Turbocharging – A transportation technology for ever higher FE

Discussion in 'Articles' started by xcel, Oct 16, 2007.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Although known for performance improvements, the modern day turbo will help achieve fuel economy targets … if applied correctly.

    [xfloat=left]http://www.cleanmpg.com/photos/data/506/Front_Page_Turbo_Diesel_Presentation_Graphic.jpg[/xfloat]Wayne Gerdes – CleanMPG – Oct. 16, 2007

    Fuel efficiency and CO2 reduction are coming to the forefront as fuel costs continue to rise and concerns over future energy supply and continued climate change increase. Surprisingly, one of the technologies that can reduce these increasing tensions is the common turbocharger.

    CO2 targets are being discussed throughout Europe, the U.S. (led by California), Japan, China, Canada, Australia, Taiwan, and Korea. These discussions have brought fuel economy standards, automobile and fuel taxation, and also emissions awareness to the forefront as motivators for both manufacturers and consumers -- sparking the pursuit of increasingly fuel efficient vehicles.

    Enter the turbocharger - a key technology which allows improved fuel economy while simultaneously reducing both CO2 and SMOG forming emissions in a cost effective manner for the ever growing automobile owning populace.

    “It is increasingly clear that the internal combustion engine - diesel and gasoline - with its potential for further efficiency improvement will remain the dominant platform for the next 20 years, combined with different levels of hybridization,” says Alex Ismail, President of Passenger Vehicles - Honeywell Turbo Technologies.

    CO2 – A Global Imperative

    [xfloat=left]http://www.cleanmpg.com/photos/data/506/CO2_emissions_vs_future_years.jpg[/xfloat]CO2 Emissions Standards by Region-Light Vehicles

    Around the globe, automobile manufacturers are constantly being challenged to meet more stringent standards - leading to steadily higher fuel economy requirements and by association, a corresponding reduction in CO2 emissions.

    Today, Europe and Japan have the most stringent fuel economy standards in the world. In the next ten years, Europe, China and California will have fleet average GHG reductions resulting in a striking 20 percent decrease when compared to the 2002 baseline. The California Greenhouse gas standards, if realized, could significantly narrow the gap between US and EU standards.

    Diesel penetration in US light vehicles is expected to grow to 12 percent by 2015 according to JD Power Consultants. Gasoline engine downsizing will also be more broadly adopted. Turbocharging will play a key role as the U.S. increases its focus on FE and reduced GHG emissions over the coming years.

    A revolution in engine efficiency and performance

    Engine downsizing – achieving equivalent power output from smaller and more fuel efficient engines - will drive CO2 reduction. Turbo technology in both diesel and gasoline powertrains will allow this evolution to occur.

    Why turbocharging?​

    A turbocharger is effectively an air pump using engine exhaust gases to deliver better engine efficiency and performance. These exhaust gases drive a turbine wheel, which is coupled to a compressor. This supplies more air at increased pressure to the engine’s combustion chamber than a normally aspirated configuration would. The compressed air is very hot as a result of both compression and friction, so an intercooler is used to reduce the temperature - increasing the density and allowing even more air into the combustion chamber.

    Thanks to this increased air density from the intercooler, a larger amount of fuel can be used while maintaining the same air-fuel ratio, which results in more power and increased efficiency from a smaller engine with lower levels of SMOG forming and GHG emissions. The turbocharger now becomes a fundamental emissions control addition, notably for NOx reduction. Turbocharging coupled with high pressure fuel injection and advanced combustion solutions makes combustion not only more thorough and fuel efficient, but also cleaner.

    Turbo Diesels allow a 20 - 40% increase in fuel economy over conventional gasoline powered vehicles, and turbo gasoline engines can allow a 10 - 20% increase in fuel economy over similarly sized, non-boosted engines with equivalent performance. In the US, we can expect to see a noticeable increase in the number of turbo diesels with markedly higher fuel economy and lower CO2 emissions.

