Audi 4000 Turbo quattro Conversion

The Intro

The Project








Total Bill

Engine Specs

Special Tools
I am very fortunate to have a supportive and understanding wife.  In June 2002 I finished a 6 odd month project of painting her CRX Si.  She understands the merit of nice, paid for, older cars.  We have also moved 3 times since I started on a Rabbit race car which is now for the most part done.  So when I proposed the idea in early December 2002 for this project she supported it fully.

I found the motor on marketplace (see links).  I am located in VA and it was in NY so I had to have it shipped.  Luckily the company I work for was willing to let me use their trucking accounts and discounts.  The motor began life in a 1985 5000 turbo automatic.  I am told the car had very low mileage for a car this old.  I did however decide to fully rebuild the motor.  Since cams for this motor are hard to find and too expensive for my budget I kept the stock cam, but did port the head.  Originally I considered making my own intake and exhaust manifolds, but in light of how much other things had to get done on the project I just decided to keep them stock....for now.

There are a few parts I had to source else where as they were already gone before I bought the motor.  One was a shroud and one was the coolant after run pump.  I decided to keep the A/C in my car, but there will be a pesky turbo in the way now.  For now the compressor is not installed.  All other components are still in place I just have the lines blocked off.  I have a Dodge NEON A/C compressor that I am going to use since it was originally designed for R134a and is smaller than the York unit that came with the 4000.  I will be mounting it on a custom mount on the radiator side of the engine.  Since it is cool out now the urgency on this part of the project is gone for now.

My first planned change had been to move the battery to the trunk.  This is a good idea anyway since we already have way too much weight up front.  It also makes room for the waste gate.  In the trunk on the passenger side my car has a little compartment for tools or such things.  I am planning to remove this and put the battery box between the raised floor rail and the outside wall where this compartment had been.  I decided to put this off until I already had the dashboard apart for wiring.

In tearing apart the motor I came across one surprise.  The thermostat was destroyed.  I have never seen anything like it. It is even a German thermostat.  I found all the pieces either in the thermostat housing or in the water pump housing.  No secondary damage was done.  Aside from that every part removed so far has been in excellent condition.  The turbo's axial and radial run out passed with flying colors.  All cylinders look great and in general the motor is in excellent condition.  The seller of the motor had said it ran very strong even for a turbo car.  I found out why.  The lower wastegate hose that limits boost had a large hole in it.  This means the boost levels were well above stock.  It is no big deal as I just replaced it, but it is good to know why.

I was surprised to find that this motor uses 38 mm intake valves.  I guess I had assumed it used 40 mm intake valves like in VW GTI heads.  I was also surprised by how huge the valve stem is at the back of the valve head on the exhaust valves.  I shopped around some for alternative valves and had no luck.  I guess the 2v per cylinder VW stuff is just getting too obscure.  I had thought I might drop the sodium filled valves and switch to standard VW exhaust valves, but ceramic coat them.  The sodium filled valves are very heavy and as you can see below they have huge stems at the base.  I know the sodium helps manage the heat of a turbo motor, but the weight and size can't help things.  I think modern thermal coatings on a standard valve might give better overall performance.  For those who are interested I go into more detail on valve weights and sizes in the engine section.

Here is a picture of the block partially disassembled.  I still can't get used to 5-cylinders.