Engineering questions comparing Prius and HCH 06

If I remember right the HCH has 110 @ 6000 rpm and the prius does the same 110HP with only 5000 rpm. You have to factor in the electric assist which adds 28more horsepower to the 67 of the engine.. the transmission is completely diffrerent too. Torque is not limited to certain gear ratios... its available at any time or speed to my understanding.

You can also start here http://john1701a.com/ and go from there.. at the bottom, download all the manuals etc.

 

I'll just offer this non-engineering reply to the first item.

These "issues" of ICE horsepower, size of electric motor, torque, acceleration and how they are translated, via the CVTs, to actual "power" in various scenarios, have been bandied about in excruciating detail---often by engineers, with the rest of us as very interested onlookers---since the first Yahoo Prius group in early '01.

After all is said and done, and you've gained some intellectual understanding of how the two systems work (and the HCH is very uncomplicated) you're still likely to be more satisfied and "knowledgeable" by the simple expedient of taking each car on, say, a fairly long (20-30 min.) test drive, preferably over the same route, including at least a small hill and a stretch of open road where you can accelerate up to 60 MPH or more. Nothing will tell you what those configurations "mean" like the way they FEEL to you.

The best exposition of the Prius planetary "split power device" (not a true CVT), including visuals, is by Graham Davies. He has two websites. Just put Graham Prius into a search engine.

 

Hi.

I have found the following site very helpful to better understand how the Prius works. I know it doesn't make you any wiser on the HCH - but still...

http://www.hybridsynergydrive.com/

 

If it helps, recall that power [horsepower] = torque * RPM. So for
an engine like that in the Prius, which has a fairly flat torque
curve [and the throttle management tends to enforce that], the power
output has almost everything to do with RPM. In fact, you can almost
directly map kilowatts to RPM which is why a tach is bloody useful.
.
http://techno-fandom.org/~hobbit/cars/prius-curves.gif
.
_H*

 

Not really a technical factor, but Prius is a hatchback design, and ALL seats can be folded down. HCH's rear seat is fixed because of the batteries. That reason alone eliminated the HCH from my consideration.

 

True, the Prius is incredibly versatile!

 

If you can take the time to read the Hybrid car stuff at this site you will have an idea about the differences in the Honda system and the Toyota's hybrid system. It over symplifies a bit but basically I think it's pretty good.

http://auto.howstuffworks.com/hybrid-car.htm

If you keep reading through it you will come to an explination of the Prius and the Insight. The Insight and the HCH use the same parallel hybrid system. The Prius uses a series/parallel system that is much better.

 

One thing I've been led to understand is that the HCH has more power at the expense of economy, so if you want muscle, get the HCH and if you want more MPG, get the Prius.

 

1. Work = Force X Displacement. You can put a ton of force and if it doesn't move, you did no work done. The same goes for Horsepower = Torque X RPM. Both HCH and Prius have peak horsepower of 110. So, maximum power is exactly the same if the conditions are right. The question you want to ask is what about the time it is not at maximum. How is the power delivery and power response time difference between HCH and Prius? Prius wins here due to more powerful battery and mechanically simplier.

2. Prius battery has 1.5 times more energy than 06 HCH battery. Prius protects the HV pack better and it will last longer than HCH.

3. Prius electric motors operate in 500 volts and the battery at 201.6 volts. There is a booster that raise battery voltage to 500 volts so reduce energy loss. HCH does not have such feature and is electrically anemic.

3. PSD is the Power Split Device. This gear set can split or combine power.

Pic from Graham site.It can split power from one source to two other seperate paths. Think of a triangle where if you pull on two angles, the area of the triangle remain the same. What will happen to the other angle? The 3rd angle would become larger. Label the three corners with Gas, Electirc, and Regen energy. Try to balance these three power sources so that you use all three at the most efficient state wisely all the time. That's the balancing act that multiple 32-bit CPU do depending on the speed of the car. Your right foot commend how big the triangle should get (size of triangle=power). Some people ask for manual transmission for Prius. They do not realize that they are asking for this balacing act that computer does millions of times per second.

 

I'm still amazed that I was able to fold down the front and rear seats and VERY EASILY put 2 - 3" x 10 foot PVC drainage pipes in the car with the hatch and all windows closed. It is extremely versatile, the size is deceptive.

 

You must be talking about the accord? Doesn't "HCH" stand for Honda Civic Hybrid?

