Project MR2 Turbo: Wet vs. Dry Autocross Performance Comparison

J.G.
Update by J.G. Pasterjak to the Toyota MR2 Turbo project car
Oct 7, 2020

How does rain affect the handling of our 1991 Toyota MR2 Turbo? Thanks to a unique opportunity at a Dixie Region SCCA autocross at South Georgia Motorsports Park, we can now share some GPS data measured with our Garmin VIRB action camera. 


The rain that day was light but thorough. As a result, the track surface was very evenly dampened but had very little standing water or puddling. 

The Falken Azenis RT660 tires performed exceptionally well in the wet, providing very similar lateral breakaway characteristics to how they did in the dry. The wet track just lowered the limited a bit. And that’s kind of the dream, isn’t it? Grip is reduced, but all of the same characteristics come through. 

As in the dry, the car tended toward understeer on turn-in, which is reflected in the video as similar initial turn-in speeds followed by a greater drop-off speed as we back off the throttle to restore front grip. 

You can see this tendency fairly dramatically near the start: In the wet, we actually get a better launch off the first left-hand corner. But because we have to back off to keep the nose in the line, the car is faster in the dry by the next maneuver. 

During extended cornering, the Falkens and the MR2’s mid-engine chassis again teamed up to deliver impressive grip. During the right-left combo that starts about 16 seconds into the dry-run video, you can see that our speeds in the wet only fall by about 2 mph, or around 4%. 

More evidence of that grip: In the decreasing-radius corner that begins around the 30-second mark in the dry-run video, our speed at the most aggressive part of the corner is about 4 mph faster in the wet, but the minimum corner speed is about the same in both runs, albeit at different places.

Maybe most impressive, however, is the way the car puts down power. Certainly, the engine being right over the rear wheels has a lot to do with this, but during our first wet run we were still getting into the throttle rather gingerly. Turns out that it didn’t matter: However hard we stomped the gas, the car just thrusted out, with additional understeer being the limiting factor in the wet instead of throttle-on oversteer. 

We've come to two conclusions here: First, the chassis and the tires are great for limited-traction situations, and second, we need more power. Insert smiley emoji here.

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Comments
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ChrisTropea
ChrisTropea Associate Editor
10/7/20 3:59 p.m.

It was really cool to watch through this a few times and pick up on where the speed was scrubbing on the wet lap. I like the sound of more power too. 

 

JG Pasterjak
JG Pasterjak Production/Art Director
10/7/20 5:32 p.m.
ChrisTropea said:

 I like the sound of more power too. 

 

It will actually sound about the same, just slightly wooshier.

300zxfreak
300zxfreak Reader
10/25/20 12:30 p.m.

In reply to JG Pasterjak :

Slightly wooshier is always a thing,except for tires, and intake plenums, and maybe tacos.

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