Topic: calculated camshaft from gaenssle

[Aurel]

Hi,
did anybody calculate a camshaft from the German company gaenssle (http://www.gaenssle.de/).
Did anybody have a 3D model of the valve train (cam to valve). i know that gaenssle did calculate camshafts for cb750 engines but when i what a calculated cam i have to pay the how measuring from the cam to the rockers and the valve.

[johno]

Hi Aural,
fooling around with cams is fun, BUT may not be so much fun if your trying to reinvent the wheel and have to pay for the privelage,

The profiles have changed over the years from symmetrical to assymetrical to Polydine and I cant pronounce the latest style but to be honest I dont think you could improve on the main styles of cams on the market now and there are lots of choices with at least two real good camshaft threads on this forum.

I think your asking about the sohc rocker ratio, if so 1:1

If you want the biggest meanest cam in the world email me cos while duration is easy and lobe centres  etc I am keen to chase .500 lift or more and the rocker ratio and included valve angle in the head make that impossible, so I would be happy to help pay to get around those restraints in an economical way
cheers johno

[bear]

I'm with you Johno,

They can jam big duration up their jumper, but I'd give my left one for .500 of lift.

Cheers,
Brian

[Aurel]

The valve train is a mass-spring system. Gaenssle calculate a cam profil that I can use softer springs with the same duration. When I have all the geometry of the valve train and the weights of all moving parts and the spring rate, he calculate a cam with the most duration that's useable with a rev limiter without valve chattering. When i use lighter valves and other springs and a racing camshaft i can not be sure that the springs are to soft or to hard. I want the right profil and spring rate for my mass spring system. Have a look on the page http://www.gaenssle.de/Englisch/FrmSetE06.htm

[scottly]

Slipper-type rockers don't have a fixed ratio, as the nose of the cam lobe sweeps across the face of the slipper: in this example, the wear pattern is about 13mm across, and the ratio varies from about 1:1 to 1.5:1.

[turboguzzi]

Aurel, we all envy you for having the  time to  play with one-off , DIY,  primary drives and cams
After 46 years on the market and as an object of serious tuning, you'd think all there's to be known about sohc 750 cams has been discovered,  but what do i know?
maybe there are 20 hp hiding in that magic software...
Scottly, you are right about ratio, claiming a fixed ratio for a rocker system is wrong unless it's a roller folower. any sliding contact introduces variable geometry/ratio

[PeWe]

Cheap taylor made cams would be fine.  Possible to rewake the old profiles no longer on the market or send in a cam to copy but with more lift and maybe slightly more duration to be nice to the valve train and avoid valve float or seat bounce. Yes, I've read Action Fours old catalog

I'm currently waiting for an old cam I found on eBay that can be like my Action Fours SS-1 cam (.360/.360 lift) but hopefully with a little bit more IN lift, Andrews D (.385 lift). It can be the A cam too, similar duration but .345/.345 lift.

The old Yoshimura cams would be nice to test. http://www.satanicmechanic.org/yoshicam.shtml

[turboguzzi]

my 0.02$ ? before taking sohc cam design to the next level, where no-one stepped before, consider making new rockers too. there are technical limits on profile imposed by the available pad area, location, curvature and even clearance to the rocker central section..... 

[TurboD]

"In my opinion" as they say.

The cylinder head on the SOHC Honda has and ALWAYS will be the limiting factor to how fast or how much power these old engines will make. If a cylinder head will only flow a certain amount of air, continuing to add more camshaft will not make more power, all you will end up with is a engine that has a so so top end with no or very poor low end and mid range.

I have a computer dyno software program that I have used for 15 years for all types of engines, it has been very helpful to me in a number of areas when it comes to planning out an engine setup. I have been playing with it using a many of the currently available SOHC cams. I will say this, there are many cam grinds out there that simply don't make for good useful cams. Given the practical RPM range and limited cylinder head flow of the SOHC, many of the cams available (new and old) are simply not good choices, regardless of the application.

My tip (again for what its worth) . Pick the cam that you think will make the most power, then actually go with one a step smaller. You will be much happier.   

[Old Scrambler]

All good info...............my limited experience tells me that the cam alone is not the final answer. Yes, a performance cam will improve the power output.......but at what level and where in the rpm- range? I chose to use the 410-head because of the larger valves and ports. Then we increased the ports, installed modern valves with a steep seat-angle, bored the throats, and had a custom cam ground with wider lobe-centers.........all in an effort to increase flow capacity and move the power higher in the rpm-range. The actual lobe-shape has a very rapid opening-acceleration and closing and was helped by choosing modern springs that are thought to apply the correct amount of pressure throughout the process but with an overall lighter touch that is expected to reduce the load on the cam-tower. I was motivated to avoid valve-float by getting rid of the double-spring 1800s tech.

Would I go with a 'bigger' cam? Probably not. The current build is a 762cc motor and I am thinking this head will work quite nicely on a 915 or 970 kit. Do I want more lift? (Lift is a time sequence) Only if I want more power in the mid-range and have no plans to rev the motor above 9,000-rpms......if that. Based on advice from Megacycle Cams..........I would reduce the lobe-centers to move the power lower in the rpm-range. For the street or endurance racing, Turbo-D, Yoshimura, and our friends in Europe have good advice that doing other motor work and staying with a mild cam is the most reliable way to go. Are the carbs the right size? How about the exhaust-pipe size and length? Its all a package...........but let's not start an oil discussion  

[PeWe]

Cam discussion would be perfect.   Cam reviews of all CB750 cams ever made..... This can help Aurel to find his cam design. And others too, like me
Yoshimuras philosophy about cams for racing is interesting. The hotter cams feels to be better when the power comes hard at higher rpms but might not be the best choice. The cams with less radical lift and overlap give a broader power curve....

I found the article on Internet and posted it in another thread.
http://forums.sohc4.net/index.php/topic,147470.msg1679064.html#msg1679064