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Startup Working to Commercialize Direct Injection Ethanol Boosting + Turbocharging
25 October 2006
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| 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
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October 25, 2006 in Engines, Ethanol, Fuel Efficiency | Permalink | Comments (52) | TrackBack (0)
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2 fuel tanks, one that collects water due to ethanol's chemical nature. The potential to downsize the engine is nice...but having E-85 or ethanol available at every other corner gas station is going to be a challenge.
Posted by: allen_Z | Oct 25, 2006 12:00:44 PM
It doesn't need to be on every corner, you'd only fill up the ethanol tank every 3 to 10 refills depending on how big your gasoline tank is and how much high-torque operation you use. Once the ethanol runs out it would just limit the turbo boost to a very low level until you filled up the ethanol tank again. It's a very creative way to satisfy both the desire to run good old regular gasoline for economy but still have all the power of a big engine.
The only major downside I see here is that typically highly boosted engines have the most turbo lag since on a low bost engine, it just adds another 30% more atmospheric pressure to the manifold - this implies they're going to run 1 bar or more (100% or more additional manifold pressure) which tends to translate into a strongly felt rubber band effect common to older turbocharged engines.
Posted by: Sid Hoffman | Oct 25, 2006 12:36:18 PM
Interesting concept, though downsizing with regular GDI with cam phasers and intercooled turbocharging plus thermal management and mild internal EGR in part load already yields 15-20% today, without the need to maintain a second fuel tank.
Another general issue is customer acceptance of downsized engines, especially in upmarket models. Even with compensation shafts, a turbocharged I4 will exhibit greater vibration and a different sound than a V6. Turbo lag is perceived negatively. Moreover, high engine displacement has long been a status symbol.
Btw, turbo lag can be masked in a number of ways, e.g. with an electrically powered supercharger (e-booster). This requires either a high voltage grid or, power electronics plus dedicated supercaps. VGT turbos, which also sharply reduce turbo lag, cannot long tolerate the very high engine-out temperatures of SI engines running at nominal power. Either the duration of such excursions has to be managed via the engine controls or, very expensive exotic materials must be used (cp. current Porsche 911 Turbo).
Posted by: Rafael Seidl | Oct 25, 2006 1:19:41 PM
"every other corner gas station"
Not at every corner, or even at every gas station. Most gas stations are at street corners/intersections. Perhaps it would be more accurate to say "every other gas station" or "every few gas stations", or something like that.
Posted by: allen_Z | Oct 25, 2006 1:33:14 PM
If status is a big deal, you can do small displacement 6 and 8 cylinder engines. Mazda sold a 1.8 liter V6 in the MX3 in the 1990's. Ferrari actually had something like a 2 liter V12 if you go all the way back and sold a 3.5 / 3.6 liter V8 car in the 1990's and up until a year or two ago. V8's go very well with cylinder deactivation so there's nothing saying you can't have a 2.8 liter V8 with a turbocharger and cylinder deactivation. Most folks just care about the V8 status and having lots of power, not the displacement.
Posted by: Sid Hoffman | Oct 25, 2006 1:57:10 PM
...and in the early 90s Mitsubishi had a 1.6L V-6 in the Mirage Cyborg before they went to the 1.6L MIVEC I-4.
Posted by: Patrick | Oct 25, 2006 2:14:13 PM
Most engines in Europe are I4's. People do not have the V8 fixation that they have in the US. Could go well over here, although it competes with diesel which is already very efficient. However, it could be a good way to use up some ethanol.
What is most important is the way these guys are thinking "outside the box" and the ideas they might spark in other engineers.
Nothing like $60 a barrel oil to get a few ideas rolling.
Posted by: mahonj | Oct 25, 2006 2:41:39 PM
A very creative idea. I could see some usability issues i.e. what happens if you fill the ethanol tank with gas by accident or fill the gas with ethanol. This would need some extra safety controls. I would be fine with the idea. However, I could see non-technical people having a problem with two fuel systems
Posted by: paul | Oct 25, 2006 2:57:58 PM
If a full tank is 20 gallons, at 5% ethanol should be only one gallon. Then you do not need a pump, you can simply buy a can at the gas station to fill in.
Posted by: MadMax | Oct 25, 2006 3:01:07 PM
By the way, could this system work with methanol or buthanol as well?
Posted by: MadMax | Oct 25, 2006 3:04:07 PM
And there is no problem if the ethanol picks up a little water. If I remember the MIT paper ethanol with 5-10% water works equally good. And it is cheaper to produce.
