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Is it just me, or is there very little engine braking available on the HCHI?

The other day we took a road which was all switchbacks over a steep hill, and on the way down it didn't seem to matter which position the CVT gear selector was in, it felt like the car was gliding with only the regen braking slowing it. In particular, the car wasn't being "revved up" by being pulled down the hill. I was on the brakes almost the entire way down. Luckily it wasn't a very long hill, so I wasn't worried about the brakes fading out, but it makes me worry about driving down a really long and challenging grade. For comparison, when we go over that same road in our automatic Protege it is either in 2nd or 3rd all the way down, and the engine revs to 4000 RPM or higher - without the driver's foot on the gas.

If I remember correctly, when engine braking your car disables three of the four cylinders to allow for more efficient regenerative braking. You also only have a 1.3L engine so there probably isn't much engine braking that can be had. You probably aren't really using the actual brakes as long as you are getting regen.

... You probably aren't really using the actual brakes as long as you are getting regen.

+1

I would just keep pressing the brakes, letting the car know what you want, and as long as green bars are showing, it will be mostly regen that's happening. When it tops up the charge, the green bars will go off and then you'll experience an increase in braking effort, when it switches to regular braking.

Anytime, putting it in S (Sport) should provide increased engine braking.

Anytime, putting it in S (Sport) should provide increased engine braking.

That's what I thought, but when I tried it I couldn't feel any difference.

Once your SOC is full it is free wheel-en and it requires brakes to keep your speed under control. First time this happened to the wife she almost bailed out!!! H

Once your SOC is full it is free wheel-en and it requires brakes to keep your speed under control. First time this happened to the wife she almost bailed out!!! H

I sometimes thought it bordered on dangerous. Simple solution by Honda would be to make the transition less sudden.

That's what I thought, but when I tried it I couldn't feel any difference.

When I really notice Sport's effect is on windy roads, where you need to repeatedly brake and accelerate. In D you will definitely need to brake harder. In S: take your foot off the gas and it slows much quicker, plus better acceleration.

I sometimes use the A/C for braking - with the right combination of gearing and cooling I can control the speed of the car without braking on a wider range of downhills than I'd otherwise be able to. Not such a useful technique if it's already cold, I guess :)

-Simon

Once your SOC is full it is free wheel-en and it requires brakes to keep your speed under control. First time this happened to the wife she almost bailed out!!! H

Note to self 1: run the SOC down as far as possible before reaching the top of a hill.
Note to self 2: avoid descending the stretches of road documented here http://www.mountaindirectory.com/
especially the Tioga pass road http://www.race360.com/marathon/races/detail.asp?eventid=14029.

Hi folks;

Just to add to the excellent conversation points already made:

All HCH's gasoline engines (Gen 1 and Gen 2's) are low friction power plants and even when the valves are fully open, the amount of resistance offered by their spinning crankshafts is so small that it should never be regarded as an effective vehicle stopping tool. Its not just the 0W20 oil, but also the other exotic tech that coat the rings and cylinder walls... its all there for a purpose and helping stop the car is not one of them for sure. :P

In retrospect, these engines, their construction and materials used are often not shared with their gasoline only counterparts because the name of the game is ultimate efficiency and friction reduction at the engine is still the best way to achieve it.

As usual managing the state charge is instrumental especially when you take into account the cars potential and operational limits. But even if you deplete the pack before entering a long descent, the pack capacity is still too small to ensure adequate stator regen and braking especially on long descents. Heck even a Prius has similar problems anyway.
On the HCH's: Opening the windows and cranking up the climate control (with AC and defrost option forced on) on the way down is something I found to help a bit. But in the end, ensuring that your brakes and tires are in good working order is still the best policy regardless of conditions.

Cheers


MSantos

But in the end, ensuring that your brakes and tires are in good working order is still the best policy regardless of conditions.

Well, sure, but there is a limit to how much heat a car's brakes can dissipate before they fade or fail (warp). Taking the Tioga pass road for an example. the potential energy there for a 3000 lb car from the top to bottom is mgh = roughly (3000/2.2) * 10 * 1000 = 13.6MJ. Assuming that the goal is to come to a stop at the bottom, so that we don't have to worry about the Kinetic Energy, all of that would have to be dissipated. The road is 12 miles and assuming an average speed of 60mph will be traversed in 12 minutes = 720 seconds. So the brakes need to be able to dissipate power at the rate of ~19kW for 12 minutes straight.

Of course one could always take the load off the brakes by letting the car accelerate until the wind drag stops the acceleration (not the velocity). Did I say "always"? Not on this road! http://trollstablet.com/images/roadtrip2009/IMG_1813.JPG

Apparently HCH's can get down that road in one piece, as I've never heard of a pile of wrecked ones at the bottom. Still, I bet it is an exciting descent.