Mazda's engine development

[Aufenbahn]

CVCC. And with a carburetor!!

[legion]

CVCC used a rich mixture on one side of a perforated barrier (which had its own valve) and a lean mixture on the other side. The rich mixture is used to ignite the lean mixture.

Mazda is using a small rich mixture just in front of the spark plug to compress the remaining lean mixture without a barrier.

[Seahawk]

I need pictures:



Mazda's SPCCI compression engine: Here's how it works

https://www.mazdausa.com/why-mazda/skyactiv

[red-beard]

Originally Posted by Tobra

45% thermal efficiency?

[Tervuren]

Originally Posted by Seahawk

I need pictures:

I find myself more confused by animations than I do by reading about it.

[legion]

I would think that any gains that an opposed piston engine would be able to muster from more efficiently capturing combustion energy would be lost from more complicated mechanicals (two crankshafts, for example).

[Seahawk]

Originally Posted by Tervuren

I find myself more confused by animations than I do by reading about it.

I am exactly the opposite.

The first time I went through training on the SH-60 was in 1984...very rudimentary slides but lots of words to describe systems, which we were tested on.

I of course memorized how everything worked but really didn't understand the more esoteric systems, like the fuel control system.

Going back through a shortened syllabus in 1994, they had computer animations of all the systems and it was the first time I really understood the complex interactions.

I get what Mazda is doing and now understand the concept.

[onewhippedpuppy]

Originally Posted by legion

I would think that any gains that an opposed piston engine would be able to muster from more efficiently capturing combustion energy would be lost from more complicated mechanicals (two crankshafts, for example).

I was involved in some testing of a horizontally opposed 8 cylinder diesel aircraft engine that had a single crankshaft. The cylinders were staggered slightly and shared a crank journal if I remember correctly. Very cool product that is slowly making its way towards certification.

[flipper35]

Originally Posted by legion

I would think that any gains that an opposed piston engine would be able to muster from more efficiently capturing combustion energy would be lost from more complicated mechanicals (two crankshafts, for example).

Extra crankshaft but no valvetrain.

[legion]

Matt, do you have a diagram? I can't picture how you can have horizontally opposed cylinders with only one crankshaft.

[stevej37]

Infiniti has been selling cars with it's variable compression engine for a year now.
variable compression engines

[onewhippedpuppy]

Originally Posted by legion

Matt, do you have a diagram? I can't picture how you can have horizontally opposed cylinders with only one crankshaft.

Sadly no, it's been at least 5 years and there's not much online in terms of public information. Like I said, I think they were slightly offset such that the opposed cylinders shared a crank journal but it's been a while.

[pmax]

Mazda is doing interesting work here combining the spark ignition and diesel ICE techs ... compress the fuel to almost the point of self ignition, inject a tad more into the vortex and ignite the center, creating a compression wave which ignites the rest of the fuel ... more power, more torque at lower rpm, improved efficiency.

https://spectrum.ieee.org/transportation/efficiency/mazdas-new-skyactivx-engine-gives-new-life-to-internal-combustion

[GH85Carrera]

I friend of mine has and drives his 1999 Honda Insight as his commuter vehicle.



He get 60 MPH even today. The battery pack is dead. He has to pull the fuse to the system to get it to start and run, and withing a few minutes the error lights come back on, so he is running on just gasoline. He plans to maybe pull the battery pack and guys on the internet have figured out how to test each cell of the pack, and replace the bad cells. He said it is a slow and tedious process. He said people ask him more questions about it than any of his Porsches. Many people ask if he built the car himself, as they have never seen one like it.

[Tervuren]

Originally Posted by GH85Carrera

I friend of mine has and drives his 1999 Honda Insight as his commuter vehicle.



He get 60 MPH even today. The battery pack is dead. He has to pull the fuse to the system to get it to start and run, and withing a few minutes the error lights come back on, so he is running on just gasoline. He plans to maybe pull the battery pack and guys on the internet have figured out how to test each cell of the pack, and replace the bad cells. He said it is a slow and tedious process. He said people ask him more questions about it than any of his Porsches. Many people ask if he built the car himself, as they have never seen one like it.

The really fun thing about a fuel efficient car, is you can "race" your best MPG efficiency without the risk of blue lights from say, racing MPH.

There are very competitive males I know that track these things, and are all out to beat eachother. The end result is they pay attention to their driving, look ahead, and do their best to maintain momentum without giving it up.

[unclebilly]

Originally Posted by onewhippedpuppy

I think Infiniti has come out with a variable compression engine, also a cool idea.



It's both a compression and spark ignition engine, and goes between the two modes depending on load. Best of both worlds between a diesel and gas engine, but using gas and at a cost comparable to a standard gas engine.

Wasn’t Porsche the first to market a variable compression spark ignition gasoline fueled car? Sometime in 1975???

Anything with a turbo is variable compression...

[pavulon]

Originally Posted by stevej37

Infiniti has been selling cars with it's variable compression engine for a year now.
variable compression engines

Having owned a rotary, I'm biased toward Mazda but this Infinity take on variable compression looks like a mechanical engineering exercise gone wild.

[pavulon]

Originally Posted by unclebilly

Wasn’t Porsche the first to market a variable compression spark ignition gasoline fueled car? Sometime in 1975???

Anything with a turbo is variable compression...

Turbo Corvairs showed up in 1962.

[stevej37]

repost: selectable squish


Raising an engine’s compression ratio improves fuel efficiency during low-load operation, but it can also lead to catastrophic detonation when maximum power is requested. Engineers have long sought to navigate this challenge with a variable-compression-ratio engine, and Infiniti promises to implement its solution in early 2018 with a complex system of links in the crankcase.

There’s more than one way to skin this cat, though. German powertrain engineering company FEV proposes a piston wrist pin that passes through an eccentric bushing at the top of the connecting rod. As the bushing rotates, the piston moves vertically relative to the rod, in turn adjusting the compression ratio. The position of the bushing is determined passively by a pair of miniature pistons inside the connecting rod that rotate the cam in reaction to combustion and inertia forces. FEV’s 1.7-liter turbocharged inline-four demonstrator can adjust its compression ratio from 8.8:1 to 12.0:1 in 0.2 to 0.6 second.

[Sooner or later]

I bet that puppy ain't cheap.