3rd gen Prius aeromod thread

[Vman455]

Originally Posted by veloman

The air intake mod is interesting. What about water/moisture entering when it's raining?

The effect of gravity on buoyant gases (such as air) is negligible, so they can travel up a section like the 12" of PVC that goes up and over the support structure before entering the horizontal flex tube and traveling to the airbox. Water, on the other hand, is very much affected by gravity, so water droplets and spray that enter the duct will drain out the open pipe at the low point of the intake. If some droplets happen to make it to the airbox, the filter is on the top of the box, with flow direction up and through the filter, another check on water intrusion.

If the inlet is submerged in water it's a whole different story; then the engine vacuum could potentially pull the water all the way into the intake. I made sure to site the duct high enough to make that unlikely.

A production example is the Challenger SRT Hellcat airbox:



The short tube is open to the front of the car; the filter sits on the top of the box and air flows up and through. The bottom is open for drainage and a secondary intake if the tube is blocked.

[California98Civic]

It is interesting that Toyota apparently thinks cold air, or cooler air, is better for fuel economy. ...the warm air versus cold air debates continue...

[Xist]

I thought that was moot with modern cars.

[mpg_numbers_guy]

Originally Posted by California98Civic

It is interesting that Toyota apparently thinks cold air, or cooler air, is better for fuel economy. ...the warm air versus cold air debates continue...

If cold air makes more power, then the engine runs at a slightly lower load for a given speed, which reduces efficiency, or at least that's how I've always looked at it. But with modern CVTs having infinite gearing, maybe it matters less now on newer cars.

[Xist]

Except that people do not like CVTs, they want to feel the shifts! Just like Ye Olde Toilet Paper customers complained that they wanted to feel the splinters!

It is not like that? Then it is just like some other thing!

[aerohead]

Originally Posted by California98Civic

It is interesting that Toyota apparently thinks cold air, or cooler air, is better for fuel economy. ...the warm air versus cold air debates continue...

I'm gonna guess that, they're going for charge density and power output from small displacement, and handling fuel economy via the entire suite of electronic and variable mechanical engine management technology now available.
One carmaker has recently debuted a double-walled, insulated intake manifold.

[MetroMPG]

With all the other tricks Toyota has thrown at squeezing ever more efficiency from the Prius, I'm a little surprised they don't have some kind of vane in the intake to pull cold OR warm air depending on power demand.


Or maybe there's too much thermal inertia to make that approach responsive enough when the driver calls for "FULL STEAM AHEAD" from the engine room?

[aerohead]

Originally Posted by MetroMPG

With all the other tricks Toyota has thrown at squeezing ever more efficiency from the Prius, I'm a little surprised they don't have some kind of vane in the intake to pull cold OR warm air depending on power demand.


Or maybe there's too much thermal inertia to make that approach responsive enough when the driver calls for "FULL STEAM AHEAD" from the engine room?

I suspect that it's complicated, between a winter cold start and summer restart, cold catalytic converter, and fully-warmed.
The Atkinson-cycle isn't known for torque, and if the CPU sees the throttle position sensor calling for wide open throttle, the motor assist is going to kick in, contributing it's torque and power, all the way up to the governed top speed.
In a winter scenario, where a heat-riser might be helpful, once the exhaust has some heat in it, and the intake tract is at a higher temp than ambient, on a call for more power, it may not be that much of a liability, since the electric motor is always at 100% available torque.
The CPU will always know the air mass, and ROM look-up tables will dial in the direct injection to optimize air-fuel ratio, plus ignition and valve timing, for best performance under the full spectrum of design conditions.
Ya just gotta love the integrated circuit and sensor technology.

[hayden55]

Originally Posted by MetroMPG

With all the other tricks Toyota has thrown at squeezing ever more efficiency from the Prius, I'm a little surprised they don't have some kind of vane in the intake to pull cold OR warm air depending on power demand.


Or maybe there's too much thermal inertia to make that approach responsive enough when the driver calls for "FULL STEAM AHEAD" from the engine room?

Don't worry. Toyota just read that and put it on the list of possibilities. GM too.