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Startup Working to Commercialize Direct Injection Ethanol Boosting + Turbocharging

Ethanol boost with turbocharging promises a cost-effective means to obtain high fuel efficiency in gasoline and flex ethanol/gasoline powered engines.

MIT scientists and engineers earlier this year founded a company—Ethanol Boosting Systems, LLC (EBS)—to commercialize their work on direct-injection ethanol boosting combined with aggressive turbocharging in a gasoline engine. (Earlier post.) The result is a gasoline engine with the fuel efficiency of current hybrids or turbodiesels—up to 30% better than a conventional gasoline engine—but at lower cost.

EBS has a collaborative R&D agreement with Ford, and anticipates engine tests in 2007 with subsequent licensing to Ford and other automakers. If all goes as expected, vehicles with the new engine could be on the road by 2011.

The foundation of the approach is the enhanced knock suppression resulting from the separate, direct injection of small amounts of ethanol into the cylinder in addition to the main gasoline fuel charge.

Efforts to improve the efficiency of the conventional spark-ignition (SI) gasoline engine have been stymied by a barrier known as the knock limit. Changes that would have made the engine far more efficient would have caused knock (spontaneous combustion).

The injection of a small amount of ethanol into the hot combustion chamber cools the fuel charge and makes spontaneous combustion much less likely. According to a simulation developed by the MIT group, with ethanol injection the engine won’t knock even when the pressure inside the cylinder is three times higher than that in a conventional SI engine. Engine tests by collaborators at Ford Motor Company produced results consistent with the model’s predictions.

With knock essentially eliminated, the researchers could incorporate into their engine two operating techniques that help make today’s diesel engines so efficient: a high degree of turbocharging and the use of a higher compression ratio.

The engine would operate with a wide range of ethanol consumption from a minimum of less than 5% up to 100%. A knock sensor would determine when ethanol is needed to prevent knock. During the brief periods of high-torque operation, fractions of up to 100% ethanol could be used. For much of the drive cycle, vehicles are operated at low torque and there is no need for the use of ethanol.

The combined changes could increase the power of a given-sized engine by more than a factor of two. But rather than seeking higher vehicle performance, the MIT researchers cut their engine size in half. Using well-established computer models, they determined that their small, turbocharged, high-compression-ratio engine will provide the same peak power as the full-scale SI version but will be 20 to 30% more fuel efficient.

The ethanol-boosted engine could provide efficiency gains comparable to those of today’s hybrid engine systems for less extra investment: about $1,000 as opposed to $3,000 to $5,000. The engine should use less than five gallons of ethanol for every 100 gallons of gasoline, so drivers would need to fill their ethanol tank only every one to three months. The ethanol used could be E85.

Given the short fuel-savings payback time—three to four years at present US gasoline prices—the MIT researchers believe that their ethanol-boosted turbo engine has real potential for widespread adoption.

To actually affect oil consumption, we need to have people want to buy our engine, so our work also emphasizes keeping down the added cost and minimizing any inconvenience to the driver

—Daniel Cohn, MIT senior research scientist and CEO of EBS



John Schreiber

from the wiki: The demise of the MG Rover Group in 2005 led to a halt in production of the famed "name" Rover V8 after 40 years.

The engines are still in use, as some of them still run;)

Direct injection allows the evaporative cooling effect to occur without loss to intake ports, valves, and cylinder walls.


Doesn't the Saab biopower already have boost controlled as a function of ethanol content?


@JOhn Shreiber.

That's what I wrote about DI chap, I KNOW it's better than port injection as the heat pickup is less from the surrounding parts. Andrey was arguing that PORT injection provided improved charge cooling when compared with DI. That is CLEARLY not the case.

You're being pedantic. The V8 is no longer in production however, there will be examples running for years. That is splitting hairs.


"every other corner gas station"

Not really. You could buy ethanol at your favorite liquor store.


Keep in mind, in the 60s, horsepower was rated without belt driven accessories taken into account (so-called "gross" hp ratings).


Glad to see work on ethanol to raise octane/compression.

