their rates are. I have a good idea of what the rates I received are from measuring the coils and have compared to the same process on other known hyperco and swift springs since I have something like 20+ springs sitting around here. I wont state here what I think they are cause they seem to want to keep their secrets.
But, I suspect this car would be very happy at 12k/16k based on my measurements and NF goals. With no LSD, I think we have to be real careful with how much bar is used. Too much rear bar could make things unhappy in low grip areas.
Rodney!
Looking for a hot receptacle
ah, that is typical. I have asked what rates are via a phonecall on various coilovers and am met with the generic response "it is proper for your application". As you and i both know, we may need to go up/down depending on car setup, so i need to know what the starting rate is. I guess i could always test them myself, but i don't have access to a spring tester.
you are saying 12k front 16k rear would be a good starting point, providing valving is up to par?
It absolutely will. I run my eibach rear bar on full soft and am seriously considering going back to the stock bar. The car rotates reasonably, but it can be a bit loose if you have any steering input in and the back overpowers the surface.
This sorta comes back to what Im thinking is a good use for bias to deal with that. If the rear slips too early on exit (oversteer) then shift forward and if it pushes on exit then shift rearward.
The idea being that if say the front can take 60% and the rear can only take 50%, then 50:50 would bring both to 50% leaving potential for 10% more up front. I know its a very simplistic example, but shifting to the opposite end of what's slipping did seem to work pretty well this weekend.
I've played with the bias a lot, and it always makes me slower.
The bias only applies when the wheel is turned and you're on the power. Given it ends up applying to every corner in the whole run, you might make up one area, but you give it up everywhere else. It never seems to pay off (for me).
I find I do better pedaling it when needed in the loose spots, and letting the e-diff do what it can.
YMMV of course, just my experience.
I do run some front bias in the wet once I find the car to be tail happy in most corners.
Not 100% true.
The actual limit on almost all Teslas is the battery. Tesla got sued for this and lost years ago after advertising "691 HP" on the P85D because that was the max power output of the front and rear motors added together. But the battery had a limit of 415 KW, which is 557 HP, so the car could never deliver more than that. Kind of like saying an ICE motor is 500HP but then putting a fuel pump in the car that can only support 400HP and programming the ECU to limit to 400HP but claiming it was a 500HP car. Not cool Tesla.
The Model 3 has a lot of different motor/inverter options over the years, as well as different battery packs, and for sure some of the combos of motors adds up to more than the battery can put out. Not sure anyone really knows or has datalogged what really happens when you move the bias around. There is a reasonable chance you do get more power out of one axle than you would at 50/50 (but not all the power if you go 100% bias for sure).
Would probably be pretty easy to test though, even on the street. Just go do a 0-60 run with no track mode on, track mode at 50/50, then track mode 100% front and then 100% rear. See if the peak in the 100% rear or front case is higher than the 50/50 cases.
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You don't need to go through all those steps, it is stamped on the front springs.
The MPP.R spring kit is a stiffer set of springs that are right near the limit of what the Sports dampers can handle. If anyone needs more than that (running slicks, aero) I would recommend our competition coilovers which will knock your teeth out but perform very well.
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