Yeah I know... I'm more leaning toward changing when a 3 with carbon sleeve motors will hopefully go out... And more range...
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Autocross- SCCA EV-X Class vs. SS
- Thread starter RacerChris
- Start date
Yeah I know... I'm more leaning toward changing when a 3 with carbon sleeve motors will hopefully go out... And more range...
Nice.
I may go this route at some point, but I already have my vette taking a fair amount of my car parts annual budget
Though 1K for those adjustable control arms is very excessive IMO... 2.7K for Coilover is the norm but expensive anyway...
Anybody here had trouble on concrete?
After switching to RT660s, I had a nice PAX result last week on decent asphalt, and the tires felt like they had tons of grip. This week, on a large concrete lot, I'm like half a second behind where I was on PAX relative to top street tire results when I was running on pretty beaten up 265-wide RS4s. I was hoping RT660s to do a lot better on concrete, but the opposite happened. Can't even say I felt them push or overheat.
It was a sunny day in the mid-80F's, don't think tires even needed any spraying. I was getting 120-130F tread temps around the whole tread upon returning to the grid.
I was contemplating registering for Nats (just 3 people at the moment in EVX), but given how much I sucked on concrete not sure I'd bother.
After switching to RT660s, I had a nice PAX result last week on decent asphalt, and the tires felt like they had tons of grip. This week, on a large concrete lot, I'm like half a second behind where I was on PAX relative to top street tire results when I was running on pretty beaten up 265-wide RS4s. I was hoping RT660s to do a lot better on concrete, but the opposite happened. Can't even say I felt them push or overheat.
It was a sunny day in the mid-80F's, don't think tires even needed any spraying. I was getting 120-130F tread temps around the whole tread upon returning to the grid.
I was contemplating registering for Nats (just 3 people at the moment in EVX), but given how much I sucked on concrete not sure I'd bother.
Ahh, the magic carbon sleeve rotors that have a max RPM that is lower than the current M3P.
The Plaid motors are amazing, but it isn't due to the carbon sleeve. I'm with you that I really want a M3P that can keep 500 HP above 50 MPH though. I don't think anyone has found they are that much more efficient though.
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It isn't just surface- different courses favor different kinds of cars. I don't think you can determine anything from two events. I've been to events on the same surface where I can't even raw time a BRZ or Miata, and I've been to courses where I can beat them by 4+ seconds.
You're lucky you have any EV's at your nats tour. Packwood this weekend in the Pacific Northwest had zero. We have no charging nearby so you have to spend $300+ a night for a hotel just to have any reasonable charge at the event. Go bring the EVX heat- we need to show the world what these cars can do.
So continuing to update on my findings with setting the wheel config:
I ran my 265/35R19 (26.3" diameter) PS4S's today for a few runs. I left my tire config on Zero G. The very first time I slid the car at all, I got all the traction control complaints and shutdowns.
Switched config to 20" Performance- ran 7 more runs, no issues
Swapped to 275/35R19 A052's (26.6" diameter). Forgot to switch wheel config. First hard brake and turn corner, same issue.
Switched config back to Zero G, 4 more runs with no issues.
I'm now pretty confident that the wheel config really does matter against tire diameter, at least in aggressive AutoX.
Side note- when in Grid, I switched to Zero G, but got a weird message about needing the key card, which I closed. System rebooted but DID NOT tell me TPMS was reset. On that run, I had the same issue. I went back in, changed to a different setup, got the TPMS message, then back to Zero G, got the TPMS message. No issues after that. If you don't get the TPMS message after the reboot, I'm pretty sure it didn't take.
I ran my 265/35R19 (26.3" diameter) PS4S's today for a few runs. I left my tire config on Zero G. The very first time I slid the car at all, I got all the traction control complaints and shutdowns.
Switched config to 20" Performance- ran 7 more runs, no issues
Swapped to 275/35R19 A052's (26.6" diameter). Forgot to switch wheel config. First hard brake and turn corner, same issue.
