1st Gen R53 Cooper S Supercharged vs Turbo

:cornut: So...............for my little pea brain...............one needs multiple Turbo Chargers in series to equal a single(large I suppose) Super Charger or is it more complicated then that? This is very interesting to me, more more please.

Jason

 

I don't want to hear whoosh or whine! I just want it to go fast!
Quietly!

Dave

 

^^^ pea brain? Hardly? I've learned a lot on MA. .. And have a long way to go to catch up with most of the true hands-on experts here.

Actually a fixed geometry supercharger has an optimum efficiency at one speed. Same with a turbo. If the supercharger is a roots blower type then options are somewhat limited. If it is a screw compressor then its possible to use a slide valve to vary the volume ratio over a range of speeds. True the supercharger doesn't suffer lag like a turbo. A supercharger can be thought of as proactive. A turbo is more reactive. Thus the lag... A turbo with variable inlet vanes could be designed to spool up fast and yet have more than sufficient volume so it doesn't choke at high flow. It's doable but can get a bit complicated (read that as expensive).

On a supercharger arrangement, the engine must overcome the mechanical losses of the compressor. The crankshaft "sees" the compressor load. On a turbocharger arrangement, the compressor and turbine are not mechanically connected to the engine crankshaft, so the engine does not see that load. Whew .....

 

^^^Great information. SCs don't have to have parasitic losses. The one that use to on the Thunderbird had a bypass system that allowed the intake air to go around the SC. This relieved the the pressure and dropped the power consumption. I think there was even a test version that had a clutch on the pulley (like in Mad Max).

The only problem with all of it is cost. Turbos are cheaper that is why there used more than SCs. Too bad.

 

:cornut: Thanks Paul(I'm Jason Paul by the way). So what about 'twin Scroll' turbo (that MINI loudly proclaimed on 07-09 R56) and 'over boost'(taking high rpm torque from 172 to 192 ft/lbs)? Did this level the playing field any or was it MINI hype?

Jason

Great Article @.................modified.com/tech/modp-0906-twin-scroll-turbo-system..........(answered my own question)

 

Mostly MINI hype.... But the "twin scroll" is a way to introduce turbine inlet flow more efficiently...to reduce lag. The link below shows the twin scroll on the left in the photo. Compressor section on the right.

http://en.m.wikipedia.org/wiki/Turbocharger

 

:cornut: After several hours of researching this subject( superchargers vs turbochargers/superchargers all kinds/turbochargers all kinds/exhaust manifolds all kinds/economy/street/racing) at a large number of Professional Sites and not wanting to start a 'Fist Fight', I'll just say; choose the one you want, stick with it, and never listen to the 'other side.' I will leave the opinion and address of 2 of the sites.

1. 88total.com/techpagesupervsturbo
Max Performance: Turbochargers prevail over Superchargers. With speeds as high as 150krpm, boost levels near 30psi, new light weight designs, they are capable or producing more power than Superchargers.
2. automotivearticles.com/supercharger vs turbocharger
...............the Turbocharger reigns supreme in terms of engine power output.

Whew!
Jason

 

^^ that is excellent advise. Buy what you like.... It's all good....

 

:cornut: Thanks Paul.

Jason

 

I think that's the real answer in a nutshell, and having owned both, I would rate my current R53 as vastly superior to my previous R56. I also currently have an R60, so I feel the difference every day. No contest.

But, like beauty, "feel" is in the eye of the beholder, so pick what you like.

 

Umm........think you may have forgot.......Top Fuelers.......:biggrin5:


From Wiki:

Superchargers
The supercharger can be a 14-71 type Roots blower although Screw blowers are also sometimes used. It has twisted lobes and is driven by a toothed belt. The supercharger is slightly offset to the rear to provide an even distribution of air. Absolute manifold pressure is usually 3.8-4.5 bar (56-66 PSI), but up to 5.0 bar (74 PSI) is possible. The manifold is fitted with a 200 psi burst plate. Air is fed to the compressor from throttle butterflies with a maximum area of 65 sq. in. At maximum pressure, it takes approximately 900 horsepower (670 kW) to drive the supercharger.

The calculated Power output of these engines is most likely somewhere between 8500 and 10,000 horsepower[citation needed] (approximately 4500-6000 kilowatts), which is about twice as powerful as the engines installed on modern Diesel locomotives, and approaches the power output of the largest aviation turboprop engines, with a torque output of approximately 6000 lbf·ft (8135 N·m) and a brake mean effective pressure of 80–100 bar (8.0-10 MPa).

For the purposes of comparison, a 2009 SSC Ultimate Aero TT, the world's most powerful production automobile, produces 1,287 hp (960 kW) of power and 1112 lbf·ft (1508 N·m) of torque.
[edit]


:crazy:

 

Actually I know a few top fuelers that run turbos for a different reason. Remember that the supercharger also requires shaft power to actually drive the compressor. The engine crankshaft "sees" the HP gain but also sees the supercharger mechanical parasitic losses too. So for example to get 250 Hp to the rubber, the actual engine output might be 270 Hp... (Assuming 20 Hp to drive the SC). A turbo is not mechanically connected to the crankshaft .. So it's losses are not seen by the engine.

A turbo system does not burden the engine...a supercharger does.

Again... Both systems can be made to work very well...It's all a matter of design preferences.

 

Oh I know Top Fuelers really can't compare to anything.......if you notice, it takes around 900hp to drive the TF SC :eek6: :crazy:

 

I saw a dragster that had a bunch of scuba tanks to supply compressed air to the engine. They must have had a monster regulator on them!

Hey, it only had to go 1/4 mile!

Dave

 

Toro's racin blower does not burden the engine....

 

^^^ Sweet!

 

I guy I know with a drag car uses a water cooled intercooler... in the seat next to the driver is a large stainless steel tank of ice and water. He pumps ice water through the intercooler to sub cool the intake air into his turbo car. The turbo air intake is at least 5 inches in diameter. To get the chilled water as cold as possible, he adds salt like in an old ice cream maker.

 

^^^^^ why not just add a Snoopy Sno Cone Machine.
It would cool the air for the motor and provide a refreshing treat for the driver.:lol::lol::lol:

 

Nope, I don't think that's the reason. Superchargers are not as fuel-efficient as turbochargers. As others have said, a supercharger draws crankshaft power to run it, whereas a turbocharger uses exhaust gas energy which would otherwise be used to make noise. The turbocharger still takes some energy from the engine in the form of exhaust back pressure, but it's a small proportion.

Some of the 1930s supercharged cars had two levers under the dash, one to clutch in the supercharger and another to open the exhaust valve that dumped the exhaust out the side before the silencer and tail pipe. I once followed an open top one being driven enthusiastically on the two-lane public road and the driver's overtaking technique was to reach down and move the levers to get power to overtake - plus the rise in noise level meant that most other drivers just pulled over anyway!

I don't think top fuel cars are a valid comparison since any turbo lag would be much more damaging for them than the small gain in top end power from a turbocharger - they might be a good application for the combined turbo/supercharger engines like VW make, but I suspect the complexity would prevent them being rebuilt fast enough for drag use.