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| Joined: | 03-12-2005 |
| Location: | Kingman, Arizona USA |
| Posts: | 532 |
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In any event, some of the 'standard' cam designs mentioned above were intended for use with turbocharged engines, and the fact that they also work fairly well with normally aspirated ones is probably sheer good luck.
As the valves in a 907 engine can hit the pistons if things go badly awry, I'm not sure that really high lift is a particularly good idea. The valve train mass is so low that you might get better overall results with less lift and a fairly abrupt cam profile. One must also consider the side forces that are applied to the cam followers; these can not be allowed to get too high or wear will increase tremendously and you might even lose more power than was gained from the greater lift.
As far as the MOP is concerned, as was noted, one can set any MOP within reason using adjustable cam gears. Lotus apparently chose the MOP to comply with emissions regulations, and back in the late 1960s and early 1970s, no one really understood how all the various engine design parameters inter-related -- they just knew that they had to meet the specs in order to use their engines in cars sold in the US. In any event, the 907 engine was developed first for racing, and supposedly just happened to be a fairly low-emissions design. (Or, which I personally think is more likely, the designers were brilliant enough to accomplish both.)
As somebody knowledgeable once said, decades ago, "You can do anything you want with an engine if you just want to start the race. Finishing it, well, that's another matter."