tooter's manifold adventure...

[tooter]

Originally Posted by Bluevitz-rs

I think you're confusing it with a 2 stroke. Atkinson cycle is the same as Ottos. The only difference is that Atkinson has a shorter compression stroke than power stroke. On the Prius, this is achieved through intake cam timing and duration. The intake valve is held open much longer allowing some of the intake charge to be pushed back on the compression stroke reducing the energy required to compress the intake charge. This in turn rises the efficiency of the engine by effectively making the power stroke longer extracting more energy.

You're right. Hybrid engines acheive the Atkinson effect with valve timing.

Found this by searching How does a Prius hybrid engine work:

"Its engine only runs at an efficient speed and load - In order to reduce emissions, the Prius can accelerate to a speed of about 15 mph (24 kph) before switching on the gasoline engine. The engine only starts once the vehicle has passed a certain speed. And once the engine starts, it operates in a narrow speed band."

The bottom line is that installing a different throttle body on the engine might impair the optimum performance in that very narrowly tuned rpm range.

This explains why they use that weird intake manifold.

[JustDidIt]

Originally Posted by tooter

In order to reduce emissions, the Prius can accelerate to a speed of about 15 mph (24 kph) before switching on the gasoline engine. The engine only starts once the vehicle has passed a certain speed. And once the engine starts, it operates in a narrow speed band."

Currently I have enabled the EV mode hack which is standard on the EU and JDM Gen2 Prius This allows the prius to use the Electric motor only up to 34mph as long as the there isn't much demand for power. If I romp on the gas from the start - during heavy acceleration or hills both the ICE and MG2 move the car along.

Because I use the Torque android app paired thru Bluetooth with the ELM327 to monitor the cars sensors (no OEM tachometer) I can see the ICE running & RPM at all most all times except during stops at lights when the ICE shuts off to conserve gas.

Originally Posted by tooter

The bottom line is that installing a different throttle body on the engine might impair the optimum performance in that very narrowly tuned rpm range.

This explains why they use that weird intake manifold.

If I wanted to maintain the MPG vs HP, i'd prob leave the intake manifold and throttle body as is....but since HP is more what I am looking for with MPG to spare....guess I won't know unless I try. :)

[tooter]

Originally Posted by JustDidIt

If I wanted to maintain the MPG vs HP, i'd prob leave the intake manifold and throttle body as is....but since HP is more what I am looking for with MPG to spare....guess I won't know unless I try. :)

That's the spirit.
If it doesn't work out you can always simply go back to stock.