    European Turbo Diesel vs. Conventional Gasoline comparisons

    BMW 328i vs. 330d

    Parameter328i330d% inc./dec.
    TurboNA3rd gen VNT
    Engine Displacement3.0L3.0L
    Weight (kg)1,5551,610
    Max Power (HP)272231
    Max Torque (Ft-lbs@RPM)236@2,750369@1,750 +56%
    Top speed (mph)155155
    Acceleration (0 - 62 mph)6.1 sec.6.7 sec.
    Mileage US-mpg combined32.7*38.6* +18%
    CO2 emissions (g/km)173*160* -8%

    * Based on Euro Urban/Extra Urban Combined.​

    BMW X5 vs. X5d

    ParameterX5X5d% inc./dec.
    TurboNA3rd gen VNT
    Engine Displacement3.0L3.0L
    Weight (kg)2,0752,160
    Max Power (HP)272235
    Max Torque (Ft-lbs@RPM)232@2,750383@2,000 +46%
    Top speed (mph)140134
    Acceleration (0 - 62 mph)8.1 sec.8.1 sec.
    Mileage US-mpg combined23.1*29* +26%
    CO2 emissions (g/km)244*214* -12%

    * Based on Euro Urban/Extra Urban Combined.​

    Honda Civic vs. Civic iCDTi

    ParameterCivicCivic iCDTi% inc./dec.
    TurboNA2nd gen VNT
    Engine Displacement1.8L2.2L
    Weight (kg)1,2511,389
    Max Power (HP)140140
    Max Torque (Ft-lbs@RPM)128@4,300251@2,000 +96%
    Top speed (mph)127127
    Acceleration (0 – 62 mph)8.9 sec.8.6 sec.
    Mileage US-mpg combined36.8*46.1* +25%
    CO2 emissions (g/km)152*135* -11%

    * Based on Euro Urban/Extra Urban Combined.​

    MB 350 vs. 320 CDI Blutec

    ParameterE350E320 Blutec% inc./dec.
    TurboNA3rd gen VNT
    Engine Displacement3.5L3.0L
    Weight (kg)1,6901,750
    Max Power (HP)272226
    Max Torque (Ft-lbs@RPM)258@2,400398@1,600 +54%
    Top Speed (mph)155155
    Acceleration (0 – 62 mph)6.9 sec.6.8 sec.
    Mileage US-mpg combined24.2*32.2* +33%
    CO2 emissions (g/km)231*194* -16 %

    * Based on Euro Urban/Extra Urban Combined.​


  2. Vooch

    Vooch Well-Known Member

    Re: Turbocharging – A transportation technology for ever higher FE.

    one wonders what would be the MPG difference between Gas & Diesel if one used engines with the same torque ( ie a itty bitty 80kw diesel versus a 200HP gasoline engine )
  3. rweatherford

    rweatherford Times my Mileage by Six

    It's also not fair to compare MPG for different fuels.

    I had a car that I turbocharged myself. It was a 2.3L 4-cyl. I gained 100 HP from 180 HP to 280 HP, and 2 MPG on the highway with the same premium fuel. I custom tuned the ECM myself for HP and cruising economy. The economy gain should be compared when comparing HP ratings to fuel consumption in the same car.
  4. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Rweathwerford:

    ___It is not what you are doing to a current engine, it is what you can do with a smaller engine that will run far more fuel efficient 85% of the time and using the turbo to maintain the performance similar to that of a much larger motor when needed. Consider the Accord’s 2.4 HP and Torque vs. RPM curves. The most I have ever used was ~ 80 - 90 HP! To bad the Accord was not equipped with a semi tall geared 1.5 w/ DI and a turbo for an lmpg in the mid 50’s ;)

    ___Another take is consider the soon to arrive European and Asian super diesels. The turbo allows the performance while the diesel allows the thermodynamic efficiency and the excellent FE! The iCDTi listed above offered scary FE no matter what scenario it was driven in all the while having the ability to take an almost 3,000 # vehicle to 60 in less then 9 seconds and stick like glue in the process :)

    ___Good Luck

  5. rweatherford

    rweatherford Times my Mileage by Six

    Then why not label this article gas versus turbo diesel? That is what they are comparing in the vehicle stats.

    I understand what the article is saying, but it doesn't compare apples to apples in how turbocharging effects fuel consumption.

    Again. I would compare HP to HP and then fuel economy. A 50 HP gas and 50 HP gas turbo engine would follow the article title. For the most part current turbocharged gas engines in available cars get worse gas mileage than a similar sized NA gas engine because the turbo engines are large enough to cruise down the highway in a vacuum state with no boost. The turbo only increases the efficiency during times of high loads.

    If you want to compare diesel and gas fine, but understand that diesel should ALWAYS get better economy when compared in gallons. Try dividing the MPG by BTU per gallon for each fuel. You will find a lot of the difference there without the other stuff.