The HCH is "less" powerful... it only developes the same horspower by rpms being reved 1000 rpms higher "to 6000" instead on 5000 rpms for the prius. They had to rap the engine rpms out higher to look as good on paper and even compete?
A few specs:
The honda engine is only 1.3 liter instead of 1.5.
The Electric motor on the HCH only delivers 20HP compared to 28 of the prius.
The Honda battery is smaller at 5.5 Ah instead of 6.5 of the prius
http://automobiles.honda.com/models/specif...me=Civic+Hybrid
http://automobiles.honda.com/models/specif...Category=Hybrid

Without going into further detail, the only thing I hear that may be nicer on the honda is the radio and speakers... all other amenities are less.
Oh...and it also gets less MPG! AND the base MSRP is more!
The Prius also has more shoulder, head both front and back, leg and luggage room!
Much more versatile too!... Toyota seemed to put alot more money, thought and technology for less money to us!.. the final product performs better AND is more efficient!

You can also go here to compare the two: http://www.toyota.com/toyotacomparator/dis...ModelCode=prius
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Now what does fit your specs is the Honda Accord!... the 2005 starts at over 30K in price.
http://automobiles.honda.com/models/model_...e=Accord+Hybrid
This is a whole different beast.... you have to decide if you want to rocket with 255 hp with the gas mileage of a non hybrid or whether you want economy.

If they start taxing the hybrid.. this car will screw you, Because your MPG is marginal AND you willl be paying for mileage!

 

I think you may be refering to the KWH rating of the battery converted to horsepower? That is 28. The main traction motor MG2 has 67 HP.

 

The Prius maximum hp of the gas engine and electric motor occur at different rpm's and therefor, they cannot be added directly together. The Prius is rated a combined 110 hp.

 

Both cars have a type of CVT. CVT is a Continuously Vatiable Transmission. Direct translation: no gears. This matters to the driving experience because everything is smoother. As a result, you have to remember that engine RPM has nothing to do with output speed. I don't know about the HCH paralle system yet, but the Prius is designed to take any extra power from the engine and store it in the battery so it's not a complete waste. This and regen are the two ways the battery gets charged.

"Traction Battery" refers to the actual high voltage battery. If you just say "battery", most people (except hybrid owners) will assume you mean the 12V battery that runs the computers and lights. The electric motors (there are two) interact with the battery to either move the car, take the extra engine power and convert to electricity. There is an interesting point where it is more efficient for the extra energy from the engine to be put through the electrical system and then back into the wheels through the main electric motor instead of stored in the battery.

There is a good technical article in an issue of Electronic Design on my desk. I need to get the reference and scan the article for everyone.

 

The gas engine RPM should be independent of the electric motor RPM.

 

Well lets see.... to make sure I'm following you correctly....
20 is the HP of the Honda Civic Hybrid
15 is the KW of the Honda electric motor.

28 is the HP of the Prius battery http://www.toyota.com/prius/specs.html
21 is the KW of the prius battery.... same link as above...
67 is the HP of the Electric motor of the prius.

Seems the numbers don't add up exactly.. only close....

But the finally hybrid tally of both seem to be 110HP,the main difference other than the optimum torque from the prius transmission, is that the prius gets that cumalative HP with only 5000 rpms... the Honda has to do 6000.00
I wonder how much higher the prius's HP would be if it was rapped out to 6000rpm to be even steven?... Since its a bigger engine, it may be substancial?

 

Hmmm. My understanding of HP is: HP = Torque * RPM. I don't think that the battery can be rated in that way. The ICE, MG1, and MG2 can be but not the battery. HP and kW refer to work, I think, and the battery isn't capable of applying a force to displace the car. Only the motors and ICE can do that.

 

yea. your right technically, but I think what they are saying is the battery can deliver that many Amps @ a given voltage to deliver so many HP. If I remember right from my hydroelectrics I used to know.... one Horsepower = about 740 watts or so?
Its a relative term thats no good unless the electric motor can also perform the job with that given energy.
740 watts (one HP) X 28 = 20720 watts (21KW)

 

Trust me, the cars are impossible to compare in writing -- you have to drive them. I rented a 2005 Prius for a weekend when I was deciding whether or not to buy it, and while it had really high MPG without even being driven remotely gently, I found some relatively minor faults with the car that just made it not very enjoyable for me.

So I waited for the 2006 HCH to be released and liked it immediately. I love the steering, visibility, ride, comfort, amenities, and looks of the car. I am getting worse mileage than I did with the Prius, especially considering I've been driving the car relatively gently, but it has less than 900 miles on it and it's possible it'll improve.

Basically, the Prius has a superior hybrid system, but that system was placed in an inferior car in my opinion. But both cars are excellent and I suggest you try them both.