Posted by: MadMax | Oct 25, 2006 3:07:19 PM
Methanol and butanol have totally different calorific count, or energy density, or whatever you want to call it.
Methanol: 55,000 btu/gal
Ethanol: 78,000 btu/gal
E85: 82,000 btu/gal
Butanol: 105,000 btu/gal
Gasoline (for reference): 110-114,000 btu/gal
It makes it extra hard to do precise fuel metering if you're not sure what's in the tank. The good news is all the alcohols have reasonably similar octane values, so in that sense, any of them would work reasonably well.
Posted by: Sid Hoffman | Oct 25, 2006 3:23:33 PM
At $1000 it sounds good for people who like/need frequent power boosts. Would it be effective on a Toyota Prius or Honda Hybrid? Would it allow the use of smaller, lighter ICE generator?
Adding a one gallon plastic ethanol tank should not be a major problem. Fill-ups with reusable one gallon ethanol Jerry cans such be simple enough.
Could it be combined with windshield wipers liquid? Low quality ethanol is a good glass cleaner.
Posted by: Harvey D. | Oct 25, 2006 3:31:03 PM
Interesting idea, but couldn't a similar system use high octane gasoline? If there were a way to not destroy the catalytic converter such a system might get much higher MPG if the injector used 120 octane leaded gasoline. Nasty, but might be worth a cost/benefit before we judge it too much.
Posted by: Mike Z | Oct 25, 2006 6:56:00 PM
One thing nobody's noted so far: ethanol (and methanol) burn much cooler than gasoline, so operation on 100% alcohol for maximum power would stress the turbo's hot section a lot less. Doubly so if there was a substantial fraction of water in the alky.
Posted by: Engineer-Poet | Oct 25, 2006 7:37:13 PM
Methanol would work great in this application because MIT is relying on the Latent Heat of Evaporation (methanol has a way higher LHE than ethanol) and Octane of the fuel to lower the knock limit. Since they are using small amounts, methanol would be even better than Ethanol.
Butanol would not work as well because it has a lower LHE and lower octane than either methanol or ethanol.
Also, the ECU would really not care what fuel(s) are used as long as there is a wide band sensor and the long term and short term trims are able to adjust to a wide variety of AFRs.
Posted by: Joe | Oct 25, 2006 7:43:16 PM
Methanol injection could act as a form of intercooling past the turbo compression stage. There might not be a need for an intercooler.
Posted by: SJC | Oct 25, 2006 9:13:51 PM
This sounds like a good idea, but for an estimated cost increase of only $1000, it is way too optimistic. The turbocharger with intercooler and wastegate control etc. will cost ~$2000 USD extra. And then, there is another set of high-pressure alcohol direct injectors with at least four of them, AND another high pressure fuel pump for these alcohol direct injectors, which will cost at least another $1000 USD. Plus an alcohol reservoir that must be strategically placed and protect from collision-induced fire hazard, since alcohol can burn without a flame that would at times be even more hazardous than gasoline with yellow flame. This is a concern in Indy Car Racing which uses methanol. Plus more careful calibration and higher quality sensors, better programming, etc. to avoid catastrophic engine destruction at high boost. It doesn't take long or much to destroy an engine from preignition at high boost.
Can ethanol injection be done via the same gasoline port injectors? Probably not, due to lead volume inside the injector, the time lag in introducing the ethanol hence the power boost may be longer than the driver would want when instant power boost is needed.
So far, I've tallied over $3000 USD to $3500 USD of extra cost for ~30% gain in fuel efficiency. By comparison, a Camry hybrid at 40mpg is 42% better than a 4-cyl Camry at 28mpg, and costs ~$4000-5000 USD more when compared to a 4-cyl Camry loaded with similar luxury options. The Camry hybrid accelerates much faster than the non-hybrid version, so some of the $4000 cost increase in the Camry hybrid is justifiable based on the increase in performance alone. Now, if the Camry hybrid was made to use the Prius' engine and drive train, the mpg improvement would be even more dramatic, perhaps at 60-70% that of the 4-cyl Camry, at comparable or slightly slower acceleration, but with even less cost differential, given the fact that Prius drive train is smaller hence cheaper and mass-produced at higher number.
Posted by: Roger Pham | Oct 25, 2006 9:29:33 PM
this sounds much better than hybrids:
cheaper
no heavy unmaintainable battery pack waiting to die and cost $$$ to replace
more easily scaled up to high output
improvement in steady 70 mph efficiency, not just stop and go efficiency like hybrids
Posted by: shaun mann | Oct 25, 2006 11:33:17 PM
My Lord, what a shame for MIT.
