Turbocharger vs Supercharger

Discussion in 'Community' started by MrCommunistGen, Mar 14, 2004.

  1. MrCommunistGen macrumors regular

    MrCommunistGen

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    #1
    Was just looking at some sweet cars online and realized that I don't know the difference (if there is one) between a turbocharger and a supercharger. Can anyone tell me the difference?

    -MCG
     
  2. eyelikeart Moderator emeritus

    eyelikeart

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    #2
    They both essentially do the same thing, but are powered differently.

    A supercharger uses a belt connected directly to the motor, while a turbocharger gains power from the exhaust stream.

    This should help u out some. ;)
     
  3. Josh macrumors 68000

    Josh

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    #3
    Thats basicaly it.

    Except their uses are a bit different as well.

    A supercharger delivers an increased power boost throughout the entire RPM range, and due to a lack in low-end power, it is best suited for V6's and above.

    Turbo chargers build pressure/spool up and boost their engine at high RPM's later in the range. Because i4's are very torquey and have a lot of power down low, you will use a turbo charger on a 4-banger.
     
  4. evoluzione macrumors 68010

    evoluzione

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    #4
    in addition, a turbo delivers more oomph, so you feel the benefit more, (unless you have a low pressure turbo that is) but it is only in a certain rev range, as mentioned a supercharger is across the band delivered a more, say, refined increase in speed. the turbo uses exhaust gases to spin a turbine, after the engine (obviously) whereas a supercharger (or Kompressor if you have a Merc) compresses air which is good for ignition, the colder and more dense, the better. :)

    personally i prefer the kick of a turbo cutting in, way more fun. :p


    oh, and they're not solely used on 4 pots, suzuki had a tiny car, the cappuccino, which i believe was an 800cc (yes, 0.8 of a litre) V8 twin turbo. how mad? :cool:
     
  5. Opteron macrumors 6502

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    #5
    Background, it didn't take engineers long to figure out that if you force more air into a clyinder, you'll get more power. And that's all Super and Turbo Charges do Force more air into the engine.

    Firstley Superchargers, there are several different designs, these include the Lysholm compressor (used in the Eunos 800,) positive displacement, Centtrifugal compressors. The Rotary motor also was initally designed as a supercharger. That aside, Supercharges are attached to the crankshaft of the engine, thus provide Instant boost with no lag. This is why the top end dragsters use very very large supercharges.
    Since a super charge isn't subject to the high tempreatures of a turbo, intercooling is not nessary.
    The other advantage of a supercharger is that there is never any "serge" between gear changes out when slowing down. because the compressor is directly linked to the motor.
    Supercharges for general road use tend to operate at lower boost levels then turbos because the are tends to be cooler, thus more dense.

    [​IMG]
    (It's that thing sitting on top)

    Now Turbocharges
    this is where the street machine is heading. Powered by the engine's exhaust gasses this is a very fuel efficient way of increasing engine preformace.
    [​IMG]
    This is basically how it works, but to prevent turbo surge, blow-off valves are added, and to control boost external wastegates are used. Also due to the extreme tempretures intercooling is a must.
    One of the major draw backs to turbo's is the lag time, this is the time between when you put your foot down and the turbo spools up enough to create enouh boost to make a difference. While this time i very small (<1 seconds) in a racing environment this can be a major problems. This problem has been redused over the years, and in some cases been elimated (WRC.)
    [​IMG](this is an image of the air flow of the turbo intake.)

    Today turbocharging is becoming more and more popular, because in normal city driving where the engine opperates at low RPM the turbo doesn't produce much boost thus fuel economy is execelent, however when you put your foot down, you can feel the power. (Also that crazy Blow-off valve sound.)

    Remember doing any forced induction modifactions will mean higher clyinder pressures and higher over all engine tempreatures. Thus upgrading the pistions, conrods, valves, camshaft's, head gasket, etc is a must if you expect you engine to last.

    [​IMG] (The power of turbocharging is now all over motor sport, especially the WRC, this is a cleica Gt4 ST-205, from a few years back. THe WRC cars run up to 30PSI (2bar) of boost, while indy cars have a max avaliable bboost pressure of 45PSI. Most new road cars with turbos run arround 6-8PSI of boost just to give you an idea.
     
  6. Opteron macrumors 6502

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    #6
    P.S: (sorry for the large post)

    Finally with expected power gains for a steet going car
    with N.A engines ~75kW/L is the max avaliabe (piston engine)
    With turbo charging ~100-160kW/L can be expected with reasonable engine life. Note to reach above 150kW/L mark substancial modifications must be made.
    Similar gains can be expected for Supercharging, but with ingeneral highr fuel consumption.
     