    Fuel type BTU/US gal
    Regular Gasoline 125,000
    Ethanol 84,600
    Gasohol 120,900
    Diesel 138,700
    Liquefied natural gas 90,800


    125,000 BTU gasoline / 36.8 miles = ~3400 BTU per mile
    138,700 BTU diesel / 46.1 miles = ~3000 BTU per mile

    The turbocharged diesel is actually only 13% more efficient thermally. (if I did my math correctly) Some of that comes from having no pumping losses. How much actually came from the turbocharger and not from the also higher static compression ratio?

    I think you see where I'm going.

    I'm not too thick skulled to understand what they are doing here.....

    The performance is produced from TQ curve multiplied by the gears available to produce ft-LBS TQ at the wheels. The higher average the curve within the RPM range used by the tranny produces more acceleration for a given peak HP number. It's simple math.

    I think the article is great, but the sidebar comparisons are a bit misleading due to different fuels.
  6. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Rweathwerford:

    ___You are getting all mixed up in the BTU content of fuels and what a turbo can do for HP straight out. We already know all about a given fuels BTU content. What you may not be so familiar with is gasoline refining BTU input vs. diesel #1 or #2. The two make up for one another “well to wheel” a lot more evenly then the BTU content of the refined fuel after the fact.

    ___As for the article, what we all have to consider is the FE for a given vehicle. If you want to speak about a SI-ICE with a turbo, where do we look for an apples to apples comparison? The turbo-equipped gasoline based engines are mostly hopped up HP monsters with garbage for FE to begin with and that is why any comparison of them was left out. The CI-ICE (diesels) have gasoline counterparts to compare against with similar output as seen in the tables but look at the FE!

    ___Another note to follow up on is Ford’s EcoBoost program. It was originally the TwinForce program and by using a turbo and DI with a smaller engine, they are getting the same output as a larger ICE but without having to consume nearly the same amount of fuel for said output.

    ___A turbo helps make up for the smaller but more fuel efficient engine although there is an expense in doing so :(

    ___All in, most here would take a turbo-diesel over a normally aspirated non-hybrid and in some cases, even a hybrid of similar size and capability if the price was right. Europe is a prime example …

    ___Good Luck

  7. rweatherford

    rweatherford Times my Mileage by Six

    Re: Turbocharging – A transportation technology for ever higher FE

    I'll admit to not knowing the difference in "well to wheel". An explanation would be nice. I'm guessing it has to do with the heat required to refine the "oil" into gasoline instead of just diesel. What counts I guess to me is $ per mile and I have not figured that in the examples either. Diesel costs more at the pump even though it is easier to refine. Some of this is tax.

    1988 Chevy Sprint had a 1.3L NA and Turbo motor for a few years. Turbo was 31 / 39 and NA was 37 / 44.

    1988 Dodge Shadow had a 2.2L NA and Turbo motor. Turbo was 18 /26 and NA was 22 / 30.

    1992 Dodge Shadow had a 2.5L NA and Turbo motor. Turbo was 18 / 24 and NA was 20 / 29

    1992 Dodge Stealth had 3.0L SOHC, DOHC and DOHC Turbo. All engines basically received 16 / 22 ratings.

    2006 Subaru Legacy had 2.5L DOHC NA and Turbo. Turbo was 17 / 24 and NA was 20 / 27

    Is that enough examples? None of those engines are HP monsters. Even the Legacy only has 250 HP. GM makes NA V8's with better FE in larger / heavier cars and with more HP.

    2008 Chevy Corvette with a 500? HP 6.2L V8 rates at 16 / 26 MPG. This beats or matches every turbo motor listed in highway mileage except the 1.3L Sprint. I can even add 4700 lbs full size V8 cars that have 23-25 MPG highway ratings.

    So what is the advantage again of the smaller turbocharged motor? Perhaps we haven't added enough new technology to these older examples. (most of those turbo motors were considered the highest tech for those dates) The old pushrod V-8 holds it's own pretty darn good against the turbo motors. NA is a different story.

    This sounds like Mazda's tech used in their CX-7? I'm not familiar with it so I'm a bit out of the loop on what Ford is doing.

    Sure why not? But is it economically an advantage or just MPG? I like diesels too.
  8. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Rex, I think you both are talking past each other. What Wayne is trying to get across is that you can either have a NA engine producing X performance, or you can have a SMALLER engine which is turbocharged and ALSO producing X performance. The two comparable engines are DIFFERENT sizes. Your examples are pitting the same sizes against each other.

