4 pattern hyd roller cams

[roverman]

All aboard the Comp Cams band wagon... Nascar technology, for street use. Longer intake runners need more intake lobe duration, to match the output of shorter runners-fact. Comp is claiming gains of 5-20 hp. and up to 1,000 more usable rpm., with their hyd roller grinds. How did this high tech get by "Dynomation" and "Pipemax" ??  Onward, roverman.

[crashbash]

Would running Dynomation and Pipemax with the long runner and then the short runner specs give you good numbers to use on cam design?  ie long runner lobe, short runner lobe, etc........

[roverman]

David and clan, I have neither, but perhaps Dan Jones or Fred Key could chime in ? As I recall with Dynamation, you do enter runner lengths. Onward,  roverman.

[DiDueColpi]

Scatter pattern cams are not new.
Vizard coined the name in his A motor book.
Siamesed ports were robbing each other of charge velocity so he simply changed the cam grind on a per cylinder basis to even things out.
Racers have been doing this for years to overcome intake, cyl head or exhaust deficiencies.
It really isn't an ideal fix. It's just used as a crutch for a design flaw that can't be overcome any other way.
I don't think you would see one on an optimized fuel injected motor.
Using a varying pattern cam on a street motor is problematic.
Fuel consumption and emissions go out the window.
Improvements are targeted at very specific rpm ranges with corresponding loses at others. Idle quality becomes interesting.
In a race car it's a last resort after every other fix has been tried.
One interesting though just occurred to me though. You could use a scatter pattern cam to level out the torque curve of an engine.
With various cylinders peaking at different rpms you could flatten out the torque curve of an engine making it much more usefull in certain applications.
But we're building sports cars not trucks.... aren't we?

[Dan Jones]

Yes, in Dynomation you enter runner lengths.  I generally average the short
and long intake runner lengths but you can also run the short and long lengths
separately.  Dynomation has an optimization loop for cam specs and induction
length (can be run simultaneously).  Pipemax predicts the good and bad exhaust
lengths.  Back in the Can Am days, you'd see different length independent
runner stacks in an attempt to widen the torque band.

Dan Jones