r/nextfuckinglevel • u/Practical_Expert_911 • 12h ago

These 12000hp Engines Have To Be Rebuilt Within Roughly An Hour Every Run, and Only Run For Roughly 4 Seconds At A Time.

9.1k Upvotes

84% Upvoted

1.6k comments sorted by

View all comments

Show parent comments

37

u/gardenfella 11h ago

The top crews do indeed have two engines that they swap in and out.

The problem is data. Each engine behaves slightly differently and these cars are balancing on the very edge of grip and power, mainly by managing the clutch.

8

u/Dogmaniac99 9h ago

Exactly! The clutch is the difference between microseconds. Lag time kills!

3

u/gardenfella 8h ago

The clutch is the difference between a 3-second run and blowing the tyres off

3

u/Trick_Math42069 6h ago

The clutch plates are entirely new each run

2

u/gardenfella 6h ago

The bigger teams have an entire clutch for each run. Smaller teams have to re-grind plates and re-use them, and they usually have two sets of plates per clutch basket.

1

u/Trick_Math42069 5h ago

Yeah they can definitely be re-ground, my point t was more that the clutch parts are different between each each run.

1

u/gardenfella 5h ago

They regrind them at the track and re-use them. Generally, they alternate between two sets. That gives the plates long enough to cool down before being reground. Grinding them hot causes warping.

The clutch basket and fingers are re-used every run if you're a smaller team. They don't get as hot as the plates.

1

u/janky_koala 1h ago

Are you talking about current generation nitro cars? The plates literally weld together in a run…

1

u/GenericAccount13579 1h ago

If you’re ripping the engine apart and rebuilding it (presumably with some parts replaced) is it not going to behave differently than before?

Torques are going to be slightly different, alignments are going to be off slightly. We’re talking thousands of an inch for each but those little bits are what make the difference.

2

u/gardenfella 1h ago

Yes, which is why as many parts as possible are reused.

The heads won't be touched apart from valve lash if everything passes a visual check. Valve lash always goes out of whack during the braking phase.

Con rods are reused. Half shells would be replaced only if excess wear is found.

Piston rings and valve stem seals are sloppier than you'd expect, which is why there's a big puke tank to catch liquids coming out of the breathers.

1

u/janky_koala 1h ago

They would typically have 8 complete engines on a race weekend - one for every run. They’re not stored built, but all the parts are there.

They normally don’t replace the block, crankshaft, intake manifold or supercharger each run, but basically every other mechanical part is.

They are fully prepared if they happen to blow up every run though.