Cafe Racer Forum banner

21 - 31 of 31 Posts

·
Registered
Joined
·
1,683 Posts
ok, but the change of valve lift/ rate of angular change happens in the same "pattern" whether you go "up" the cam profile or "down" the cam profile...

I'll wait to see what you come up with and if I have time I will model something in solidworks based on some youtube vids.
 

·
Registered
Joined
·
1,683 Posts
What's the goal here? You guys trying to figure out how to advantage variable valve timing on a budget, or come up with a better way to open and close a poppet valve :unsure:
You want to get more performance out of an ancient 2 valve per cylinder CB350, put fuel injection on it, that would be money way better spent!
For me, this is purely intellectual curiosity...
He's looking to do something actually practical, I'm guessing.
 

·
Registered
Joined
·
1,425 Posts
Discussion Starter #23
What's the goal here? You guys trying to figure out how to advantage variable valve timing on a budget, or come up with a better way to open and close a poppet valve :unsure:
You want to get more performance out of an ancient 2 valve per cylinder CB350, put fuel injection on it, that would be money way better spent!
the goal is a better understanding of engineering, ultimately getting to the point of being able to design a cam for an engine to your own specs, i.e. to pursue knowledge for knowledge's sake, which is never a waste of time imo.
 

·
Registered
Joined
·
1,683 Posts

Harvey crane had a website that had a lot of high level information on cam design, I can't find it anymore except quoted excerpts whenever a real intellectual discussion is taking place.
 

·
Registered
Joined
·
1,683 Posts
You might benefit from purchasing a comprehensive engine simulator software package that allows you to see and play with different cams.

 

·
Registered
Joined
·
1,683 Posts
speed-talk forum has historically had many professional engine experts participate and might be a resource. Most of the stuff on there is beyond me, but I did particpate in theor group buy to get pipemax a few years ago...
 

·
Registered
Joined
·
5,622 Posts
imho
The length of the lever changes so the speed the valve moves can be manipulated, but you still can't have the valves crashing into the piston or each other, or carrying so much momentum that they want to fly off the cam, then you would need to Desmo it, plus you can't have the valve slam shut too hard.

I seen where MV was doing valve design testing for the F3 and were able to yield several extra horses by changing a valve angle by only 4 degrees. :cool:
 

·
Registered
Joined
·
1,425 Posts
Discussion Starter #28
where I'm at currently with the tool I'm developing. now I can design a curve section specifying boundary conditions and mid-segment constraints, and the program will solve for those with a polynomial of chosen order, assuming the order is great enough to satisfy the conditions. I can then design the next segment, plot the two together, optimize, etc. The next steps are to allow saving of the specs of the combined curves, allowing import into other functions of the program, for things like pressure angle analysis, vibration analysis, and finally, drawing the cam lobe based on rocker setup. this is about 1/5th of the whole program I have in mind, but it's a pretty big part hours-wise... also, when finished, I will freely distribute it, I am using matlab student now, because I am in a class, so I couldn't justify trying to make money off an educational license.


102977
 
21 - 31 of 31 Posts
Top