The Engine

When it came time to choose the engine, I had to have 8 cylinders.  These are famous for being the beating heart of these classic mahogany runabouts.  Unfortunately, these engines tend to be expensive; especially marine V-8’s.  While researching, I found that the industry standard, Mercruiser, was not only prohibitively expensive, but overweight, outdated, and under-powered.  While looking for alternatives, I found that Toyota/Lexus engines are much more affordable.  These engines are half the weight, incredibly reliable, fuel efficient, and they make more power.  As I did more research, I also found that Toyota tried to produce a boat in the late 90’s.  While the boat powertrain was praised frequently, the boat failed due to the hull warping under speed.  Toyota canceled the project and has since stayed in the automotive industry.

Next, I found a rear-end wrecked Lexus SC430. This car is equipped with a Toyota 3UZ-FE: it is all aluminum, 430 lbs, 350 HP with 300 lb-ft of torque.  We purchased the engine, wiring harness, gas pedal, immobilizer, and engine computer.  I reached out to a Toyota master mechanic who agreed to provide wiring diagrams, parts, and advice.  Over the following three weeks, I worked to recreate the wiring harness to enable the engine to run outside of the car, on the engine stand.  This was a much harder task than I initially thought since I had to eliminate the wiring that I did not need while reconnecting the wires I did need.  I also had to find ways to “trick” the engine into thinking it was in a car.  In order to start this particular car, the car had to be in park with a foot on the brake.  To make the car start, I had to fake these signals.  I also had to find a way to bypass the car’s security system.  Each car’s key has a RFID chip similar to credit cards.  These chips have a code that authenticates that specific key to that specific car.  Without the chip, the car will not start even if the physical key is the exact same.

I also had to do preventative maintenance on the engine; replacing the water pump and timing belt.  This ensured the reliability of the engine, allowing the engine to reliably run for the next three or four seasons.  Finally, I had to replace the manifolds, radiator, oil cooler, and alternator.  Cars are air cooled; this means that water circulates through the engine, which then gets cooled by air passing through the radiator.  Boats use the water from the body of water to cool the engine and its other components.  Because of this, I had to replace lots of the stock parts with marine parts to ensure no problems occurred when the engine is placed in the boat.  I was able to use some of the parts from the Toyota boat, but I also had to modify/custom make parts that they no longer sold.

After weeks of hard work, I started the engine for the first time:

There were initial throttle and fuel pressure problems, both of which you can hear in the video: the throttle isn’t responding correctly, even though I am moving the pedal.  Shortly afterwards we fixed those issues, the engine has started reliably ever since.  After the initial success of the engine start, I took the engine to school to give a presentation on the work I had been doing.  I presented the engine by strapping it to the back of a pickup and driving to school so I could show my teachers exactly what I had been working on.  This is the test startup from that morning:

Since then, I have fabricated motor mounts, aligned the engine and dropped it in place. I have rewired everything so that the wiring fits properly in the boat, and the engine runs reliably.