SAE papers describing Prius c

So I should drive below 70 mph my Gen II and C to avoid transaxle overheating?

Is there a separate air or water cooled transaxle heat exchanger for the C? I have not noticed one on my GenII.

What is the Gen II transaxle model number?

What is the C's tranaxle model number?

Thanks.

 

I bought them too. It has a lot of great information. It sure satisfied my curious mind.

 

I just had a chance to read the PowerPoint and PDF files that Danny got from Toyota. They pretty much cover the important parts of the SAE papers. There is some original content in the papers speaks 'engineer' so I don't regret buying them. But I'm not sure the extra details are that good of a buy for $23/each ... unless you're very curious about things engineering.

Bob Wilson

 

Ok,

Having taken a peek at the Consumer Reports review and their 'defense,' we can speculate on what it would take to make the Prius c (all Prius models,) into something CR would love. First, this is my current understanding of the CR requirements:

• 0-60 mph at 10.0 sec, less than 11.0 - we don't know the exact number but it is in this range. Certainly 10.0 seconds meets the threshold.
• "driver position" - a better seat and wider steering wheel adjustment, possibly an extra 1-2".
• "noise" - flipping the engine so the exhaust is forward will take a little time. For a short term fix, heavier exhaust pipes and noise absorbing, engine/transmission mounts.
• "busy" - add caster angle for more straight-line stability
• "handling" - reduce the electronic steering assist so more mechanical feel is in the steering wheel

The hardest problem is acceleration because this is going to take an extra 10 hp, 7.5 kw. So this would require an extra 52 A at 144 V and that is not going to happen. However, if the power-split device is used, the current drops to 14.5 A (battery voltage) and only 4.2 A. at voltage boost range. The rest can come from the ICE _IF_ it can make a little more power at maximum acceleration. Only 7.2 hp is needed and this is feasible.

Toyota has variable valve duration as well as angle technology in at least one Lexus model. Fitting this technology into the 1.5L engine is not impossible, a new head would be required. But it would allow the Atkinson engine to move to an Otto cycle in high power, demand mode. Fortunately, Otto cycles are reasonably efficient at high power settings.

Another approach that does not require a new head is supercharging. Turbo is desired but in a small car, a challenge. An electric turbo would be another approach but I don't have enough information to determine if this is practical.

Now there is one 'wild card' solution that could improve "handling" and mileage . . . fully inflated tires. The traditional problem is the ride becomes harsh. But this can be mitigated by improved shocks, front and back. Replace the sidewall flex with a two-stage shock that has a soft, limited distance lower-resistance followed by a long distance, high resistance mode. The shock replaces the lower pressure, sidewall flex so higher pressure, lower rolling resistance tires can let the car get 'thrown around the track.' But is this effort wise?

How many Prius does Consumer Reports sell?

Perhaps the best answer is to pluck 'low hanging fruit,' things that only change manufacturing specifications, but don't jump through the costlier hoops, engine and drivetrain, just to please the reviewers of Consumer Reports who want a 'track car.'

Bob Wilson

 

I find this piece very interesting:

 

Me too! All of these little changes add up and help explan the crazy numbers we are seeing with these little cars.

 

^
I'm impressed with your 61.4 average so far, any tips?

 

Turbocharging a Prius C size engine shouldn't be a problem.
Turbocharged 600cc class Kei cars have been around for decades in Japan. Turbocharging scales well.
You can even get peanut whistle sized turbos for 125cc engines.

Slightly different topic, I believe Mazda already has engines that vary between pseudo Atkinson like a Prius to Otto cycle based on power requirements. If it's able to run in Otto cycle when needed and has direct injection, a C size engine should be able to develop 120 hp. Developing the electrical muscle to balance that in the torque splitter might require a different HSD though

 

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Drive slow (60mph max on the freeway), avoid making frequent short trips, don't use AC excessively, keep your tires inflated properly or even a tad overinflated and use gliding techniques whenever possible. My mpg recently is simply a reflection of my long freeway trips (50mile minimum). I do not suffer from frequent warm up periods like those with shorter commutes. I also have very fuel efficient tires and I don't use the AC most of the time.