The great camshaft comparison....

[Dr.Jeff]

That's easy, if you overlay the two graphs, you would compare the areas "under the curve" ... the difference in this is the nett change in lift/rotation.
The other question your asking is "what's best for the stock engine" well unfortunately that's not such and easy answer.and comes down to a few of the points I tried to make in my "short summary" but I guess if I had to choose just one point it would be this one.

Thanks Steve. The example you gave for a stock engine, walking through the various points, helped a lot. When I read your important points previously they made sense from a theoretical view, but having a single example to apply everything to brings them together more.

I totally agree that making any one change singularly will not work, but must be combined with a balanced system of changes. And I'm really not trying to find the perfect cam for a stock engine. But asking it that way was an attempt to try and relay my questions. Perhaps a better way to ask it would have been for a description of how the important points come together applied to a real example that the majority of us can relate to. And that is what you did, thanks.

Regarding looking at the graphs and comparing the areas under the curves to compare cams. So looking at the heights for lift, widths for duration, and relative curve locations for timing, is it fair to then compare them in a general sense? By that I mean not necessarily looking at the actual values (numbers) and calculating the mathematical formulas, but more just the overall "shapes" of each cam. In order to get a rough feel for how that cam might interact with the other parameters of a particular engine, as compared to other cams. For example, be able to see that one is more of a high RPM heavily modified engine cam, just by how it "looks" on the graph. While that may seem like a overly simplified shortcut to assessing things, wouldn't it be a fair way to get a "feel" for what a particular cam is? Or is that just too simplified?

Just to be clear, I am not discounting the need for accurate calculations and consideration of all factors to determine a appropriate cam choice. Just trying to get a better idea of how to quickly compare cams in a general sense. This has always been difficult when looking at the offerings from various cam makers/suppliers. The information they give is typically very incomplete and vague, but often they show a graph. So having a better understanding of how to view those graphs might help a lot.

 

[fiatfactory]

I really don't mind the questions Jeff, as this discussion is actually helping write this chapter of the book... you'll see that a lot of this thread will find it's way into the appropriate chapter, which is how the whole book thing came about in the first place... simply collating a pile of my answers to questions in threads into one (semi) coherent text...

To better explain the use of the line graphs to visualise the differences in lobes, I'll get around to measuring a 5/55 9.2 cam ... about the worst stock cam ... and overlay it against the 4333059...the best stock cam... and I'll see if I can figure out how to shade the "area under the curve" I was talking about... and then I think then it will all make a lot more sense to you (and probably quite a few others reading along)

The aftermarket cams will all have their own strong and even some weak points... and yes that discussion is all coming, but no one is paying me to do this, so it gets done "after hours" .... 5 cams have taken about 25 hours of time so far just to compile the data.

SteveC

 

[Dr.Jeff]

Appreciate it Steve. Glad that you understand where I am coming from. And I was getting ahead of things a bit, but wanted to inject thoughts of how to interpret things as you are able to add more data. Thanks

 

[Tom Ginefra]

The aftermarket cams will all have their own strong and even some weak points... and yes that discussion is all coming, but no one is paying me to do this, so it gets done "after hours" .... 5 cams have taken about 25 hours of time so far just to compile the data.

Steve,
Your experience and insight are invaluable to us all, and "any effort" you make to enlighten us is very much appreciated. As anxious as we all may be to see the results of your research, we all understand the effort (and time involved) in not only doing this but documenting it all, as well. THANK YOU!