Quote:
Originally Posted by spinzero
But if that is the case then doesn't cascade charging sound more like the traditional sequential turbo? This would certainly take care of boost threshold issue, although as long as they use a big turbo (or two small ones for that matter) for high RPM, throttle resonse will never be instantaneous.
As far as I understand, VNT is the same as variable geometry turbo, in which case I don't think the price of such engine can come down to 3-series level anytime soon. The only petrol car that uses this is the 997 turbo. And if BMW does use this technology, it will be one of the most advanced engines that have, and will be very unlikely to be positioned below anything but the most outrageous NA engines.
I guess the confusion comes from the term cascade charging, which I've never heard of. Hector, do you have a link that connects this term to VNT?
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here they are, sorry don't know how to paste so i'll write them out;freepatentsonline.com/6134890.html and findarticles.com/p/articles/mi_mOFZX/is_10_69/ai_110471904
in both articles they use the term "cascade of vanes". not sure that this resolves the issue- i hear what your saying about the cost but i've only found the term cascade linked to vnt or variable geometry turbo and not to sequential. btw- found them googing: "cascade turbocharging". these 2 were on page 1, didn't go any further.