Back in the '80s, small, 1500cc turbo engines that could barely rev at more than 10,000 rpm powered all Formula 1 cars. However, they could deliver mind-boggling levels of power because their turbochargers could produce very high boosts.
Les Wright from Australia is currently restoring a Benetton B186, chassis No. 05, including the tub, the wings and the infamous BMW 1.5-litre, four-cylinder turbo engine.
From the dyno sheets, we can see that the restored engine produced 802 bhp at 9700 rpm.
The power band of the BMW was known to be peaky. We can see that the engine is going from 450 to 800 horsepower in about 1000 rpm, between 8600 and 9700 rpm.
Note that the boost used was 3.3 bars, which is 48.5 psi.
Back in 1986, BMW used a boost of 5.5 bars (80.8 psi) in qualifying trim, for a power of 1300 bhp. A year later, in race trim, the boost was down to 3.8 bars (55.8 psi) for 900 bhp.