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      07-04-2010, 09:47 AM   #7
Richbot
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Drives: Jerez Black E90
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The S65 is not equipped with valvetronic and never has been, and this engine will most likely die when production of the E9x M3 is discontinued, so a valvetronic version is unlikely. BMW didn't stop production of valvetronic as it is still available on many, if not most, of their other gasoline engines.

With just about every hot-rodding trick in the book thrown at it and some fancy cam timing devices to make it tractable at low rpm, the S65 is just a tiny, normal motor like any hot Honda engine. I do think 450whp on pump gas is asking a lot, 2.0l K20's making 225whp NA have a lot lower parasitic drag than a 4.0l S65 that has to sling around twice as many pistons, rods, valves, and so on. I bet the key to NA power (at least without changing displacement) on this motor is going to be getting it above 9,000rpm safely and camming it to match the flow at those rpm's. Most of the NA dyno charts seem to peak at or near the fuel cut, and plateau rather than drop dramatically. If supercharging weren't so cheap and easy I bet we could see some really cool builds but for now it just seems a little pointless unless you're crazy enough about NA engines to want to stay that way. I'm crazy enough but not interested in putting in the work, so keep us posted!

The Toyota Atlantics make incredible specific output for such an ancient design, but when the useful life of the engine is measured in hours, it's not so attractive anymore. I just got done shopping for racecars recently and the event-to-event cost on the atlantics is an eye-opener.


EDIT: Forgot, there is probably a way to use a set of factory cams to make a new grind. If you can find someone who can do a welded high-hardness overlayment (this is a technique used in everything from steel rolling machinery to Ford cylinder liners) sometimes called plasma arc metal deposition or other marketing-heavy terms, you could build up a few mm of material on the lobes and use that to machine from. For a one-off (well, two of each) it might be a good idea, especially for prototyping a cam which you may wish to change more than once.
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Last edited by Richbot; 07-04-2010 at 11:55 AM.
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