Date: Fri, 29 Apr 2016 15:39:38 +0000
Reply-To: Jim Felder <jim.felder@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jim Felder <jim.felder@GMAIL.COM>
Subject: Friday: New VW Engine--it's Miller (cycle) time
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From Gizmag.com today:
Manufacturers are leaving no stone unturned in the quest to improve the
efficiency of their internal combustion engines. Just this week, we've seen
a fastidiously engineered diesel engine
<http://www.gizmag.com/ford-ecoblue-diesel-engine/43016/> from Ford
and a camless
engine <http://www.gizmag.com/qoros-qamfree-camless-engine/43045/> from
Qoros. Now Volkswagen, no stranger to doing whatever it takes to lower
consumption (figures), has joined the party by releasing a 1.5-liter Miller
Cycle <http://www.gizmag.com/audi-high-efficiency-two-liter-engine/37428/>
engine
tasked with improving fuel consumption and increasing low-down torque.
Volkswagen's engineers say there are a number of improvements that come
courtesy of the improved thermodynamic efficiency associated with Miller
Cycle engines. An increase in the geometric compression ratio has,
according to VW, allowed for improved efficiency in the load range most
customers will actually use, while the final compression temperature has
been lowered through early closing of the intake valve and the expansion
cooling that brings.
Thanks to these improvements, VW claims its new engine offers up peak
torque from just 1,300 rpm, while also improving fuel economy by 1 l/100 km
(235 US MPG) compared to the current 1.5-liter TSI engine.
Working tandem with these big changes to the combustion cycle are a number
of small changes that, when combined, contribute to the longevity and
efficiency of the engine. On the 110 kW (148 hp) version of the engine, the
cylinder liners are coated with an atmospheric plasma spray to cut down on
friction, improve heat dissipation and improve corrosion resistance.
The engine's cooling system has also come under the microscope, and now
will make sure the water in the crankcase and engine remains stationary
while the car is warming up. As well as cutting the amount of time spent
without the engine operating at ideal temperature, VW says the system helps
warm the cabin more quickly on cold mornings.
Although it's usually used on high end, big displacement engines, VW has
even fitted cylinder deactivation to the new engine, allowing it to run as
a two-cylinder under light loads.
An increasing injection pressure 350 bar has improved the mixture formation
in the engine, which should also lead to lower particulate emissions.
Interestingly, the release makes it very clear the efficiency and emissions
improvements are unlikely to show up under test cycle conditions, but
argues that they're likely to have a "distinct impact on the customer's
everyday driving."
The new four-cylinder engine will find its way into showrooms later this
year in 96 kW (129 hp) and 110 kW (148 hp) guises. It's currently on show
at the Vienna Motor Symposium.