mx5cartalk.com

It could be that you have an imbalance in the impeller assembly.
This can be caused by a few different things like one of the vanes has cracked and a little chunk has fallen off, something has come through your air filter (I do hope you are running an air filter) and broken a bit off a vane, or the bearing is cactus.
It's also possible that the oil feed pipe has a partial blockage and at certain revs the oil is not going through properly and the bearing is running dry.

You'll have to pull the turbo off and have a close look inside it.
Don't forget, they spin anywhere up to 100,000 revs, so even a tiny flake coming off one of the impellors can cause a huge vibration.

While the impeller assemblies are checked thoroughly before assembly, a minute, microscopic crack could have been there from new and is only now showing up as a problem.

Let us know how you go.

turbo rebuild - $1000

New turbo

$1150
GT2560R

All GT series turbos need the restrictor. ..... Pull the inducer hose and look at the turbine imho

silverback2002 wrote:I am running a GT2560R turbo.

I have put the restrictor in the oil feed as recommeded & I run a 3AN line.

But somesome said not to use the restrictor as the MX-5 doesnt produce that much oil pressure so it is not needed.

I didnt want to take the chance in blowing the seal.

Has anyone installed a GT2560R and run this little restrictor that sits in the fitting.

If you suspect there is an in-balance issue I would be getting this looked at ASAP, if you leave it too long you will be in for a major turbo failure guaranteed. The biggest killer of turbos is over speeding, not oil supply, saying that inadequate oil supply will hammer the bearing cage quickly (they are made of plastic on the GT series).