Only partly right in a very small way.Oh, by the way, I may be wrong but as I understand it, there is still one thing that sets these cars apart besides the manufacturer logo, its the block, I still think they have to run the manufacturers block, ie ford block in ford car, chevy block in chevy car, etc. of course by the time they finish machining them, it really doesn't matter.
True that the engine block (and heads and intake manifold) must be "manufactured" by the manufacturer in question. That does NOT mean that the part even remotely resembles anything near to a production part. The implication is, and what the marketing guys hope you believe, is that the part started out as a sort of production part that was modified, rubbed and finished for racing. Wrong. ALL the parts are application specific race parts that do not resemble production parts.
Each manufacturer designs the engine they intend to race in the 'cup series and submits it to NASCAR for approval. Once approved, all teams running that brand must use the approved block, heads and intake manifold. Getting a part "approved" is far more politics with NASCAR than technical or production related.
Think about it....how could a Toyota pushrod 'cup engine be something that could be used in a production application when Toyota has never made any sort of motor even remotely resembling that...??? PURE race parts. Period.
Not that any of the other manufacturers run anything resembling production. The small block Chevy engine used in NASCAR is a derivative of the SB2 (small block 2) racing engine that was submitted and approved about 10 years ago. It's ancient ancestor was the chevy small block...but the SB2 heads have equally spaced exhaust ports..not the siamesed exhaust ports of the conventional small block chevy. And the SB2 used today in NASCAR isn't even remotely recognizable as the Gen3 small block (LS2/LS6/LS7/etc.) in production today. The SB2 doesn't even have the cam on the same centerline as the old small block did. Same with the Ford and DC motors. The only quibble here is that the Chevy/Ford/DC motors did originally begin with production engines ages ago and still maintain some faint resemblence in terms of deck height, bore spacings, etc... Toyota, with no history to hamper them, just designed the optimum racing engine and submitted it....and NASCAR, in their haste to get Toyota onboard, approved it. Didn't it show when they immediately ran at the front of the pack in the very first truck race they entered and would have won had they not realized that that would have been a SERIOUS faux pas and sandbagged at the end so as to not totally tip their hand as to how much of an advantage they had right out of the box.
Interesting note for the Daytona 500 coming up. The ZO6 Corvette is the Pace Car with the new 505 HP LS7 engine. In pure stock trim it has practically the same top speed as the NASCAR race cars and makes at least, if not more, HP than any car in the field!! Got to be a first for the Pace Car to be the fastest car on the track!! With the restrictor plate motors the field would be spotting the Corvette about 10 HP !!