Gas & diesel engines are converging

[artificialist]

Originally Posted By: blackman777
Originally Posted By: blackman777
- SkyActive G-motor is 14:1 (highest compression for a gas engine)


I recently learned the American market only gets 13:1 because Mazda thinks Americans are too dumb to remember to use premium fuel. (sigh)


It isn't because Americans would forget to use premium fuel. If that was the case, Mazda would probably never have been able to make the RX-7 Turbo or RX-7 twin turbo.

The reason Mazda uses 13:1 compression in the usa is because people without high performance engines would prefer to use 87 octane fuel.

 

[Shannow]

Originally Posted By: artificialist
It isn't because Americans would forget to use premium fuel. If that was the case, Mazda would probably never have been able to make the RX-7 Turbo or RX-7 twin turbo.


The wankel has about the lowest octane requirement known to man...that's not an example.

 

[brandini]

Originally Posted By: Shannow
Originally Posted By: artificialist
It isn't because Americans would forget to use premium fuel. If that was the case, Mazda would probably never have been able to make the RX-7 Turbo or RX-7 twin turbo.


The wankel has about the lowest octane requirement known to man...that's not an example.

In theory yes, but in the manual, its 91.

And it's due to octane differences in our gas vs theirs as well as market differences and competition. You have to compete with your category so when someone says 'requires premium' you're not the only one that does, that sticks out when comparing compact SUVs.

 

[blackman777]

Originally Posted By: artificialist
The reason Mazda uses 13:1 compression in the usa is because people without high performance engines would prefer to use 87 octane fuel.

Well some USA citizens would rather have the full 14:1 compression sold in Japan, Australia, and Europe even if that meant running 89 or higher (like a Chevy Volt). It means higher MPG.

 

[blackman777]

More info:

The Skyactive-D (diesel) engine uses a throttle body! Quote: "When the throttle is partially closed while the engine is running, the EGT skyrockets due to a big increse of hot exhaust gas being retained in the cylinder due to the exhaust valve opening on the intake stroke and the suction created by the throttle plate, speeding the particle trap's regeneration without using an outside power source."

 

[blackman777]

Oh and:

The Mazda diesel has a BSFC of 0.26 lbs/(hp*h) which is 53% efficiency! That blows-away the VW-TDI at only 43%

 

[jrustles]

Originally Posted By: blackman777
More info:

The Skyactive-D (diesel) engine uses a throttle body! Quote: "When the throttle is partially closed while the engine is running, the EGT skyrockets due to a big increse of hot exhaust gas being retained in the cylinder due to the exhaust valve opening on the intake stroke and the suction created by the throttle plate, speeding the particle trap's regeneration without using an outside power source."


Wow, didn't know that! Very interesting.