Maybe R&D break's in engines but racing teams do not. They build em, drive em, and blow em. Those engines are brand new each time around.

 

excellent point, each car is driven a certain distance by manufacturers, and you'll see it on the speedo, when we break in test vehicles we usually put on 100 miles or so. so with the manufacturers it might be 200-300 additional. so who knows, im going to work on a g37 on its first 3000 mile service and check the engine, i'd like to see how it held up.

 

and i guess all the people who break in their engines on dynos dont know what they're doing either lol.

 

I've built a few engines in my time and torn a few down, and while I am by far no expert some things just seem obvious. If you concider the engine is a "wearable" piece, meaning that does wear out. It does expand and contract. The metal in the engine - esp. the rings and bearings - do have wear and fatigue limits, and they must mate to the cylinder wall or journals - but they don't do this instantly. It would be intersting to look a the edge of a piston ring under a microscope after 1 mile, then 100, then 1000 and then 10,000 miles. My gues is you would see the edge profile changes over that time. IF you can accept that assumption then it shouldn't be such a leap to say that if you jump in a new car and rev the engine high and run it hard that you would be imparting pressures that the rings an bearings havn't gradually worn to. Instead the a "forced" to, making pars flex and fatigue in a greater state than if the are worn to the cylinder wall. IF you can accept that then it makes sense that a break in period makes sense, esp. if you intend to keep the car for extended time. If you let the ring seat to the cylinder wall you'll get a tighter seal. I do agree however that in a modern engine there is very little damage that can be done if you run the car like you want withing the rpm range. Yeah you might limit the engines life by a few percent, but I know very few people that will keep cars their car this long.

 

^think your last couple of sentences say it best. clearances have gotten so much tighter as cars evolved but so have machining techniques. so sure there will be wear but i dont think its as dangerous as older engines. so you lose a few 1000 miles at the end - i dont see very many people running these cars to 200,000 miles yet lol.

 

excellent points, i agree and the g's engine is a modern work of technology, just drive have fun and enjoy.