  7. JamesDPS macrumors regular

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    #7
    Opteron: nice posts! I thought I had a good understanding of the differences, but you explain them very accurately and concisely -- so much clearer now! (and, yes, i LOVE the sound of the blow off valve...:D)
     
  8. briankonar macrumors regular

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    #8
    so if you were going slow in a jeep (rock crawling for instance) a turbo would never kick in right? it would only kick in on street driving (say starting from a stop sign)? I got my sister's Jeep when she moved to california (4 cylinder automatic :eek: ) and i'm contemplating either selling it for a manual sport, or putting some money into making it a little faster (acceleration is embarassingly slow). i offroad alot though, so i wouldn't want to f**k the grip (it has excellent torque).
     
  9. russed macrumors 68000

    russed

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    #9
    that is basically correct, turbos only kick in at a certain rpm. can you immagine if you were rock crawling and then you tapped the accelerator slightly and then all of a sudden in kicks the turbo and you fly off the rock! the reason is the same for most modern rally cars, it offers them more control at lower rpm yet they can have the power on the straights or under heavy acceleration.

    with regards to you doing work on an engine of a jeep, why bother, they are not really meant to be fast, they weigh loads, save your money and buy a new apple! and then that would be money well spent.
     
  10. dragula53 macrumors regular

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    #10
    differences

    What the poster above said is true.

    superchargers are belt driven
    turbochargers are exhaust driven.

    turbos are good for higher exhaust flows and their power curve reflects a higher efficiency at higher rpms (more exhaust, more boost).

    superchargers are good for lower engine speeds, and their efficiency reflects lower efficiency at higher rpms (harder to spin a belt faster).

    nothing to do with engine size or anything. bigger engines push both equally better. larger displacement=more exhaust=more boost pressure. and more torque=less affected by load of supercharger.

    I personally prefer turbochargers, only because I can always dump the clutch a little harder if I need to haul some butt. not so with supercharger. you lose a lot of that upper rev range.

    just had to throw m .02 in there
     
  11. Powerbook G5 macrumors 68040

    Powerbook G5

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    #11
    I love turbos, they are a blast. Superchargers are okay, but since they are driven off the belt, they take power from the engine resulting in a loss of power and efficiency whereas a turbo relies on exhaust to spin up the turbo so you don't see that sort of loss. Granted, you have "lag", but it is hardly noticeable in most cases, and once the turbo kicks in, you will most definitely forget about it ;) My car has a modest SOHC I4 with 3 vales per cylinder, producing about 110 HP and 120 lb-ft of torque on the N/A version of the engine if I remember correctly. The turbo brings it up to 145 HP and 200 lb-ft of torque, so you can see the boost. Even though it only has 145 HP, it is a real beast around 3,000 RPM to 5600 RPM. I read Car and Driver specs of it from the 88-89 model year and they claimed about 6.8 secs to 60 and a top speed of 138. My engine has about 165,000 miles on it and I had it tested at Moroso and it hit 60 in 6.4 seconds and a top speed of 142. I'd say that's pretty good for such an old car with the original turbo and everything. For real kicks, it's great around town between 2nd-3rd and 3rd-4th gear changes, it sometimes literally launches with the front hopping up and can peal out all the way to the end of 4th gear before I shift to 5th if I really push the throttle and shift it just shy of redline. It's not good for the tires or the car in general, but every once in a while you are in need of some theropy. :D
     
  12. Nuc macrumors 6502a

    Nuc

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    #12
    Another thing to add.

    I don't know if this was covered, but if I'm not mistaken turbochargers are a little harder on the engine than a supercharger. So the engine won't last as long using a turbocharger.

    Check this site out, from what it seems this would be the best way to go. Navigate around and check out all of the cool things they have, my buddy has done research on these guys and it seems legitimate. Cost is a little high but hey talk about torque and horsepower.

    ENDYN

    Nuc
     
  13. Powerbook G5 macrumors 68040

    Powerbook G5

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    #13
    Both ways are hard on the engine because of the added pressure being put on it. Typically, with a car that comes stock with a turbo or supercharger, they add heavier springs, valves, cylinder walls, etc, and also lower the compression ratio to compensate for it.
     
  14. JesseJames macrumors 6502a

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    #14
    Aw heck. Just get a car with big cubic inches. The you won't have to worry about blowing your engine or lack of longevity.
    I'd love to have a new Pontiac GTO. Yeah it looks bland but when you crank it over. You'll smile every time.
     
  15. Powerbook G5 macrumors 68040

    Powerbook G5

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    #15
    How many big 5 liter V8s can claim upwards of 30 mpg when still delivering insane levels of acceleration and high speed spurts?
     
