How long would an engine last at redline?

There is no one hard number.  It really depends on which manufacturer made the engine and how well it's been looked after.

I remember years ago, someone I know told me about a motorcycle rally he used to attend in his youth and one of the annual traditions was to take an old motorcycle and lock the throttle fully open.  They took bets how long it would take for the engine to either seize, throw a rod, etc.  Some of them would go for quite a while others self-destructed under a minute.

DEPENDS on how the engine was DESIGNED! EUREOPAN engines and NOW many DOMESTIC Ones use OIL SPRAY JETS that focus clean oil At the piston WRIST PINS< and SKIRTS! This LOWERS FRICTION and allows for SAFE HIGH SPEED ENGINE RUNNING! OLDER cars like in the original CORVETTE cannot run very long on the AUTOBAHN as they just BLOW UP! OIL SPRAY JETS have been used by VW BUGS for DECADES now! ALL EURO engines feature this type of thing,  And now MOST American ones have it as WELL! TOUGH QUESTION< TOUGH answer! MOST engien wil NOT do well at those speeds< BUT>>> Now many engines used by GM< for example use OPEL TURBP engines from GERMANY and some use SAAB derived engines from SWEDEN! They WILL last at highest speeds, cuz they have OIL SPRAY JETS inside them! CLEAN OIL Lis focused RIGHT at the piston WRIST PINS and SKIRTS and under the engine block where the piston travels! Thays can last FOREVER at high speeds! In EUROPE there are MANY ROADS with NO speed limits! We are SO backward in the USA! We have NO bullet trains or MAG LEV trains! We are mostly CONSUMERS. I EVEN texted silly TRUMP ONCE with the idea to redo the DETROIT TRAIN STATION< that has been IDLE for decades, and install MAG LEV TRAINS going to CHICAGO< NEW YORK< D.C. and BOSTON! He never answered! He is TOO BUSY covering up his MISTAKES and sending out ANNOYING TEXTS about how GREAT he is! 

The simple answer is:  UNKNOWN

-Engine overhaul mechanic and general automotive mechanic since 1972

Until it blows up :))

Seriously likes already been said engine manufactures a big part of it however

But a give you a bit more of an answer yes will run at top speed until the fuel Runs Runs out but Won’t do the engine any good and especially on red line.  Where it out faster

It’s not a great idea but yeah sure is fun :)

A race car probably runs on full throttle about 30% of the time? Rebuilds are usually done after a few hundred miles. So for a production engine, I would guess about 100 miles at most . A Ferrari or Lamborghini would probably last longer although full throttle would be at higher revs. 

Doubtful if a tank of fuel would last that long. Supercars do 1-2 mpg when flat out.

A sound engine and transmission would last longer than one tank of gas.

Think about it. Engines and trannies last for years. Hundreds of tanks of gas.

cars today have an auto cutout at redline ..and no car today can drive on the redline ..not possible ..however there are cars that can be driven at high speed for many hours without any problems ..i have driven over 160 mph for over two hours on the german autobahn ..i even got nicked for speeding on it ..i was doing 110 ..pulling a camping trailer!..did not know they were limited to 100..most performance cars are limited to 155mph and above that the limiter stops them ..they do this every day for years 

what car have you driven that could make redline in top gear? How long did you hold it at full speed? Where the road is long and straight enough to hold it at full noise for a couple of hours you cant carry enough fuel to make the next stop.

Most cars will not be at redline at their top speed, but they would still probably suffer damage operating continuously at full power before they ran out of gas.  Aircraft engine manufacturers, for example, specify how many minutes their engines can be operated at full power before they must be throttled back (even though they have to be capable of operating at full throttle for many hours on a test stand before an  engine is issued its Type Certificate by the FAA).  Car engines have similar limits, but manufacturers generally don't bother publishing them because it's a bit harder to put your foot to the floor and keep it there on public roads, and because cars don't fall out of the sky if they have engine trouble.  The manual for my car says nothing about it.  On the other hand, my BMW K100 manual specifies that the max rpm allowed is 8600rpm.  It doesn't say for how long, but it does say that the maximum continuous allowable engine rpm is 8500rpm, so while that's pretty close, it suggests it's not safe to run at the max.

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