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Start-up Eco-Motive developing dual-fuel “H” engine; parallel, independently fueled piston banks

The H-engine—basically two separate engines housed within the same engine block—comprises two switchable parallel piston banks, independently fueled by gasoline and CNG. Click to enlarge.

Startup Eco-Motive has developed what it calls the first dual-fuel “H” engine; it recently received a patent (#8807098) on the design. The H-shaped engine comprises parallel left-side and right-side vertical inline piston banks, each having a crankshaft and pistons, a cylinder head, and individual fuel feeds, but sharing a common power transmission system. Each piston bank operates independently of the other but is housed within the same engine block and has separate lubrication systems.

The Eco-Motive H-motor—basically two separate engines housed within the same engine block—can be powered by either gasoline or compressed natural gas (CNG), at the driver’s decision. The chosen engine is mechanically or electrically selected via an engine bank selector box using a selector control which selects the fuel type and engages a drive gear on the crankshaft of the selected engine, and transfers power to the transmission. The selector control actuates a transfer system that prevents simultaneous operation of both engines. The vehicle stays in that fuel mode until changed by the driver.

Click to enlarge.   Click to enlarge.

The crankshafts for each bank are centrally and longitudinally located below the respective banks. The left-side fly wheel and the right-side fly wheel (or other suitable equivalent) permit balancing of the left-side crankshaft and the right-side crankshaft respectively. The first flywheel and the second flywheel may be offset, such that a forward and a reverse sliding gear may engage either a left-side crankshaft or a right side crankshaft to the transmission.

The selector control is able to slideably direct-engage the first flywheel to the input shaft of the transmission. Other gearing, balancing, power transmission means and the like may be employed, according to the patent.

The H-motor is fed by dual gas tanks on either side of the drive shaft. A fuel inlet for each tank can be located on the side of the car where its tank will reside. Exact specifications may vary depending upon the OEM.

The engine was invented by Herns Louis, veteran of more than 30 years in the parts manufacturing industry ranging from automotive to aerospace, specializing in computerized parts machining. This twin-bank engine is a result of Louis’s experience, along with his vision to help meet an emerging market need for more efficient, lower-exhaust CNG engines.

An OEM can adopt our idea to any internal combustion engine with an even number of cylinders to any truck, SUV or car they currently build, regardless of its transmission or configuration. The technology can be easily adapted to existing engines, making the implementation very cost effective.

—Herns Louis, founder and CEO of Eco-Motive



Ridiculous, it's already enouph costly one engine so 2 engines is prohibitive just to save few money on fuel.

If ever the goverments stop subsidizing research we gonna be better serve because for now it's a system that give money to fraudulent lab researchers.

Better buy a proven^patent than giving money to stupid research.

Roger Pham

This can be a good idea, and is done with private money.
Having separate engines, one for each type of fuel, allows for optimization of an engine to the specific fuel type in order to obtain the most fuel efficiency and durability. For example, NG engine requires modifications to the valves and valve seats, valve timing, fuel injection system, ignition system, compression ratio, lubricant, etc.

A typical family sedan having 2.4-liter engine and 150 hp engine can now have 2 engines of 3-cylinder 1.2-liter each, each engine producing 75 hp. Running on only one engine at a time, the operator will see a significant gain in fuel efficiency as the result of engine down-sizing alone, because the small engine can operate closer to its peak efficient point. The increase in weight and cost will not be much, and will be recuperated from savings in fuel efficiency and fuel cost. Purchasing price could be somewhat less than that of a gasoline-electric hybrid, and a lot, lot less than the purchasing price of a PHEV. However, the city mpg gain will be less than that of a HEV or PHEV due to the lack of braking energy recuperation.

According to the referenced patent, "The selector control actuates a transfer system that prevents simultaneous operation of both engines." This can and should be modified to allow simultaneous operation of both engines upon pushing the gas pedal more than 1/2 way down, in order to maximize power potential so that performance will not suffer.

Overall, a good and practical idea that may command higher market penetration than current market for HEV's and PHEV's, due to the potential for somewhat lower purchasing cost, as well as the use of lower-cost NG fuel instead of gasoline fuel, and the gain in fuel efficiency from engine down-sizing.


Trying to kill the italics.

I'm with gor on this one.  The major thing you'd want to do for different fuels is to change compression ratios.  There are many ways to do this without duplicating the entire engine, and they'd all be lighter and cheaper.  Furthermore, you could adapt to many different fuel mixtures instead of just two.