Not only does it work, that has been known for decades, but it matches well to the supply. Ethanol will not be available in sufficient quantity for use as the primary fuel for quite sometime.

Sure, you can find E85 here and there in corn states, and we can import. Not enough. And E85 has nothing to offer in boosting diesel performance.

Several comments show a lot of knowledge about alcohol/water injection. I think it best to stay away from methanol, and fancy dual injection schemes. Go for research on blending ethanol directly into the primary fuel, gasoline or diesel.

Roger Pham

What you have in mind is turbocharger for diesel, which should cost a lot less than turbocharger for gasoline engine which runs stoichiometrically hence its exhaust is a lot hotter than diesel's exhaust.

I've recheck the prices of Edelbrock and HSK turbocharger kit for gasoline cars (Civic and Accura Integra) and the listed prices are ~$4000-6000 USD, while discount prices ranges from $2700-4000 USD. Remember that the MIT folks proposed here high-boost charging that require larger turbocharger which costs more, and intercooler is a must with high boost, hence additional cost.

Direct fuel injection requires much-higher-pressure pump and costlier injectors (piezo) due to more precision control necessary, due to the need to very finely atomize the fuel particle for quick evaporization and mixing in the higher pressure of the compression stroke. This technology is still new, hence more costly than low-pressure port-injection that has been in use for decades.


Shaun mann;
The replacement cost for a hybrid battery is a myth.
"Myth: Hybrid batteries will fail and stick you with a $2,000-plus repair bill.
Reality: Unlike digital camera and laptop batteries that are fully charged and discharged, a hybrid operates in the middle 60 percent of its charge, without being charged beyond 80 percent or discharged less than 20 percent. In addition to that, fans in the battery pack that keep it cool, plus the fact that the battery does not charge or discharge below freezing temperatures, help to ensure its longevity. Dave Hermance, Toyota's executive engineer for advanced technology vehicles, says that with these conservation measures, "we think it's a life-of-the-vehicle battery." Toyota said it has yet to have a charge-related warranty claim."


It does not matter much what media is cooling intake valve: intake air or liquid. The result is about the same: heated intake charge.

Direct injection of water mixtures is not an option. Water droplets pulverize lubricating oil film on contact with cylinder walls. Wartsila tried direct water injection on their marine diesel engines to decrease NOx generation, and abandoned the practice. On the contrary, with port injection unevaporated part of water droplets experience explosive atomization and intense evaporation when they enter low-pressure zone immediately adjacent to valve poppet in combustion chamber(same with gasoline), and does not pose mentioned risk. I strongly believe that choice of straight ethanol direct injection was made because of this issue. But elimination of water significantly decreases charge cooling potential.

Why port injection is better then direct? Volumetric efficiency of IC engine is limited by tight passages at intake valves. Partial evaporation of water/methanol/ethanol injected before intake valves significantly cools the air and make it appreciable denser. Second, cooler air has lover viscosity and hence less resistanse (and less heating-up) when passing through intake port. Increased volumetric efficiency translates into more power, or allows for engine downsizing or better yet arrangement of intake valves closure closer to Atkinson/Miller cycle, which will benefit engine efficiency at all loads, not only at full throttle.

But any way, potential increase in efficiency could be in the range of 5% max, not nearly 30% shamelessly claimed by MIT PR people.


No it's not the same Andrey. Two words: latent heat of evaporation.

Turning a liquid fuel into a vapour requires a lot of heat. This is one of the main benefits for DI, that heat source is the intake air NOT the intake valve. Result: cooler charge.

By increasing the density of the intake charge in the cylinder DURING the intake stroke, then more charge can be drawn into the cylinder and vol eff is improved. You need to go read some SAE papers (I can recommend some of the original Mitubishi papers from 1998 by Ando San) as a starting point).

A lot of time is spent in developing DI injection in preventing ANY spray contact with the walls, that's part of the job of the combustion system development. You don't just chuck an injector in there you know...


