Question. Why would someone purchase a twin-turbo car over a Supercharger? I fully understand my choice, but I wanted to hear from the rest of this community what your preference would be and why.

Thank you.

 

The energy to spin a turbo comes from the exhaust gases and is essentially free. The energy to run a supercharger comes from the engine itself and therefore fuel. A supercharger will consume about 10%-15% of the engine's output. Even under light throttle there will be significant parasitic loss. A supercharger has the advantage of not having any "lag" but can never be as thermally efficient.
So, in theory, a turbo engine should get better gas mileage than a supercharged engine of the same power level.

 

I have owned both an SL600 V12 twin turbo, and an SL55 AMG supercharged V8. In doing do, I got to experience firsthand the so called achilels heel of both cars. The V12 have coilpacks that can wear out, they look like a long socket holder from your toolbox with a dozen sockets stuck on them. There's one on each side of the engine. Not the most difficult thing to remove and replace, but I was a shop tech working with engineers for a lot of years and have $40,000 in tools in my garage. So the average guy might not find it a bit of fun. Lifting the intercoolers outa the way holding them up with bungee cords suspended by the hood, makes the job easier so you don't have to completely remove those. Those coil packs cost a pretty penny though and there's a guy (one in the world that I know of) who rebuilds those. With any and all of these engines it's advised to use only the spark plugs outlined in the car's owner manual, with no deviation or substitute. Replacing those at or before 50K miles may reduce the chances of your coilpacks needing rebuild or replacement. Buying spark plugs directly from NGK on their own website, is best. The other "achilles heel" with twin turbos, is that they turbos have coolant lines of their own that are proprietary you have to get those from Mercedes, and one day those will surely begin to leak. Not that they're weak or bad, just that everything on earth, is gonna one day leak... Those coolant lines aren't cheap, to buy, or to have a shop replace them. Just something to expect one day, if you buy one of the V12s that have 15-20 years and 75-80K miles or more, on them. When my turbo coolant lines sprung a leak, the shop guys advised to get a new water pump and thermostat at the same time, since the car had 85K miles on it. Cheap insurance, you don't want to burn up this motor!! Right? Even so, these repairs should not deter you from buying one of the V12 R230s if that's what you want. The cars are excellent and incredible in my opinion and I'd not be afraid of owning one again. A friend of mine now owns my SL600 and he visits here every summer with the car, driving it about 1000 miles to get here. Loves the car completely. When I sold my SL600, I had sellers remorse so I bought an SL550, with the 400HP M273 engine, also a fine car, but after a year or so I missed those "extra" horses. Bought an SL55 AMG with the fabulous M113K supercharged V8. Fantastic car. Being AMG, has a little louder growl than the 600 which is more stately elegance, but also quite fast. The supercharged V8s have a dual belt pulley system one belt runs the supercharger. Getting one of these cars with 85K miles on it, you want to remove the belts and check all those pulleys. Mine had a water pump with the feel of loose gravel in the pulley, a sign of impending failure. The dual idler pulley I'm told costs around $700 from Mercedes and the crank pulley has a molded rubber piece between the 2 beltways that can deform after 15-20 years and 85K miles, from heat, etc., and that pulley also costs around $700 from Mercedes. You need to know that your belts and pulleys are in new/fine/excellent shape if you have one of these SC engines. I needed new water pump, both those pulleys, and whenever replacing a water pump always new thermostat as well, so that was the SC V8 version of the coolant lines on the V12. Really, just normal maintenance on parts that are going to wear out with age. Nothing to be scared of. For my somewhat aggressive (fast) driving style, I prefer the SL55 AMG, which I have now, and really love the car. Mine is the 2003 SL55 AMG the same model and year car that Motor Trend asked Mario Andretti to test drive for them on a track in Napa's wine country. He zoomed it at 208MPH got out of the car and said it was "awesome, awesome" and he loved it. The video of that episode was on Youtube but they removed it due to copyright issues in the US. But, using a TOR browser that masks your location, you could watch that video. They did 0-60, 100 to zero stops, slalom, etc, this was when the car was first introduced. The M113K engine is said to be the "best engine MBZ ever made", it has so much power and amazing amounts of torque, from idle. The AMG versions of these cars, have bigger wheel bearings, bigger/stronger rear subframe, a few other things that are made stronger than the non-AMG versions. Either one of these cars, would satisfy almost any driver, they drive like just about nothing else. Besides the engines, the R230s have the roof system and the ABC suspension system that make these cars a little more complicated than most other cars, but the R230 is such a fantastic car that I'd never ever want to be without one, as long as I live!
I think the SC V8 will have less maintenance needs coming up, than the V12, though.

