2 Liter Turbo 4's

DGS49

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Apr 12, 2012
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The high-end automotive world has been largely overtaken by 2-Liter Turbo 4's (2LT4's). Everyone from GM to Mercedes, to Porsche, to Volvo, to VW, and on and on and on, has handed up their version of a 2LT4 as their "base engine of choice" in high-end cars, performance cars, sporty cars, and so on.

But for generations, it has been "common knowledge" in the automotive industry that one of the keys to high quality and reliability is to minimize the number of moving parts, and particularly those that move at high speed and require constant lubrication. All of these 2LT4's have complex dual overhead cam arrangements, and turbocharger impellers and compressors turn at tens of thousands of revolutions per minute and require constant lubrication.

Also, it has long been common knowledge that higher compression engines have a shorter service life (other than Diesels, of course, which are made for high compression), and turbocharging artificially increases compression dramatically when accelerating, thus placing all of the engine components under incredible stress.

Recent advances have eliminated the delay in power delivery ("turbo lag") that used to be endemic with turbocharged engines, so that unless you are aware specifically that your are driving a car with a 2LT4, you would imagine that the car has a much larger displacement engine. In fact, there are few complaints from drivers of 3-series BMW's, Cadillac CTS', and even mid-sized SUV's (Porsche Macan!) that the cars are under-powered.

In my extensive experience driving turbo's, the expected better fuel economy of the small displacement engine is often very elusive in practice, as the driver finds that s/he is "pushing" the small engine more than s/he would be a larger engine, just because the basic power is lacking. The EPA testing therefore often gives an over-optimistic estimate of real world fuel economy, because they "feather" the throttle in their tests. Ford, especially sees complaints from people driving their Escape small SUV with the turbo 4's, and getting 15mpg.

Are these small engines going to hold up in the longer term? Is a 3.6L V6 a better choice than a 2LT4 for your Camaro, when the performance is virtually identical?

Inquiring minds want to know.
 
Of course, EPA fuel economy standards ratcheting up are the reason, and as mentioned above, a 4 cylinder turbo tends to get very good results on the mild - driving EPA cycle.

My other question about these engines is, what exactly is the difference between the VW/Audi Four that is rated at 201hp in, say a Tiguan, and 297hp in an Audi S3? Is it just a different chip, or are engine components different?
 
I bought new a 2007 VW Passat with 2.0 turbo. Just sold it with 125k on the clock and still ran and looked great. It was a very quick car but did burn oil.

My son has a turbo four in a Subaru that is amazingly fast. WRX. It is faster than an Audi S4 with 4.2 V8.
 

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