RedlumF

I read in one thread here that the B9 S4 is rumored to have a biturbo V6.

Any thoughts on why Audi would move from supercharged to biturbo? Would the biturbo be necessarily better?

TIA.

éSe

More frugal, perhaps?

RickFLS4

I read in an older article that said Audi was thinking bi-turbo 4-cyl. in a much lighter car. I hope you are correct (and it is also lighter). The only reason for either would seem to be fuel economy. Seems to be the primary driver of change these days. Even the 4.0 twin turbo has cylinder on demand - a fairly complex solution to squeeze 5-10% (2 MPG?) more fuel economy out of cars people drive for reasons other than fuel conservation.

carguyrob

I wouldn't be terribly surprised if Audi goes this route due to CAFE requirements. The new Mercedes Benz CLA AMG is a 2.0 liter, turbocharged inline 4 cylinder engine putting out 355hp and 332lb-ft of torque. With a dual clutch transmission, they are estimating 4.5 seconds to 60mph.

http://www.mbusa.com/mercedes/benz/i...odel-CLA45_AMG

They claim this is the highest horsepower/liter engine for a production car anywhere in the world. Autoweek magazine also sees this as a S4 competitor.

m444

There is a nice article about the new MB CLA45 AMG in Autoweek. http://www.autoweek.com/article/2013...iews/130619854

"Drivetrain: transverse 2.0-liter turbocharged inline four, 355 hp @ 6,000 rpm, 332 lb-ft from 2,250 rpm; seven-speed dual-clutch automatic transaxleCurb Weight: 3,494 lbs
Performance: 0-60 mph, 4.5. sec; 155 mph top speed (manufacturer), 34.5 mpg (converted from EU liters/100km cycle"

"No matter how much fuel AMG can force into the CLA 45's four cylinders, output still comes down to air in, air out. The flow starts at an intake channel with a cross-section larger than a softball. It continues through a single, twin-scroll turbocharger with a whopping 26 pounds of boost and an expansive air-to-liquid charge cooler, then spills out through 3-inch downpipes on the headers."

RickFLS4

I guess I'm stuck in time, but V-6 SC / TT is about as far down the chain as I would go. I'm pretty sure I won't pay $50K - $60K for any 4-cylinder even if it is faster to 60 (or in 1/4 mile) than my S4. Also, I get better MPG's in my S4 than my wife Q5 on the Turnpike. 4 cylinders are always better in EPA tests but not necessarily in real world driving depending on how and where you drive. My much heavier LS-460 with a V-8 had the best gas mileage of all. If you like to drive fast, I'm not sure forced induction 4 cylinders are really the right choice for fuel economy.

In any event, if this is the future of performance (4-cyl) I guess I'll either drive older cars or forget about performance and just think of cars as transportation. Maybe I'll change my mind if I see one.

NWS4Guy

All indications from people I have talked to who work for or know others that work for VAG say it's definitely a V6 biturbo. With the changes they have done to the V8's having the heads turned backwards and nestling the turbo's into the Vee, I see this coming to the S4, so it sounds accurate.

ewingsvt

Kind of old school, but it takes hp to turn a SC vs a turbo makes hp for free basically. Packaging is certainly easier with a SC and power delivery is easier to map with a SC.

TO407S4

I agree that an SC take power to make power, but I was always under the impression that an SC was also more reliable than turbos. I guess this only matters if your thinking about keeping your vehicle. On the other hand I'm sure there will be a lot of turbo upgrades to these new cars coming down the pipe.

Tweakophyte

I still have my old-school paranoia about turbos... consumable part like brakes. I tend to keep cars a long time. Of course, turbos are much better than when I was taught that, but it's still stuck in my mind. I also prefer the low-end torque a supercharger produces.