I'm trying to wrap my brain around this one. It seems to me that a very tight rear diff would cause power-on under
steer, not oversteer. In the worst case scenario, RWD drag cars use a spool (which keeps both rear wheels locked together). Road racers generally don't use spools because the car will understeer like a pig under power as both rear wheels have to
spin the same speed. Similarly, a very tight rear LSD is trying to make both rear wheels spin at the same speed, so the rear of the car is trying to push the car straight.
I think in your case, Phil, you've got enough power to spin the rear tires, so when you tromp on the gas the inside rear tire tries to spin as fast as the outside rear tire (due to the tight diff) and goes up in smoke, causing the power-on oversteer. In my car, which has probably 1/4 the power of yours
, when I get on the gas I can feel a decided shift to understeer because of the tight Cusco rear LSD I've got.
I'm heading to Shenandoah this coming weekend. I don't think I'll be running 1:34s.