Atkinson to Otto?

jdr3366

jdr3366

Well-Known Member
I use ShiftSense Pro, so the gear I'm in always shows on the instrument cluster.

Sometimes it feels like the transmission has shifted. It's not as abrupt as the downshifting we always talk about. And the gear doesn't change, according to SSP.

In an earlier thread it was mentioned that the Atkinson combustion cycle changes over to Otto at some point. Is it possible I'm feeling the change over from Atkinson cycle to Otto?

Has anybody else experienced this?
 
Last edited:
Cool. So, what conditions cause the changeover to occur?

I found this. “It’s torque demand,” Mike Sweers, chief engineer for Toyota trucks, explains. “At constant speed, we’re running Atkinson. When you ask the engine to produce more torque and do more work, it changes over. The change is entirely in the valve timing. We have a brand-new variable valve timing system where the exhaust and the intake are completely independent of one another.”

https://www.autofocus.ca/news-events/features/atkinson-and-otto-how-toyota-blends-both-in-one-engine

So, every time you push down on the gas peddle it changes over? That seem too simple to me. It suggests that acceleration from a stop light starts in Otto. And I don't think that's what happens. But, what do I know?
 
Last edited:
I'd say it's changing injection modes. Atkinson cycle is "simulated" by the variable valve timing so it would be seamless.

toyota_2grfks_engine_ser1_05.jpg
 
whippersnapper02 said:
I'd say it's changing injection modes. Atkinson cycle is "simulated" by the variable valve timing so it would be seamless.
Click to expand...

As I understand the graph, Direct + Port Injection = Atkinson. Direct Injection = Otto.

Up to a certain point of engine load (or torque), it's Atkinson. Above that, it's Otto.

Yes?
 
jdr3366 said:
As I understand the graph, Direct + Port Injection = Atkinson. Direct Injection = Otto.

Up to a certain point of engine load (or torque), it's Atkinson. Above that, it's Otto.

Yes?
Click to expand...

This is just injection method. Otto vs atk is on it's own set of parameters but would be similar with load. Load goes up, ECU goes Otto for more power.
 
You must log in or register to reply here.
Back
Top