Next generation IMA system - Page 3 - GreenHybrid

Delta Flyer · #21 (**permalink**) 07-06-2005, 07:49 AM

The most constructive way to proceed on this discussion is to find links on how much horsepower it takes for various vehicles to cruise at 60mph or thereabouts. Otherwise, I'm afraid we are just speculating.

clett · #22 (**permalink**) 07-06-2005, 08:55 AM

Or I suppose another way of thinking about it is could an engine of half the size of the one in the Civic power it at 60mph? That would be an engine of about 650cc (half of 1.3 litres - or the equivalent of 2 of 4 cylinders).

In Japan there are laws allowing unlimited sales of "microcars" - which are limited to a maximum engine size of 660 cc. An example is the Honda Beat or Suzuki Cappucino. These cars are electronically limited by law to ~85 mph, but imports in the UK which are then delimited hit about 100mph.

I think 60mph in a Civic shouldn't be a problem, but I'll have a look for a link to power usage at 60mph...

clett · #23 (**permalink**) 07-06-2005, 09:15 AM

Ah, found the online calculator for all this:

Check out the physics explained here, or the power requirement calculator here:

http://succ.shirazu.ac.ir/~motor/fluid/power/power.htm

I used the following figures for the Honda Civic hybrid:

Weight 1,220kg
Frontal area 2.1 m2
Drag coefficient 0.28

The power required at 60 mph is about 16 bhp, including rolling and air resistance. That's about a fifth of the maximum power of the engine, so I think 2 cylinder mode at lower revs should work for cruising at this speed, if not for accelerating.

ElectricTroy · #24 (**permalink**) 07-06-2005, 11:30 AM

Quote:

Originally Posted by clett

Or I suppose another way of thinking about it is could an engine of half the size of the one in the Civic power it at 60mph?

Half of a Civic engine = 2 cylinders = 42 hp, redline. But at cruising speed the engine only turns at 2000 rpm, or about ~14 hp. (That's not enough power.)

BTW, if you've ever driven a Civic Hybrid, you already know it's at the lowest power possible. In 5th gear, the engine alone can not carry the civic over small slopes..... it loses speed. And that's with all *4* cylinders firing.

I don't see how you can downsize an engine that is already so weak.

troy

gschoen · #25 (**permalink**) 07-06-2005, 12:39 PM

The efficiency gain you get by having a "properly" sized engine installed in the first place gives you a better advantage than putting in a bigger engine and knocking out cylinders, anyway. The Civic Hybrid engine isn't like the powerful Accord Hybrid's V6, which has power to spare and gets a benefit from knocking out cylinders.

It sounds like Hondas other new technologies in the engine will provide better economy without sacrificing power. The new Civic sounds very exciting, I look forward to hearing about the final product when the previews get sent out.

EricGo · #26 (**permalink**) 07-06-2005, 04:59 PM

I'm not sure why discussion continues regarding two cylinders.

Check out the animation. All four cylinders fire all the time; the 'low power' cycle is a change in valve timing.

Stevo12886 · #27 (**permalink**) 07-06-2005, 05:12 PM

Quote:

Originally Posted by Schwa

What do y'all think -- is this a significant enough improvement to put the new Civic into a category of it's own? To me it seems like there's enough changes to deserve an HCH II category, considering it can do some sort of EV mode, so that technically makes it a full hybrid.

I give a hardy yes, new drivechain+new chasis= new car..IMHO of course.

Still hoping for a 5 door anounced

EricGo · #28 (**permalink**) 07-06-2005, 05:32 PM

"Still hoping for a 5 door anounced"

I couldn't agree more.

Schwa · #29 (**permalink**) 07-06-2005, 06:23 PM

Quote:

Originally Posted by ElectricTroy

If you can't do EV at highway speeds of 60+, and you can't plug it in, then it's *not* a full hybrid, imho. A full hybrid would be primarily an Electric Car (daily drives) + a small gas generator for recharge (long distance).

I think you are confusing a series hybrid / parallel hybrid comparisons with full / partial hybrids. Personally I think the distinctions are being blurred, but in general (especially here) full hybrids are the Prius, FEH and Toyota SUVs, since they can operate in full electric mode, and the Hondas were considered mild hybrids since they required the ICE power to move. I'm not saying you are wrong, or even that there are strict definitions, I'm just trying to clarify what I was referring to.

see http://www.greenhybrid.com/discuss/glossary.php?t=F

The kind of car you are describing is what I want, btw... Basically an EV with a backup generator.

Delta Flyer · #30 (**permalink**) 07-06-2005, 07:04 PM

I acknowledge the new Civic engine is going to use all four cylinders all the time as EricGo pointed out. Dissapointed Honda has not tried a 4/2 cylinder version but hope they eventually do.
I liked the link Clett had on horsepower estimates of a vehicle cruising at 60mph. Call me a wishful thinker if you want, but based on what the Insight and Accord can do, it seems reasonable something like it can be done on the Civic. To elaborate: the hybrid Accord has a 6/3 cylinder engine. The 5-speed Insight does something similiar - the 3-cylinder engine goes into lean burn cruising at 60mph on level roads, cutting fuel consumption by about a third. Again, there is the IMAS ("Insight II") concept car with the 4/2 cylinder engine (which is probably vaporware, but Honda apparently thinks it's possible)
The concept of cylinder deactiation is simple - make a gasoline engine big enough to accelerate to cruising speed then use only as many cylinders as necessary to maintain the cruise. Implementing it is another story. GM tried it in the 1980's with their Cadilliac. Since the IMA also functions as a flywheel, the implementation of cylinder deactivation is easier to do.