Supercharger vs. Turbo in Gas

[stevechumo]

Of course a supercharger system will burn more gas than a turbocharger system due to the power loss to the belt. However, does anyone have any info. on how much more gas a supercharger will burn than a turbocharger for a given same psi or horsepower output? Approximately what's the percentage and some examples, please? I heard it's about 20% more but I'm not sure if it's right.

For examples given the same hp & same car. With a turbo, a car will run the tank empty at 300 miles. And with a supercharger, a car will run the tank empty at 240 miles. Am I right or wrong?

 

[Blown SC]

Supercharger uses MORE fuel..I think NOT..

Highway cruising is same as NA...10ltrs to the 100k.

Around town..Same as NA..UNLESS you drive with good spirit..hehhehe (As do most)

You are Wrong in your example mate,,Sorry..

Also..No one runs 6psi with Turbo's !!

A Super Charger actually helps the use of all combustables that enter the cylinder.
In other words it make for more efficiancy than an NA engine..BUT..We slam the pedal more so it will consume more fuel..(Thats the Problem)
Owner/Driver is the fuel user..NOT the Engine... hahahahah

 

[Lextreme II]

Right foot is the key. Heavy right foot, more gas.. light right foot, less gas. Like Neil said, supercharger actually save gas. The engine have to work less because the charger is pumping air into the engine. However, with big injectors, increase fuel pressure, larger fuel pump and heavy right foot is where the gas drop very fast. Normal daily cruise would not make much different.

 

[stevechumo]

That makes sense. So how about the load & stress on the longer belt that has to run the supercharger? Those power are consumed in turning the supercharger and they're not free as in the case of turbocharger. I've seen a lot of reputable aftermarket manufacturers making lighter pulleys and claim them to increase horsepower, although it might affect the efficiency of the alternator...ect? Such as in the case of our electric fan vs. the hydraulic fan, and somones converted from hydraulic fan to electric fan to free up some horses. Please don't hesitate to give me any info.

 

[Murphy]

I have no numbers for you but I would like to say that turbos are far from "free" power. The extremely high exhaust back pressure ahead of the turbine (usually higher than the boost pressure) combined with the requirement for relatively low-overlap cams that this causes, costs a lot of power. Probably just as much is lost this way than is lost driving an efficient supercharger (i.e. NOT a Roots type!).

 

[Zuffen]

Light pulleys and undersized crank pulleys will save you a small amount of power.

The best I've seen is an smaller waterpump pulley only. This can give you a few hp as long as you know there is still sufficient cooling flow to work. This won't work on our engine as a change of pulley size has big implications on cam timing.

If you really want to gain horsepower AND save fuel take off the air conditioning compressor and throw out all the Luxo items in your car including the stereo. If you save 5hp with the air and truf 200kg of goodies it will go faster and when driven sensibly save gas.

 

[rarson]

Yeah both setups depend on how much boost you're running and how you drive the car. Since the SC will most likely be bypassing while cruising or idle, it's not really adding any extra load to the engine.

I prefer turbos because they are more efficient. However, seeing as how the 1UZ is a nice healthy V8 perfectly capable of spinning a big twin-screw, I'm very tempted to build an '03 Cobra killer.

 

[stevechumo]

To be honest, you all make sense and are very reasonable. However, I just read a very interesting article tonight in the DSport magazine, which is a modified sportscar magazines like Import Tuner, Turbo, SportCompact...etc. The article is about how much fuel is sufficient for a modified car. It gave an example of a car that makes 600 Hp at the wheels. And the fuel sufficiency needs to be calculated for the whole crank Hp due to other accessories, and not just the rwhp. As a result, it stated that a turbo car needs to be calculated for 750 hp of needed fuel and a supercharger car needs to be calculated for 857 hp, which is about 12.48% different. Their formula is this:

Turbo Fuel Sufficiency = rwhp/.8
Supercharger Fuel Sufficiency = rwhp/.7

I checked back with my books but they didn't mention much about the gas sufficiency between turbocharger & supercharger. Except there's only a small amount of parasitic drag of power that supercharger lost, and the backpressure of power that turbocharger lost.

