Turbocharging – A transportation technology for ever higher FE

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

  1. phoebeisis

    phoebeisis Well-Known Member

    Re: Turbocharging – A transportation technology for ever higher FE

    rweatherford,
    I get your point-one TURBO 4 CYL CAR-a Saab 900 2 lt--matched the FE of a normally aspirated 4 cyl Saab 900 2.3-corrected 1995 # 18-26.It certainly made more power,and it accelerated faster.Yes,I know it is "cheating" to compare it to a 2008 6 cyl Accord 21-29(AT), but I just can't resist.
    Why,why aren't there any FE specific spark ignition cars out there?Heck,the Euros have been paying 2X-3X what we pay for gasoline; if it was "easy" it would have been done.
    Yeah,the "it would have been done already if it is easy" is a CS argument, but there it is.
    The biggest "problem" is that the 4 cyl NA motors have gotten soooo good.They can use pretty high compression with small, compact ,efficient CC's and variable valve timing to get good mpg at low loads,and if you need more power-just dial up the RPMs,and the same tech-VVT etc-gives you all the power you need without the detonation that has always limited Turbos.The turbo has to dial up the fuel air ration,and dial back the timing-hurting FE to get the power.All the while that turbo is sitting there plugging up the exhaust flow(hurting FE at low loads which is where we use cars 95% of the time).
    Yes,you would certainly think you could just make the turbo 4 cyl small enough-1 liter vs 2 liter-to make it a FE winner.It does use all that almost free energy(7 hp used/lost per 100 hp produced is what I have read), it "should" work.
    We might never see this tiny turbo spark ignition motor.What would be the point; it would be as costly as a TDI,and not as efficient in any respect.
    My guess is we won't ever see the TINY spark motor turbo because the small TDI just makes a lot more sense ,since it is "better" in every way and TDIs diesels don't have much of a detonation problem.The spark motor might have a tiny weight advantage over the TDI, but not enough to matter.
    The exhaust energy will be used for something else in gasoline engines-make electricity, or to pressurize a tank for initial city accel.
    Charlie
     
  2. xcel

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

    Hi Charlie:

    ___The reason I see the small-turbo possibly coming to the US is because the auto makers have yet to figure out how to get the Diesel emissions down to meet Tier II/Bin 5 without all the expensive add-on’s. The turbo’s are not that expensive but the injectors for the 2,000 BAR common rails are as expensive as the engines itself (consumer prices)! What a BMW rep told me a few weeks ago is the Diesel engine itself has a 30% premium over and above the gasoline engine (engine only) not including the emissions control equipment. The last time I had heard what an engine cost was a few years ago when somebody told me Mazda was supplying Ford with the 2.3 in the Ranger for $1,200. I could not confirm that price however. Who wouldn’t take a turbo-charged super-diesel for a $500 upcharge (< $2K for the engine itself) vs. the $6 - 10K garbage the Big 3 are charging for the PowerStrokes, Duramax’s and Cummins units in the HD trucks. Just throwing other info out there …

    ___If the emissions control stuff can be worked out for a reasonable price, I do not see why we would not all be driving diesels, diesel hybrids and diesel PHEV’s other than the fact the fuel costs more than gasoline through ~ 75% of the year even though is costs less to refine :confused:

    ___Good Luck

    ___Wayne
     
  3. koreberg

    koreberg Junior Member

    The 1995 eclipse gst with a turbo 2.0 liter gets higher city, higher combined and lower highway than the 1995 eclipse gs with a na 2.0 liter engine.

    The gsx of course gets about 3mpg lower because of awd.

    Engine displacement doesn't tell the whole story. Although a 6.2 liter engine sounds much larger compared to a 5.4, because ibc engines typically only have 2 valves per cylinder instead of 4 per cylinder in a dohc they need larger piston surface area to allow for the same intake valve area. Its just a different way of doing the same thing. Because fuel/air mixtures have to be pretty much the same, larger displacement does not always mean more fuel usage. Of course the higher lowend torque of a ibc engine allows for the fuel sipping (if you can say that of a 6 Liter engine) 70mph at 1000rpm.
     
