Re: Increasing top speed

Posted by PackardV8 On 2012/3/27 7:55:04

Quote:
"The thing is, with the speed of modern traffic I'd like to think I could travel at 50-55 mph (although the others near my home would prefer 90 -100 mph!!"

Yes!! This has become a problem for me too with my 48 Indian motorcycle. A problem despite 40 years of trying to make even just a 70 mph interstate hiway cruiser out of it. Nothing worse than becoming a moving road obstacle. And nothing worse for image of vintage tin collectors too.

I'm no Packard streight 8 expert by any stretch of imagination. But nearly all prewar engines regardless of make or manufacture were 2500 rpm engines (SAFE SUSTAINED rpm). 2800 rpm on an optimistic starry eyed day looking thru heart shaped rose colored glasses.

Regardless of what u do in terms of hi-speed axle gears or overdrives be sure to use tyres that will yield as large an OVERALL diameter of wheel/tyre as possible.

Most likely when u get REAL SERIOUS about running 70-80 mph (SUSTAINED) u'll have to drop a modern V8 in it. LImitations are limitations.

The very long stroke engines of the prewar era (say over 4 inch stroke) will wear piston rings real fast at rpm levels above 2500 rpm. But as prewar flat head engines thay are rather ez to re-ring at short intervals too. U just have to decide how much money u want to spend, how much time in maintence, how heart set u are on engine originality etc. U WILLL make a COMPROMISE. I promise. OR u'll poke along at 50 mph the rest of your life.