 

[Lextreme II]

There are many kind of superchargers and turbos not to mention intercooling. Too many factors involved. The article must compare an apple to an apple.

 

[spf_lexus]

I am very close to bolting up my procharger and as all of us know its essentially a belt-driven turbo. The belt is where te loss will come from just like the excessive backpressure from a turbo. My question is how will the MPG on a centrifugal SC compare to a exhaust driven turbo MPG? I expect no changes in MPG in cruising/indle (possibly a slight increase) but it really doesnt make boost untill 2-3k. And no boost means no fuel added so driving across town "light foot" should see the same MPG as i have right now in N/A.



Also, steve thanks for bringing up MPG on these 2 FI systems but if i wanted to keep my stock fuel delivery would 6psi w/ NO FMU workor a centrifugal?

 

[Jake Breyck]

a neat test this would be. use the exact same car, bolt a turbo on it drive it a 1000 miles calculate mpg, take of the turbo and bolt on an SC, do the exact same drive, calculate, you can even compare diffrent SCs, the key would be to not change a thing, dont mess with the fuel sustem, tune or anything, parts can be upgraded to handle boost but not swapped out for diffrent parts wile changing the boosting device... anyone got a turbo setup and a few diffrent supercharger setups they will loan me for a few months ill do the test.

 

[stevechumo]

a neat test this would be. use the exact same car, bolt a turbo on it drive it a 1000 miles calculate mpg, take of the turbo and bolt on an SC, do the exact same drive, calculate, you can even compare diffrent SCs, the key would be to not change a thing, dont mess with the fuel sustem, tune or anything, parts can be upgraded to handle boost but not swapped out for diffrent parts wile changing the boosting device... anyone got a turbo setup and a few diffrent supercharger setups they will loan me for a few months ill do the test.

LOL...I have the same dream as you do...:approve: But that's what I read in several turbo and supercharger books. If you have the correct have the proper turbine housing and downpipe for the turbo, you'll eliminate the backpressure a lot. If you try to spin the supercharger by hand, it's not easy.

...Also, steve thanks for bringing up MPG on these 2 FI systems but if i wanted to keep my stock fuel delivery would 6psi w/ NO FMU workor a centrifugal?

I guarantee it'll work just fine up to 8 psi. You'll also need a Walbro 255 lph hi-pressure hi-flow fuel pump. A hi-flow fuel pump isn't enough. Before you run this, pour some Slick 50 fuel injector cleaner for a full tank. Drive untill it's empty. Do it a second time to make sure your injectors are clean. If you need help, come down to OC and meet us. :burnout:

 

[Spinall4]

for an apples to apples comparsion, I looked at the EPA fuel economy for some cars that offer both a S/C model and a non S/C model of the same motor.

Example number one: 2002 pontiac Grand Prix GTP vs GT (these have the same 3.8l motor).

GTP city: 16mpg GT city: 17mpg
GTP hwy: 25mpg GT hwy: 27mpg

you can go to this website to check http://www.fueleconomy.gov/feg/sbs.htm

Ford Lightning(sc)5.4 auto 2wd vs F150 5.4 auto 2wd

Lightning city: 11 mpg F150 city: 13mpg
Lightning hwy: 15 mpg F150 hwy: 18mpg

2004 Mini Cooper S (m/t) vs Mini Cooper (m/t)
cooper S city: 22mpg cooper 25mpg
cooper S hwy: 31mpg cooper 33mpg

I know these are all eaton s/c setups, but no oem uses a whipple style charger, and the aftermarket is full of disinformation (I've seen tons of arguments both ways, some saying that since the whipple is much more efficient it requires less fuel, some saying that because of higher internal gear multiplication that it requires more fuel) , I believe all of the setups I've shown also use a "bypass valve" that is supposed to improve fuel economy when the s/c is not being used.

 

[XR8tt]

This sort of debate could go on forever as there is too many variables..
What works fine on one system won't be ideal on another..
Wide lobe centres help turbo's !! It also helps fuel efficiancy to a point..
Cams with plenty of duration lets some induction through to exhaust and low rpm... Too many variables...