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Mazda CX-7: Bring the diesel version to the USA!

22 messages,  Last post on Mar 01, 2009 at 11:14 AM

You are in the Mazda CX-7 Forum. Your Hosts are steve_ & tidester

What is this discussion about? Mazda CX-7, Diesel, SUV

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#19 of 22 Re: Anyone interested..?? [wwest] by tidester HOST Feb 26, 2009 (10:14 pm)
Replying to: wwest (Feb 26, 2009 5:08 pm) I suspect the off-boost FE improvement might be in the range of 50%   What would be the basis for your suspicion? Is it just a hunch or are there real world numbers behind it?   tidester, host SUVs and Smart Shopper Replies to this message: wwest (Feb 28, 2009 2:17 pm) tidester (Feb 28, 2009 9:59 pm) wwest (Mar 01, 2009 11:14 am)
#20 of 22 Re: Anyone interested..?? [tidester] by wwest Feb 28, 2009 (2:17 pm)
Replying to: tidester (Feb 26, 2009 10:14 pm) Well, first, this engine uses DFI, Direct Fuel Injection, for which 12:1 compression ratio is now typical. But in order to allow for the increased "effective" compression ratio as the turbo spools up the "native", off-boost, compression ratio is only 9.5:1.   So "off-boost" this engine is quite heavily derated/detuned and runs in that mode 95-98% of the time.   Cadillac just happens to have two V6s in the market at the moment, one with DFI and one without. Compare the two and you get my theory. Replies to this message: tidester (Feb 28, 2009 9:59 pm) wwest (Mar 01, 2009 11:14 am)
#21 of 22 Re: Anyone interested..?? [wwest] by tidester HOST Feb 28, 2009 (9:59 pm)
Replying to: wwest (Feb 28, 2009 2:17 pm) But you're suggesting that a 26% increase in compression ratio (9.5 to 12.0) will lead to a 50% increase in fuel efficiency. I don't see how that follows.   tidester, host SUVs and Smart Shopper Replies to this message: wwest (Mar 01, 2009 11:14 am)
#22 of 22 Re: Anyone interested..?? [tidester] by wwest Mar 01, 2009 (11:14 am)
Replying to: tidester (Feb 28, 2009 9:59 pm) The power increase from CR would result in less turbo on-boost time......   The turbo wastegate could be held open for low to moderate levels of acceleration.

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