Audi 4000 Turbo quattro Conversion

The Intro

The Project








Total Bill

Engine Specs

Special Tools
As you would expect there are changes that have to be made to the car before the new motor can go in.  They may both be 5 cylinder engines, but the KH and its later brother the MC do require more engine compartment space.  As noted earlier in this web site the battery must be moved from the engine compartment to somewhere else in the car.  The easiest which requires essentially no fabrication is in the trunk.  I was even able to run the battery cable without removing the back seat, but it would have been much easier if I had.

Of course you need to find a way to pass the cable through the fire wall.  I drilled a hole while I had the A/C equipment out and put a grommet to protect the wire.  I ended up making my own battery post using a grommet, some nylon washers, and a stainless steel bolt.  The red cable in the picture below goes to the starter.  Unfortunately due to the larger down pipe there is not much space to route it.  I did cover it in a heat reflective sleeve.  At the recommendation of a quattro lister I put a 200 amp circuit breaker in the trunk so if this starter cable ever does fry I won't have a fire on my hands.  You can see it circled in the picture above.  It is almost invisible.  The two 60 amp fuses that send power to the rest of the car is overkill, but it was a convenient and clean way to get from size 1 cable to the factory power leads.

The reason for moving the battery is to allow room for the waste gate.  The other common problem the waste gate causes is interference with the passenger side steering tie rod.  This has to be bent slightly to allow room.  This is detailed at the bottom of this page.  I test fit the motor without the clutch attached to make sure everything will fit around it.  

Several sites I have seen have the fuel distributor mounted into the fender well.  Others use an Ur-Quattro fuel distributor which is supposed to make life much easier.  I chose instead to mix and match things.  I did not want to cut the fender well since it is structural and I did not want to have to deal with reinforcing later.  First the 4k box does not fit because the KH distributor is taller and the hood will not close.  The next thing I tried was to mount the KH distributor to the top of a '83 GTI air box.  This causes some problems since the air metering plate is towards the back of the car and there is not enough space to run a pipe to the turbo intake between the distributor and the intake manifold.  Since CIS (continuous injection system) is always delivering the same fuel to each injector you can mix and match which cylinder goes to which port on the distributor.  I decided to flip the distributor around so the air plate was towards the front of the car.  This of course messed up all the fuel lines.  I ended up removing all the KH fuel lines except for the cold start valve which I just flipped around 180°.  This is the only fuel line that still goes over the top of the manifold like the stock system.  For the rest of the injectors I used a combination of stock 4k lines and '83 GTI lines.  I used the GTI lines for the longest run to the 1st and 2nd cylinders.  I ran all the injector lines around the back of the intake manifold.  I think it ends up looking better that way.  I put them all together in a reflective heat shield tube.

I ended up making a lower intake box out of part of a GTI box and some stainless steel sheet metal.  I wrapped the exposed sides with heat rejecting foil.  It is held together with pop rivets.  It fits under the hood with about 1/2" to spare.  Since I now have to turn the intake air very rapidly I was not able to use mandrel bends like I have everywhere else.  I fabricated the pipe shown below.  One side is a section of 3" exhaust tubing squashed into an oval.  That is mated to a 2.25" piece of exhaust tubing with a mandrel bend into the factory turbo inlet hose.  The 1" pipe off the side is part of the bypass valve system 

Another big problem that faces 4kqt swappers is where to put the intercooler.  The 5k IC is very thick and angled back.  It seems like it might be perfect, but there is just not enough space for it anywhere.  There have been lots of ideas of where to put it, but none of them worked for me.  The other alternative is to get an Ur-Q IC, but that again didn't seem like the best solution.  I came upon an Isuzu IC that was fairly large and fits (just barely).  You can see below the size difference.  There are a few nice things about this IC.  First it is thinner, second it is a single pass unit, and third it does not have crimped on end caps which I hear can cause trouble at high boost. 

I test fit the bigger IC a few ways.  What seems to work the best is with the fittings upward with the bottom of the IC resting all the way down on the bottom of the bumper cover.  I had to run the output of the turbo under the motor, but then the outlet of the IC is about a 10" mostly straight shot into the KH throttle body.  It is important to me to keep this car a "Sleeper" so I don't want to change the bumper cover.  It is a very tight fit.  After removing the center section of the front sheet metal of the car I only replaced the upper half of that part in order to latch the hood and hold the grill.  The lower half is fabricated to hold the IC and tie the front end back together as well as connect to the front motor mount.  This little sub frame connects to the bumper shock mount bolts as well as the sheet metal in a few places.  With this arraignment the IC ends up about 3/8 to 1/2" away from the crank.  I think I will also have to add some sheet metal flow directors at some point to maximize airflow through the unit.

Above is a picture of the IC sub frame pre-paint..  It is bolted to two bumper shock bolts on each side and then through bolted to sheet metal on the bottom with two bolts on both sides.  It is amazingly strong. I am quite sure you could pull the car out a ditch using it.  I didn't weight it, but I think it is lighter than the intercooler itself.  It looks sort of like a brush guard, but it is invisible when the bumper cover is on.  I am fairly sure the front of the car is stronger than it was before.  I did have to put some more tack welds in the uni-body to make up for my removal of material, but it is quite stiff now.  I also had to put one aluminum diagonal strap behind the drivers side headlight to strengthen that side for hood closure.  It is now very solid.