    The idea is similar to what Honda has done with IMA. How do you get a really efficient engine? You downsize it to small displacement. What happens to your power? It goes out the window and performance for "drive-ability" becomes "unacceptable." Their solution was to bolt a motor to the engine to augment the torque when needed. The rest of the time you are using a really small engine sized for mostly steady state functionality.

    Now apply the same technique to this situation. Get better efficiency by downsizing the engine but maintain performance by bolting on a turbo that kicks in for those times you need more power.

    In both cases a hypermiler manages really high mileage by avoiding the augmenting components (the motor for IMA and the turbo for the application above) when driving. That's how Wayne got insane mileage out of that iCDTi he tested, and it is also how he got insane mileage out of his Insight. I'm doing my best to follow suit. ;)
  9. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Rweathwerford:

    ___What Sean said ;)

    ___Diesel is closer to crude then gasoline and when you add the extra energy used to refine gasoline, they are a lot closer than the BTU content of the final product would lead you to believe.

    ___The advantage of a small turbocharged motor is as simple as looking at idle consumption of a 1.8 L ICE and a 2.4L one. The 2.4 while idling is in the .3 gph range while the 1.8 is in the .2 gph range.

    ___Because a turbo is only adding a massive increase in HP at high boost, that is exactly when you need it while your foot is into the pedal. Otherwise you are pushing more metal back and forth, up and down and round and round for no other reason then it was designed for a particular size.

    ___Re-read the article above again because I believe you may be missing the following?
    ___It describes Si-ICE with the additional statement describing diesels. I previously mentioned ecoBoost. Search here or on the net and it will give you all you need to know about that as well.

    ___As for the final question(s)? A smaller motor with similar construction and HP when needed will have better FE. This is why some are considering the smaller Turbo’ed CI and SI motors for future vehicles. The Volt is yet another spec’ed for a 1.0L turbocharged SI-ICE. Also consider a diesel without a turbo has so little output it cannot compete. With one, it has all the HP you need when you want it but when you do not, it will sip fuel like it is swimming in the stuff. Turbo’s increase HP in both smaller cap CI and SI-ICE’s.

    ___Good Luck

  10. diamondlarry

    diamondlarry Super MPG Man/god :D

    Re: Turbocharging – A transportation technology for ever higher FE

    Awhile back, a friend of mine and I were discussing the advantages of a turbo on an engine the size of the one in my Saturn. In most cases, a turbo is there to enhance performance only. To make a turbo enhance FE, you would need one that was sized for an engine that was smaller than the engine it's going on. For example, a turbo for a 1.3-1.5L on a 1.8L. This way, the turbo would always be on the edge of being spooled up and would have extra torque for pulsing and you would be able to stay in a lower gear to keep rpm's down. The trick would be to keep your foot out of the pedal. It would probably be about like trying to stay out of assist on an Insight?
  11. rweatherford

    rweatherford Times my Mileage by Six

    I did give you guys real world examples that you asked for, plus a big V-8 that matches the smaller lower HP 4-cyl turbo cars. These real world results to the 10-20% statement.

    After looking some more I've found some Saab cars that are better examples for the arguement.

    1995 Saab 900 had 3 engines. 2.0 turbo, 2.3 NA, 2.5 NA. Highway MPG is 26, 26 and 23 respectively. I'm not sure on HP output.

    1995 Saab 9000 has 3 ratings for 2 motors with automatics. 2.3 turbo, 3.0 v-6 and another 2.3 turbo They are 25, 24 and 23 MPG. I'm not sure why one engine gets 25 and what looks to be the same engine gets 23? Perhaps a HP rating change on one of them.

    I understand that using a smaller turbo motor is the idea. I think if you put the 1.3L turbo from the Swift into the Corvette you might be dissapointed in the MPG and performance.

    If you are going to be turning the turbo motor on and off all the time I suggest using a ball bearing turbo with liquid cooling CHRA and some type of oil pressure reserve system. You would be much less likely to score the bronze bushings and have oil coking problems.

    This is a good discussion and I think the idea has good merit. History has not proven to be a good guide.
  12. lightfoot

    lightfoot Reformed speeder

    Re: Turbocharging – A transportation technology for ever higher FE

    I've been wondering if Honda optimized the Insight ICE for HP rather than torque, especially giving up low rpm torque, knowing that the IMA adds torque as needed at all rpm's? By "optimized" I don't mean "sized", I mean designed within the 1.0L displacement (e.g., cam profiles, valve sizing, VTEC programming, etc). Also, if you have enough torque-on-demand low down you can gear the thing to keep the rpm's low and further improve FE. At the high rpm end the ICE develops the additional HP to overcome increased air drag and maintain higher speeds. Hopefully I'm explaining this clearly??

