Mazda Skyactive driven in the UK
06-05-2011, 11:50 AM
#1
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Thread Starter
Mazda Skyactive driven in the UK
http://www.honestjohn.co.uk/news/gre...azda-skyactiv/
very complete write up with some very encouraging numbers
very complete write up with some very encouraging numbers
Last edited by zoom44; 06-05-2011 at 11:01 PM.
06-05-2011, 12:18 PM
#2
From the article:
I wonder if this would translate to the rotary engine. This would take us back to the exhaust ports being in the rotor housing instead of the end/center plates to make use of a scavenging long tube header (which I have wanted for 7 yrs). It would also take us back to having overlap to achieve that scavenging effect.
SKYACTIV petrol engine
A normal petrol engine has a compression ration of around 10:1. In a Ferrari F458 or a Formula 1 car, this is raised to 12.5:1. Mazda’s new 2.0-litre SKYACTIV petrol engine has a compression ratio of 14:1, the highest of any petrol engine in the world.
The upsides of an extremely high compression ratio in a petrol engine are superior efficiency, more torque and better fuel economy.
The problem would normally be uncontrolled combustion (or ‘knocking’) due to the return of residual gases from the exhaust manifold to the combustion chamber.
Mazda overcame this three ways: By using a specially long 4-2-1 exhaust manifold to scavenge residual gases, by employing sequential valve timing to optimise mixture airflow and reduce pumping loses, and by employing longer piston stroke, narrower bores and a cavity in the piston crown to create a stratifies air-fuel mixture around the spark plug and promote smooth growth of the initial combustion flame.
A normal petrol engine has a compression ration of around 10:1. In a Ferrari F458 or a Formula 1 car, this is raised to 12.5:1. Mazda’s new 2.0-litre SKYACTIV petrol engine has a compression ratio of 14:1, the highest of any petrol engine in the world.
The upsides of an extremely high compression ratio in a petrol engine are superior efficiency, more torque and better fuel economy.
The problem would normally be uncontrolled combustion (or ‘knocking’) due to the return of residual gases from the exhaust manifold to the combustion chamber.
Mazda overcame this three ways: By using a specially long 4-2-1 exhaust manifold to scavenge residual gases, by employing sequential valve timing to optimise mixture airflow and reduce pumping loses, and by employing longer piston stroke, narrower bores and a cavity in the piston crown to create a stratifies air-fuel mixture around the spark plug and promote smooth growth of the initial combustion flame.
06-05-2011, 12:26 PM
#3
Momentum Keeps Me Going
Very prudent of the Mazda magicians, improve overall efficiency and performance systemically, then only add extra apparatus and complication when and if needed down the road.
I think Mazda must be the anti-Chrysler lol based on that approach!
I think Mazda must be the anti-Chrysler lol based on that approach!
Last edited by Spin9k; 06-05-2011 at 12:28 PM.
06-05-2011, 12:26 PM
#4
From the article:
I wonder if this would translate to the rotary engine. This would take us back to the exhaust ports being in the rotor housing instead of the end/center plates to make use of a scavenging long tube header (which I have wanted for 7 yrs). It would also take us back to having overlap to achieve that scavenging effect.
I wonder if this would translate to the rotary engine. This would take us back to the exhaust ports being in the rotor housing instead of the end/center plates to make use of a scavenging long tube header (which I have wanted for 7 yrs). It would also take us back to having overlap to achieve that scavenging effect.
if they figure out a way to keep the peripheral port while keeping emissions low, then Rotary engine will be much more competitive (easier)
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