There was some concern in the 911 purist community regarding Porsche’s decision to twin-turbocharge all Carreras moving forward. You see, purists hate turbos on sports cars because of turbo lag. Here’s an explanation of what that is and what it does.
Turbochargers come with turbo lag. Anyone who says otherwise is either lying, confused or misled, as Motor Trend’s Jason Cammisa explains. He even drew a clever little graph to illustrate the differences in power delivery between a turbocharged engine and a naturally aspirated engine.
Not being the most well-versed in technical terms, I sought the help of Jalopnik’s tame engineer, David Tracy for a layman’s breakdown. Here’s how he explained it to me:
1. In intervals of 500 rpm, he measured the peak power between 1,500rpm and 6,000 rpm. So that means he knows the engine’s peak power at 1,500; 2,000; 2,500...6,000 rpm.
2. He set the engine speed steady at each RPM point (1,500; 2,000; 2,500...6,000 rpm.), and then opened the throttle 100%. That’s when he started his stopwatch (when the throttle was opened 100%).
Once the engine made the peak power number measured in step 1, he stopped the stopwatch, and plotted the time.
So, an example point:
Dyno test 1. We’re at 2,000rpm. We measure the peak power on our dyno to be 300 hp.
Dyno test 2. We set the engine speed to 2,000 rpm with throttle closed, then we open the throttle fully. We start stopwatch. The engine power quickly climbs until it hits 300hp, then we stop stopwatch.
We do this process for all rpms between 1,500 and 6,000 and plot the times.
So you can see that the Porsche takes longer to make peak power at early revs. AKA: turbo lag.
However, this wasn’t something that Cammisa or Randy Pobst found to be an issue when tracking the car. You keep the revs so high on a racetrack anyway that the lag hardly matters.
But as for the day-to-day feel, I’ll leave that up to you.