Dual-fuel injection is established practice in performance cars for years. Port injection was proven decades ago to yield the best results because of:
1) evaporation of fuel in intake air makes air more dense;
2) cooled air has way lower viscosity, unlike liquids.
The best results are achieved with methanol/ethanol mixed with water injection, not just high-octane fuel. The practice of water injection into intake air is routinely employed on diesel engines. On high-performance gasoline engines it is standard feature even on semi-production performance cars.
Optimization of dual-fuel injection to downsize engine, boost effective compression ratio, and hence yield better fuel efficiency is really something new, but yield could be in the range of 5% gain max.
This hype is surely to compete with my “scum of the year” award with EESTOR and Hy-Drive.
Posted by: Andrey | Oct 26, 2006 2:07:07 AM
Fraid you're wrong there Andrey, DI even with gasoline achieves far better charge cooling that port injection as the fuel evaporates directly into the intake air during the induction stroke and does not pick up heat from the inlet valve and port wall which is what actually happens in a port injection engine.
This whole proposal could be massively simplified by just running the entire car as an FFV with boost pressure a function of alcohol fraction. Quite easy to acheive without the addition of a separate fuel system.
Most of the knock advantages can easily be achieved with DI and twin phasors by using alternative charging methods. Sounds like these chaps need to spend some more time playing with DI VVT....
Posted by: Ruaraidh | Oct 26, 2006 2:35:09 AM
Good old GM tried a version of this Circa 1962. Note the serious performance with only 5psi of boost, a single barrel carb, and no intercooler. The engine mentioned is currently still in use in Land Rovers. As for # of cylinders and small displacement, The Benelli Sei has a 750cc six, and is as smooth as a 3phase induction motor @ 60hz, IMO.
Jetfire Engine
In 1961, the F-85 had a 155 HP version of the 215 ci. (3.5L) engine, and the Cutlass had a 185 HP version. The 1961 versions of the motor were rated at 155 hp, but later years saw increases - up to 200 hp normally aspirated for the Buick version and 215 hp in turbocharged form from Olds (the 62-63 Jetfire).
In 1962, Olds, along with AiResearch, introduced a 'turbocharged' (called Fluid Injection) version of this engine, which put "Turbo Rocket Fluid" (½ distilled water, ½ methyl alcohol) into the carb. Along with a 10.25:1 compression ratio, yielded 0-60 in 8.5 seconds (with the manual tranny). The turbo was a Garrett TO-3 with an integral wastegate, the first. Unfortunately, due to the 10:1 compression ratio, boost was limited to only 5 psi, not the best use of a turbo.
The induction setup itself is fairly sophisticated (especially for 1962), with something like 54 separate connections to the intake system. The turbo has an integral wastegate, being the first mass production turbo application to use a wastegate. This was arguably the most complex induction system build to that time, with something like 50 different hose connections in the intake system (pressure sensors, wastegate, fluid injection, fuel, etc).
Olds attempted to get around the boost lag problem by using a high compression ratio (10:1!), which limited boost to only 5 psi. Fluid injection (Turbo Rocket Fluid) was used (a water/alcohol mix) to suppress detonation. Properly running cars will not go into boost if the "Turbo Rocket Fluid" reservoir is empty. There is an automatic shutoff for this. Parts for this injection system are even harder to get than the turbo parts.
The carb is a rare single barrel Rochester side-draft unit, whose only other application was on the Corvair Turbo. While they resemble the Corvair carb, they are much larger.
The Olds' turbocharged Jetfire was supposedly quicker than the 4V version, but it had maintenance problems due to its complex mechanics for that era. It attained the magic goal of 1 HP per CID. A power boost on the order of 40% was claimed. The automatic Cutlass with 10.75:1 compression gave 195 HP @ 4800 and 235 lb/ft @ 3200. The Jetfire's 10.25:1 compression gave 215 HP @ 4800 and 300 lb/ft @ 3200.
Source: http://www.442.com/oldsfaq/ofjet.htm
Of course SAAB can give you this performance today with 140 ci (2.3L) or less.
Increasing BMEP is the answer, and biohols are the correct fuels for doing this in SI engines. Any serious arguments against MIT's work in this area have pretty much been made moot by Harry Ricardo. One would do well to start their research by reading his works.
http://en.wikipedia.org/wiki/Harry_Ricardo
Posted by: John Schreiber | Oct 26, 2006 3:03:26 AM
Think you'll find the P51 Mustang had water alcohol injection in WWII...
No ones arguing that alcohols aren't a way forward, just that this proposal is more complex than it needs to be to achieve the desired results.
