The orignal Warp speed only went to 7 or 8.

Ah, yes the warp. When Gene started the Next Generation he decided he needed to sort of rationalise and re-calibrate the warp speed scale. Those numbers didn�t necessarily correspond to particular velocities in the original series. There was some sense that warp one was travelling at the speed of light and warp 2 was maybe five or six times the speed of light. It was kind of an exponential scale.

Gene decided that, in the Next Generation, we were going to come up with a chart, define these things more precisely, and establish that warp 10 would be equivalent to travelling at infinite velocity.

In the original series we saw the ship go to warp 13 or 14 in some extraordinary circumstance. Typically, we would be travelling between warp 5 and 8. But Gene decided; 'We�re going to say that the Federation Starfleet decided we�re going to recalibrate the scale and bring some order to it.' So sometimes you see some inconsistencies between the original series and Next Generation unless you take into account the fact that the speed scale was readjusted.