I worked on the subject couple of years ago. Direct injection cools the charge more effectively than port injection, no questions about it. But port injection not only cools the charge, but also improves volumetric efficiency. What approach is more beneficial from point of view of improved efficiency – remains to be seen. My penny is that old-fashion port injection should be better any way.


Coling the charge directly in the cylinder does inprove the vol eff as the capacity of the cylinder to hold air is improved. This effect is one of the main advantages of DI!

The only way pre-cooling the charge less effectively by PFI before it passes through the inlet valve will improve vol eff is if the inlet valve is so marginally sized that this presents a problem. Remember the vol eff is also increased by the fact that the fuel vapour no longer passes through the valve either...

It doesn't remain to be be seen, it's been published in many technical papers over the last nearly 10 years since the inception of GDI in the marketplace in Europe. DI has been around for quite a while in Europe at least.


GDI has nothing to do with discussed subject. Main GDI advantage is local charge stratification, which allows rich mixture near spark plug (combating self-detonation and improving ignitability, etc.) and lean/strait air beyond.

All effects we are arguing about are well beyond simple qualitative analysis. I do not nearly have means to argue the subject on quantities levels, which will ultimatively define the results.

However, I do have doubts about technical issues allowing advertised technology to be realized. Positioning of ethanol injectors in swept volume of piston compression rings is out of question. Positioning of it in upper unswept level will pose incredible heat stress on injector components WHEN IT IS NOT IN USE. Simply put, injector will be nearly red-hot when full-throttle event will trigger ethanol injection. Classic example of fuel vapor lock. Even employing flat- pattern injection, some injected ethanol will contact engine head surface. I believe that such liquid injection will pose destructive stress on ceramic coating of engine/piston heads, eliminating possibility to use this incredibly advantageous technology.

All in all, I have grave doubts that (I insist on the number) 5% potential increase in thermal efficiency will justify the troubles.

However, the project no doubts is justified to be fully funded, researched, and reported. I just do not like the hype that it is better then hybrids. Too many people around who actually could believe it.


You don't clearly understand about all the benefits of direct injection whether GDI or alcohol. You need to read some more papers. You can get a lot of benefits from GDI even when running GDI with homogenous charge preparation, ie not stratified, I know, I've developed GDI engines....

I do think that two injection systems, as proposed here, is missing the point. Better, as I said before, to have a single injection system, FFV sensor and variable boost levels to suit level of alcohol in the fuel.



In their red herring paper MIT guys perform theoretical estimations on assumption that port injected ethanol is 100% evaporated on intake valve and does not contribute to intake air cooling at all. Now, Robert, from all people you should know that it is not the case. Most of the fuel/ethanol/methanol/water injected into intake port is evaporated in combustion chamber.


Andrey:  Gross efficiency increase may be on the order of 5%, but the smaller engine has reduced friction and always operates in a more efficient part of its map.  That's where the 30% comes from.

It makes a difference; I got much better mileage out of my 2.2 liter turbo-4 than my 3.2 liter V6.  Less reciprocating mass, less friction.



Smaller engine has higher friction losses then bigger one, because it has to rotate faster to deliver necessary hp. Yet it has, as you rightfully noticed, way less pumping losses on part throttle. And forget about 30% increment increase in fuel economy promised by any engine technology. It is by definition a scum.

You are grossly misinformed about fuel efficiency of turbo/NA engines. In case of gasoline-powered, moderately-driven, American-overpowered family sedan NA engine offers slightly better overall efficiency than turbocharged one. Make no mistake: turbocharging of diesel is a must, turbocharged gasoline engine is the most powerful one which could be fit in particular engine bay, and turbocharged gasoline engine has slightly better fuel efficiency if driven really hard. Drive for turbocharged engines in Europe and especially in Japan is justified mostly by their taxation scheme which has vastly different taxation brackets for engines of different volume.

When the field is level, 2.7 V6 is better for family sedan then 2.0 L4 turbo. It is not only my opinion. Japanese carmakers are sticking to it too.


Sorry, Andrey, but you're wrong.  The smaller engine can provide cruise power at similar RPM, just at a higher manifold pressure.  If it's turbocharged it can reach a much higher MP.

