Nissan announces 2.0L variable compression ratio engine

[niky]

Originally Posted by RedDevil

Road&Track had it featured nicely:

Variable Compression Engine - How Infiniti VC-T Works

I covered it more thoroughly months ago...

[cRiPpLe_rOoStEr]

Originally Posted by niky

they're claiming V6-like power... meaning 250-300+ hp... though that's not too terribly far out for a two-liter turbo nowadays.

That's why it doesn't seem so likely to reach production. And with direct injection becoming more widespread, a fixed high compression ratio is actually more suitable than a variable one.

[MetroMPG]

This is not going to help the cause:

Infiniti QX50's New Engine Falls Short in CR's Fuel-Economy Testing

The automaker says its technology delivers best-in-class mileage, but our results show it’s among the worst

https://www.consumerreports.org/fuel...economy-tests/


CR registered 22 mpg in their "real world" test, vs. an EPA rating of 26 mpg combined.

[Vman455]

That's too bad for Nissan. The hammer of bad publicity is about to come down on them.

I've come to really dislike CR. They play to the public's overconfidence in its own intelligence with their air of scientific inquiry, when their process is, "Hey, we removed the controls on all the variables that actually allow you to compare things like vehicle fuel economy with any consistency. Now we're going to scream about how our results varied! Oogie boogie!" Meanwhile, John Q. Public thinks that because they write, "...CR runs its own tests to simulate what consumers are more likely to experience in daily use," their results are perfectly valid and applicable to Mr. Public's own use case because they used science-y words like "test" and "simulate."

[MetroMPG]

Whereas I don't like them simply because they hate the Mitsubshi Mirage.

What's not to like in a spiritual successor to the Geo Metro???

[MetroMPG]

I want to give CR some credit for making claims in a somewhat controlled fashion. They're at least doing track driving only, at set speeds, and correcting for temperature variation.

The government’s tests vs. ours

Road tests. Consumer Reports’ fuel-economy tests are conducted on our track and on public roads. Testers splice a precise fuel meter into each test car’s fuel line to measure how much gas is consumed. Each car is then run through highway and city drive loops, with each performed multiple times by two drivers.


The city test is conducted on a loop that’s set up on our track to reflect driving in a suburban area. It’s marked so that a driver must maintain specific speeds in certain sections and stop the car at specific points for set idling times. Highway mpg is measured by driving on a particular stretch of sparsely used freeway near our test track at a steady pace of 65 mph.



Each driver runs the test in both directions to compensate for wind and the slight difference in grade.


Our raw results are corrected for temperature using a formula established by the Society of Automotive Engineers. But we don’t test if it’s too hot, too cold, too wet, or too windy. Our overall mpg is a weighted composite of city and highway mpg measurements.

From: https://www.consumerreports.org/cro/...-gap/index.htm



An interesting trend from their conclusions (I believe this refers mainly to city driving):

[hayden55]

I've never been a fan of diesel. But since we're talking about killing diesels here... It sure wouln't be hard with the current fuel prices.
In my city in AR gas: $1.829 Diesel: $3.039
That pretty much kills diesel right there, even enough for me to consider a gas burning f250 over a diesel version.

[Angel And The Wolf]

Originally Posted by ksa8907

I thought hydraulically actuated valves were going to allow complete and independent control of effective compression ratio?.

Yes Start with the highest compression ratio your fuel can handle, for maximum displacement, and delay the intake valve closing as needed to lower the compression ratio as low as possible for the power needed. Of course, adjust the fuel injection map.

This system has too many reciprocating parts.

[samwichse]

Fiat's Multiair system is mechanically a lot simpler and seems to do a pretty good job.

https://www.youtube.com/watch?v=Td9Gz_h7Qpg

I've been very impressed with the cold start gas mileage.

Rumor has it, the turbo GSE 1L engine with multiair II (direct injection) will be replacing the NA 1.4L in the base Fiat 500 in the US for 2020!

[rmay635703]

Originally Posted by samwichse

Fiat's Multiair system is mechanically a lot simpler and seems to do a pretty good job.

I've been very impressed with the cold start gas mileage.

Rumor has it, the turbo GSE 1L engine with multiair II (direct injection) will be replacing the NA 1.4L in the base Fiat 500 in the US for 2020!

I always hoped for the twinair diesel