Repair-It

The Pirelli P Zero Trofeo Rs are essentially street-legal racing tires so tacky that, during development testing, they occasionally stuck to the pavement better than to the wheels they were mounted on. To keep the Pirellis from slipping around the rim, the wheels on production Z/28s are media-blasted to increase friction at the mating surface, a common practice in racing.

There are, of course, stiffer springs and bushings, and the downsized wheels allowed engineers to drop the center of gravity by 1.3 inches and use smaller and lighter anti-roll bars. The cornerstones of the suspension are four spool-valve dampers, a technology used by Red Bull Racing as it claimed four Formula 1 championships between 2010 and 2013. Until now, the closest these shocks have come to a production car is Aston Martin’s $1.8-million One-77.

Spool-valve dampers don’t use electronic components or magnetic fluid, and they are neither driver-adjustable nor adaptable to road conditions. Instead, the spool valve’s merit lies in tailor-shaped internal ports that improve the precision and effective range available to engineers as they tune the shocks. They work magnificently. The Z/28 transitions from left to right to braking and acceleration with nearly imperceptible load transfer. It is stoic and stable as it bounds over the curbing and hunkers into hard braking through the tight corkscrew of Barber’s eighth and ninth turns. On the road, firm doesn’t mean harsh, either. As we bomb over a bridge deck that is set two inches above the road that abuts it, I tense in anticipation of a jarring impact—it never materializes.

My Z4M Coupe had a relatively small 3.2 liter engine, but got rotten mileage. It usually averaged about the same as my Jeep Wrangler. Which should tell you something. Of course that engine did put out over 100HP/Liter. Considering that engine was designed 12 years ago, I don't think I'm out of line grumbling about the C7's very meh, specific output.

Your Z4M is a perfect example of a car which would be faster, cheaper and more fuel efficient with an LSx small block chevy under the hood.

Not necessarily. The car would be be much heavier, be nose heavy, have far too much torque for the vehicle's weight/tire size (You'd have to start off in 2-3 gear to prevent wheel spin), and the V8 wouldn't fit anyway do it its much larger size.
And while I see your point. I do have to disagree with your statement that specific output is irrelevant. It is a benchmark from a engineering perspective. Which would you consider the superior engine? The engine making 250hp, or the one with identical displacement and weight that makes 400? That's an easy answer

Not true. The LS2 6.2L only weighs 418 lbs so in fact it would have been probably 50 lbs lighter than the iron block 6 in your BMW. Also the V8 would move the center of gravity for the powerplant back closer to the firewall since it is not as long.

As for specific output, it's not just irrelevent for a street engine, it's utterly irrelevent. Internal friction goes up with the square of rpm and high specific output engines are generally DOHC with the attendent high valve train losses, so they tend not to make any better fuel economy than the bigger displacement engines which have higher pumping losses (except those with cylinder shutdown). Think about the absolutely atrocious mileage rating of the recent M3 BMW 4.0 v8 (now gone). It was 14/20 mpg vs the Camaro (200 lb's heavier and no cylinder de-activation to boot) 16/24 mpg.

In that sense the M3 4.0 was an utter engineering failure compared to the LS2 6.2. It had 100 ft lbs less peak torque, it had significantly poorer fuel economy, it was heavier by 30 lbs, it was wider and much more expensive to manufacture. Yet by your twisted logic it would be the "better" engine since it had higher specific output. That makes zero sense.