  4. phoebeisis

    phoebeisis Well-Known Member

    Re: Turbocharging – A transportation technology for ever higher FE

    Koreberg,
    I kinda' liked the Eclipse,but once again it doesn't "beat" the NA version.It was a sporty sort of car,so the turbo version was't tuned for fe.There is something to be said for bigger disp motors turning very slowly.If they were given enough FLYWHEEL they could turn just 800 RPMS at 65mph with fully opened throttle plate. Unfortunately they don't have heavy flywheels,and they want quick acceleration,so most big V-8s turn about 2000 RPMs at 65,and the throttle plate isn't half opened.
    Wayne,
    The $1200 for the 4 cyl sounds dead on.Right now you can buy a new GM 5.7-for 96-99 GMs for $2200 delivered! This is a retail delivered price from a online dealer.It is a NEW Goodwrench-motor, not rebuilt-,so GMs actual cost must be under $1500.$1200 for a much smaller motor sounds about right.Wow--$500-for a 25% improvement in FE-hey sign me up! The average 12,000 mile per year 20mpg person would make up the $500 in one year!
    Yes,the Big three minted $$ with that $5000+ markup(actually much more because they wouldn't discount the TDis the way they would the spark motored vehicles)on their TDIs.Worse yet,the motors are literally 2X the power and size that they actually need.Adequate power-175 hp -and enough gearing is all a work truck would need to tow 12,000 lbs,and the vast majority of 3/4 and 1 tons tow heavy maybe 1% of the time.
    GMs plan to use a 1000 cc Turboed spark motor as the generator in the Volt is a good indicator that turbo spark motors can save gasoline-but they aren't doing it yet.
    Thanks,
    Charlie
    PS I would love to get my hands on one of GMs "generators".Heck,I could use it to drive a DIY electric motored plug in Suburban.It could get by with maybe 1000 lbs of batteries instead of 3000 lbs.I'm guessing it puts out maybe 60 hp-40 kilo watts maybe?Might get the equivalent of 25 mpg in the city on the gasoline generator,and maybe 50 mpg on plug in power(maybe 10 mile plug in range with cheap heavy lead batteries)I do lots of under 10 mile trips.
     
    Last edited: Jan 28, 2008
  5. ILAveo

    ILAveo Well-Known Member

    Re: Turbocharging – A transportation technology for ever higher FE

    I'd estimate that you'd want ballpark of 225 hp (though I prefer torque measurements) with reasonable gearing. The 6 cyl F150 (202hp) at work won't quite hack pulling our 12,000lb skidloader and trailer around safely.

    Your point is good though.

    I've thought about series hybrids too--the big advantage is that you could design the engine to only run at its maximum efficiency and use the battery to provide extra power at peak loads instead of using a throttle, turbo, or activating more cylinders (or whatever).

    The generators I've used in the ballpark of 40kW have been largish, diesel, trailer mounted units---you'd probably have to tow them for your DIY series hybrid, and they use around 1 gallon/hour of fuel. A better bet for component size might be a 12.5 kW RV generator, but I'm just dreaming here; the price (~$10K) is too rich for my blood.
     
  6. rweatherford

    rweatherford Times my Mileage by Six

    If 330 HP is enough for 80,000 lbs......?
     
  7. seftonm

    seftonm Veteran Staff Member

    Re: Turbocharging – A transportation technology for ever higher FE

    A close comparison between a small turbo and bigger NA engine can be found in the old VW 1.8T and VR6.

    2001 5-speed GTI:
    150hp 1.8T: 22/28 mpg
    174hp 2.8 VR6: 18/26 mpg

    2002 5-speed GTI:
    180hp 1.8T: 21/28 mpg
    200hp 2.8 VR6: 18/26 mpg

    The new 2.0T is more efficient and more powerful with direct injection, but there is no longer a similar powered NA engine to compare it to.
     
  8. koreberg

    koreberg Junior Member

    I believe the engine in the r32 is the replacement for the vr6.
     