My 2.2 liter turbo I-4 had about 190 HP.  So did my 3.2l V6 (which had 24 valves to the turbo's 8).  The 4-cylinder car routinely got 30+ MPG on the freeway, the V6 got 24-26.  An ethanol or methanol-boosted 4-cylinder would have been a good replacement for the V6.

Roger Pham


Engine efficiency correlates the most with volumetric efficiency. Running at high volumetric efficiency results in less pumping loss, less engine friction, and more vigorous, more complete combustion and higher combustion temperature hence higher Carnot efficiency.

For a given horsepower output, a smaller engine can run faster or a larger engine can run slower and still have the same volumetric efficiency hence comparable efficiency.

However, you cannot run an engine at high volumetric efficiency below certain rpm, depending on the engine bore size, due to the risk of detonation in homogenous charge combustion. Therefore, if the engine is quite large and hp requirement is too small, the engine can't be lugged down too low but must be run at some higher rpm than necessary for maximum volumetric efficiency, hence efficiency suffers. So, if you would reduce the engine size to maximize volumetric efficiency at a low hp requirement for cruise, then you must either make the engine capable of very high rpm, like in F1 engines capable of ~18,000 rpm, OR, you would turbocharge the engine to give you higher output for a given displacement to make the car capable of high acceleration and hence can compete in the market place.

Direct Injection gives superior power and efficiency by enabling higher compression ratio and slightly higher charge concentration, but costs more. WWII fighter aircraft got hp boost by water and methanol injection without requiring Direct Injection. German WWII fighters have fuel injection, while British and American fighters use carburetor, but all of them have benefited greatly from methanol and water injection for a substantial increase in power without engine detonation.



Running smaller engine at wider throttle opening means less spare torque available for acceleration. Smaller engines tend to be geared to run higher RPM at cruise.

The main disadvantage of turbocharged gasoline engine is that turbocharger is useful only on full power. At any other condition air intake is throttled, making turbocharger unused. Now, how often you use full power and for how many seconds? Meanwhile, geometrical compression ratio should be reduced, and this negatively affects engine efficiency all the driving time. If you check specs of currently offered models, you will find that turbos are used only on uplevel performance models. There are some exceptions, like Saab, but their turbos are of so-called low pressure variety and are fitted primarily to improve low-end torque with very moderate hp gains.

This is very interesting and challenging subject, and I hope to continue this discussion in more resent post (to get input of more readers), when appropriate theme surfaces.

Running smaller engine at wider throttle opening means less spare torque available for acceleration.
A turbocharger allows a similar ratio between cruise and WOT manifold pressure, and thus cruise and WOT torque.  I got plenty of torque out of my 2.2 liter once the turbo spooled up; I only had to downshift for rapid acceleration or at high altitudes (and not always then).
Smaller engines tend to be geared to run higher RPM at cruise.
Both my turbo I-4 and NA V-6 were geared at about 2500 RPM at highway speeds.  It was my Volkswagen NA I-4 which was geared at an annoyingly noisy 3200 RPM (the car really needed wider ratios or another gear).
Mark Dawson-Butterworth


Please take into account intake behaviour as well as combustion processes. Forced induction, whether turbocharged or supercharged, allows greater VE over the whole rev. range because chamber filling is better. However, we also now have variable cam timing and lift to play with. Perhaps this is why the boosted variable compression engines have not come to market sooner, because VCT is cheaper and can yield great improvements in low end torque versus top end power, as well as helping meet the dreaded emissions targets.

One of the biggest advantages I have seen with ethanol blends is the ability to run closer to MBT spark because of the higher octane rating. We need to be careful we're not confusing benefits of increased octane with charge cooling benefits.

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I think the most potential from this idea concerns the further establishment of an ethanol refueling structure in the US. More and more stations will have to install ethanol tanks and pumps for these dual injection cars and this will help with the diffusion of flex-fuel vehicles beyond the midwest corn belt all leading to an ever-growing market for ethanol that will help to make cellulosic ethanol more cost effective to manufacture on a large-scale.

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