Drivesolo
Well-known member
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.
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.