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Location:
Perth, Western Australia
Registered:
October 2004
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Location:
Melbourne
Registered:
January 2003
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 06:53
 
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Are you referring a SAE engine , TM cylinder head ? if so the lift is half the stroke generally . The finger followers are rolling ball suspended in pressurized oil , not flat faced as the friction will not allow 13.000 rpm . For the motion under continuous acceleration there are charts of the camshaft velocity's in racetech engineer magazine , i think a few months ago . Also the firing order , or big bang theory will come into play with the camshaft profile design . The effecienty of those engine is getting close to f1 , properly more SAE hp per litre than next years engines . I would suggest you use the one cylinder lotus software that your uni should have , next time i look at the prototype heads for next year that are being flowed atm i will see if there are any specs on camshafts and forward you them . And if you can make the design optimize the engine performance enjoy europe because thats where you will be working after finishing the course .
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Location:
Perth, Western Australia
Registered:
October 2004
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:03
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Wasn't really the question i was asking.
We are just given the constraints and we have to find a suitable profile.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:07
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| Matt-itude wrote on Wed, 05 October 2005 13:57 |
Hey all,
I am doing a uni project on the design of a racing camshaft profile.
The requirements are 290 deg crank shaft duration @ 1.27mm lift and maximum valve lift required of 9mm. The engine has a max rpm of 13000 rpm, all using a flat faced follower.
Is it safe to assume, that the best performing camshaft profile would be one that opens as quick as possible to 9mm lift and then holds it for as long as possible before closing as quick as possible.
All while keeping the follower motion under continuous acceleration and trying to avoid infinite jerk (derivative of acceleration) and to avoid issues like valve bounce and avoiding critical contact stresses?
I would assume this leads to an asymmetrical cam profile. Is there any real problem with this, and or are are any of my assumptions incorrect?
Thanks for any educated advice you can give me
-Matt
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Not problems at all. The cam is the easy part, tailoring the valve spring to make it work is the harder part!
That's were the jerks come in to play (yes, I know what 'jerks' are) and hence with that amount of lift, duration, and revs you may well have to look at dual interference valve spring to provide an inherent damping quality to the spring.
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Location:
Perth, Western Australia
Registered:
October 2004
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:13
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we are given a simple spring constant to work with so we dont have to worry about that part of the design.
but designing the cam to rise as fast as practical and fall as fast as possible while nothing breaking is the best design?
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Location:
Melbourne
Registered:
January 2003
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:20
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dual interference valve spring , are not really needed . Sure that great for old school heads and valve which suffer from spring harmonics and valve float like 4age and early ford and boxer motor designs . But with the materials and mass of the valve drive train parts , and the most important factor in controlling that from occuring the valve length . This doesn't occur in SAE engine , so normal springs are used , as per most modern bike engine operating at 13.000rpm+.
What is the camshaft based on being used in ?
