Quote:
Originally Posted by cbaber
Why would lean burn not be achievable? Its been proven many times that leaning out the mixture at low loads at highway speeds results in a big jump in economy. Of course there are tons of variables and you would need a good base to start from, specifically something already designed for economy. But to say its not achievable based on only your experiences is a little harsh.
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Also remember that the d15z1 and I think the HX motor as well have special swirl combustion. hey're designed to withstand the high heat that is created in lean burning.
Try taking a stock d16z6 si engine and just lean the fuel injectors out to 20:1 air fuel ratio and you're going to destroy the engine. The engine has to be designed to go to lean burn in the first place.
Sure leaning out the A/F ratio to like 14.7:1 from 13:1 will realize a gain, but from my limited tuning experienece, you don't want to mess with high AF ratios on a normal engine.
"VTEC-E is a variation of SOHC VTEC which was used to increase efficiency at low RPM. At low RPM, one of the two intake valves is only allowed to open a very small amount, increasing the fuel/air atomization in the cylinder and thus allowing a leaner mixture to be used. As the engine's speed increases, both valves are needed to supply sufficient mixture. A sliding pin, which is pressured by oil, as in the regular VTEC, is used to connect both valves together and allows the full opening of the second valve. The engine runs at normal performance using the second cam position that would typically be tuned for high-RPM performance in other two-stage VTEC designs."
Taken from
http://en.wikipedia.org/wiki/VTEC#VTEC-E