Spinning will add mph?
I rely on trap speed mph to measure performance gains from mods that I have done. It works reliably when used this way. But I shouldn't use my trap speed in comparison with somebody else's to draw a power similarity, because trap speed is also affected by weight, transmission efficiency, shift-points, etc. However, between similar cars and setups, mph should give you a pretty good ballpark indication of how well each car is putting down whatever power they are making.
For me, trap speeds usually don't vary greatly between runs when I hook or spin lightly. It is usually within a 1 mph range. When I was near stock, spinning a little bit helped not only mph but sometimes ET as well. If I spun too much, both ET and mph suffered. So you can't assume that more spin will make higher mph. I think there is a fine line to be drawn on the amount of spin to see benefit vs. mph lost.