Honda CBR 250 RR 48.5 x 33.7 mm 62.26 cc/cyl 4 cyl. 249 ccs 13,567 13,500
Honda CBR 250 RR 48.0 x 34.5 mm 62.43 cc/cyl 4 cyl 250 ccs 13,252 13,500
Yamaha FZR 400 58.1 x 40.5 mm 107.37 cc/cyl 4 cyl 430 ccs 11,289 11,500
Kawasaki EX250 62.0 x 41.2 mm 124.39 cc/cyl 2 cyl 249 ccs 11,097 11,000
Honda CB-1 55.0 x 42.0 mm 99.79 cc/cyl 4 cyl 399 ccs 10,886 11,000
Honda NC35 55.0 x 42.0 mm 99.79 cc/cyl 4 cyl 399 ccs 10,886 11,000
Honda CBR 600 F4 67.0 x 42.5 mm 149.8 cc/cyl 4 cyl 599 ccs 10,758 11,000
Yamaha 1999 YZF-600R 65.5 x 44.5 mm 149.95 cc/cyl 4 cyl 600 ccs 10,274 10,500
Yamaha YZF-R6 65.5 x 44.5 mm 149.95 cc/cyl 4 cyl 600 ccs 10,274 10,500
Honda CBR 600 F2 65.0 x 45.2 mm 149.99 cc/cyl 4 cyl 600 ccs 10,115 10,000
Honda CBR 600 F3 65.0 x 45.2 mm 149.99 cc/cyl 4 cyl 600 ccs 10,115 10,000
Kawasaki ZX6 64.0 x 46.6 mm 149.91 cc/cyl 4 cyl 600 ccs 9,811 10,000
Honda CBR 600 F1 63.0 x 48.0 mm 149.63 cc/cyl 4 cyl 598.5 ccs 9,525 9,500
Yamaha YZF600R 62.0 x 49.6 mm 149.75 cc/cyl 4 cyl 599 ccs 9,218 9,000
Honda CX500 78.0 x 52.0 mm 248.5 cc/cyl 2 cyl 497 ccs 8,792 9,000
Kawasaki Ninja 60.0 x 52.4 mm 148.16 cc/cyl 4 cyl 593 ccs 8,725 9,000
Yamaha FZR600 59.0 x 54.8 mm 149.8 cc/cyl 4 cyl 599 ccs 8,343 8,500
Suzuki K6A 68.0 x 55.8 mm 202.6 cc/cyl 3 cyl 608 ccs 8,193 8,000
Honda VT500C 71.0 x 62.0 mm 245.5 cc/cyl 2 cyl 491 ccs 7,374 7,500
Husaberg 500 cc 95.0 x 70.7 mm 501.1 cc/cyl 1 cyl 501 ccs 6,467 6,500
KTM Duke LC-4 620 101 x 76 mm 608.9 cc/cyl 1 cyl 609 ccs 6,016 6,000
Honda NX650/XR600 97.0 x 82.0 mm 605.9 cc/cyl 1 cyl 606 ccs 5,576 5,500
Note engine rpm and set limiters
[Updated on: Wed, 05 October 2005 07:23]
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Location:
Melbourne
Registered:
January 2003
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:35
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Owe as a reference , most engines using dual interference valve spring where normal springs where before , have a limit of 10.000rpm , after that spring life is normally reducted to the springs needed changing after every run of the engine {race} , this is mostly due to the spring pressures that have had to be used to control the poor performance of the valve operation and the associated problems which come with this . This means the spring will weaken very quickly if not break other this limit of if left in a compressed state . Just look at most early f2 engines , inbetween races the smart people where out there undoing camshafts in the heads to relieve the stress on the spring inbetween races .
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Location:
Perth, Western Australia
Registered:
October 2004
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:43
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its the honda cbr 600... but again the question is far more simple than that
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Location:
Melbourne
Registered:
January 2003
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 07:55
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| Matt-itude wrote on Wed, 05 October 2005 03:43 |
its the honda cbr 600... but again the question is far more simple than that
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Honda CBR 600 F1 63.0 x 48.0 mm 149.63 cc/cyl 4 cyl 598.5 ccs 9,525 9,500
13.000rpm ?
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Registered:
January 2004
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 09:12
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improvedae86 are the rpm figures you give max rpm? as I note quite a few are much lower than the operating rpm of the motors in actual use, such as cbr250rr, nc35(I owned one, nice little bike), r6 etc etc, just curious?
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Location:
Melbourne
Registered:
January 2003
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Re: Camshaft Design and Optimisation
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Wed, 05 October 2005 10:52
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| 170bhp wrote on Wed, 05 October 2005 05:12 |
improvedae86 are the rpm figures you give max rpm? as I note quite a few are much lower than the operating rpm of the motors in actual use, such as cbr250rr, nc35(I owned one, nice little bike), r6 etc etc, just curious?
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yeap , some have years and some don't , as long as the SAE engineers know i guess .
[Updated on: Wed, 05 October 2005 10:59]
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