Switched config back to Zero G, 4 more runs with no issues.
I'm now pretty confident that the wheel config really does matter against tire diameter, at least in aggressive AutoX.
Side note- when in Grid, I switched to Zero G, but got a weird message about needing the key card, which I closed. System rebooted but DID NOT tell me TPMS was reset. On that run, I had the same issue. I went back in, changed to a different setup, got the TPMS message, then back to Zero G, got the TPMS message. No issues after that. If you don't get the TPMS message after the reboot, I'm pretty sure it didn't take.
I get that the course design matters, and if everything was a slalom we'd be losing to Miatas every time. That said, over the past couple years of semi-regular autox-ing after a long hiatus, I've been at a reasonably stable delta in PAX relative to the same people at the top, on courses ranging from very tight and technical, to fairly high-speed ones on huge lots. I had caught up with them the prior weekend on asphalt, only to have the worst result since coming back to autox this past weekend.
It's certainly possible that the cause was 100% driver performance, but it did not feel like I left too much time out there. So, I think there's a reasonable chance that it was either the setup that did not work on this concrete (it's a weird-ish site with older concrete that has a directional grain to it), or maybe RT660s need different pressures on concrete. Hence my inquiry.
superflyrolla
Member
Has anyone autocrossed on the Nexen SUR4G tires? I think I got one of the last sets for a reasonable discount. I'm curious what pressures to start with.
My street alignment is something like -1.6 front left and -1.7 front right, or something like that, so some shim. I remove the shims for autox.
I don't recall where the rear camber is but I haven't touched the tie rods, just leave the rear where it's at.
Maybe I should be adding some rear neg camber???
SK360
Member
You don’t adjust tie rods after pulling front shims? How much toe out does that give you?
I gridded next to a guy the other day who's running these on a Mustang. I don't think he bothered with air pressures, but spent most of the time between runs spraying them
A couple of turns on the tierod is what, 2.5mm? Ballpark 150 mm away from the pivot point? About a degree of toe-out, per sideYou don’t adjust tie rods after pulling front shims? How much toe out does that give you?
Guy at my club was running them yesterday on his BRZ and blew his remote oil filter off in the middle of a run.
Is that the feedback you wanted?
think I was around 33-36 range. 275 on 10.5"
I think they are pretty fast once they warm up a touch.
SK360
Member
MPP recommends 2 full turns in when going from full shims to no shims. I’m trying to find a happy medium of slight toe in for street that goes to 0 toe or slight toe out with shims out without adjusting the tie rods. Going to play on the alignment rack tomorrow.
Falking Falken.
Just 10 runs on these and the dreaded rubber seam separation has already began. Can see it clearly on two tires, and a hint of it on another.
Just 10 runs on these and the dreaded rubber seam separation has already began. Can see it clearly on two tires, and a hint of it on another.
Lindenwood
Active Member
I just ran my second AutoX, but this time with a lot of goodies installed. This is all on my 2022 M3P, picked up 5 May 2022 (now with 5700 miles on it from several road trips).
Disclaimer 1:
I have a lot of experience off-road on both two and four wheels, and a good amount of sport bike experience on the road, but until a month ago my only real performance “driving” on pavement was nitro RC cars back around the turn of the century. This post follows my second-ever AutoX, with the first being a month ago.
Disclaimer 2:
I made a lot of changes at once, and didn’t put any real effort to control any particular variables, so I admit some of this is difficult to precisely attribute.
That said, bottom line up front, it all honestly worked…
MPP Compression Rod Bushings:
In comparison to stock, I can definitely tell the steering feels more stable under hard braking and maneuvering than before.
MPP Master Cylinder Brace:
In comparison to stock, it feels like there is less pedal force required. In my first race I specifically felt like I was having to stand on the pedal (hyperbolically) for hard braking, but now locking up the tires takes appreciably less effort, and it is also definitely more linear with less travel required to get the same force.
