Engine "Braking".......Does it hurt the motor ???

Chris Hill · 11-03-2008, 06:30 PM

My gut says no, but I think Jeff is correct on the rod being loaded more. If your engine is running 7,000+ rpm, then you let off the gas, vaccum in the intake system goes through the roof. Intake runs high vaccum, not much air if any is compressed during compression stroke and the net load on the rod may be greater than at the top of exhaust stroke when rod is slowing down the piston. You would have to look at cylinder pressure traces to make sure though.

But to answer Rusty's original question, we've done it both ways with our stockers, and both ways seem to work ok

11-03-2008, 06:30 PM	#3
Chris Hill Senior Member Join Date: Jan 2002 Posts: 655 Likes: 8 Liked 244 Times in 26 Posts	Re: Engine "Braking".......Does it hurt the motor ??? My gut says no, but I think Jeff is correct on the rod being loaded more. If your engine is running 7,000+ rpm, then you let off the gas, vaccum in the intake system goes through the roof. Intake runs high vaccum, not much air if any is compressed during compression stroke and the net load on the rod may be greater than at the top of exhaust stroke when rod is slowing down the piston. You would have to look at cylinder pressure traces to make sure though. But to answer Rusty's original question, we've done it both ways with our stockers, and both ways seem to work ok __________________ Chris Hill https://ihmusedparts.com