  9. Shrek

    Shrek Kaizen Driver

    Re: Turbocharging – A transportation technology for ever higher FE

    Maybe the VW 1.4 litre engine with both turbo and compressor

    (http://www.vwvortex.com/cgi-bin/artman/exec/view.cgi?archive=7&num=1496&printer=1)

    is an example of turbo used for FE. VW is notorious not wanting to give up performance to increase mileage, and this is what they came up with a while ago.

    I don't remember the FE of these engines/cars, but if you compare against conventional petrol engines with comparable HP, I guess this turboengine is more economic.
     
  10. phoebeisis

    phoebeisis Well-Known Member

    Shrek,
    Wow,that is a typical German tour de force of engineering.Kompressorvorgelage??-I love that language-don't use 3 words when one huge one will do.Still,the 48 mpg in what I think is their hy loop is awfully good.This certainly "proves" the "turbocharging(with a touch of belt supercharging) can improve FE" that the thread started with.I'm not sure who could afford it, but it would get the same FE ( with a little less low rpm performance)with the belt supercharger I think.
    ILAveo, I suspect that the F-150 sure isn't geared(or suspended or braked) to tow 12000 lbs-it is probably rated to tow maybe 5000 lbs? Watch the History Channel or WW2 movies.All those Army Trucks-all up weights of maybe 15000 lbs-probably don't make 100 hp(probably NA gasoline engines),and they managed to move lots of cargo long distances on crummy roads.It doesn't take much HP to move 15000 lbs at 55 mph even with aero coef close to one.Current vehicles are much more aerodynamic.With enough gearing 175 hp from a 2-3 liter TDI would do it.I like straight sixes for TDIs(no counterbalancers), but a 4 would probably be more FE.The Cummins could get by with less bore and less stroke if it only had to make 175 hp.
    I'm just guessing that the 1000 cc Turbo that drives GMs Volt Generator would be about 40 KW-60 hp-since I think the Volt might need about 60 hp to hold 85mph on a level Highway.Maybe this is an overestimate??
    The 3.5 kw generator sitting under kitchen table has a 5.5 hp ohv motor and is supposed to use .3 gal hr while putting out 1.5 kwatts(2 hp worth of electricity).If GM used it, sized up to make 60 hp it would use 30x the gasoline-9 gallons per hour to make 85mph(9 mpg).30 of them would weigh 3000 lbs-about what your Diesel gen weighs.
    I'm guessing that GM's 1000 cc spark turbo would make 60 hp(my guess) at maybe 4000 rpms with 7.5 lbs of boost? The motor itself-with radiator turbo,exhaust plumbing-should be under 200 lbs-maybe less.
    Thanks,
    Charlie
     
  11. rweatherford

    rweatherford Times my Mileage by Six

    Industrial engines are WAY overbuilt. The old Cummins in the Dodge trucks had several HP ratings. 160, 180, intercooled, non-intercooled, 5-speed, 6 speed, automatic, automatic w/OD. The engine alone is 1000 lbs.

    Any of these configurations will pull 15000 lbs with no problems as long as you aren't trying to maintain 80 MPH up hill. 60 MPH is about right. The problem with 3/4 - 1 ton pickups is the drivetrain can't handle the TQ produced at low RPM that these engines are capable of creating. For that reason Cummins redesigned the B-series for the Dodge truck to be lighter and higher revving so that they could "match" the HP ratings of other manufacturers ( HP ratings seem to sell cars and trucks) and keep the TQ numbers near the 600 ft-lb range as to not destroy the rest of the truck.

    The fact is that in top gear the old trucks will match the performance (towing power and MPG) of the newer trucks. However if you want to get in a race then the newer higher HP trucks win due to being able to rev to 3000 + RPM. (stock trucks)

    We have 7 Dodge Cummins trucks ranging from 1994-2006. Several of the older ones have been turned up a bit and you can't get even a modified transmission to always hold the TQ available with 35 PSI of boost at about 1500 RPM. There is almost never a need to downshift unless you HAVE to go faster, or the tranny won't hold.

    Most of these trucks will maintain 10 MPG in top gear at full load. Anything less than full load just raises the MPG. Empty on the highway at 60 MPH it is not unusual to maintain above 20 MPG. That is a 4x4 @ 7000+ lbs.


