Slow acceleration vs. Fast IMA-assisted acceleration
 

Does anyone know which is better? I've tried both but I have no idea which would be better for gas-savings. On one hand, mashing the petal puts the charge to use as the IMA is used more to get the car to cruising speeds. On the other, slow acceleration is the more efficient way to get to cruising speeds in gas-only cars.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

My two yen on the subject:

In my own personal experience, that may be different from that of other members, is that one should engage the IMA as fully as possible (without actually going pedal-to-the-metal) to accelerate. When you reach your desired speed, use the coasting methods described in this forum.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

Generally, what's effective in a conventional car is effective in a hybrid. The penalty of aggressive acceleration is mitigated somewhat in a hybrid because you don't force the ICE to work much harder. But you're using up energy from the battery which you ultimately must replenish. The most fuel efficient strategy may depend on the battery charge. If it's full, you might as well use some of it or else you'll waste energy when you press on your brakes with no room to regen. If the battery charge is low I would use it sparingly.

The reality in the HCH is that it's fairly impractical to accelerate from a stop with absolutely no assist. You can only accelerate VERY slowly without assist.

My rule of thumb, for better or worse, is to use no more than three bars of assist for acceleration whenever possible. It prevents the ICE from going into the high rev range.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

Using full assist with low ICE will use up the battery very quickly. Full assist with full ICE (flooring it) is better for the battery but is worse in the short term, if not the long term, since the ICE is inefficient when used that way.

There is a sweet spot and others have reported it at around 2000 rpm. Accelerating with the engine at 2000 rpm, on level roads at least, sounds optimal.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

How can you produce full assist with low ICE utilization?

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

By "low" I was speaking relatively. Applying moderate pressure to the gas pedal can result in full assist while the engine is at 3000 rpm or so. Low compared to the 5000 rpm it runs at if one were to floor it.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

I don't have the equipment, but is it possible to hook something up to the OBD-II to read fuel load over time, such that one can do both a slow and quick acceleration to speed to see which is more fuel efficient?

Jeff

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

Oh, okay. 3000 is about as high as I'll go, so I consider it high. I think I've taken the HCH to 4000 only once, briefly, climbing a steep hill. I don't think I've ever pushed any car to 5000 RPM. Well, maybe I did when I was 18.:)

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

Hi;

I wonder has anyone ran their HCH ll wide open, Gas Pedal On The Floor with Full IMA Assist? Battery Pack Fully Charged.

If so how does it perform?

I'm not looking for a {Knock-Down} fight on why you don't do that with a Hybrid. It is simply a question to anyone that has tried their HCH ll out to see if they could get out of Harms-Way if an Emergency Situation called for it.

Example: Like a Tractor Trailer truck Running up Behind You::angry:

Thanks;

Terry

BTW: Please lets not go off the Deep End on this, it's just a {Question}.

Re: Slow acceleration vs. Fast IMA-assisted acceleration
 

I did this one time, after breaking in the car on a straight away. I had a full charge but a near full tank of gas. The best performance will occur with full charge and little fuel in the tank. The fuel is added weight, every 100 pounds takes about 0.1-0.12 seconds of quarter mile time. Anyway, I didn't time the car but low speed acceleration from about 5-35 MPH was fairly fast in about the 1500-2000 RPM range which is when the IMA puts out the most torque and gets the car rolling quickly to speed. In the mid range from about 3000-3500 RPM the car seemed slow and like it was missing something. However, above 3500 RPM the HI-VT cam kicks in and the power is back in making the car feel somewhat fast. I did this through passing gear, and acheived to what I estimate 70 MPH or so in what I guess to be a quarter mile based on my past experience with building and racing cars. I will do a more accurate and percise test, with my computer soon. Bottom line, its by no means a sports car, but it has power despite fables about hybrids being slow and lethargic and manages to get out of its own way just fine.