Are we thinking about the hybrid the wrong way?
 

Best I understand it a hybrid has 2 power sources. Sadly though battery technology is way behind what our needs are.

While driving my max, I noticed the scan guage tells me only 50 hp (or less) is required to keep the vehicle moving. I've also learned that pumping losses are one of the biggest fuel economy disadvantages of the throttle body equipped gas engine.

If a sedan were equipped with a rear axle from a truck with a motorcycle engine attached to the rear axle, and the front wheel drive car remained intact otherwise, wouldn't better economy be acheived by using the underpowered motorcycle engine for cruising? This is also assuming a fuel injected motorcycle engine, which would be slightly more efficient, and a water cooled one would be more ideal. Have the fuel from the car's OEM tank routed to the motorcycle engine as well as the OEM engine. The MC engine would likely have to be run at WOT or nearly so to produce the necessay power, but that is more efficient anyway. The advantage vs a battery powered setup would be less weight, and likely less room required (I had initially thought of a similar arrangement, substituting the MC engine with an electric motor and battery pack)

Is there any merit to this idea, or will it simply be buried into the pages of my many unfounded ideas based on incomplete data?

The 2010 Prius weighs about 165 pounds more than the 2010 Corolla. Can you build your hybrid with less than 165 pounds added?

Also, the space taken up by the battery is not noticeable (it's behind the back seat and under the rear cargo floor), and the electric motor is integrated with the "gearbox" under the hood. I don't know if a motorcycle engine driving the rear axle could be made to take up less room.

The Prius computer tries to run the engine in an area where its BSFC is lowest, and by driving it a certain way you can help to keep it there. So I'm not sure that throttle body pumping losses are as big of an issue as with normal ICE cars.

Been working on this for years. Study the BSFC charts of many engines and you will notice a pattern and a fairly consistent BSFC amount for many different engines, with the largest difference between gas and diesel.

On those engines that are configured for economy, you will find that most of the performance improvements applied recently are relatively insignificant, beyond fuel delivery systems.

By this I mean at peak BSFC even a 2 valve 3.8 liter push rod Buick V6 dating back to the 60s can still compete if it has the latest fuel injection technology.

Gearing, aero, and other improvements when used in a combined strategy can have significant improvements.

With modern power plant technology the idea of a smaller engine working directly through a differential for cruising speed efficiency would probably provide some improvement to a limited degree at somewhat of a weight penalty.

My preference is capacitive storage and engine pulse and glide to the storage reservoir, with infinitely variable drives to the individual wheels and high efficiency regenerative braking for those situations where stop and go is the only option.

Engine size is not really a great factor if you consider that greater engine power would reduce the fuel consuming recharging of the capacitive storage system. In other words the current propensity in US cars to have much more engine than you really need, does not automatically mean a mileage penalty, if the fuel consuming percentage of run time is a smaller percentage of total vehicle operational time in proportion to the difference in available maximum engine power.

regards
Mech

The pruis may weigh only 165 pounds more, but how much do those packs cost? Lead acid is the only affordable source I can think of and they're not cheap either!

Funny thing about my Max is how mpgs seem to go up around 80 mph.....wonder if ~2500 rpms is the magic area of the BSFC?

Program in an x-gauge to show you average mpgs. That will show you the truth. You will see higher mpgs at higher speeds when you go down a hill or anytime you let off the gas because you are traveling faster. Travel faster over time and I can pretty much guarantee worse mileage.

The Prius packs aren't cheap, but they're NiMh, not Li-Ion, so they're more reasonable. And with the number of Prius' that have been sold, economies of scale should come into play to lower the price. I guess the real question is, can you build the extra-engine hybrid cheaper than Toyota can build a Prius?

And can that second engine go 100,000+ miles without any maintenance at all, to include oil, and meet current emissions standards?

The electric motor in most cars will go far longer than the ICE. And they require virtually no maintenance.

Hi,

You may be ready to understand the drag formula:
One of the earlier, vehicle drag formulas had just two terms:

D = 190 + 0.42*(V*V) :: NHW11 drag formula from Toyota sales material
D = C + B*V + A*(V*V) :: the formula the EPA now uses

V = velocity
A = constant 1 (aerodynamic drag)
B = constant 2 (typically transaxle drag)
C = constant 3 (usually rolling drag)
190 = NHW11 rolling drag, typical
0.42 = NHW11 coefficient of drag times area, typical

Regardless of the drag formula used, you can calculate the power needed to sustain a vehicle speed. So let's see how it works in the real world:
http://home.hiwaay.net/~bzwilson/pri..._MPG_Rev_B.jpg

• Drag power line (red) - the power needed to keep the car rolling on a flat, no wind condition in HP on the right axis.
• Motive fuel needed, blue - the amount of fuel needed per mile to keep the car rolling at that given speed assuming 31% conversion of gasoline to motive energy on the left axis.
• Motive and vehicle overhead fuel needed, gray - the amount of fuel needed per mile to keep car rolling and powered assuming 31% conversion efficiency. This includes the idle overhead of a car which is independent of speed.

The point is drag, both rolling and aerodynamic are the primary forces the engine(s) have to overcome. But at low speeds, vehicle overhead becomes the limit. What you are proposing, carried to its logical extreme, is a very large number of small but very efficient engines. These engines come on as needed to provide motive power or are off. The two-engine solution, one being half the power of the other, is a similar solution. But the hybrid uses another trick.

Our hybrid-electric cars have a broad power range, efficient engine but there are times when the engine power provided exceeds the vehicle demand while remaining efficient. In these cases, the engine banks this extra power in the battery so later, the engine can be off instead of running in lower power, inefficient bands.

The battery can do one more trick that no fuel engine can accomplish, bank kinetic energy from either braking or while descending a hill. But this could also be done using a hydraulic system, which has some desirable, peak power capabilities over current battery storage systems. My understanding is some formula one cars are looking at a flywheel-electric system but no consumer production versions, yet.

Universally, reduce drag both rolling and aerodynamic, and everyone wins. But in power systems, we're all fighting the 2nd Law. The hybrid has the ability to bank power and extend their efficient power bands while minimizing inertial losses.

Bob Wilson

F1 cars used a system called KERS (Kinetic Energy Recovery System) which could store regenerative energy in a flywheel or battery system (depending on team) and release it as extra power when the driver hit a button. Its advantages were a burst of speed to help overtaking which is a criticism of F1 at the moment - the cars are so closely matched that overtaking is rare.

The system wasn't universally liked and a lot of teams would run a car with and one without and often find the advantage on long straights was nullified by the extra weight on corners. Some teams didn't bother at all.

It was abandoned after the end of the 2009 season.

Other systems have also been used including hydraulics, air compression etc.