We have to do what?

By Clinton HulleyPorsche 917 Replica
Porsche 917 on track
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By now the Porsche 917 has done a few races. The main issue we have had was the supercharger belt that breaks from time to time. We just kept spares of the belt. If a belt brake at a race we can just swap it out. What I found was the toothed belt pulleys profiles weren’t 100% correct so it wears the belt out. We decided we could live with this and just change the belt out every so many hour of running.

To the next race

We got everything ready and loaded for the next race weekend. To this point, we have done quite a few events with the car. Its been a few years since I built the car originally. The Porsche 917 goes out for the first race, on the 3rd lap the Porsche gets a black flag.


My boss comes off the track and speaks with the marshals. They did a drive-by sound test and the car is to load according to them. Nothing has changed on the exhaust since I did the new system. The exhaust may have become a little louder due to the exhaust damping material burning out but still. The exhaust can’t be that much louder than it was originally.

The marshals indicated that the Porsche will not be able to compete until the exhaust is sorted out. This is a joke, there is just no space for fitting more exhaust boxes in the car.

The exhaust fix

The next week we sent the car to an exhaust shop and asked them what they could do to. After a few days, they called us to come to fetch the Porsche. The Porsche was a lot quieter than it was but the exhaust looked really ugly.

New Exhaust system on Porsche 917

What we decided was that we will run the ugly pipes on the Porsche 917 for the track. We would fit the “nice” pipes for the Hill climb event when we go again. There are no sound limits on the cars for the Hill Climb. The new pipes didn’t affect the power of the car, at least not what you could notice on the track. The Pipes just looked ugly.

Racing again.

After the exhaust fix the Porsche 917 went to a few race events without major issues. We did about 3 races after that and we ran into an issue, a big issue. My boss was doing the first race of the day and the car was running really well. Suddenly my boss heard a loud bang and the car started losing momentum and there is just no power. The smoke was pumping out the back of the car.


After 9 years the engine died, opening up the rear engine cover there was oil everywhere. We loaded the car up and took it back to the workshop. After inspection, we saw a few holes in the block. The motor grenade itself. Everyone just thought well the motor has lasted 9 years so maybe it was just too much.

Opening up the motor

At this stage, I wasn’t working for the company anymore but kept contact and knew everything that was going on. The guys took the motor out and opened it up. The bearings started seizing onto the crank, 2 rods were broken and one piston was missing, it was laying in pieces in the dry-sump pan. There was one valve that came loose in the head and the piston knocked it right through the cylinder wall. This engine was a complete write-off.

Building a new motor

As the company had about 200 of the VK45DE engines in stock getting a new engine wasn’t an issue. The motor was stripped down and modified for the Porsche 917. It was about 2 weeks later and the car was rebuilt. The guys started the car up and it was idling nicely. When the boss heard the engine running it was a few seconds and he was down at the car. The nose of the car was open so he could reach the pedals from the outside.

He gave the engine a blip and suddenly the engine just locked up. The engine didn’t want to turn over again. Not even by hand. The engine was seized up solid. No one checked to see if the oil light was on and that there was oil pressure on the gauge. What a big and expensive mistake.

Stripping the engine out again

So after stripping the engine out and assessing everything they found the engine ran dry without any oil. The system was exactly like the previous motor so there is no reason why there should not be any oil pressure. What the guys found gave me the reason why the first engine died after 9 years of good running. In the remote oil filter housing, there is a pop-off valve in case the filter element gets dirty. The pop-off valve would open and let oil through so the engine won’t starve of oil. What happened is the cover that keeps the spring in place came loose and the spring forced the cover over the oil port. This cut off all oil to the motor and that is why the original engine just exploded. Engines just can’t run without oil.


This is the reason why the second engine failed straight after startup. This meant 2 engines failed because of this stupid issue. As the car wasn’t going to be ready for the next race the boss had an idea. He wanted more power a lot more power. Enough is never enough…


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