RWD vs. FWD: Part 2 – Improvements

Now that I’ve built and tested a FWD Miata, my thoughts have turned to improving the study for the next round of experiments.

Upcoming Changes

First off, the FWD Miata doesn’t handle as well as I’d like. I like a FWD car that steers automatically with lift off oversteer. What I made felt sort of pig-ish. I know from real-world experience that my Yaris can be made to oversteer quite a bit by changing tire compounds front and rear. But I don’t want to do that as most cars come from the manufacturer with a square setup and most racing is done using the same compound front and rear. So I’ve got a bit of tuning to do, but I have to keep it in the spirit of an NA Miata to be fair.

In the next version, I’m not going to give the FWD vehicle a power or weight advantage. On the one hand, every FWD vehicle is going to be slightly more efficient than RWD, but on the other hand, racing regulations don’t always give such a bonus to FWD. Let’s see what the differences are and then determine if some bonus/penalty should be created to equalize them.

Previously, I made the various file modifications by hand and had two separate data directories that I swapped in and out. I had to re-start Assetto Corsa every time I made vehicle changes. Going forward I’m going to script everything so that all of the builds are in the game with a unique name, so it’s simply a matter of choosing a model from a list. This will also make it easier to keep track of the various data files in Race Studio. All of the code will be available on GitHub.

Methods

Previously I compared laps at Brands Hatch Indy and Karelia Cross. I’ll probably still use Brands Hatch, but I may drop Karelia Cross. I can change grip without changing surface easily enough. I also want to add some other analyses. Here are the things I’ll be doing.

  • Drag strip – 0-60 and 1/4 mile times
  • Skid pad – maximum sustained lateral Gs
  • Lap times – on short tracks with laps ~ 1 minute
  • Race Studio Analysis for in-depth analysis
  • Subjective comments about driving experience

Experiments

Here are the experiments I’m planning.

  • Weight distribution – what is the ideal weight distribution for a FWD vehicle? Motivated by the thought “how can I improve mid-corner speed of the FWD platform?”
  • Grip variation – who wins when the grip is very high or very low? Motivated by the thought “why exactly do FWD vehicles have an advantage in the rain?”
  • Power variation – who wins when the power is very high or very low? Motivated by the thought “is having more power just like having less grip?”
  • Elevation – who wins when the track is flat vs. lots of elevation changes? Motivated by the thought “FWD should be worse up hills and down hills”.

2 thoughts on “RWD vs. FWD: Part 2 – Improvements

  1. The way you’ve laid out your experiments makes me think you’re already on to something, but I’m curious if weight distribution and grip variation are related to each other, and similarly power variation and elevation delta. e.g. If weight distribution is why FWD has an advantage in the wet.

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    1. I’m pretty sure weight distribution is not the advantage of FWD. I did an experiment where I drove a 60/40 FWD on dirt and it was well faster than RWD or 67/33 FWD. I think a 50/50 FWD vehicle might be amazing except from a dead stop.

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