924Board.org

[simsport]

I have heard the main problem with the 924 turbo is the poor drain to sump of the oil.

A guy over here in the UK fitted an IHI turbo higher up in the engine bay which stopped the problem.

A firm called Central Audi/VW in Ellesmere Port , England offer a hybrid turbo for the 924 giving more boost and less lag.

Simon Cooper, the guy there used to work for me. He has developed several diesel turbos and knows a great deal about what does/doesn't work with a turbo.

Cheers
Simon

[John H]

You're right one of the main causes of failure is the poor draining but Porsche have tried to remedy this by the retro fitting of the vent line to the cylinder head - this relieves some of the pressure in the drain line and seems to help with longitivity.
However if you look after the turbo by lettign it cool down this also helps. I run two oil coolers that also help keep the oil temperature at nice "warm" level which also helps the life of the turbo.

[Cbass]

[Dave951M]

Cbass-

Still, I think I would stay with the K26 to eliminate a bunch of fabrication. These turbos can take a lot if properly cared for. Newer doesn't always mean better. The Garrets and other turbos may be "better" but you will have to put in a bunch of work to mount them, and then you don't benefit from all the work and testing the factory did on the original K26. You are your own test program.

[Cbass]

I agree, it is a lot of trouble if you don't have to do it. I'm just keeping my options open if I have to buy a new turbo, the Garretts cost almost half as much...

[John H]

One thing you have to look at for the “after market” turbo’ chargers is the compressor and turbine wheel combination.

If you look at the Garret for example there is a whole multitude of combinations – you can have different compressor wheels on the same size turbine and then the same again different turbine wheel on the compressor.

By looking at the compressor maps you should be able to take a reasonable guess as what should work on the car. To get the best you will then need to run a series of full power then swap compressor and turbine wheels and housings. As the compressor maps for the K26 are not readily available you have to calculate what will work.

The cost of a rebuilt K26 is probably less than the messing around to fit a Garret or any other unit. A Garret wouldn’t last any longer than the K26 if it’s not maintained. The turbo charger what ever make is only as good as the care it’s given.


If you go for the aftermarket unit make sure what ever you make to fit is suitable to be used as a pattern - that way you can re cover some of your costs by selling a "kit" to retro fit another brand of turbo.

[Cbass]

Thanks John. Aside from the watercooling, my other reason for swapping would be to get an electronically controlled wastegate. I like the idea of using the APC boost controller, so I don't always have to use really high octane gas.

Then again, if I fitted an external wastegate, I could use the APC anyways.

[924 turbo]

The 924 turbo has an external, dual-port wastegate. You can use electronic control to your heart's content.