I dont know of many 4 strokes that can rev higher then 13,500. At 18k top ends will melt away fast and i really cant see bottom ends holding up to that for very long. I know of some race engines that can pull revs like that, but these are $30,000 race engines that are built just for this nothing else.

Oval piston? I have never once heard of that, thats something new to me i work with engines everyday and went to school for high performance R&D and never once heard of something like this.

The variable valve timing i have heard of, the 4.6 and 5.4 modular V8s use this now.

Whole thing sounds like some guy that knows a little bit about engines made it up to get people talking, but then again this is 2006 anything is possible, guess time will tell.

TR

 

Honda has used oval pistions in the past....8 valve head on a single??? 18,000 rpm? That must be a typo, spoke to my father in law who is a mechanic for an Indycar team, and he said that you'd end up with a big mess if you tried for those RPM's. Heck F-1 engines turn 14-15k rpm's and have to use hydraulic driven valves vs. cams as mechanical cams would just destroy everything.

Still, I am an optimist and I think there is some truth in what he's stated...


TPR

 

well the yamaha 250 revs to 12,000, and the 450 revs to 11,000. so a improvement over those engines could at most be 14,000, and i dont think a single can pull that much, if anything it'd be Twin. then you could have 8 valves

 

I remember a 2 cylinder Honda oval piston bike. Like a V4, but the pistons in each bank were like siamesed. 2 connecting rods and 8 valvle per cylinder. Yamaha tried 6 an 7 valves before the 5 they use now. They couldn't keep the middle exhaust valves cool enough to prevent damage.

 

I don't believe for 18000 rpm's either...

Just to make something clear, the F1 of today can do 18000 to 19000 rpm and the 2.4L V8 of next year should pass the 20000 rpm...[img]i/expressions/face-icon-small-wink.gif[/img]

Pout

 

i dont believe that at all. o and the yz250f revs to 13500

 

I don't think we will see anything close to that, but most of that tech already exists. Oval pistons were an idea tried on an extremely limited produced Honda (GP -like 4 stroke) back in the early 90s .. i think it was a V4, with 4 oval pistons and eight valves. Honda had experimented with 500 and 750cc versions. They had tried different configurations with some that spun as high as 22,000 rpms. The bike was a tech marvel but way too expensive to produce... producing an oval bore and oval pistons was a nightmare and there were many other challenges. Ultimately, I think they made a 100 or less and I think they sold for nearly 100k. I believe you could not just buy one, but rather, had to be someone special and basically be offered the bike.

There is a pic at the bottom of this site of the NR 750.
http://www.motorcyclistonline.com/ne...es/rockshow04/


http://community.webshots.com/photo/...93441190MNTmuy



*Thanks to Brad H for the new picture !
Who can forget the NR. It had so many firsts for a production motorcycle : Where do I start ? 747cc Oval Pistons in a V4, turn indicators in the rear view mirrors, real carbon fibre bits, twin fuel injectors, twin spark plugs, titanium con-rods, titanium coated alloy frame to prevent scratches, 260kph, 15,000rpm. It is reputed that at least 200 patents where registered to create the NR.
Strangely it weighed in at 220kgs !
Quite a hefter for a 750 even back then and especially so today and guess what ... yours for only AUD $83,000 and this was in 1992.
Is this the worlds most expensive prod bike ?
This bike was strictly limited edition, only a 1 month production run
and that was it.
Was the headlight and under tail muffler treatment 'copied' by Ducati ? Perhaps someone can tell me ! This was Honda demonstration of technical superiority - which it certainly was. I remember the intricate tail treatment very well.
I wonder if any still exist ?
The picture is an NR which is the track configuration.

http://www.cs.wisc.edu/~john/vfr/specs/92-nr750.html

 

Really dont keep up with the bikes too much, more of an American V8 kinda guy hence thats what i do for a living. I know if i have a oval piston i'm in trouble[img]i/expressions/face-icon-small-shocked.gif[/img]

 

I think this guy did this last time when the YFZ was coming out.

 

I remember this rumor a long time ago