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

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

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

 

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

 

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.

 

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.

 

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.

 

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

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

 

OK So Toyota has been vague about why they didn't want to go with a low sulphur diesel ICE. How about an E-85 option? Someone that lurks here or frequently posts should have an answer for this.

 

I'd gradually cut the size of the ICE,
reduce the weight of the car,
reduce drag at motorway speeds
increase the capacity of the batteries,
use more of the power of the electric motor
(I believe peak power is only currently available if taken from the ICE)

The ICE should be just powerful to hold the car at speed
the electric motor fills in the peak power demand

So......
efficient 1400cc or what about a 1000cc bike engine

 

<div class='quotetop'>QUOTE(Graz @ Nov 4 2007, 07:13 PM) [snapback]534701[/snapback]</div>

Hi Graz,

The Prius injectors are big enough for E85 right now. Minnesota State ran tests on first generation Prius and E85. Add a turbocharger and a way to sense the Ethanol fraction, and the next Gen Prius might be able to dynamically adjust to the Ethanol fraction. Its possible that similar mileage from E85 as standard gasoline by adjusting boost pressure could be achieved.

 

quote name='holycow99' date='Nov 4 2007, 10:41 AM' post='534604']
Hi donee,

Wow, this 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 battery(?), the '09 Prius should bring down the 0-60 time to well below 10 sec. It'll be quite a hybrid with 8-9 sec 0-60 and >60 mpg fuel economy.

Thanks donee and othersfor the informative replies,
[/quote]
Unfortunately Toyota is slightly increasing the size so it won't be as fast as if it stayed the same size. Again one article has quoted a target of one second faster (or just under 10 seconds) 0-60.

Since as Donee says all of the power for the Prius comes from the gas engine Toyota is going to have to use some good tricks to make much of a leap from the current Prius,

The only no brainer increase in efficiency is the control electronics. They are around 95% efficient but in some modes power has to travel through the electronics twice when both mg1 and mg2 are in use. Newer electronics can make the efficiency 99% at no additional manufacturing costs <but costs for redesign/development>.

So there is an easy 5%. Lighter weight is another key but still that is expensive if size increases.

The next bit will probably come from the turbo. A low pressure turbo can actually make an engine more efficient. That can also be combined with engine downsizing for more mpg but Toyota is not downsizing it.

A real cool idea is a turbogenerator where a generator is directly connected to the exhaust vanes of an exhaust turbine and feeds the batteries/power electronics directly. While some think this would cause more backpressure then the additional power it creates there are designs that have a significant net gain.
That is another 5% to 15% more energy wrung from the gas but I would not call that an easy fix.

The rest and the most popular talk about more mpg is the batteries of course.

 

But E85 made from corn uses more oil in making it than would be needed to make the equivalent amount of petrol. Well so I have read.

 

I really don't think the '09 will be THAT different ... my guess would be maybe a little larger engine AT MOST and a slight facelift, but basically the same style, etc. 2010 model year will be the MAJOR re-design imho.

 

If the next generation does not go Li ion, I would expect some significant change in the engine. Personally I would like a smaller engine to improve FE. A smaller turbocharged engine would be nice. They should be able to tune the Hybrid system to reduce turbo lag through use of the electric motor torque.

If they dont go Li Ion, I dont see how they can significantly increase FE without an engine modification.

I don't think they will go smaller or much lighter.

 

Why would a larger engine improve fuel economy surely it has to be smaller?

Here's the target
http://users.vnet.net/w123d/w123d/articles/dod.htm

 

<div class='quotetop'>QUOTE(patsparks @ Nov 5 2007, 07:55 AM) [snapback]534882[/snapback]</div>

I've heard that too. Do you think Soy Beans would produce better?

 

Sugar cane is the most effecient for ethanol production actually.