What ICE would you pick(or wish) in '09 Prius?

[holycow99]

Okay, the focus on the all new '09 Prius seems to be on the battery part (plug-in and/or Li-ion). How about the ICE part? What is the rationale behind Toyota's picking of the current ICE (1.5 litre, 76 hp)?

I for one wish a more powerful one, perhaps like the one in Honda Civic hybrid (1.3 litre, 110 hp).

[hampdenwireless]

<div class='quotetop'>QUOTE(holycow99 @ Nov 3 2007, 10:51 PM) [snapback]534506[/snapback]</div>

Okay, the focus on the all new '09 Prius seems to be on the battery part (plug-in and/or Li-ion). How about the ICE part? What is the rationale behind Toyota's picking of the current ICE (1.5 litre, 76 hp)?

I for one wish a more powerful one, perhaps like the one in Honda Civic hybrid (1.3 litre, 110 hp).
[/b]

Toyota has quoted that the next engine will be 1.8 litre no mention of horsepower. They target despite an increase in size the 0-60 will drop one second and the mpg will increase. Most articles reference a turbocharger, but I personally think there is a chance of a first in a car TURBOGENERATOR.

http://jalopnik.com/cars/gossip/artificial...urbo-178661.php

http://www.autoexpress.co.uk/news/autoexpr...yota_prius.html

http://www.autoexpress.co.uk/news/autoexpr...urbo_boost.html

[tballx]

None. But of course, that won't happen yet.

[patsparks]

I don't even know why Toyota make a 1.5 litre engine.
Most make 1.2L 1.3L 1.6L 1.8L and 2.0L I thought it was odd when toyota bought the Tercel and Sprinter to Australia with 1.5L engines when the corollas all had 1.6 litre engines. Must be a tax thing in Japan.

I'd just like a little better acceleration, maybe work on the launch lag, and much better economy. Mostly I'd like a wagon version and a MR2 hybrid too.

[efusco]

While a smaller yet high HP ICE is certainly an option it would create difficulties with the emissions ratings as well as fuel economy as it would mean going to an Otto cycle ICE instead of the current, more efficient and cleaner Atkinson cycle.
Hence the apparent decision to go with the larger 1.8L Atkinson cycle to extract a little more 'umph' while still getting the benefit of good FE and low emissions.

[donee]

Hi Holycow99,

You know the overall horsepower of the Prius is 110 hp, and the acceleration matches that of a similar ICE only car that Toyota makes with a 145 hp engine?

People have been buying HP numbers, but what they really use is acceleration. The Prius as it stands is a pretty good mix of acceleration and fuel economy. With the various forms of Hybrid technology, HP rating alone is not the whole story. This is similar to Amory Lovin s comments on Electricty.

There is a problem with thottled engines. Its called the "partial power" problem. When the typical engine in a standard car is at 1/3 of its hp rating or below, its efficiency is half that of its maximum efficiency capability. Or about 12 % of the fuel energy makes it into shaft turning energy, rather than 24 % typically.

There is also a basic rule of engines that the bigger the difference between the burned temperature and the exhaust temperature, the more energy is delivered to the piston. This turns out to be parallel to expansion ratio (which is the same as compression ratio in standard cars, but not the Prius).

By using the Atkinson Cycle and the Miller valve train, the Prius achives 25 % efficiency at 1/3 rd power, and even more optimally. It does this with a 13:1 expansion ratio, and blows back some of the intake in one cylnder to the chamber behind the throttle valve making that air available for other cylinders without the drag of the throttle valve. Other engines cannot run 13:1 expansion ratio, because that would also require a 13:1 compression ratio in those engines. Which would require super high octane (AV-Gas) fuel, not sold at road vehicle gasoline stations. And that gas would have less fuel energy, besides.

Since all the energy from the Prius comes from the engine, using a standard engine would half the the highway mileage. As at highway speeds, engines are very lightly loaded. So rather than 55 mpg, the mileage would be closer to 28 mpg. City mileage would probably not drop as badly, with special technique driving however.

Is the 2008 Civic Hybrid quicker than the 2006/7's ? The 2006/7 Honda Hybrid are reportedly ( http://www.edmunds.com/insideline/do/Drive...45/pageId=67421 ) around 12.4 seconds in the 0 to 60 mph accelleration (with a 1.3 liter 8 valve engine), versus sub 11 seconds for the Prius.