MPP Comfort Adjustables:
They are indeed more comfortable overall, but most importantly they maintain significantly more control over bumps during hard corners. At the AutoX yesterday there was a notable bump in the middle of a ~35-40mph curve that was giving a lot of people fits—a kart driver was catching air over it—but after the first run I literally didn’t have to think about it. I am still a little worried I should have gone with the Sport versions, but these Comforts on 6/6 from full stiff (which I arbitrarily selected from the 12/12 I was running prior to the race) seemed pretty competent. I suspect I’ll be down close to 0/0 once I get better tires. I am running all-seasons right now because until my first race a month ago I thought I wouldn’t care about racing and extreme performance……-_-.
MPP FUCAs, Rear Camber Arms, and Rear Toe Arms:
This all started because I was trying to balance out the pretty severe understeer I experienced during my first race. The primary recommendation was FUCAs, with acknowledged benefits to the other alignment parts. With toe plates and careful camber measurement with a micrometer and a 24” Square, I have been able to dial in the alignment myself. The FUCAs are comically easy to adjust, and using the 1 hex = 1mm toe rule, I was able to get the toe re-dialed on the first try after removing the shims while Supercharging.
I ran the race with the following specs:
Front: 0 degrees toe and negative 3.0L / 3.2R camber (I think I need to tweak the FUCA mounts to get them even), with 15mm spacers on the Ubers.
Rear: ~1.5mm rear toe out and negative ~2.2 degrees camber, with 20mm spacers on the Ubers.
38 PSI cold pressure (peaking at around 43).
Tire wear is much more even this time around after the AutoX day and, most importantly, I really experienced much more neutral handling balance compared to the significant understeer I faced the first time! Additionally, turn-in feels more precise than it did, even at just moderate loads.
I finished 6th out of 15 PAX (4th of 15 raw) on my all-season tires. Everyone who beat me had 200TW tires from what I could tell. Fastest raw time was a 31.38 to my 31.96, but fastest PAX was 25.04 (Ford Fiesta ST) to my 26.69.
Otherwise, next up is a CTS-V BBK with Girodisc 370x34mm rotors and MPP lines (still figuring out pads). Those are in preparation for what I hope is an HPDE or two this year. I am still figuring out what I want to do for wheels/tires—I might move to a condo in Florida in 6-7 months and would just switch to PS4S full-time so I don’t have to mess with two sets. I am also pondering on an adjustable rear anti-sway bar to help offset the cushy Comfort coils and transfer handling bias a hair more forward, but I will probably just start with running a few less pounds of pressure in the front tires than the rear next.
@MountainPass @MasterC17 @tm1v2 @Sam1 @gearchruncher @dsgerbc @Motion122 @SK360 @dfwatt
Disclaimer 1:
I have a lot of experience off-road on both two and four wheels, and a good amount of sport bike experience on the road, but until a month ago my only real performance “driving” on pavement was nitro RC cars back around the turn of the century. This post follows my second-ever AutoX, with the first being a month ago.
Disclaimer 2:
I made a lot of changes at once, and didn’t put any real effort to control any particular variables, so I admit some of this is difficult to precisely attribute.
That said, bottom line up front, it all honestly worked…
MPP Compression Rod Bushings:
In comparison to stock, I can definitely tell the steering feels more stable under hard braking and maneuvering than before.
MPP Master Cylinder Brace:
In comparison to stock, it feels like there is less pedal force required. In my first race I specifically felt like I was having to stand on the pedal (hyperbolically) for hard braking, but now locking up the tires takes appreciably less effort, and it is also definitely more linear with less travel required to get the same force.
MPP Comfort Adjustables:
They are indeed more comfortable overall, but most importantly they maintain significantly more control over bumps during hard corners. At the AutoX yesterday there was a notable bump in the middle of a ~35-40mph curve that was giving a lot of people fits—a kart driver was catching air over it—but after the first run I literally didn’t have to think about it. I am still a little worried I should have gone with the Sport versions, but these Comforts on 6/6 from full stiff (which I arbitrarily selected from the 12/12 I was running prior to the race) seemed pretty competent. I suspect I’ll be down close to 0/0 once I get better tires. I am running all-seasons right now because until my first race a month ago I thought I wouldn’t care about racing and extreme performance……-_-.
