Super charged vs. standard engine?

As with a turbocharged car that extra power isn't free. It does come at the cost of much lower mpg and higher engine wear if you have to be the first across the intersection all the time. But those generalizations apply to a normally aspirated engine too. OTOH if you drive like most other drivers and stay with the flow of traffic I don't think you will notice a big difference in milage and added engine wear will be negligible.

A supercharger, like a turbocharger will eventually wear out and have to be replaced. But you can say that about several other automotive accessories too. So if you need (or want) the extra power that comes from a supercharger then go for it.

Both of my cars have turbochargers, and I find the the added power to be very helpful at times. I would drive both the standard and supercharged version of the Cooper and base a decision on what seems to work the best for you and whether it is worth thre extra $$. The supercharger probably comes as a part of a package, so you will be getting (and paying for) several other goodies as well.

The Cooper is a very attractive car in either configuration imho.

Thanks for your insight. I gather from your remarks that having a super charged engine does not add any significant maintenance factor or should I say reliability problems over a standard engine.

I will test drive both versions when I get an opportunity but just wanted a heads up from the technical group and not rely on dealer sales staff.

-Larry

in article snipped-for-privacy@z14g2000cwz.googlegroups.com, John S. at snipped-for-privacy@cs.com wrote on 7/19/05 12:27 PM:

really enjoyed my 96 Pontiac Bonne V6 traded it at 120K miles and it was still running like new very strong - lots of torque admit that I sold it before the supercharger failed fearing the $2k repair cost I believe it was an Eaton s.c. in it. Pretty neat, a low profile screw type air pump.

With any kind of forced induction, bearings going south are probably the most common failure. They can go bad prematurely if they overheat and/or there's oil contamination/wear/starvation.

Pay attention to engine oil. Oil lubricates and (partially) cools the bearings. Regular changes using a high quality oil should reduce the chance of oil related failure, such as blocked oil passages, corrosion, abrasive, etc.

I believe Mini only recommends high performance synthetic oils.

Replacing a worn supercharger is probably less than rebuilding an engine. Even so - most of the newer ones are supposed to be more reliable than in years past; most newer superchargers are also water cooled which reduces bearing overheating. Take good care of it with regular oil changes, and it'll take good care of you.

Have fun.

You are welcome. Those Coopers just look like they would be a lot of fun to drive. I took an Austin Mini from London to Penzance and return once, and it was a blast. The sensation of speed was amplified in that tiny car that was just inches off the ground.

As long as you keep the maintenance up you should not have any problems, but that goes for any engine.

A supercharger or turbocharger does essentially the same thing and both result in more power for the car without changing the physical size of the powerplant much. At one time both type of compressor had reliability and performance problems, but those days are way behind now. Both are reliable accessories.

As someone else noted the turbo runs in engine oil, so just be perform regular oil changes and use synthetic. I've always changed oil every

3,000 to 3,500 miles no matter the car, and I've used synthetic in my cars since 1996. I see the difference at 200,000 miles when the engine still runs smoothly, gets good milage and when you look down into the oil gallery there is no evidence of sludging. Frequent oil changes are a cheap alternative to a prematurely wornout engine.

A supercharged car can actually save a bit of gas in normal driving. An engine is not efficient at low throttle settings. In fact, it would be most efficient at wide open if it were not for power enrichment programming to aid drivability.

If we have two engines, one with large displacement giving a certain horsepower, and another that is smaller, but turbocharged, then in normal driving at partial power- say ordinary street driving, the turbocharged car is running at a higher percentage of throttle, and hence a little more efficient.

This is the same rationale that makes hybrids so efficient. Use a small engine and run it at a higher percentage of its power capability. Also, especially in a series hybrid, the IC engine does not need power enrichment because the electric motor does not create drivability problems.

I thought a supercharger was demand based, i.e. not running at light throttle openings

Efficient as measured by mpg?

A mini is a car to buy because you love the great style and/or go-cart like handling. Buy it because you are passionate about it.

Um, cuz' last I checked the reliability for mini coopers did not have great relatively. Both S and regular.

Brian- Thanks for the URLs they provided some interesting reading. I have got to make a call into the dealer in Scottsdale and set up an appointment for test driving. Not too many dealers in the state of Arizona and probably not a buyers market:-)

-Larry

w on so any technical advice would be appreciated.

Synthetic is not needed to get long life out of a turbo. I had a Dodge Omni GLH turbo. I sold the car with 153k miles on it without touching the turbo. I used whatever brand name oil was on sale and changed it every 3k miles. I also let the car idle for a minute or so before I shut it down. That the core was water cooled also helped.

---------------- Alex

No, that more accurately describes a turbocharger. Until you get enough exhaust gas flow, it is basically doing nothing. To get more exhaust gas flow, you need to step on the throtle some more.

----------------- Alex

I didn't think superchargers were running full time, but were brought into use by a clutch.

Not necessarily.

Centrifugal gear driven superchargers also had very little boost at low rpm. Positive displacement ones such as Roots and the GMC style gave boost at all rpm.

There were also some engine driven chargers that had a complicated drive mechanism that did respond to throttle position in terms of speed of charger. These were for street machines. I think there was a clutch that either kicked in, or speeded up the blower speed on higher throttle openings.

The old centrifugal McCullochs (later Paxton) used a variable ratio drive pulley.

nate

It is possible to do it that way, Mel Gibson's car in 'Mad Max' comes to mind, but most do not have a clutch. They are 'on' all the time.

------------ Alex

I call bullshit on that one, wasn't the "mad max" blower a GMC x-71 or similar? That would be a positive displacement (Rootes) type blower, if the drive were disengaged the engine wouldn't run at all unless some kind of bypass were provided.

Looks cool as heck on film though :)

nate

I think you are right, Nate. It was a GMC type, with Hollywood drive.

Useless trivia: Robbie Coltrane (Haggrid in the Harry Potter films) is a gearhead. He made a documentary out of buying a 1949 (?) Cadillac in California and driving it across the US to the port of New York to ship it to his home in the UK.

He also hosted an interesting miniseries called Robbie Coltrane's planes and automobiles. Each episode looked at a breakthrough in motive systems. The ones that I can recall are the gas turbine, the diesel engine, the two stroke engine, the V8, and the supercharger.

The episode on the supercharger looked at automotive racing in the 1920's and aeroengines of WWII. Both of these situations involved competition between the british and the germans.

Daimler-Benz introduced supercharging to auto racing with an on-demand system that only began supplying boost near WOT. A british racer (whose name eludes me) got tired of being smoked for a couple of races and convinced his sponsor to pay for mounting a paxton blower on his bentley. The engine was not built up to take the strain of the boost, so he did not finish the next race. Score one for british pride, anyways, as the germans had to keep running their supercharger to keep up, and their engine failed first, allowing a normally aspirated bentley to take the win.

People say that all a supercharger does is cram more fuel/air mixture into the cylinder, but that is a very simplistic and inaccurate description, as it leaves important stuff out. What it does it make the engine behave like a larger displacement engine, with a higher ratio. So a 2 litre engine with an 8:1 compression ration, and 7 psi of boost, will behave as a 3 litre engine with a 12:1 compression ratio. Unfortunately, the similarity ends at top dead center. The 2 litre supercharged engine only expands the air charge by a factor of 8, not 12, so it is as if the exhaust valve of the larger, higher compression engine opened after the piston had only gone two thirds of the downward stroke. This explains why supercharging reduces the efficiency of an engine, as it increases the power. Turbocharging is more efficient than an accessory driven super charger, because it uses the power that is expelled out of the exhaust (by effectively openning the valve before BDC) to drive the compressor.