It was a common thing to do on race cars so the red line was straight up. I think a lot of classic 911 race cars had that and GT40s, but certainly not restricted to just those cars.
I've heard that old bush pilots used to do the same for all the engine gauges - at cruise everything should be pointing straight up, so you can see at a glance if anything's not running as it should.
It was a common thing to do on race cars so the red line was straight up. I think a lot of classic 911 race cars had that and GT40s, but certainly not restricted to just those cars.