Voyagers do have very good acceleration, not suprising since they have a power-weight ratio of about 16hp per tonne, compared to 12hp per tonne on a HST. The Super Voyagers though have an extra 10tonnes per coach, and this brings the acceleration down to around 13hp per tonne. Ok, that's still higher than a HST, and they are slightly faster, but I never said they wern't, but with slack taken in and hard driving a 2+7 HST can keep to Super Voyager times one none tilt sections, and they did. The figures arn't that accurate anyway, since that's engine power, not power at rail, so the figures for both should be lower, but the Voyager will be effected more due to higher auxiliary loads, all of which are coming from the engines. Super Voyagers are an advantage on sections where they can tilt, but away from those areas they will loose out to Voyagers, and are barely better than HSTs. Where a 220 and 221 are coupled, the 221 can't tilt anyway, and holds back the 220 due to the extra weight. Actually, if you take a look at the railway performance society fastest times, where HST and 221 times are listed together there is little in them, e.g Darlington to Newcastle has 24:59 for a 2+7HST and 24:57 for a 221 (23:57 is the fastest for a 91). Another example is the times from Cheltenham to Birmingham, up the Lickey Incline. Fastest HST is 32:55, fastest 221 is 32:53.