Above is a picture of my front motor mount.  There was no room for a factory style mount with this larger intercooler.  I cut over half of the stock mount off.  Since the center is a hole I ran a bolt through the hole and used a Rabbit rear shock washer as a clamping surface.  I used a pair of rod ends and made a small connection piece by welding two nuts to a steel sleeve.  So far I have noticed a vibration at idle from the front stainless strip on the bumper.  I don't have all the fasteners for this piece and that may be making it worse. I am going to make something up to hold it better and I hope that will stop the buzz.  Either way you can't hear it from the drivers seat just if you are standing right next to it.  When driving it is very smooth.

For this first stage I don't have an A/C compressor installed. I already have sketched up some mounts, but I did not want to delay things any further.  I will probably take care of that in the spring now.  In the picture on the right above you can see how tight things are even without the A/C compressor.  I had to make some coolant hoses to fit around the IC piping.

Another issue that had to be dealt with was the clutch.  My donor motor was an automatic.  My stock clutch has never slipped no matter what I threw at it, but I figured it still might not be up to the task of the turbo.  Most people change over to the 240 mm diameter clutch used in the turbo cars.  I decided not to do this for a few reasons.  First the clutch kits are quite a bit more money.  Second I did not have a 240 mm flywheel so there is more money.  Last the most common turbo flywheels are very heavy.  I decided to reuse my stock JT 228 mm flywheel with a high performance clutch.  The price was good compared to changing over to the 240 mm and it probably can handle more motor.  I chose to use a stage II SPEC clutch.   The new clutch is the one on the left.  The pressure plate with the SPEC kit is very similar to stock at least from an exterior view (except it is blue).  The big difference is the segmented disk.  The dark portions are lower and do not contact the flywheel surface.  Of course the material is also different.  The SPEC clutch is Kevlar if I remember correctly.  The center section of the SPEC clutch is stamped SACHS.  The reason the center sections look different is that the one I took out was not SACHS.

As discussed elsewhere on this site (and on every other turbo swap site) the passenger side tie rod won't work as is if you are using the factory exhaust manifold.  It needs to small bends in it to fit around the waste gate.  Fortunately for me my work has a 40 ton stroke controlled hydraulic straightening press that made quick work of the job.  I actually spend FAR more time fighting the rust on the adjustment bolt so I could get it back close enough to the correct length for a drive to an alignment shop.

For those who want to undertake bending the tie rod themselves here is what worked for me:

If you measure from the beginning of the round portion of the tie rod (not the cast part, but tube section) starting at the rack the first bend I had was at 2.5 inches.  This bend was towards the back of the car as the tie rod is installed in the car.  The second bend I made was at 5 inches from this original reference point (or 2.5" from the first bend) and this was the same degree bend just back towards the front of the car.  What you end up with is the outboard portion of the tie rod is parallel to in the inboard portion, but offset.  I think mine is offset about 2" and comes very close to touching the wastegate stainless steel bellow pipe to the down pipe.  I think I might use slightly more offset if I tried it again to give a little more clearance.

I don't have a picture of it right now, but the 5kt oil cooler fit quite well in the 4k.  I removed the horns and their bracket.  I pitched the bracket.  Then I took each of the horns and drilled two holes in the very bottom of the passenger side fender under the headlight and mounted them separately there.  Then I mounted the oil cooler to an existing hole just under the frame rail under the air box.  I don't have any air ducting for now, but I plan to in the future.  The routing of the stock lines took some trial and error, but it worked out and you can still get the horizontal oil filter on and off.


Oil Cooler Update

As I understand often happens with the factory parts my oil cooler lines started to leak.  Bad.  Luckily I only lost about 1/2 to 3/4 of a quart before I caught it.  However it still made a mess of the under side of my car and my driveway.  I figured instead of trying to patch it back up I would start fresh.  

I have had a used oil cooler I bought at a used NASCAR parts store 3 or 4 years ago that was used for a time in another car.  I reaquired it and found a perfect spot for it.  The old location was out of the direct air flow.  Lowering it would have made it too close to the ground for my comfort.  So I stuffed the new oil cooler behind the grill.  It will not have the greatest amount of flow since the engine is so close behind it, but it will have a clear shot at air from the front.  Below is a shot of it mounted in place.  What remains is to make some shrouding to keep air from going around it.  The grill fits over it perfectly and there is even a bit of room left between it and the engine.  Of course now a belt change would be much harder.  I will likely paint the aluminum black at some point as you can see it a little through the grill once it is in place.

Below is a picture of all the parts.  I chose the push on Aeroquip.  It is less expensive, but still not cheap.  The hose was $40 for 15 feet!!  I paid $30 for the used Setrab oil cooler.  Including that everything pictured below came to $140 with shipping.