So I recently put cherry bombs on my GMC with the 454, and I have been giving the truck you know what lately. When me and my coworker were test fitting some exhaust tips, he got in and absolutely stomped it in park at least one time. Then today, when I was revving it up for a video, I floored it not knowing how fast it would rev, and did about the same my coworker did. Both times sound like it was near 4200 rpms, which I know isn't very high, but this 1986 454 Big Block is a low revving engine. Watch this video with a Dodge Charger 392 revving up to it's rev limiter in park. My big block sound close to this rpm, though a little higher. The reason i'm worried is because when you floor it down the highway, the transmission doesn't let it go that high. I'm thinking GM made the transmission to where it wouldn't get that high, and doing it twice in a row has me worried that I could have damaged it in some way.
https://youtu.be/cXeoDfPL9sw?t=107
![RcFlashlight [BANNED]](https://i0.wp.com/i.postimg.cc/fLKMkt8H/ban-user.webp?resize=96%2C96 "RcFlashlight [BANNED]")
If you had damaged it you would know.
Generally speaking, over revving the engine will spin a connecting rod bearing.
Hey Doc...I am learning a lot about the mechanical aspects of cars here. Would you please explain what you mean by "spin a connecting rod bearing"? And what effect does that have on the engine? Thank you.
I have the same question as avalon. Not sure exactly what you mean by "spin a connecting rod bearing".
I have the same question as avalon. Not sure exactly what you mean by "spin a connecting rod bearing".
Connecting rod and crankshaft bearings on an engine are actually fluid bearings, they are thin steel shells with a small gap between them and the crankshaft journals. Oil pressure maintains the bearing clearance so there is no metal-to-metal contact, the crank and rods actually run on a film of oil.
When you over-rev an engine beyond its design tolerances the pressure on the bearings can become so great that the oil is breached and the bearing shells contact the crank, spinning metal-to-metal, grinding them up, scoring and ruining both. This ultimately leads to severe internal engine failure as illustrated in the photo in my previous post ("throwing a rod").
Thanks for that @chucktobias
The piston rods are connected to the crankshaft and use two bearings. Over revving the engine will sometimes cause the bearings to fail (overstressed, wear, etc.) and actually spin instead of being locked in position in the rod as they are supposed to be. This damages the rod and the crankshaft. The engine will start to make what are known as knocking noises. The solution is to disassemble the engine and, in most cases, rebuild it.