AutoX comparison of a Leaf

This past Saturday, I took the Leaf and my 350Z out to an autocross practice day at Sanderson Field in Shelton, WA. I was able to run a direct comparison between the two cars to see how they compared to each other and possibly get some understanding of the dynamics of the Leaf and where it should be classed per the current 2012 SCCA PAX/RTP.

2011 Nissan Leaf :
- SCCA Class: ???
- 17x7 wheels; 215/45 – 17 Hankook Evo V12

2007 Nissan 350Z
- SCCA Class: CSP
- 18x9.5(F), 18x10.5(R) wheels; 275/35-18(F), 275/40-18(R) Nitto NT01
- OS Giken Clutch-type LSD
- Nismo S-Tune suspension, Whiteline suspension bushings, Stillen adjustable sway bars
- Project Mu ceramic brake pads, Motul RBF600 Fluid
- Nismo S-Tune cat-back exhaust, K&N drop-in filters

I ran in 2 sessions for a total of 12 runs (6 in each car), VDC turned off on all runs. The course was fairly open, giving an advantage to high horsepower cars. My fastest runs were both on the last run for each car, w/ weather and course conditions being the same:

Fastest time in Leaf: 59.303
Fastest time in Z: 51.504
PAX coefficient for CSP: 0.857

Based on what those times the relative PAX coefficient for the Leaf is; 0.744. H Stock is currently 0.799. This would mean that if the Leaf does get classed in 2013 it should be expected to be in the lowest possible class; H Stock. Even then it would be at the bottom of its class. The Leaf was on new HP tires and not on R-comps like the Z, however they were 10 mm wider and a 45 aspect ratio. As for the NT01’s from the Z, they are essentially non-competitive in comparison to the top DOT legal tires for autoX. They were 3 years old, the fronts were cording on the outside shoulders and had seen many heat cycles from track days and well over a hundred autoX runs. This would probably put them on par w/ a UHP tire. The Leaf’s times might have been faster by a few tenths or the Z’s slower by a few tenths if equal tires were used. But the overall co-efficient for the Leaf would probably not have been much greater.

As far as the performance of the Leaf, it seems that the biggest issue(s) that holds it back was intentionally done and may be correctable. The ABS is too sensitive, if it could be allowed activate a little later the Leaf would brake better, this is would not only would improve motorsport applications but real world use as well (is the regen to blame?). The suspension stoke is woefully long and stiffness of the springs are far too light for a car of its weight. I initially thought that the steering would’ve been more of an issue, but it wasn’t. It would probably be better if a half turn could be taken out of it. It would allow for better road feel and the power assist would be less overwhelming. There was the trademarked under steer from a FWD car but it was not nearly as bad as w/ other FWD cars. The front suspension is terribly camber challenged. A lot of it is due to the amount of body roll but even then at 45 psi in the fronts, I couldn’t keep the tires from going beyond the tread. However, the greatest hindrance that limits the Leaf is the slow ramp up on full throttle application when exiting a corner. I have not really noticed it when attempting to accelerate in a straight line, but for some reason it seems as though the VDC is not completely disabled even when it says it is. That alone would probably have been worth about a second in time on my runs.

Thanks to a DCQC in Tumwater, WA which is about 25 miles from the autoX venue and to Taylor Shellfish Farms (Thanks again Steve) for having an available L2, about 9 miles from Sanderson Field. It was only possible to accomplish w/ those facilities being in place since I live about 92 miles away (184 miles round trip). For my first 3 autoX runs in the Leaf I was at 1.1 kW/mile. For my entire time at Sanderson Field I achieved an efficiency of 1.4 kW/mile, which included several laps at low speed to service the course and travel to and from the pits.

Thanks for the report!

The LEAF certainly doesn't make all that great of a driver's car, especially when pushed to the limits. Though nader has shown quite well that the LEAF can be pretty quick with enough meat under the car and stiff enough suspension!

In the SCCA stock class - suspension modifications are pretty limited from what I can tell. Looks like front sway bar (that no-one makes), shocks/struts and adjusting the alignment are all good. It appears that one may be able to use camber bolts if the service manuals says that is acceptable?

For a daily driver, it sure seems like some mild sports springs with a decent alignment and decent tires would go real long ways towards making it more fun to drive.

Good to see there are some racers and handling enthusiasts here.