This sounds like specsmanship on the part of Honda, without any real world meaning. Ever notice that car makers never spec 0-60 times? They leave that up to the road-test magazines. Sounds like Honda taking advantage of the first-glance buyer who can only judge by the HP number. And if you used that 1.3 liter engine at 110 hp comonly, what about durability? A standard Civic is rated at 113 hp and its engine is 1.8 lites.

[madler]

How about a modern (low-emission) turbo-diesel? Maybe the 2010 model would be better, since that's when the US will require all diesel fuel to be low-sulphur.

[efusco]

Toyota's already decided to not go the diesel route...their reasons are pretty vague..on the order of 'we've chosen to go a different direction'.

[HolyPotato]

<div class='quotetop'>QUOTE(holycow99 @ Nov 3 2007, 09:51 PM) [snapback]534506[/snapback]</div>

I for one wish a more powerful one, perhaps like the one in Honda Civic hybrid (1.3 litre, 110 hp).
[/b]

Just to be pedantic, the HCH's engine is 93 HP (110 hp combined with the IMA).

[holycow99]

<div class='quotetop'>QUOTE(donee @ Nov 3 2007, 10:01 PM) [snapback]534526[/snapback]</div>

Hi Holycow99,

You know the overall horsepower of the Prius is 110 hp, and the acceleration matches that of a similar ICE only car that Toyota makes with a 145 hp engine?

People have been buying HP numbers, but what they really use is acceleration. The Prius as it stands is a pretty good mix of acceleration and fuel economy. With the various forms of Hybrid technology, HP rating alone is not the whole story. This is similar to Amory Lovin s comments on Electricty.

There is a problem with thottled engines. Its called the "partial power" problem. When the typical engine in a standard car is at 1/3 of its hp rating or below, its efficiency is half that of its maximum efficiency capability. Or about 12 % of the fuel energy makes it into shaft turning energy, rather than 24 % typically.

There is also a basic rule of engines that the bigger the difference between the burned temperature and the exhaust temperature, the more energy is delivered to the piston. This turns out to be parallel to expansion ratio (which is the same as compression ratio in standard cars, but not the Prius).

By using the Atkinson Cycle and the Miller valve train, the Prius achives 25 % efficiency at 1/3 rd power, and even more optimally. It does this with a 13:1 expansion ratio, and blows back some of the intake in one cylnder to the chamber behind the throttle valve making that air available for other cylinders without the drag of the throttle valve. Other engines cannot run 13:1 expansion ratio, because that would also require a 13:1 compression ratio in those engines. Which would require super high octane (AV-Gas) fuel, not sold at road vehicle gasoline stations. And that gas would have less fuel energy, besides.

Since all the energy from the Prius comes from the engine, using a standard engine would half the the highway mileage. As at highway speeds, engines are very lightly loaded. So rather than 55 mpg, the mileage would be closer to 28 mpg. City mileage would probably not drop as badly, with special technique driving however.

Is the 2008 Civic Hybrid quicker than the 2006/7's ? The 2006/7 Honda Hybrid are reportedly ( http://www.edmunds.com/insideline/do/Drive...45/pageId=67421 ) around 12.4 seconds in the 0 to 60 mph accelleration (with a 1.3 liter 8 valve engine), versus sub 11 seconds for the Prius.

This sounds like specsmanship on the part of Honda, without any real world meaning. Ever notice that car makers never spec 0-60 times? They leave that up to the road-test magazines. Sounds like Honda taking advantage of the first-glance buyer who can only judge by the HP number. And if you used that 1.3 liter engine at 110 hp comonly, what about durability? A standard Civic is rated at 113 hp and its engine is 1.8 lites.
[/b]

Hi donee,

Wow, that is lots of info to digest for a newbie like me. So Prius' engine is a special breed. No wonder it gives 55 mpg at highway speed, whereas normal engines are typical half of that. If "1.8 litre engine" rumor quoted by others is true and that coupled with a more torquey electric motor, the '09 Prius should bring down the 0-60 time to well below 10 sec. It'll be quite a sweet hybrid with 8-9 sec 0-60 and >60 mpg fuel economy.

Thanks donee and othersfor the informative replies,