"TwoFortified" (twofortified)
12/12/2014 at 14:08 • Filed to: None
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"TwoFortified" (twofortified)
12/12/2014 at 14:08 • Filed to: None | 0
| 22 |
...what will happen if I WOT for, say, 4 seconds?
I'm not sure if I have a rev limiter. I'd like to find out, ideally in neutral.
I actually have a reasonable understanding, mechanically, of what might happen. Perhaps the torque/RPMs will be too much for my timing belt. Perhaps my valves will float so bad, that my engine destroys itself. Perhaps the RPMs will just stop rising...again, presumably due to valve float. Perhaps I'll torpedo my fuel pump (though, that shouldn't happen...) or my spark plugs.
But, like, as a guy in a car, what will happen? The only thing I can think is that my RPMs would stop rising, or I'd bounce off of a rev limiter, or my engine would crunch to a stop.
Advice? Thoughts?
Funktheduck
> TwoFortified
12/12/2014 at 14:10 |
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That engine bay........
macanamera
> TwoFortified
12/12/2014 at 14:11 |
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Aaron M - MasoFiST
> TwoFortified
12/12/2014 at 14:14 |
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Here's an interesting answer from Wikipedia that would apply to most modern(ish) engines:
"Engines with hydraulic tappets (such as the Buick/Rover V8 ) often have in effect a rev. limiter by virtue of their design. The tappet clearances are maintained by the flow of the engine's lubricating oil. At high engine speeds, the oil pressure rises to such an extent that the tappets 'pump up', closing the valve clearance and preventing the valves fully closing. This sharply reduces engine power, causing speed to drop."
In other words, even without an artificial rev limiter the vast majority of engines would eventually settle on an RPM level...albeit a very high one. Older engines with solid tappet lifters may not...but most engines with solid tappets are old enough that they'd probably break something fast.
Gamecat235
> TwoFortified
12/12/2014 at 14:14 |
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In my experience, as someone who accidentally forgot to reconnect the rpm sensor on his 626 (worst car ever) when changing the water pump, you will rev past the redline, lose a TREMENDOUS amount of power, take FOREVER to come back to normal idle (well, not really, but it was a much slower fall off than normal) and then you'll fret about what you just did to the engine life. There is no rev limiter if you have disconnected it.
(this was done while driving, it was not a good thing).
youshiftem
> TwoFortified
12/12/2014 at 14:15 |
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TwoFortified
> Funktheduck
12/12/2014 at 14:16 |
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I wish mine was so clean.
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TwoFortified
> Aaron M - MasoFiST
12/12/2014 at 14:17 |
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Um, correct me if I'm wrong, but it sounds like Wikipedia is describing Valve Float...Which, yeah, will happen. And yes, I have hydraulic lifters.
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TwoFortified
> youshiftem
12/12/2014 at 14:17 |
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Oh gall. I don't want that. BUT I MUST KNOW!
Evil-B
> TwoFortified
12/12/2014 at 14:17 |
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It could go pop, i would advise against it.
jebusmoses
> TwoFortified
12/12/2014 at 14:17 |
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My speculation tells me that valve float would effectively limit the engine speed at some point, especially if it's a non-interference engine
Party-vi
> TwoFortified
12/12/2014 at 14:18 |
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With no rev limiter my dad's 357ci V8 in his Wrangler revved high enough to blow the shit Keith Black pistons apart and out the exhaust, taking some valves and piston ring bits with them. Don't do that.
thereisnospork
> TwoFortified
12/12/2014 at 14:18 |
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If your engine is non-interference, probably nothing too bad: your valves will start to float and that will rob your power and prevent effective combustion, and 4 seconds might not wreck any bearings.
If your engine is interference, the valves will float until they hit the pistons...
In general though, it is a natural tendency for any ICE to rev until it destroys itself if ungoverned/restricted.
Ntovorni
> TwoFortified
12/12/2014 at 14:19 |
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Trevor Slattery, ACTOR
> TwoFortified
12/12/2014 at 14:22 |
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Something like that...
Textured Soy Protein
> TwoFortified
12/12/2014 at 14:27 |
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"Now me and the mad scientist gotta rip apart the block and replace the piston rings you fried!"
Tohru
> TwoFortified
12/12/2014 at 14:28 |
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Aaron M - MasoFiST
> TwoFortified
12/12/2014 at 14:30 |
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Valve float is when your camshaft is spinning so fast that the valve doesn't have enough time to open and close before the camshaft lobe comes around again. What this is describing is the oil pressure in the lifters rising to the point that the lifter itself forces the valve open, regardless of cam position. The result is the same (valves staying open through a combustion cycle) but the mechanism is different.
Solid lifter cars can have valve float, and may get it at relatively lower speeds considering the larger clearance between lifter and valve.
'Wägen, EPA LOL
> macanamera
12/12/2014 at 14:37 |
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Cannot unsee....
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macanamera
> 'Wägen, EPA LOL
12/12/2014 at 14:38 |
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scared tractor is scared
bradleyjames518
> TwoFortified
12/12/2014 at 16:02 |
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Curiosity killed the car.....
If only EssExTee could be so grossly incandescent
> TwoFortified
12/12/2014 at 16:02 |
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Big metal thing go boom.
kanadanmajava1
> TwoFortified
12/12/2014 at 18:38 |
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My friend used to race old Mazda 616s from 70's He found out that the Mazda inline-4 that was used in those destroyed rod bearings immediately then the engine speed climbed to 6200 rpm. It didn't cause any massive explosions. The engine just started clanking heavily. You could rebuild the engine if you shut it down immediately after the damage occurred.
The whole engine was pretty bad design and it made the 13B wankel look pretty reliable engine.