I had an 04 350Z from late 2003 until middle of 2011 but never did do AutoX. I also did live in the Puget Sound area for ~9 years.

I don't think camber bolts are allowed per SCCA Stock class. But anything to give it more negative camber would help. Like w/ most front end strut setups, if it's lowered (and the Leaf can be lowered A LOT) it gains negative camber from it's geometry. I've seen some vast improvements on cars w/ struts that have suspension issues in stock form just by lowering (w/ the better suspension of course) 2 or so inches. Improvements of over 2 seconds is not unheard of. I think the Leaf would benefit from that greatly. I can see it having the potential to be lowered about 3 inches. In addition to the lower CG and better tire contact in the corners, it might eliminate some of the electronic nanny's interference if whatever sensors it uses takes into account body roll. If there were some way to completely disable the electronic controls that limit it, the car would be so much faster in AutoX. But of course all of this would not be w/in Stock class rules. I think it would put it in FSP, which has an indexing of 0.838.

I believe the OEM sway bar(s) can be made stiffer. I've heard of someone welding split tubing to the straight sections of a stock sway bar to give it more stiffness. This mod would be legal per Stock class rules but I can see how it would lead to fatigue failure w/ enough use. IMO any focus of a Leaf becoming a viable car for AutoX should be in Stock class solely because there just isn't any real aftermarket support for a Street Prepared class build or beyond.

cwerdna - This is my 2nd Z33. I had and '03 and started competing w/ it in AutoX w/ that back in '03, eventually winning a local championship w/ it in '05. Upgraded to my current '07 when the VQ35HR came out. The Z33 was never the best in it's class in AutoX, a good car for the sport, but never classes properly IMO. Where it really shines is when it can put it's power and broad torque range to use on a big track.

Another observation that I made on the day I took the Leaf autoXng was the temperature bars:
- From the drive to my place to the Tumwater QC: 6 bars.
- After charging to 98%: 7 bars (uh-oh...)
- After the driver to Taylor Shellfish Farms to pick up 40 minutes of charge and arriving at Sanderson Field: 6 bars
- After my first 3 runs: 6 bars
- After 2 more runs from my co-driver: 6 bars
- After my last 3 runs: 6 bars
- After charging for 40 minutes at Taylor Shellfish: 6 bars
- After charging at the Tumwater QC: 6 bars
- Arriving home (12 hrs later, after nearly 200 miles traveled and 20 degrees warmer than when I left): 6 bars

From my observation it would seem that QC-ing may causes more battery heat than a full day of AutoX-ing.

Drivesolo said:

From my observation it would seem that QC-ing may causes more battery heat than a full day of AutoX-ing.

Click to expand...

That's been other people's experience even driving on the track where loads are much higher - the battery barely heats up even under prolonged full throttle. The battery's internal resistance seems to be much higher when charging than when discharging.

Drivesolo said:

I don't think camber bolts are allowed per SCCA Stock class. But anything to give it more negative camber would help. Like w/ most front end strut setups, if it's lowered (and the Leaf can be lowered A LOT) it gains negative camber from it's geometry. I've seen some vast improvements on cars w/ struts that have suspension issues in stock form just by lowering (w/ the better suspension of course) 2 or so inches. Improvements of over 2 seconds is not unheard of. I think the Leaf would benefit from that greatly. I can see it having the potential to be lowered about 3 inches. In addition to the lower CG and better tire contact in the corners, it might eliminate some of the electronic nanny's interference if whatever sensors it uses takes into account body roll.

Click to expand...

I also have to wonder if the a-arm suspension bushings are extremely soft and allowing additional dynamic camber under load from the shoulder wear than many people see. They certainly look squishy. In my experience with lowering strut-based cars, there's a limit to how far you can go before you get to the point of diminishing returns and the roll center starts getting jacked up - 2" lower is typically it unless you further modify the suspension geometry. Bump travel is also a big issue if one is concerned about maintaining some ride quality!

Anyway - the biggest issue is that there's only really 2 commercial options for lowering the LEAF - Tein coilovers and they also have lowering springs - but both have to be imported from Japan which significantly raises the price.

Drivesolo said:

I don't think camber bolts are allowed per SCCA Stock class.

Click to expand...