Shouldn't cause too many problems as long as it automatically reverses at full throttle.
I think someones 'havin a lend'.

Roger Pham

Try to design a 4-cylinder 2.4-liter family sedan to run on both NG and gasoline to see how efficient can you run on NG with that engine, vs a 3-cylinder-1.2-liter engine optimized to run on NG.

The cost difference is less than the cost differency between a 4-cylinder engine and a 6-cylinder engine, or well under $1,000 USD here due to the small cylinder size. If 2-cylinder engines like Fiat multi-air twin are used, the cost differential will be negligible.

The weight difference for the 1-engine vs 2-engine setup is negligible because total displacement will be the same between 1 vs 2 engines.

First of all, the R+M/2 octane number for gasoline is 87, while 120 for NG, meaning NG engine can run on much higher compression ratio than gasoline engine. Variable compression ratio (VCR) mechanisms are more difficult and complex and hence not used in commercial engines. You can gain 10-15% in efficiency just as the result of high compression alone.

Second, a 1.2-liter engine will run at nearly its peak efficiency at cruise. We are talking here about 20% thermal efficiency vs 35% thermal efficiency at cruise just on engine downsizing alone! Idle fuel consumption will be a lot less for a 1.2-liter engine vs 2.4 liter engine. Efficiency on NG operation is very important because CNG container is far more bulky, heavy and expensive than gasoline tank.

Third, you just can't beat having dual power plants in one vehicle. It means the difference of being stranded in dangerous areas of the road vs getting home safely.

Try to design a 4-cylinder 2.4-liter family sedan to run on both NG and gasoline to see how efficient can you run on NG with that engine, vs a 3-cylinder-1.2-liter engine optimized to run on NG.

You need to be able to operate when one or the other fuel tank is empty.  Try to design a 1.2-liter engine which meets your performance targets and emissions when your vehicle normally gets a 2.4-l.  Don't forget that you'll have cold starts every time you switch one on, which will be an issue for emissions.

There have been a great many schemes for variable compression, from hydraulically-movable piston crowns to eccentrics which shift the crankshaft to an engine block hinged on the crankcase.  I'm sure that it is cheaper to use one of these rather than building two separate engines (two crankshafts, 4 camshafts, extra balance shafts...).  If you do that, you also get the capability of running with any CR between the limits, not just two values.  That allows optimizing the geometric CR for variable fuel mixtures (e.g. FFVs) and anything that varies the air charge, such as boosting or Atkinson/Miller valve timing.

So long as NG is much cheaper than petroleum, I expect that most users would go for a dual-fuel engine tuned for 87 octane and simply eat the cost of lower efficiency.

Roger Pham

Keep some fuel on both tanks, but run mainly on the cheaper fuel.
The coolant circuit will always keep both engines at operating temp.

You can't have too big a NG tank, ergo you have got to make the engine as efficient as possible.


On reflection, trying to understand the possible benefits.

In a stationary application or maybe marine application when emissions in port are important or similar - then one may be able to gain a parts count reduction from generator or other load device and associated cost advantage or improved reliability robust dedicated single fuel engine. Or when fuel supply or costs are problematic.

It may be advantageous in order to meet appropriate technology status such as a hospital generator in some (lucky) third (or majority) world where fuel supply or costs fluctuate wildly.
To the point where it gets so bad you ordinarily need a backup engine.
( I hate to think of the fuel quality in that situation and may go back to the start with higher tech filters, fuel analysis and adaptive combustion strategies variable comp/timing multiple injection events via the various current strategies.

But for the application described it is bringing almost every problem we have with ICE, from GHG fuels to weight to the implicit lack of versatility that have been identified and strategised by mainstream manufactures for the last 10-20 years.

Implicit is the inability of the design team to overcome the fueling problem.
While all manufactures find adaptive fueling problematical and insiders will level that 'it' is more serious than they let on. with too many current attempts failing in the feild.

Couldn't help but wonder:

" invented by Herns Louis, veteran of more than 30 years in the parts manufacturing industry ranging from automotive to aerospace, specializing in computerized parts machining."

There is a lot of 'work' in this one.

Roger Pham

Let me help you to further understand the possible benefits of this dual-engine-dual-fuel setup:

The most important aspect is to allow one engine to operate as close to the peak efficient point during cruise using the cheapest fuel, while the second engine can come on to provide power boost when more power is called for. Each engine is optimized for just one type of fuel to maximize fuel economy and engine durability.
Each engine of the pair will be of 1/2 size of the typical single engine that they will replace, so no major increase in weight or cost.