MPP FUCAs, Rear Camber Arms, and Rear Toe Arms:
This all started because I was trying to balance out the pretty severe understeer I experienced during my first race. The primary recommendation was FUCAs, with acknowledged benefits to the other alignment parts. With toe plates and careful camber measurement with a micrometer and a 24” Square, I have been able to dial in the alignment myself. The FUCAs are comically easy to adjust, and using the 1 hex = 1mm toe rule, I was able to get the toe re-dialed on the first try after removing the shims while Supercharging.
I ran the race with the following specs:
Front: 0 degrees toe and negative 3.0L / 3.2R camber (I think I need to tweak the FUCA mounts to get them even), with 15mm spacers on the Ubers.
Rear: ~1.5mm rear toe out and negative ~2.2 degrees camber, with 20mm spacers on the Ubers.
38 PSI cold pressure (peaking at around 43).
Tire wear is much more even this time around after the AutoX day and, most importantly, I really experienced much more neutral handling balance compared to the significant understeer I faced the first time! Additionally, turn-in feels more precise than it did, even at just moderate loads.
I finished 6th out of 15 PAX (4th of 15 raw) on my all-season tires. Everyone who beat me had 200TW tires from what I could tell. Fastest raw time was a 31.38 to my 31.96, but fastest PAX was 25.04 (Ford Fiesta ST) to my 26.69.
Otherwise, next up is a CTS-V BBK with Girodisc 370x34mm rotors and MPP lines (still figuring out pads). Those are in preparation for what I hope is an HPDE or two this year. I am still figuring out what I want to do for wheels/tires—I might move to a condo in Florida in 6-7 months and would just switch to PS4S full-time so I don’t have to mess with two sets. I am also pondering on an adjustable rear anti-sway bar to help offset the cushy Comfort coils and transfer handling bias a hair more forward, but I will probably just start with running a few less pounds of pressure in the front tires than the rear next.
@MountainPass @MasterC17 @tm1v2 @Sam1 @gearchruncher @dsgerbc @Motion122 @SK360 @dfwatt
When I measured it myself, one turn is 5mm of toe on a 19" wheel. You're gonna get 20mm of toe change across both sides. I wish you luck, but I don't think a happy medium is possible.
@Lindenwood I think you'll ultimately want separate autox wheels so you can run more focused tires. You could go in on a 2nd set of wheels now, sized with that in mind, but start them with street-friendly summer tires as your summer wheels, and keep your allseason set for winter while you still need that.
Then after you move to a warmer climate, switch the new wheels to autox or track tires when the street summers wear out, and switch the allseason wheels to street summer tires when the allseasons wear out.
That's probably what I would do. I'd be wary of cooking a street-focused tire like the PS4S too easily though once you get confident and fast on track days. As in, you might trash them before your move i.e. before you're ready to switch wheel/tire roles.
Then after you move to a warmer climate, switch the new wheels to autox or track tires when the street summers wear out, and switch the allseason wheels to street summer tires when the allseasons wear out.
That's probably what I would do.
I'd be wary of cooking a street-focused tire like the PS4S too easily though once you get confident and fast on track days. As in, you might trash them before your move i.e. before you're ready to switch wheel/tire roles.
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@Lindenwood In fact, if you're going to dual use a single tire for summer street + track...I'd try something like the Goodyear Eagle F1 Supercar 3 (SC3) before the PS4S (or anything in the PS4S category). The SC3 should hold up to track use better while still being street friendly enough. SC3 sizing is limited but since you haven't bought new wheels yet, you can get a size with SC3 availability.
I haven't used the SC3 but I've heard good things in this regard from people I trust.
I haven't used the SC3 but I've heard good things in this regard from people I trust.
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