    Also, perhaps the turbo-diesel is in effect using a similar two-phase scenario with different components? The diesel motor's forte is low-end grunt, and then the turbo adds in more and more HP as the rpm's and speeds rise. Possibly variable DI timing could reshape the diesel's FE/torque/hp characteristics as needed at different rpm's and loads, or perhaps variable valve timing (VTEC) could help?
  13. lightfoot

    lightfoot Reformed speeder

    Re: Turbocharging – A transportation technology for ever higher FE

    Is it possible that gearing differs?
  14. rweatherford

    rweatherford Times my Mileage by Six

    Re: Turbocharging – A transportation technology for ever higher FE

    Yes very possible.

    I also hope that the direct injection finds MPG gains due to the ability to run higher compression ratios without the worries of pre-ignition and detonation issues. This might also allow running 87 octane instead of 91 octane for most turbo motors.

    We might also find the same gains on a NA motor as well, which might neutralize the gain in the turbo motor.

    Only new research and time will tell. It is pretty exciting stuff.
  15. diamondlarry

    diamondlarry Super MPG Man/god :D

    Re: Turbocharging – A transportation technology for ever higher FE

    You are right, a 1.3L turbo would be too small for a Vette. I'm not up on what size engine Vette's have nowadays but, if they still have the 5.7 for example, you would want a turbo from something closer to a 4L and above. Although in the case of a Vette, you probably don't need a turbo anyway with the loads of torque they already have. I drove a Camaro that basically had a detuned Vette motor with ~375 HP that, with the 6-speed transmission, I think I could have fairly easily gotten 40 mpg or higher in it because of the gobs of torque it had in 6th in the low speed P&G range.
  16. rweatherford

    rweatherford Times my Mileage by Six

    The Vette is currently a 6.2L all aluminum motor and the optional 7.0L small block. Really amazing stuff. High performance and decent economy if driven properly. I understand this is not a 50 MPG car, but it's not supposed to be. What is interesting is it beats several "economy" cars and delivers 500 + HP.

    I think the direct injection will find more efficiency for gas engines.
  17. phoebeisis

    phoebeisis Well-Known Member

    We still don't have one example-current or from the 80's-of a gasoline-spark ignition-car getting better mpg with turbo charging. The current crop of turbo motors- mainly in 4 cylinders in hot rods get laughable mpg-numbers -Mazda speed 3 18-26 vs 24-32 for the Mazda 3 with MT.Heck,what is the point?The current Accord AT 6 cylinder get 19-29,and I would bet it accelerates more quickly with an average driver.I wouldn't bet that those Turbo 4 cylinders are a heck of a lot lighter,and by most accounts they are a bit fragile.
    The usual response to this-turbo spark ignition motors don't deliver FE better than non turbo motors -is that the manufacturers are going for performance, not FE.
    My suspicion is that the manufacturers have discovered-rediscovered-that spark ignition motors deliver slightly better power to weight(4 cyl turbo vs 6 cyl normally aspirated), but they don't deliver better FE.
    Why??My guess is that they just can't make up the efficiency loss they suffer from the drop in static compression.They usually start with a 1.5 drop in compression.The efficiency gain from recaptured exhaust energy just doesn't make up for the loss with the lower compression.I'm also suspicious about how these motors are getting away with close to 15 psi boost.Usually problems started-detonation-at over 5 psi boost.I think they solved this problem by injecting more fuel to cool the charge,and letting the cat con clean things up downstream. Yeah,they can retard ignition etc,and dial back the boost, but that defeats the purpose of the lighter smaller motor making - more mechanical energy- per gallon.
    Turbo spark motors are still a bust-just like the 1980's.
    If might be better to use exhaust turbine to spin a generator on a gasoline/electric hybrid-charge the battery etc.
    PS-TDIs completely different story-they can take lots of boost with "lean" fuel,and they have very high static compression.
    PPS-It is worth mentioning that the POS GM diesel(no turbo charger!!) from the 80's got better mpg in Suburbans(15-22) etc that the current spark motored ones,and it matches the hy mpg of the Hybrid Tahoe.Yeah, it was slow, but so what-it was a POS poorly developed 2 valve pushrod motor-from 25 years ago-and it matches the best current hy FE??)
    Are we really sure that Turbo charging the intake is the best-most efficient FE wise- use of that almost free exhaust energy??Sure doesn't look that way to me-not on spark motors.
  18. rweatherford

    rweatherford Times my Mileage by Six

    I ran two engine configurations turbocharged both with similar HP outputs.

