Final cylinder pressure not CR is the determinant factor. I suspect that most bike engines have significantly more valve overlap than car engines, leading to lower FCP for the same CR, thus more resistance to knocking.

 

That's not really true. Motorcycle engines can last for a very long time if proper maintenance is done. I had a bike I road to revline daily, a CBR600F3, and it had 40k miles when I got rid of it, and I bought it new. I did very minimal maintenance on it and it ran like new when I parted with it.

 

40K!?!? That bike had been nowhere!
My old motorcycle instructor had a ZX-11 that went twice around the dial. He eventually got rid of it 'cause he crashed it. And he would ride that bike 12 months a year in Calgary. Those small Japanese motors can go for ever.

 

Yeah, I only had that bike about a year and half to two years though I parted with it via totalling it My GSX-R750 had about 30k miles when I got rid of that. Both were ridden a lot in a short time, and hard. No more bikes for me though, fiance says.

 

Porsche Carrera GT 5.7-liter V-10 Engine

Compression Ratio: 12.0:1

Bore x Stroke: 98.0 x 76.0 mm

Redline: 8400 rpm

http://www.roadandtrack.com/article.asp?se...1&page_number=1

 

Chris

The BMW M3 has 12,5:1 compression ratio, at least here in Spain. We use 98 oct fuel

 

2006 BMW E60 M5 5.0-liter V-10 Engine (S85)

Compression Ratio: 12.0:1

Bore x Stroke: 92.0 x 75.2 mm

Redline: 8250 rpm


Reference: Nov 04 issue Bimmer magazine