You are here: Forums SUVs Mazda CX-7 Mazda CX-7: Bring the diesel version to the USA!

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

Messages Page 3 of 3 1 2 3 Prev Next Last

Go To Msg # Search This Discussion

#18 of 22 Anyone interested..?? by wwest Feb 26, 2009 (5:08 pm)
I went by the Kirkland Mazda dealer today to look over the CX-7 and collected a brochure. Before I actually buy one to experiment with/on I was wondering if anyone in the Puget Sound region might be willing to participate in an experiment to improve the FE of the CX-7, possibly substantially so.   What I would like to do is mill the head of a CX-7 engine to get a compression ratio of 12:1. 12:1 has become typical for a DFI, Direct Fuel Injection, engine, but since the CX-7 is turbo charged the factory's "native" compression ratio is, as it must be, quite a bit lower in order to provide for the additional "compression" from the turbocharger as it spools up.   During the experiment the wastegate would have to be "wired" open so the effective compression ratio could not rise (much) beyond 12:1.   If anyone owning a CX-7 is interested I would be will to pay the costs purchase and install a new factory head once the experiment is complete.   I suspect the off-boost FE improvement might be in the range of 50% Replies to this message: tidester (Feb 26, 2009 10:14 pm) wwest (Feb 28, 2009 2:17 pm) tidester (Feb 28, 2009 9:59 pm) and 1 more...
#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.

Messages Page 3 of 3 1 2 3 Prev Next Last

Go To Msg # Search This Discussion

You are here: Forums SUVs Mazda CX-7 Mazda CX-7: Bring the diesel version to the USA!