    With 9.5:1 CR I used 9 PSI of boost to attain 280 HP with 2.3L on 91 octane.
    With 8.5:1 CR I needed 14-15 PSI of boost to attain the same 280 HP on 91 octane.
    The stock engine had 10:1 CR, 180 HP NA and used 91 octane fuel. Notice that the extra PSI of boost just creates the correct dynamic CR needed for the HP (TQ) level attained.

    I adjusted spark advance and ran rich under high power to keep detonation at bay. I eventually detonated on a dyno leaning out the mix on the 9.5:1 motor. The 8.5:1 motor was safer even at 15 PSI. I still had some minor issues with fuel delivery that were unrelated to the CR / boost level.

    I don't remember what the 9.5:1 CR engine was on MPG, but the 8.5:1 CR motor attained 34 MPG on the highway. This was better than I could do with the stock motor. Some of this could have been tuning a little lean at cruise and using more spark advance. This engine used 4 - 55lb/hr injectors which are very large. It idled fine with low pulse width numbers and ran stock fuel pressure.

    I was going for power and not FE on this car. It just so happened that good tuning produced good FE even with the low static CR. The turbo was also sized to attain full boost at ~2700 RPM and would hold it to 7500 RPM. During cruise the extra airflow was vented to atmosphere during cruise and was instantly available cruising down the highway.

    It was a great learning experience because at that time no one was turbocharging that particular engine so I had to do all the research, figure air flow for turbo sizing, injector sizes vs RPM range desired, ECM tuning, etc. I then created my own exhaust manifold (very crude, but effective) and put together my own kit. It had a few hiccups, but came together pretty nicely and is still on the road today with someone else. Total cost was $1500-$2000 and I learned a TON.

    I see the hypermiling crowd as a very creative group that can go a long way toward FE goals with collaborative work, which many have already done. I unfortunately will be restrained in what I am personally doing due to the functionality and reliability of my vehicle being the family car. However, I love reading about some of the projects, theorys and experiments. This is the new "hot rod" era IMHO.

    I think battery technology and brushless motors will push the electric cars forward in the mix of preferred power sources.
  19. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    ___Something to add here … We all know Turbo’s add HP so a small motor can be jacked up for the high HP “wants” somebody may ask for. When cruising down the road, even the largest behemoths are using all of 30 + HP with most sedans in the 25 HP range. This is where the small ICE’s kick @$$ as they just do not consume fuel at the rate a large and choked down motor does while trying to supply that minimal of a load. It is similar idea to the hybrid. Atkinsonized small motors for the highway cruise and the valve tricks and hybridization to remove the sucking fuel like a drunken sailor during initial accel but still allowing decent accel performance for most when they want it. The higher performance additions do not add to the FE but are included for drivability in most cases.

    ___Small motors do not drink fuel like large ones while supplying the same low HP requirements under most driving scenarios. DoD is yet another prime example of this … In the case of a turbo, when you want to use the HP, the turbo spools up and you receive what you want but you will not be saving any fuel during that period. They are only there for the performance period which for most vehicles is less than 95 + % of the time a particular vehicle is driven. For us, that means ~ 0% of the time of course ;)

    ___Good Luck

  20. pdk

    pdk Beacon of Sanity

    Re: Turbocharging – A transportation technology for ever higher FE

    You're on the right track. "Well to wheel" is the total energy and emissions cost in all stages of a particular fuel's energy path. This includes energy needed and emissions produced in mining, drilling, or cultivating the fuel, refining it, transporting it, and ultimately using it in an automobile. So, it's everything from taking the fuel from the oil well until it drives the wheels of a car. It's a good way to do an apples-to-apples comparison of different fuel systems.

    You should read up on stuff by Sherry Boschert, she does a lot of work on plug-in hybrids and has a comprehensive study on well-to-wheels efficiency of a lot of different types of fuel (gasoline, diesel, ethanol, electric, etc.).

    It turns out that electricity backed by even dirty, dirty coal is FAR cleaner than a purely gasoline energy path in terms of emissions (except for sulfur oxides, but those can be dealt with at the source). Anyone who says "electric cars just trade one fossil fuel for another" have no clue what they're talking about.

Share This Page