 

When I had a coilpack go south on my V12, I removed it, sent to get rebuilt, then removed the other side and replaced all 24 spark plugs, then when the coilpack returned I put it all back together. Never looked into what a shop (indy or MBZ dealer) would have charged for that job. Certainly would have been an obscene amount. When I wanted new spark plugs (16) on my SL55, I also got new wires set, buying the correct parts shopping online. Parts cost about $400, I'm a pretty good shopper. Replaced all those parts, then called two MBZ dealers giving them the car's VIN, asking how much to replace all spark plugs and provide new wires. First dealer said, $3,950.00 plus tax"!! Second dealer quoted about $500 less. Ridiculous, nothing short of robbery. You need to know how to work on your own car. I'm sure that my indy shop guys would have done the job for around $700, still a lot of dough for something I could do myself.

 

Mrvedit....gas mileage is your argument? These cars are not known for being economical in miles per gallon. The point I was driving at is that the Supercharger is simpler than the turbo. The turbo goes south, and that's two fists full of cash to fix. On the other hand, when a supercharger goes south, you're talking about a third of the price to fix. I have driven both, and the puker factor is always greater than the turbo. Every time I got into the Supercharger, I always got excited, and that never fades away. At least that's my experience.

 

Is this a general question or in the context of the R230?

If a general question, there's a reason why turbocharging is widely favored by the automotive industry in everything from economy cars to exotics.

Less about gas mileage and more about efficiency in how the power is made. A turbocharger system effectively uses "waste" to make power, while a supercharger requires an "investment" to make a return.

In practice, superchargers can be great on larger engines, but fail to be effective or impressive with smaller ones.

In the context of the R230, I'd likely lean towards the supercharged M113K over the turbocharged M275...although both are exceptional engines.

 

Thanks to @tonylinc for taking time to write a great comparison between his SL600 and SL55.
As you detail, these cars are stupid expensive to maintain at a dealership. I bought my 2004 SL600 four years ago from a MB/BMW dealer with only 21,000 miles on it. The dealer replaced the expensive coils, spark plugs and batteries before selling it to me. Their "internal" invoice was about $4000. Fortunately I enjoy doing all work myself.

@Yankee_LT - I thought you question was just theoretical, not specific to MB models. I think most enthusiasts would prefer a supercharged car, especially because they sound so much better. Turbos act like an additional muffler.

 

I'm very sure that their internal cost is different from what they would charge a customer. New coils, plugs and batteries for a 600 would be way more then $4000. Coils cost about $2000 each. I bet the bill would be $10,000 for that at a MBZ dealer. I knew when removing and replacing my coilpacks, to take my time and not be in a hurry. I think I looked at a few videos of people doing the job first... Once I had the failed one off, I realized it was the best time to replace all the spark plugs and I was sure happy when it was all put back together and running beautifully.

 

I'll take "Large Displacement NA AMG Motors" Alex (for the Jeopardy fans) ;-)

Give me the M156 in the R230 over either of the other choices. Few things rival the sound of that motor as it approaches 7k. Maybe not quite the straight line speed of the V12, but way more than enough to put a huge grin on your face.

 

Yes, I'm limiting the topic to R230s.

 

I don’t have any data, but I suspect more supercharged engines(like you see at the racetrack) blow up their engines, than turbocharged.
Turbochargers are protected by wastegates, and are far enough away from the combustion to not be as dangerous.
Turbos are very reliable if oiled well, and treated well thermally, which includes rpm speed before and after peak demand.

 

If we are comparing the SL600 and the SL55, based on how fun each is to drive, put me down for team SL600. Don't get me wrong, I love them both, I am just partial to the massive torque of the 600. From an ownership standpoint, maintenance on the SL55 is quite a bit easier mainly because packaging a supercharger in the valley of a V engine is a simple design compared to a twin turbo V.

 

In my own experience the SL55 has more torque than my SL600, but it's been a few years since I drove the 600. Also, my 600 had (has) a Renntech tuned ECU, and my SL55 has some aftermarket pulley on it, I have no idea what it is. But my SL55, just the most incredible thing I have ever owned. If I won the Mega Millions, I'd probably be buying more of both these cars. but the first I'd look for would be an SL65 Black Series. LoL Of course, in that imaginary scenartio, money is no object. I have not really heard of the supercharged M113K engines blowing up. Have they?

 

All in all...The MBZ I have always wanted, except for the 300-SL Roadster, would be the SL55. I would opt for the '08 production year, although I hear that the '05 production run is pretty much bulletproof.

 

The 113k engines don’t have more torque, the power delivery of a positive displacement supercharger allows for immediate boost, as the turbo comes on later and not as quickly.

As for the turbo vs supercharger, the turbo is much more efficient and works much better on smaller displacement engines. Superchargers don’t work very well with small displacement engines, simply because they take lots of energy to operate.

You can make a very small displacement engine that meets fuel standards as well as cramming lots of air into it under full throttle with a turbo, not so much supercharged.


Daily driven I like the screw blowers for immediate satisfaction, the turbo cars are usually much faster, but the power delivery is not as instant.