  16. dragula53 macrumors regular

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    Jun 23, 2003
    #16
    mileage

    2004 Corvette Z06

    405 hp
    29 mpg

    naturally aspirated


    gets better mileage than my 227 hp subaru impreza wrx.

    and from the factory, turbocharged engines generally come with lower compression and heavy duty parts to compensate for the extra pressure

    the site a few posts above is talking about taking a factory honda engine and throwing some sort of aftermarket forced induction into the picture.

    I tend to agree with the site... superchargers are a much easier aftermarket upgrade than a turbocharger.

    moo
     
  17. carbonmotion macrumors 6502a

    carbonmotion

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    #17
    The GTO is pretty freaking sweet.
     
  18. Powerbook G5 macrumors 68040

    Powerbook G5

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    #18
    I know, the GTO is pretty good. Isn't it based on the Australian Holden? Great how GM had to go to an Australian car to bring an American musclecar back. I know the Corvette can claim great gas mileage, but that is using the nasty "skip shift" method of skipping gears and running it relatively mild on the throttle. If you were to do a lot of high powered driving, I can guarantee you will not be seeing 30 mpg averages.
     
  19. synergy macrumors regular

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    #19
    You will see that with any car/engine regardless of turbo charged or not.
    But with the torque of the V8 in the Vette even at mild throttle you will feel the power.
    Alot of turbocharger engines with manual transmissions also are kept in the higher rev ranges in order to keep the turbo spooled and the engine in the optimum torque/HP range which will also lower you MPG averages.

    I was reading on some site about a hybrid sports car. The car was Italian I believe with a Toyota hybrid system in it. That would get better gas mileage in your everyday driving, but probaly drink like a hummer when pushed.
     
  20. Opteron macrumors 6502

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    #20
    If you were really rock crawling in "LOW RANGE" then the Engine would no doubt be reving quite hard, to produce the nessary toruqe. However I'm not to familliar with the Jeeps. I know this is the case with the Pajero, Partol, Land Cruser and other real 4WD's.
     
  21. Opteron macrumors 6502

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    #21
    Go Australia, pitty Holden still have to use the Backwards American PuchRod V8 in the car.

    However if you were talking about the 1998 Mitsubishi GTO then that would be a different matter. 3.0L Quad cam MIVEC, Twin turbo, 4WD.
     
  22. Opteron macrumors 6502

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    #22
    To PBG5,
    GTO: 300kW, 5.7L
    52.6kW/L

    BMW M5: 367kW, 5.0L
    73.4kW/L

    both cars are N.A
    GMC/GMH are to my knowlege the only company who still persist with dated pushrod 2valves per clyinder techknology. Evey one else hase moved to SOCH, or DOCH with 3valves (merc) or 4 valves (everybody else)

    Also as I stated before the great thing about turbos is that arround the city they arn't very active thus the car behaves as if it were N.A. But when you grab it by the neck it just grins and boots.

    Finally forced induction engines have compression ratios from 7.8-9:1
    and N.A engines can have anywhere form 8-12:1
    Any higher and detonation (engine knock) becomes a problem, and have very ill effects on the motor.
     
  23. Powerbook G5 macrumors 68040

    Powerbook G5

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    #23
    What point were you trying to make with those specs? I'm a bit confused, I hate to admit.
     
  24. Bigheadache macrumors 6502

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    #24
    I think Audi V8s are 5 valves per cyclinder now as well. (I think on the S4)

    Anyway Opteron, I am probably wrong but i heard that if you have more valves per cylinder you tradeoff torque and it changes the power curve to make it more peaky. To get around this you need to add variable valve timing (like on the BA falcon). Do you know if this is true?

    In reference to your comparison, what about Honda S2000 - its nearly 90kw/L!
     
  25. dragula53 macrumors regular

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    #25
    specs

    I dunno what why those specs were relevant either, however, I'll throw some out there too, just to be nitpicky.

    rx-7 1.3L 190KW, or 146.27 KW/L

    horsepower and efficiency has nothing to do with having camshafts. sorry.

    pushrod technology is very nearly the same age as overhead cam technology. I think maybe even newer.

    And the 'vette has a pushrod engine in it...

    NASCAR engines have pushrod engines.. 700 hp, naturally aspirated, pushrod. blah blah blah.

    I do like little 4 bangers with turbos.. but I don't find myself blinded by them.

    and for every good V8 that american auto makers make, they make 50 crappy v6 or I4's

    the are getting better though.

    Same thing with computers. I do like my macintosh. but not to the point that I hate microsoft. or think everything apple does is right or good.

    blah blah
     

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