    BTW the old army trucks had industrial 6-cyl gas engines. Sourced from several companies. They were dogs, but could pull anything slow.
     
  12. ILAveo

    ILAveo Well-Known Member

    Re: Turbocharging – A transportation technology for ever higher FE

    By safely pulling the skid loader with the F150 6 cyl I mean you can't merge safely on the freeway unless you have a downhill (or extra long) ramp--not always a choice when you don't know the roads you're traveling and you have to cross big rivers. If they dropped the speed limits down to, say, 35, no problem (or maybe gave the F150 a ton of gears). In reality we just use a bigger truck.

    Work just realized that I'm supposed to have a DOT physical card (but not CDL:confused:) to pull that size of trailer, so I probably won't have to worry about it until after my next physical.:)
     
  13. rweatherford

    rweatherford Times my Mileage by Six

    Re: Turbocharging – A transportation technology for ever higher FE

    Just FYI the DOT physical card is no biggie and takes about 30 - 60 minutes at the doctor's office if you have to wait.
     
  14. BostonDriver

    BostonDriver New Member

    Wouldn't the added torque help a lot for hypermiling also? I bet even if you factored in the higher cost of diesel right now in the US, the higher mpg of the turbo diesels would off set the difference. Throw in the lower emissions and it becomes a no brainer. Why do we in the US have to suffer from a lack of choice of fine vehicles compared with the rest of the world? It also kills me that US carmakers have yet to produce anything that can even remotely compete with the Prius. Where has American pride gone?
     
  15. rweatherford

    rweatherford Times my Mileage by Six

    Everyone was so hung up on high HP coupes and trucks they are lost. There were obviously no plans to compete seriously with small cars. I'll admit I was as guilty, but as a consumer I can change my plans instantly and purchase something else if available from another manufacturer, which is what I did. Their loss, my gain.
     
  16. xcel

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

    Hi BostonDriver:

    ___Added torque would indeed help FE but, the RPM’s and boost where the diesel is putting out its best FE is so low that I really doubt the turbo is getting involved let alone is much torque needed in the realms that most hypermilers are driving. Sort of the like the electronics of the hybrid getting in the way (they all do unfortunately) for maximum FE. The turbo does as well with its cooling requirements and such but overall, the two technologies are really close.

    ___Read the CleanMPG reviews the 2007 Honda Civic 2.2L iCDTi Turbo Diesel and pay attention to where the RPM’s were for the big FE numbers. Yes the diesel will beat a hybrid in both the performance (unless it’s a performance hybrid) and FE realms but when loaded up and in near normal driving conditions, the differentials are so close, the diesel cannot make it up due to the Fuel costs.

    ___Another for you to read … See the 1908 Centennial Reenactment of the Greatest Automobile Race-II write-up in which the Civic iCDTi went head to head with the Prius-II. For the crossing, the 2007 iCDTi was on top by just 1.2 mpg vs. the lean-burn capable 2005 HCH-I, 3.93 mpg vs. the 2007 Prius-II and 4.39 mpg vs. the 2008 HCH-II. Although the Civic iCDTi diesel was shod with snow tires, it probably only hampered its FE by maybe 1.5 mpg overall as a guess? The Diesel could walk away from the Hybrids in a performance match including top speed, acceleration and handling but only the handling is something anyone should really be concerned with as well as the FE differentials.

    ___Yet another … During the week I was fortunate to drive Cheryl Appel’s Prius-II, it allowed a 76.5 mpg over 1,600 miles of back and forth to work. During the week I was allowed to drive the iCDTi over the same back and forth to work roads and in similar warm conditions, it allowed 85.5 mpg over 1,760 miles.

    ___Ok, so what does this all mean? What a turbo can do for all of us is give a much smaller but hopelessly underpowered engine the performance to meet the average buyers needs from an acceleration standpoint. All the while when cruising down the highway, the small engine easily outputs enough HP (most non-towing vehicles take < 25 hp to hold 55 + mph) to maintain 55 mph yet we receive tremendous FE while doing so.

    ___Good Luck

    ___Wayne
     

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