Well yes I guess that's right, drive around, around and around for 500 miles at 220+ mph and it needs a rebuild, duh! For real, in the state of tune they are in I think they would last better than most high performance engines at that power level. I would like to have one on the Autobahn, suprise, suprise Mr Porsche! Twist it up to 8,000 and hold it there for 20 miles, I don't think it would even break a sweat! But I would still take the V-12!

Illmor 265A....
 

Actually, the Illmor 265A "Chevy" engine was NOT a rebadged Cosworth DFV or DFX Indy motor, but an entirely fresh design. Cosworth Engineering had nothing to do with it. Mario Illien and Paul Morgan had worked on the DFX Indy motor for Cosworth, but Roger Penske came along with backing from GM and together with Illien and Morgan formed a new company, Illmor Engineering (ILLien and MORgan) with each party taking a 25% stake in the new company. Illien designed a new 2.65 litre DOHC V8 from the ground up. While Illien's new motor bore a superficial appearance to Cosworth's motors, it was a new design. The biggest difference was that the camshaft drive gear train
on the Illmor motor was at the rear of the block as opposed the Cosworth
design having the gear train on the front. Illien did retain the Cosworth
scheme of using a gilmer belt at the front of the engine to drive the oil
pressure/scavenge and water pumps, the difference being that on the
Cosworth the gilmer belt was directly driven off one of the camshaft drive
spur gears and the Illmor used a jackshaft extending through the block
to do the same thing. The Illmor 265A was a bit more compact than the
DFX and this allowed car builders to make undertrays with wider tunnels
for better air extraction, but the 265A proved itself to patently superior
to the DFX in every respect and teams rushed to sign on for it. Cosworth
had to go back to the drawing board and create an entirely new motor to compete with it.

....Fred