K03 Overboosting?

[CaneyJ]

Hi everyone. I’m working on a project that involves turbo charging a low capacity petrol engined car in the pursuit of performance. I chose to use a small K03 turbo bolted to a custom flanged manifold; however the car seems to be over boosting.

The aim is to run the car at a low boost level of 4.5 psi and I have believe I have wound the nut on the actuator arm to the maximum but I am still getting 10 psi of boost.

I was just seeking your more expert opinions on what might be wrong. I’ve discovered it’s a VAG turbo as fitted to old TD golfs. I was under the assumption you could turn a turbo down to 0 psi where necessary, does the K03 have a minimum level? Does anyone know what level of boost they run on a golf as standard?

The turbo actuator has 2 pipes leading from it. One leads to the turbo housing whilst the other hangs loose as I assumed it didn’t do much other than send signals to an ECU type device.

What can I do to reduce boost? It has to be noted that one end of the turbo body to actuator pipe is lacking a clip so there is a chance it might be leaking. Could this be a reason for the over boost or do I perhaps have to block off the free ended second hose with a screw?

Engine: 1.9L TD (AAZ)
Year: 93-94
Model: KKK K03-003/96404
Oil cooled only
5303-970-0003
OEM No.: 028145701R
Engine Power: 75 bhp

Here are pictures of the turbo before it was fitted to the car.









I was also wondering if somebody has a part number for the gasket that goes between the top of the turbo and the exhaust manifold.

[BugsyMalone666]

Ok im not an expert with turbos, but i have been doing some research as im building an aircooled beetle with a turbo and I also own a mk3 golf so have a manual which covers the diesels.

according to the book that loose pipe goes to a 2 way valve which is electronically controlled and connected to a vacuum pump.

now im guessing looking at it that basically on idle a vacuum pump draws the actuator right open then as revs increase the vacuum pump shuts off and lets the turbo self regulate as the 2nd pipe that connects from the compressor housing to the actuator limits the boost so much.

id check all the pipes are clear and that you have connectors on the vacuum pipes to eliminate the problem.

other solutions i would suggest are taking the actuator off and using a die to cut more thread so you can practically have the gate open the whole time, replacing the actuator all together with a different single pipe type or possibley looking at a different turbo.

im just looking at my book and apparently there are 3 setups of turbo charger

the 75bhp one is off the AAZ engine which produces a maximum of 0.60-0.83 bar @ 4000rpm.

I hope that helps a bit!