turbo friction
Thread Starter
Instructor
Joined: Apr 2006
Posts: 110
Likes: 0
From: wakefield uk
turbo friction
Help please, how much resistance should there be when turning a turbocharger by hand ? like a bicycle wheel or maybe like a water pump. It's just when I drive big trucks and switch off the engine I can hear the turbo spinning for a minute after.With the amount of resistance on my Rajay I figure it would stop immediatley.
Drifting
Joined: Nov 2003
Posts: 1,637
Likes: 2
From: Honeoye Ny
IN a word: Inertia.
your big truck has alot more inertial then the wheel in your little Rajay
Ther eshould be the slightest amount of friction while under no oil pressure.
Remember it uses the same hydrowedge your crank/rod uses only in double, the bearing floats on the shaft and in the housing.
Well some do anyway to reduce the amount of fluidshear/dampen shaft motion. But that is a different discussion.
your big truck has alot more inertial then the wheel in your little Rajay
Ther eshould be the slightest amount of friction while under no oil pressure.
Remember it uses the same hydrowedge your crank/rod uses only in double, the bearing floats on the shaft and in the housing.
Well some do anyway to reduce the amount of fluidshear/dampen shaft motion. But that is a different discussion.
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Correct me if I'm wrong, but isn't your system a draw through system? IIRC, Rajays have an extra oil seal in them to prevent sucking oil into the compressor under high vacuum (idle) conditions. This seal causes a small amount of drag. My turbo (at least when it was new) would not turn at idle. At about 1000-1200 rpm it would start to spin. It makes instant boost when I need it on the track though, so I don't worry about it.
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
I had a small KKK turbo from a Porsche 924T that would keep spinning for a second or two after I let go from spinning it with my fingers. It wouldn't stop instantly. I've also had my hands on newly rebuilt turbos (new bearings, seals, etc.) that felt stiffer and would not keep spinning after you let go. I think that was due to the freshness of the seals, though, and the fact that they haven't been heated yet.
.(separate post C3 tech)
