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Tech Series: New Wave 1.8T Swap Part III

In the first two articles, I explained how I’ve come up with a much easier way for swapping a 1.8T into an earlier Volkswagen, and how and why I bought a 1997 Jetta GLX in which to test my new set-up. Yes, the 1.8T can now be installed without the painstaking process of having to cut, splice, and solder in either a standalone or factory injection system with an immobilizer to get around. Think, “Plug and Play”.

Now that I had a test car to put a 1.8T in, I needed an actual 1.8T. Instead of just buying a complete 1.8T engine to start with, I decided to build one from all of the spare parts I’d been collecting forever. This seemed like a fine idea at the time, except that I had too many parts and nothing fit together. For example, I had a Mk4 1.8T block and head, but no Mk4 accessories. I also had most of the Mk3 2.0 accessories, but no 1.8T block on which they would fit. After chasing my tail for a while, I decided on what I thought to be at the time the lesser of two evils (read: cheaper), and bought an AEB block from an Audi A4 with which I could use the 2.0 accessories and the Mk4 20v head.


Side Note: For anyone looking to do a swap, just spend the money up front and buy a complete motor from square one, it is definitely cheaper and easier in the long run – everyone I didn’t listen to along the way was right about that.

The supposedly good running, low mileage AEB bottom end I bought turned out to be bad. One cylinder wall had pieces of the piston skirt embedded into it, on top of three spun rod bearings, and heavily scored main bearings. Needless to say, it was better suited as a boat anchor. After some arguing with the place I bought it from, they gave me another one that ‘just needed a hone’. Well, I got the second engine apart and everything looked fine, except for the cylinder bores that ‘just needed a hone’. The engine must’ve sat with water in it at some point and the cylinder walls had become a bit pitted. I tried honing, but the pits were .0015” too deep, and the block needed to be bored.


By this point I was fit to be tied, and took it as a sign to order up a set of oversized Wiesco forged pistons, pins, and moly rings. I had everything a couple of days later and dropped it all off to my machinist, Golen Engine Service in Hudson, NH. Chad, the owner, called a week later to let me know I could pick up my balanced, bored, and blueprinted bottom end. I wasn’t taking chances at this point, so I also had them put together the rotating assembly (pistons, rods, and crank). They have a much more accurate way of measuring clearances than I do, so I knew everything would be ‘just right’. I also had them lighten and balance my clutch and flywheel for good measure. I figured I had gone this far, so why not? I didn’t have them take too much off of the flywheel because I built this car to drive and didn’t want the revs fall off too quickly, making it unpleasant to shift on the road.

The bottom end went on my shiny new engine stand as soon as I got it home. Since I never had a complete motor when I started this project, I had a lot of parts to buy. The advantage to this though, was that it gave me the flexibility to buy exactly the right ones. I wanted a conversion that looked like it could’ve come in the car originally. I ended up with an AEB bottom end, combined with an APH head from a New Beetle, a turbo and related manifold and downpipe from a newer Mk4 GTI, all Mk3 accessories, and a list of other miscellaneous parts that seems to go on forever. Everything on the motor or related to it was either new or rebuilt including the alternator, starter, clutch, all gaskets, seals, etc. and they all went together flawlessly. This was all done so I didn’t get stuck somewhere with something that was broken and should’ve been replaced when I did the swap… so it was built like new.

Now that I had a car and a 1.8T motor, all I had to do was combine the two…

I was pretty much waiting for the death threats to start rolling in when word got out I was un-swapping a VR6 and installing a four cylinder in its place, but it was surprisingly well received. I basically just carefully removed all components unique to the VR6 driveline (engine, trans, ECU, ECU harness, and cluster) and got ready to install the 1.8T.

With the motor assembly almost finished and the VR6 out, I moved on to cleaning the engine bay. The car was a daily driver from when it was purchased new in 1997, and had never had its engine bay washed before. I hosed it down with soap and water, then hit it with a good wax and grease removing solvent to get all the grunge and grime off. I also cleaned the suspension, subframe, steering rack, etc. I did the best I could, and when I was happy with the way it looked I put on a couple of good coats of wax.

Six weeks after I started, the engine finally went in, followed by the transmission a few days later. It seemed like up to this point everything that could go wrong had gone wrong. For example, I couldn’t put the transmission in because I didn’t have the correct dowel pins to line it up on the back of the motor properly (they were removed to machine the block). I had to wait for the dealer to order them and when they came in they were the wrong items, so a reorder was necessary. Once the correct ones came in, I went to put the flywheel on the engine, but then realized I had the wrong shield between the engine and transmission, so I again had to wait for the correct part to come in. There was a lot of trial and error to get all the correct parts, but the end result was worth it.

I decided to use the stronger 02A transmission because my Jetta was originally a VR6 car with the correct cable shift linkage and clutch hydraulics already there. I also found one with a 3.94 ring and pinion from an early 16v Passat, so that made my decision easier. I used all original 2.0 engine mounts, but since I used the 02A transmission I had to use a Mk3 TDi front motor/transmission bracket. The Mk4 turbo, manifold, and downpipe cleared the firewall with plenty of room to spare, and I even kept the stock VR6 exhaust by just trimming a few inches off of it.

Now, since I designed the system to work in place of a stock 2.0, I had to find and install 2.0 parts under the hood. The VR6 stuff had already been removed, so I installed the ECU, ECU harness, engine harness, cluster, and cluster harness from a 2.0 Mk3. Instead of swapping a VR6 into a 2.0 car, I did the opposite, but with a 1.8T in place of the 2.0. After everything was in its place and connected, I did some testing and it all looked like it was going to work. All there was to do was build some oil pressure, check for leaks, and try to fire it up for the first time. With a little luck, and some help from Chris and Jeff at C2 Motorsports, it would run… And it did on the first try – perfectly.

Next week I’ll show you exactly what makes this swap so easy and so revolutionary.

Parts I & II of this series can be found here:

New Wave 1.8T Swap Part I

New Wave 1.8T Swap Part II

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