Fordboy has two cams of mine and I’m sending him two more to have profiled. I use them for simulation work and to evaluate what the aftermarket companies are doing. With a OHC rocker set up the geometry requires a specific lobe shape due to the varying rocker ratio. As you profile, you sometimes find out that the lobe was taken from another application and while close, it may have weird dynamics. One aftermarket cam I measured had a large spike in positive acceleration at valve closing. Not good.
A smart move - for that very reason.
You really, really want to believe the cam manufacturers are doing it right, but having now seen dozens of cam profiles and comparisons, it's way too often a crapshoot.
And as with any part, the manufacturer will seldom stand behind it after it's been installed.
As to the engineering, it seems they all steal from each other.
But if you take it out of the box, run a profile, and call them on the issues, the reputable grinders will either fix it or get you a refund.
I'm reasonably certain most of the engineers at the cam companies hate it when their work is checked, and non-conforming cam profile files fill their e-mail in-boxes. And in 9 out of 10 applications, their grinds probably work just fine.
But given the small displacement of what you, me and Mark are doing, and the slim margins for error, an incorrect cam, or an improperly ground lobe can mean the difference between success and shrapnel.
Mark checked the Piper Cams when they came in last summer. They were spot on, which is great. The idea of sending cams back and forth between the US and Great Britain is not my idea of a fun time.
Oh, absolutely. When you realize there are less designers than there are camshaft grinding outfits, it should tell you something.
You also realize that a bunch of the designers have bounced around and left their mark across several places. For example, Harold Brookshire (RIP) started at Reed Cams, then went to General Dynamics, from there he went to Comp Cams as their first designer (where he started designing assymetrical pushrod lobes) and wrote their first design program, then he went out on his own (Ultradyne - which Bullet Cams bought the masters (they also bought Lazer when the owner passed away)). After that ran into cashflow problems due to core availability and the UPS strike and the Feds shut him down, then he designed the VooDoo series for Lunati, then he went from there to Custom Camshaft Company (Arrington) doing NASCAR and Pro Stock work, CCC was sold off and the lobe designs went to Howard Cams. His last stint was back at Lunati and he designed the TL2 (flat tappet) and TR2 (roller) lobe family before his health deteriorated. He did say he always improved on his designs as he moved around, but certainly had his own style (good enough for NHRA Championships, a couple Daytona 500 wins and other NASCAR wins, and other USAC, NHRA, 24hrs of Daytona, etc. wins). Billy Godbold who is the designer at Comp Cams (got his start when his PhD funding ran out in the middle 90s) certainly is influenced to a certain degree by Harold as some of their flat tappet designs look similar to Harold's and he was also coached a lot by Harvey Crane. Harvey and Harold were also pretty similar in their designs techniques.
Harvey Crane layed out all the people he accidentally got into the camshaft business:
http://web.archive.org/web/20100112082128/http://harveycrane.com:80/founders.htm#individuals . Of the ones named, only Harold Brookshire didn't steal any of his stuff.
Ideally you need to talk to a cam designer. Mike Jones (Jones Cam Design) is easy to get a hold of, Billy Godbold (Comp Cams) is accessible via social media, Harold Brookshire (RIP) was easy to get a hold of before his passing, but others are hard to get a hold of and you may have to pay a consulting fee, have died, or have moved on and are retired. I never dealt with Dema, but that's what Fordboy is for (amongst other things)!
You get what you pay for and to get what you really need, outside of a pushrod application of common tappet / roller diameters / base circle diameter, you likely will have to have a design produced, a master cut if applicable, have a core made, etc. It adds up really fast. A friend of mine has about $900 in each Triumph TR4 camshaft, and he was able to use existing lobe designs!
Most aren't maximizing performance. A lot of the common pushrod flat tappet cams are for Chevy .842 flat tappets. I know some of the UK grinders have used whatever the small Ford pushrod engine is. Other comapnies may have built their offerings off something like an air cooled Kawasaki with bucket lifters.
With OHC rocker and finger follower designs, the lobe design has to be proprietary to that particular head's / set up geometry as the rocker ratio is variable. Some other applications may be close, and for most it's good enough, but as you said, if you're pushing performance then it's not what you want.
Obviously, the diameter of the lifter / bucket will cause a ceiling to be placed on peak velocity and you could be giving up a lot of performance.
It's actually to easy to see what kind of safety factor your lobes are designed to for a flat tappet / bucket lifter type valvetrain.
Edge Distance = -1((Velocity*57.3)-(Tappet Diameter/2))
Velocity is in inches / degree. Diameter is in inches.
This will allow you to see what safety factor your cam designer is using. Pushrod engines, designers typically use .018-.020" for off the shelf stuff with a typical chamfer. OHC with stiffer valvetrain systems might be as tight as .009" for off the shelf designs. With work, you can tighten those up and gain more velocity which equals more lift area. This is why NASCAR put into place a tappet diameter rule as racers were using mushroom flat tappets. Even with the .875" diameter tappet that NASCAR ended up with, they ran their tappets with no chamfer and right out to the edge of the tappet. That's a risky place to play, but they had the resources and money to make it work.
Use this equation to plug and play and see how much velocity you could have:
Velocity = ((Lifter Diameter/2)-Edge Distance)/57.3
This will impact how much lift area you can have (even with valve lift limits).
Acceleration is the tricky one.