As far as fuel availability issue, remember that methane in natural gas is the best hydrogen carrier. In the future, Hydrogen from renewable sources can be added to waste biomass during pyrolysis to produce synthetic methane having 2/3 of energy from the renewable hydrogen and 1/3 of energy from waste biomass. So, the use of methane for fuel can mean the ability to use low-cost renewable fuel in the future. Synthetic methane will be lower in cost than synthetic gasoline due to the ease of producing it and no need for refining.

It will work for both mobile and stationary setup. When work as a stationary generator, both will run on methane. One engine of the pair will provide base load for maximum efficiency, and the other will provide additional peak load, with a power capacitor to buffer power for the second engine to start in time.


That is all well and good, minimal pumping losses suggest better fuel economy than cylinder deactivation and starting with a specific fuel dedicated engine will help too with the bonus of potential to achieve simplified technology and hence maintenance which is incredibly important and easily overlooked.

Where it fails is that in the LDV app there is a complete duplication of the fuel system adding development cost, serious weight penalty from duplication complexity and taking up the already limited available space.
For what end?

Primarily to gain an economic advantage for the spot price of different fuels.

That may interest (and should) the bean counters but make it difficult for everyone else. That duplication will - history shows - be expensive to provide.

The upfront costs will need to be justified I.M.O. there needs to be a priority need for any combination of the advantages related to necessity of having multifuel ability.

Where the fuel supply may change I.E. a mine where diesel is required (but expensive) and gas will become available then it should be able to swap out even the diesel and run gas in both allowing fast changeover without touching the powered devices.In this instance dual fuel diesel ignition gas engines are available and could run varying proportions.

There is no prospect of paired running being advantageous as the shaft power required to run heavier loads ocasionally suggests more losses at low power outputs.

The more I think of it the less it appeals.

I like the renewable hydrogen storage prospects but don't accept that even that is particularly easy, or safe as the extensive infrastructure and natural gas (methane) fuels are not greenhouse friendly.

In this world homo economicus has created,sadly, the lowest common denominator will prevail.

IMO the electron will prove to be the most efficient and suitable at least in L-M.D.V.

Roger Pham

Arnold stated:
"IMO the electron will prove to be the most efficient and suitable at least in L-M.D.V."

Most efficient, yes, but suitable?...not yet. Battery is still:

1) far too expensive ($400-600 per kWh) vs $0.50 per kWh for a gasoline tank, or $5 per kWh for a carbon-fiber NG tank, or $10-15 per kWh for a H2 CF tank.

2) far too heavy, at 75-150 Wh per kg pack level for BEV, in comparison to gasoline at ~3,000 Wh per kg assuming engine efficiency at 1/3 that of e-motor, or 1,500 wh per kg for H2 and 2,250 wh per kg for Nat Gas

3) still too bulky, at ~200-400 Wh per liter in comparison to gasoline at ~3,000 wh per liter, assuming engine efficiency is 1/3 that of e-motor, and H2 at ~1,000 Wh per liter and NG at 1,500 Wh per liter.

NG will, for the forseeable future, be much lower in cost to petroleum, while synthetic methane will be much lower in cost in comparison to synthetic gasoline.

The use of 2 engines of 3-cylinder 1.2 liter will raise the cost less than $1,000 USD in comparison to a 4-cylinder 2.4-liter engine. The weight gain will be negligible because the total displacement will be the same!
The NG tank will cost another $1,000 more, so total cost about $2,000 more, at high volume of production, of course. This is still only 40% of the $5,000 cost premium of a hybrid electric vs a non-hybrid gasoline car, with greater saving in fuel cost than the hybrid electric can do, when NG at the retail pump can be sold at 1/2 the cost of petrol per GGE.

Even when both engines are used with only fuel type, for example, gasoline, the saving in fuel cost after only a few years will still be worth the $1,000 cost premium. For example, one engine can be optimized for baseload power, with more lugging at lower rpm for higher efficiency, then when more acceleration is needed, the second engine can be started and engaged without gear downshifting, due to the toque-doubling effect of having a second engine. Thus, between engine downsizing and engine lugging at baseload, fuel efficiency may be up by 60-100%.

For people with heavy foot or heavy stop-and-go traffic, the second engine may remain at idle and can be sped up and engaged via a wet clutch at a moment's notice to provide the necessary torque boost.

Gentle, eco-concious drivers may want to select having the second engine turned off completely to save on idling fuel consumption, only to be started when really neeed, while relying on gear downshifting for torque boost when acceleration is desired.

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