Why 400cc?


37 replies to this topic
  • grayracer513

Posted March 10, 2008 - 03:42 PM

#21

If it had ports, it wouldn't need 4 cycles to make power, only 2, because it wouldn't have valves to open.

Never heard of a Sleeve Valve engine?

The only thing truly new in the rather disjointed rant you quoted (maybe) was the indirect reference to the computer controlled pneumatic valve operating systems employed by cutting edge F1 engines. Compressed air was originally used to close the valves instead of metallic springs, since springs are subject to disturbance by harmonic vibrations and air is not. From that grew the concept of using air (because it moves faster than any hydraulic fluid) or other gases to open the valves as well, and to do so independently of a mechanical camshaft, allowing infinitely variable valve timing optimized to any given situation in real time. The kernel of even that idea dates to experiments by Volvo and Mercedes-Benz in the 1960's.

  • 02WR426Cali

Posted March 10, 2008 - 05:21 PM

#22

Yeah OK. So maybe every bike wouldn't sound good with their exact size, like a 516 or 249, etc. 426 sounds cool, so I guess it just has to be a good sounding number if the exact displacement is used rather than rounding up.

  • tl1000crf250

Posted March 10, 2008 - 05:50 PM

#23

"From that grew the concept of using air (because it moves faster than any hydraulic fluid) or other gases to open the valves as well, and to do so independently of a mechanical camshaft allowing infinitely variable valve timing optimized to any given situation in real time." You know what they say" the best cam is a square cam." since you cant have a square cam use air, electric or hydraulics. Listen to grayracer513. Once they get this onto a dirt bike= great power and pollution control. Can great power and pollution control go together...lol

  • BASSic

Posted March 11, 2008 - 06:26 AM

#24

since you cant have a square cam use air, electric or hydraulics. Listen to grayracer513. Once they get this onto a dirt bike= great power and pollution control. Can great power and pollution control go together...lol


Will we get that on the next generation of MX bikes, along with direct injection?

  • The Italian Stallion

Posted March 11, 2008 - 02:04 PM

#25

Yeah OK. So maybe every bike wouldn't sound good with their exact size, like a 516 or 249, etc. 426 sounds cool, so I guess it just has to be a good sounding number if the exact displacement is used rather than rounding up.

I guess the chinaman prefered Mopar over ford.429 would have been cool too.

  • Dveitch8

Posted March 11, 2008 - 02:37 PM

#26

I guess the chinaman prefered Mopar over ford.429 would have been cool too.


Is that a racial slur:naughty: I think my yz is Japanese but dont tell anyone I think she's still trying to fit in. A really cool number would be 454 or 469 ah crap iam just gonna call mine a 469.:thumbsup:

  • Wiz636

Posted March 11, 2008 - 03:50 PM

#27

So...a question for you serious engine builders...what can we expect to be the next major advancement in thumper tech?

  • grayracer513

Posted March 11, 2008 - 04:35 PM

#28

Digital EFI is clearly the next thing, starting now.

After that, it will probably be a while before the next thing comes along, unless someone decides that they need a 45+ hp 250F, in which case desmo heads or pneumatic valve springs could be next.

  • kxracer987

Posted March 11, 2008 - 04:54 PM

#29

Never heard of a Sleeve Valve engine?

The only thing truly new in the rather disjointed rant you quoted (maybe) was the indirect reference to the computer controlled pneumatic valve operating systems employed by cutting edge F1 engines. Compressed air was originally used to close the valves instead of metallic springs, since springs are subject to disturbance by harmonic vibrations and air is not. From that grew the concept of using air (because it moves faster than any hydraulic fluid) or other gases to open the valves as well, and to do so independently of a mechanical camshaft, allowing infinitely variable valve timing optimized to any given situation in real time. The kernel of even that idea dates to experiments by Volvo and Mercedes-Benz in the 1960's.