I think you'll find the engine you're referring to hasn't been fitted to a Land Rover product for quite a while!!
Posted by: Ruaraidh | Oct 26, 2006 3:50:36 AM
Roger -
I hope you're not working in purchasing. Your estimates regarding the extra cost are way too high. Turbos have become pretty cheap since European diesels all use them and, GDI is well on its way to becoming a commidity subsystem as well. Don't assume that just because US engine technology generally lags Europe and Japan by at least a decade that it cannot catch up quickly.
Posted by: Rafael Seidl | Oct 26, 2006 4:52:12 AM
I don't think that this will be cheaper to build than a Euro 6 turbo-diesel. Neither will it have the low-end torque needed for downsizing. Ford is probably looking for options to boost it's new 3.5L V6.
Posted by: JC | Oct 26, 2006 6:01:12 AM
Ruaraidh;
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.
en.wikipedia.org/wiki/Rover_V8_engine
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.
Posted by: John Schreiber | Oct 26, 2006 6:28:21 AM
Doesn't the Saab biopower already have boost controlled as a function of ethanol content?
Posted by: clett | Oct 26, 2006 6:32:10 AM
@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.
Posted by: Ruaraidh | Oct 26, 2006 8:49:27 AM
"every other corner gas station"
Not really. You could buy ethanol at your favorite liquor store.
Posted by: Dursun | Oct 26, 2006 8:52:59 AM
Keep in mind, in the 60s, horsepower was rated without belt driven accessories taken into account (so-called "gross" hp ratings).
Posted by: Patrick | Oct 26, 2006 9:06:47 AM
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.
Posted by: K | Oct 26, 2006 9:35:32 AM
Rafael,
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.
Posted by: Roger Pham | Oct 26, 2006 12:17:20 PM
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."
Posted by: ai_vin | Oct 26, 2006 12:25:18 PM
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.
Posted by: Andrey | Oct 26, 2006 8:58:32 PM
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...
Posted by: Ruaraidh | Oct 27, 2006 12:18:34 AM
Ruaraidh:
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.
Posted by: Andrey | Oct 27, 2006 1:56:42 AM
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.
Posted by: Ruaraidh | Oct 27, 2006 2:02:32 AM
Ruaraidh:
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.
Posted by: Andrey | Oct 27, 2006 4:28:02 AM
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.
Posted by: Ruaraidh | Oct 27, 2006 7:32:17 AM
Ruaraidh:
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.
Posted by: Andrey | Oct 27, 2006 6:48:27 PM
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.
Posted by: Engineer-Poet | Oct 27, 2006 9:20:06 PM
Engineer-poet:
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.
Posted by: Andrey | Oct 28, 2006 5:23:10 AM
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.
Posted by: Engineer-Poet | Oct 28, 2006 6:51:05 PM
Gentlemen,
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.
Posted by: Roger Pham | Oct 28, 2006 7:35:52 PM
Engenner-poet:
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.
Posted by: Andrey | Oct 29, 2006 12:38:19 AM
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).
Posted by: Engineer-Poet | Oct 30, 2006 3:04:37 PM
Gentlemen,
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.
Posted by: Mark Dawson-Butterworth | Nov 12, 2006 1:03:27 PM
We deal in marine products and we are interested in buying FORD ENGINE (TURBO CHARGED)
S/no:6kh587023*5L13
120 horse power
Posted by: sky hydromarine masters ltd | Mar 1, 2007 10:39:29 PM
We deal in marine products and we are interested in buying FORD ENGINE (TURBO CHARGED)
S/no:6kh587023*5L13
120 horse power
Posted by: sky hydromarine masters ltd | Mar 1, 2007 10:41:56 PM
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.
Posted by: Matt | May 30, 2007 7:55:20 AM
Efficiency aside, if ethanol direct-injection systems can be retrofitted into existing cars, it would have a huge impact on the import tuning market as well, where large boost pressures are commonly used without much of a safety net for the engine. Extremely powerful (over 1000 horsepower) small-displacement engines could be made much more reliable.
Posted by: kismetcapitan | Nov 16, 2007 12:27:15 AM
Friends all,
While there is a measure of truth in most of the comments, it all boils down to: (1)most complete combustion and (2) highest conversion of heat produced into power. Can we all agree that higher compression increases power and cooling systems waste energy? Therefore, we must increase compression and replace cooling with direct injection of a power producing media. I suggest direct electronic injection of water not with fuel on every stroke but by itself on every other stroke as dictated by exhaust temperature.
Posted by: Greg Cottrell | Jun 30, 2008 11:35:51 AM
