Swapping a V8 Into a Toyota MR2

Note: This is the first in a series of articles on the subject.

For many years I have dreamed of owning a motor exotic supercar. Unfortunately, they unfortunately remained out of reach of me. I decided that the only way I would get one was to build it myself. I have always been fascinated by mid-engine sports cars because of their superior handling, braking and traction over a front motor sports car – even the front motor axles with rear axle shaft, which has a presumably optimum 50/50 weight distribution. I like to call them "dumbbell cars" because their weight distribution is like a dumbbell – heavy at the ends and light in the middle. This is definitely suboptimal for acceleration, handling and braking.

Compare this with a motor car, if you were to make a dumbell look like the mid-engine car, the weights would slide to the center. Now, if you want to make the dumbell or engine car rotate about its vertical axis (called "yaw" in aircraft terminology), it will make it much easier and faster. This is because the tire does not have to overcome the inertia that a front engine / rear axle would have over each end of the car. The result is that the car will be able to change directions faster and with less tire wear. The top G forces will also be much higher in an engine by car, which means that it is faster around the corners. The rear wheel when accelerating is superior, as more weight is on the rear wheels. It is strange that there are many "side effects" advantages of middle cars that the car press does not mention.

Some examples:

1) Exhaust pipes are usually very short in a motor car (compared to a front engine car), so the engine must overcome less "pump losses" or the resistance to the exhaust pipe that goes out into the tail pipe. That means more power. The exhaust system will also be easier because there is less of it. Dumbell cars have no advantage here.

2) The rear brakes make a lot of the stop against a front engine car. When braking, transfer the weight to the front wheels. This means that the rear wheels are released. The front brakes on the front engine make about 80% of the stop. That's why disc brakes on the back took a long time to catch on. They simply aren't needed behind them. A mid-car has much more weight (usually about 55 to 60%) on the rear wheels. When you hit the brakes, weight transfers forward, so during braking, can get 50% -60% on the front. Dumbell cars get some of the help that the average motor car gets, but not so much, because the engine is still ahead and still heavier than the trunk on the back.

3) The mid-engine car has no drive shaft (unless it is an AWD car, like R8 or Veyron), so there is a weight saving here.

Unfortunately, most mid-car cars are very expensive. Ferrari, Lamborghini, McLaren, Zonda, Koenigsegg, Bugatti and so on. Some of these cars are over a million dollars! Mid-engine cars also tend to be harder to work with. Switching spark plugs to the exotic is a major operation. McLaren F1 requires engine removal to replace plugs!

Within rich affordable vehicles with medium engines, Pontiac Fieros is available and there are Toyota MR2s. In any case, the cars came with 4 cylinder engines. Fieros also got V6, but the V6 players were very underpowered, with a whopping 140hp. In 1990, Toyota MR2 redesigned and upgraded the power as well. The base models got 130 hp and the high-end turbo was 200 hp, which was then quite a car that weighed 2700 lbs.

The new body was very nice, much like Ferrari 348 at the time. The building quality was also superior as it was after all a Toyota. I decided to buy a 1993 Toyota MR2 turbo in 2005 with the intention of making a Toyota V6 byte, so far made by many people. At about the same time, I found that there were some attempts to install a V8 engine in the previous MR2 (Generation 1, 1984-1989 body style or ground 1). It also tried to install a Toyota / Lexus V8 engine in an MR2 mark 2. Attempts to make V8 in the MR2 mark 2 were not completed and the project owners gave up. The reasons were not clear, but it seemed to be because the Toyota V8 was simply too long to fit into the car across, even after cutting the car hard in an attempt to make it suitable.

As a mechanical engineer who happens to be a motor traffic nut in the middle engine, I was fascinated with the possibility of putting a V8 in my MR2 mark 2. With a strong V8 engine, MR2 would be transformed into a supercar with supercar performance. The Fiero guys have been happy to change V8 in their cars for many years. Fieros have an advantage over MR2s, because their engine compartment is wider which allows a larger and longer engine, like a V8. Fieros and MR2s all have transversely mounted motors. Another advantage that the Fiero guys have had is that the Getrag Transaxle log bolts up to a Cadillac 4.9 L OHV V8 from the late 1980s / early 1990s. The latter Cadillac Northstar also bolts up without an expensive custom machined adapter plate.

At the end of 2007, another V8 was supplemented in an MR2 badge 1 (1st generation) by a guy in Europe. The car was crazy fast and would make cakes on a drop of a hat. How fun! So I took another hard look at previous attempts to install a V8 in the MR2 mark 2. What I realized was that they were trying to "keep it in the family" and using a Toyota or Lexus V8. There were not really any technical reasons to use this power plant. There was no MR2 switch, and it was too long. The used Toyota V8 (engine code 1UZ-FE) is about 26 inches long from the crank disc to the rear of the engine, or the bell housing interface. This is the critical dimension. Compare this to layers of MR2 engines such as the 2.0L 3S-GTE turbo engine that has a critical dimension of 20 inches. This dimension is critical as it fits between unibody pseudo-frame rails in the MR2 chassis.

I decided to take another approach. I started searching the internet for a V8 engine that would fit the MR2 chassis, preferably without cutting, or possibly with only a small cut of MR2 unibody. My requirement was that it would be a V8 with at least 300 horsepower, that it was available, that it would cost somewhere below $ 5000, and that it would be short enough and narrow enough to fit MR2. I managed to find one. Audi has an interesting habit of making very short V8. They do this because they want to use their Quattro driving train, but at the same time they do not compromise on handling too much. Audi seems to prefer longitudinal transverse engine and transmission arrangements. The quattro drive includes a driven front axle, which they must locate behind the engine. If the motor is too long it puts too much weight in front of that shaft, so they compensate with a shorter motor. This has the added advantage that Audi can install this engine in smaller cars that were originally designed to have a 4-cylinder power plant. For my purposes, I found that the Audi V8 engines 1991 through 2000 years are about 20.6 inches long at the critical dimension and about 29 inches wide, not including the headings or other easily removed items.

I bought a 1997 Audi 4.2L V8 (engine code ABZ) and a transaxle and started working on my project. Unfortunately, after much effort and error, I finally decided that the Audi V8 was not suitable for this motor swap. The problem was that the engine was always designed to be longitudinal. In my case, with a transverse layout, the right shoulder had to run along the side of the engine, and Audi did not design the engine with it in mind, so there are large portions of the block in the way of that axis. The starter motor, oil filter / cooler and engine mount are also on the road on that side, but I solved these problems. The nail in the Audien's coffin was the adapter plate. I decided that the adapter plate required some of the mounting bolts to be located inside the clock housing of the 6-speed shaft that I used, so it was impossible to tighten them. At that time I decided to change my approach and use another engine.

Please keep up-to-date for the next in this series of articles.