I had never heard of that. That computer controlled pneumatic valve system sounds cool to.:thumbsup:

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  • tl1000crf250

Posted March 11, 2008 - 05:48 PM

#30

I had never heard of that. That computer controlled pneumatic valve system sounds cool to.:thumbsup:


Caterpillar has what they call a huei engine that runs the injectors buy oil psi. Most of your diesel engine builders have already designed engines without camshafts just non have made it to market. As fare as the next big engine design I would say catalytic converters. I'm hopping for roller rockers, for just a little less resistance. Then again diesel engines have made there way into race cars, dirt bikes and cruiser bike... maybe a diesel crf is next.

  • grayracer513

Posted March 11, 2008 - 07:22 PM

#31

Hydraulically operated valve trains in big diesels (heavy equipment size) that operate at the dizzying speed of 2200 RPM (if that) is quite different from 11,500 or 13,500, or 17K+. Hydraulics aren't suitable for engines that run that fast.

Road bikes already have cats on them, but I can't think of a single diesel road bike. The Army has diesel dirt bikes, but don't wait for them to show up in MX. Diesels don't have the the rev range flexibility.

  • 02WR426Cali

Posted March 12, 2008 - 06:21 AM

#32

plus those army diesel dirt bikes are heavier than the stock klx 650 that they are made from. If some people think 4 strokes are heavy, just think what a diesel would weigh.

  • Windseeker

Posted March 12, 2008 - 02:50 PM

#33

plus those army diesel dirt bikes are heavier than the stock klx 650 that they are made from. If some people think 4 strokes are heavy, just think what a diesel would weigh.


Still the racing performance of Audis and such like (diesel cars) that outperform gasoline cars at the circuit races is impressive... so the advances in the diesel engine R&D will eventually make its way to bikes - road bikes first I guess - but who knows - 10-15 years from now - there might be a diesel MX bike lined up in AMA race :thumbsup:

  • tl1000crf250

Posted March 12, 2008 - 03:07 PM

#34

Hydraulically operated valve trains in big diesels (heavy equipment size) that operate at the dizzying speed of 2200 RPM (if that) is quite different from 11,500 or 13,500, or 17K+. Hydraulics aren't suitable for engines that run that fast.

Road bikes already have cats on them, but I can't think of a single diesel road bike. The Army has diesel dirt bikes, but don't wait for them to show up in MX. Diesels don't have the the rev range flexibility.


Ya, I was just putting the hydraulics out there. It does operate slower.

NO factory road bikes but cycle world just had a custom diesel in it. Did you know that the Audi R10 is just about unstoppable, it is a diesel with 650HP. It is a high revving race diesel in the Le Mans series. What you said about diesels not having a rev range flexibility is not accurate. If your talking heavy equipment and semi's they are designed with a long stroke for torque, not sort stroke like a Audi R10. Just food for thought. Until they can figure a way to lighten the diesel engines it will probably never be in a MX bike.

  • grayracer513

Posted March 12, 2008 - 04:23 PM

#35

I'm familiar with the R10. Would you consider a 6-7 liter diesel in a 3/4 ton pickup "heavy equipment"? If they had torque across a broad rpm range, they would accelerate. They don't.

  • tl1000crf250

Posted March 13, 2008 - 01:58 PM

#36

Diesels have the longest torque range out there, that is why they are used in heavy load applications. Maybe I'm misunderstanding you.:thumbsup:

  • grayracer513

Posted March 13, 2008 - 05:33 PM

#37

The typical V8 4 stroke diesel in a 3/4 T pickup pulls usably from as low as 600 RPM to around 2800, and is rev limited to about 3000. That's what, 2200 RPM?

The similarly sized gasoline V8 in my truck pulls from 1500 to about 4500; 3000 RPM. My YZ450 pulls hard from 4000 to 10000; a 6000 RPM spread.

Diesels, as typically built and delivered to consumers, have an extremely short operating range, limited to relatively low speeds, and their only ability to accelerate at all lies in their ability to work against very high gear ratios at low RPM.

  • tl1000crf250

Posted March 14, 2008 - 04:53 AM

#38

Your right since you are talking about the consumer built diesels, that is why I brought up the Audi R10. A MX bike will have to be built like that with that sort of range.
But the next bikes we will see will be electric anyway. Check out sub-forum CRF250R, the thread is -WOW CRF2ex its a cool design.

I like talking about diesels not many people do, sorry about hijacking the thread.





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