In the last post I was showing that a FWD vehicle is faster than RWD vehicle in low grip situations. This appears to be because RWD has to balance lateral and longitudinal Gs on the rear tire while FWD can dedicate all of its rear tire to grip. Because of this the FWD vehicle exits corners faster. While I was driving RWD, being careful not to spin the car, it made me think about how one has to do the same thing with a high powered car. So is half the grip a lot like twice the power?
A high powered FWD car has a specific problem: the more it accelerates, the more weight shifts to the rear, away from the drive wheels. Because of this, I don’t think FWD will retain its advantage in a high power, high grip environment. How about instead of making educated guesses, I do some experiments (I’m not just a scientist in the play world you know, it is my actual day job).
I’m using mostly the same experimental setup as before with a couple tweaks.
- RWD is a stock Miata with 200% power
- FWD is the 60/40 FWD Miata with 200% power
- Tire wear is turned off
- Fuel usage is turned off
Driving with 200% power is more fun than driving with 50% grip. In both situations, the car is sliding quite a bit, but I feel a little more in control with 200% power. Driving RWD and FWD are both so much fun, but how you get the most out of each is really different. Here’s a simple way to sum it up:
- RWD rewards precision
- FWD rewards aggression
In a high powered RWD vehicle, you can’t mash the throttle or you go spinning off track. You need a delicate balance between steering input and throttle after the brakes are released. In general, driver inputs must be nuanced to get the most traction possible.
If you drive a FWD vehicle like a RWD vehicle, it works pretty well, but the real payback is when you don’t. FWD understeers and runs wide as soon as you add throttle. So you have to get the car pointed down track more quickly. This means getting oversteer in the braking zone and aiming for a mid-track exit rather than the usual track out. Once you add throttle it pulls you out of oversteer and understeers you to the exit. I’m going to borrow a little from Mark Donohue here to make an analogy.
- RWD is like stepping onto a tightrope
- FWD is like jumping onto a tightrope
- RWD best 59.40, average 59.744 (sd 0.202)
- FWD best 59.27, average 59.572 (sd 0.171)
I wasn’t expecting this, but FWD won fastest lap and average lap. The margin was so small that out of 20 laps, only 1 FWD lap was faster than the fastest RWD lap.
In the graph below, red is RWD and blue is FWD. This is the fastest RWD lap and the second fastest FWD lap. I’ve chosen these two laps to display because they are only 0.01 seconds apart and because they show some of the differences between RWD and FWD.
The sunglasses indicate regions where the RWD driver has to have a cool head because there’s a delicate mixture of throttle and steering happening (stepping on tightrope). The shocked looking glasses are where the FWD driver has created a lot of yaw in the brake zone (jumping on a tightrope).
Conclusions and Thoughts
I was expecting RWD to win this one pretty easily, but it turned out they were evenly matched. From a driving perspective, this was the most fun test so far because I had to change my driving style to fit the vehicle. I’m a little better in FWD than RWD. That’s probably not true for everyone. I think the performance is similar enough on dry asphalt that differences in lap times are more down to driver than layout. I like driving FWD, and I’m used to driving with a lot of corner entry oversteer. So I might be a little biased towards FWD than the next driver. It’s hard to determine how general the FWD advantage is without having more drivers.
Calling Assetto Corsa Drivers
If you would be so kind, please download the two vehicles below and drive them around Brands Hatch Indy. Which one is faster in your hands?
I don’t think you need to replicate the exact driving conditions, but if you do, here they are:
- 9:00am, clear weather, optimum track condition, 20C, 0 km/h wind
- Penalties on
- Pro difficulty with no assists on
- Default setup (SV tires and whatever alignment is)
- 0x tire wear, 0x fuel usage, 0 kg ballast, 0% restrictor
- Start from pits, no tyre blankets
Note: if for some reason the files don’t work, maybe try using Content Manager to replace the sounds with the NA Miata.