1987 German GP

After the superb dominance of the Williams Honda's at the British GP at Silverstone where Mansell and Piquet destroyed the rest of the field, why at Hockenheim was Prost so quick in relation to them. If anything, Hockenheim is even more of a power circuit than Silverstone was and Honda were known for having fantastic power, and the aerodynamics of the Williams seemed to be the best too.

Good question. Prost once said the 87 McLaren TAG was the worst car he ever drove (wonder if that was before he tested the 92 Ligier? )

The Porsche engine was supposed to be well down on power to the Honda or even Ford or Ferrari, and the 87 car was basically an interim from Steve Nichols between the 84-86 car and the lowline car of 1988.

It did seem odd - IIRC correctly TAG had some new parts on the car that weekend - which explains why Prost went from being lapped at Silverstone to leading comfortably 2 weeks later on two power tracks. That said, I think Mansell would have run him close had he not retired at half-distance.

If they did have new parts, who knows also where they went for Monza, because the Macs were again much slower than the Hondas IIRC.

Very Strange!

Let's see what's written in the book Grand Prix (World Formula One Championship 1987/88) by Nigel Roebuck:

During the Hockenheim test the World Champion had lost two engines. Depressing, after the problems at Monaco, Ricard and Silverstone, but there was some cause for optimism: Porsche believed they found - and solved - the reliability problems with the TAG V6. "I cannot say what thay have done" Alain said "but they have made a . . . mechanical change which will not help us on power, but should make the engines last much better. I feel much happier about everything than at Silverstone" The first of the revised engines, for Prost's use, arrived on Friday night, and the following afternoon two more were delivered for use in the race.

So maybe the reason for Prost's race pace - despite the World Champion's comments - was the new engine?

I found the answer for the original question while reading Alan Henry's book 'The Turbo Era':

Heavier pistons with more robust gudgeon pins added to the TAG turbo's reciprocating mass, but Porsche rebalanced the crankshafts prior to the German GP at Hockenheim where Prost flew until an alternator belt snapped.

Autocourse notes

"McLaren - Small duct for gearbox radiator. Bosch and Porcshe carried out considerable development work on the TAG engine in the interests of reliability and improved fuel economy, even if it meant a slight reduction in power. Problems believed to have been caused by earlier modifications which caused engine vibrations"