Actually, they are allowed if they are referenced for use in the factory service manual or technical bulletins for "non-competition" purposes. The 2012 SCCA® National Solo® Rules state:
"Both the front and rear suspension may be adjusted through their
designed range of adjustment by use of factory adjustment arrangements
or by taking advantage of inherent manufacturing tolerances.
This encompasses both alignment and ride height parameters if such
adjustments are provided by the stock components and specified by
the factory as normal methods of adjustment. However, no suspension
part may be modified for the purpose of adjustment unless such
modification is specifically authorized by the factory shop manual for
non-competition purposes."
and
"Alternate parts listed in a factory parts manual are not authorized unless
their use is specifically referenced in the factory service manual or
in a service bulletin for the specific model."

If "camber" or "crash" bolts are specified in the factory documentation for use in repair procedures or for overcoming manufacturing tolerances which do not allow sufficient suspension adjustment, they are legal in Stock class. It is incumbent upon the owner to provide such documentation if protested, so your ducks better be in a row if you use them, with supporting documentation in hand. I have not been through the Leaf parts, service manual or technical bulletins sufficiently to see if there is any such documentation for alternate factory suspension parts, but I seriously doubt it exists at this point in time.

TT

drees said:

I also have to wonder if the a-arm suspension bushings are extremely soft and allowing additional dynamic camber under load from the shoulder wear than many people see....
Anyway - the biggest issue is that there's only really 2 commercial options for lowering the LEAF - Tein coilovers and they also have lowering springs - but both have to be imported from Japan which significantly raises the price.

Click to expand...

Unfortunately, both replacing bushings and/or coilovers with non-factory parts excludes you from Stock class in SCCA Solo:

"Suspension bushings, including but not limited to those which carry
the weight of the vehicle and determine ride height, may not be replaced
with bushings of a different material or dimension."

"Standard, as defined herein, suspension springs must be used. They
may not be cut, shortened, or collapsed."

TT

https://www.youtube.com/watch?v=n4-UDNy9kQI" onclick="window.open(this.href);return false;

This would be a much better EV autox'r, EV West E36 M3, 850ft-lbs torque @ 600rpm and 342hp just

OPECsux said:

https://www.youtube.com/watch?v=n4-UDNy9kQI

This would be a much better EV autox'r, EV West E36 M3, 850ft-lbs torque @ 600rpm and 342hp just

Click to expand...

Nah, that car would be a blast on a big track, but for autox you want a small and light car--short wheelbase, narrow width, and instant transitional response are big advantages on a short, twisty AX course. Something like the Palatov Motorsport dp1 EV Prototype with a more powerful motor and a lighter lithium-ion battery pack would be the ticket.

I thought about it briefly when Dennis was selling the car, but my practical sensibilities got hold of me before I pulled the trigger.
TT

Thanks for the report! Good to find some enthusiasts racers out here. Well, it’s correct to say that the LEAF certainly doesn't make all that great of a driver's car, especially when pushed to the limits.

Lol, it's been almost a year since I did this. I've been tempted to try it again to see if a different technique will have better results but it is difficult finding someone to help me take 2 cars down to Shelton.

The Leaf wasn't the first EV I've attempted to autoX. The first EV I've driven at a practice was based off an old sprint kart chassis I built back in '05. Dubbed the Frankenkart by a buddy, it was a proof of concept. In '09 I took an Italikart sprint kart chassis and build Frankenkart II which was by far the fastest EV I'd driven in autoX, it nearly had FTD (Fastest Time of the Day) only loosing out to a Street Prepared 911 Carrera on R-comps. I could hold it flat from the start all the way to the finish w/o ever lifting. Prior to bringing it out to a practice day I was able to measure it's top straight-line speed at 52mph w/ the gearing I used. Seems slow but keep in mind that in sections where the fastest cars were doing less than 30 mph, my kart was doing over 40 mph.

Now you're talking, Drivesolo! Something along those lines, perhaps in a Formula SAE chassis with a more powerful motor and just enough high-density, lightweight batteries to last 10 or 15 full-power AX laps would probably do the trick.

TT

Funny you should mention Formula SAE. I did FSAE back in school and when I encountered this article the other day it brought a huge smile to my face. It makes me realize that an exciting EV motorsports future might be a lot closer than we think.

http://gas2.org/2013/07/15/electric-race-car-wins-formula-student-competition-for-the-first-time/

Very cool! Any USA teams working on E-FSAE cars?
TT