The build of the Porsche 917 was going really slow. Didn’t get much time to work on the car. It was time to get the body fixed up. This was the most damage we have ever seen on the Porsche. We were lucky in the sense that we still had the mold for the back end of the Porsche. The problem was with the front of the car. I had a guy at work that was really good with fiberglass work. I took him to the car and showed him everything that needs to be done. He recon he could fix the back end without making a complete new cover. That was good news as I was battling getting resources to help me with the car.
Severe damage on the left hand side of the body, multiple cracks an body crushed on the side.
Fixing the back cover
Johan, the guy helping me with the body work took the back cover of the car and cut out the damaged section. He then put the cover back into the mold and marked out with a marker pen what section of the panel he is going to need. He took the back end out of the mold and then the magic started. Johan did a layup of the panel that he just marked out. He made the panel so that it is the same thickness as the original body.
New section kept in place with wooden supports fitted with hot glue.
Johan turned the cover upside down and used a grinder to grind a lowered section all along the join line, it was approximately 30 mm to 40 mm ether side of the join line. He cut glass fiber mat strips on the width of the lowered section. He glassed the bottom side, you could just see where the join line was. Once the fiberglass was dry he turned the body around. Once again he did the same thing and glassed the top side as well. Now Johan used some body filler to smooth the section out. He put the filler on nice and thick to that he could blend in the new piece of body nicely.
The repaired body with the body filler.
Now the time consuming part started, Johan had to sand down the complete back end. The body had some issues from a previous indecent that also had to be sorted out.
My words to Johan and everyone that helped me with the car was “This car must look like a 2 Million Rand car when it is done”. Everything has to be perfect.
Back end of the car after sanding.
Fixing the front
This was a bit more challenging than the back end of the car. There was no mold for this and everything had to line up properly. The left hand section of the nose of the car was hanging by a thread. There was really bad cracks on a big section on the side that didn’t keep its shape. It was soft as the section was crushed. Johan worked out a plan to get it fixed up. When he was done with the front of the car you could not tell that there was any damage.
The front body with the first layer of primer.
Johan had the structure of the car fixed, now it was fixing small pinholes and small marks. Like I said the car must look great.
Fitting the body back on the chassis
The moment of truth arrived, the body had to go back onto the chassis. The previous time the car was fixed after a crash it was only the back end that was fixed. The problem was that something did shift but my boss Mike wasn’t to worried about that. You could see on the door fitment that the gaps wasn’t great. The doors did there jobs but they just didn’t looked great.
We carefully put the nose on the car and started to fit all the mounting bolts. Nothing was tightened at the stage. We needed to see if the body is sitting straight and if not try to fix the issues. After some time the front was sitting like it should and it was once again bolted down. We fitted the back end of the car as well to check alignment and gaps.
Body back on the chassis.
It was a great feeling seeing the car come together. I was really great full that Johan was doing such a great job at fixing the body for me. I was getting some negative comment from some of the people at the company. They said why am I spending so much time fixing this car. It is not like Mike is going to race it again. You are not getting paid for this why do it. I said “I am doing this for Mike, he was not just a boss but also a friend”.
Fitting the doors
The doors went onto the car and that looked crap. The doors just didn’t want to sit properly. Fiberglass is a funny material. If it is kept under tension and in a hot environment it will change its shape. That is what happen with the Porsche. After the crash the car stood a few days before we started stripping the car, the doors was under tension as the body moved.
Johan had to cut the doors and get them to sit properly again. He also had to fix the gaps of the doors at it was just not right. The gaps was huge in some places and small in other. We had to adapt the doors to fit in with the body again.
Getting the doors to sit properly again.
Getting the gaps sorted.
Body ready to paint.
The Porsche was staring to look like something again. Johan’s work was done on the Porsche 917. The car was looking great. I was getting really exited to see that car back in black.
Porsche 917 almost ready for paint.
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It was about a month before I got a proper answer on what is going to happen with the Porsche. Everyone agreed with me that the Porsche will be worth more in one piece than what they would be able to get for the components. I had to put a list together of all the damage parts to get a quote.
Chassis wise there was a few damaged components. As this was a proper rebuild there was no taking short cuts. If something was damaged in the crash we were replacing it with new components. I got the quote from Bailey cars and it was pricey. The CFO asked me to split the parts up in 3 groups so we could order it over the next 3 month. I didn’t need all the parts at once so this suited me fine.
Front wheel suspension parts that was damaged.
I found a small crack in the one rear upright and this ended up being a very expensive part. This was a billet machined unit made from 7075 grade aluminium.
Upright that was damaged from the accident.
Allot of time passed before I had enough bits to start with the rebuild. My main goal was to get the car back on its wheel. This just makes it so much easier to work with the car.
So the build starts.
I got all the suspension mocked up and everything seemed to be sitting in the proper place. I measured up all the mounting points and everything was sitting in an acceptable place. Next up was getting the rear frame of the car in place and welded. The frame was build by Bailey cars but the mounting flanges was left off as those had to bolted onto the car to get the alignment correct and then welled to the frame.
Getting the rear frame to fit.
This was a really slow build as I only got about 2 hours a day that I could spend on the car. I had a hour before work and then my hour lunch time. It felt like this was never going to be done. I just had to get the rear frame done so that I could send it out for powder coating. One that was done the car would look more complete.
I think Mike would have been proud in the way we were rebuilding this car. This was going to be the best build ever.
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One of the first things normally gets done to modify an engine is fit a performance cam. One of the things that goes together with that is a Vernier gear or pulley. With the vernier pulley on the cam the cam can be setup to what ever the the driver wants. You can advance the cam and you will gain power at the top end loose low down torque. If you go the other way and you retard the cam you gain bottom end torque and loose top end power. This has always been that case with racing engines. The cam(s) has to be setup to what the driver of the car needs.
Typical vernier gear
Variable Valve Timing (VVT)
Over the years the car manufacturers was looking at making the engines more efficient. Fitting vernier gears on cars as a production part just doesn’t make sense. The question was if they do what do they set the cam too. Power or Torque.
The best would be of they could have an actuator of some sort on the cam that will allow the ECU to swing the cam form max torque to max power. Initially the VVT systems was on\off systems like the ones that Honda used on there Vtec engines. This gave them the ability to gave torque at the bottom while making power at the high revs they run.
There are a few ways that the manufactures achieved fitting VVT on there engines. One of them was to fit an actuator on the cam itself.
Typical VVT actuator
Volkswagen used a different solution on there 20 valve engines. They had a cam bet pulley sitting on the exhaust cam. The crank would turn the exhaust cam. The intake and exhaust cam was linked with a chain. Between the two chain sprocket they had a chain tensioner. This tensioner was the VVT actuator as well. While maintaining the tension of the chain via oil pressure, it could also move up and down with a solenoid unit. This meant they could tension the one side of the chain more and this would cause the intake cam position to change relative to the exhaust cam.
Volkswagen 20 valve VVT actuator
With most of the on\off VVT systems you could hear a distinctive change in sound as they revved up. The change in sound was when the VVT shifted over.
Closed loop VVT
Your normal on\off VVT is open loop VVT. The ECU switches the cam at what ever RPM it was set to. The manufacturers went a step further. With the emission laws that is getting stricter they needed to find a way to make changes anywhere in the MAPS without the driver noticing the changes. This is were closed loop VVT came in. Every cam on the engine would have a sensor on it. The ECU would monitor the cam position through out the rev range. It would follow a map on the ecu and try to reach the value. The Actuators is pulse width modulated. This means the cam has a constant 12 colt on them but the frequency varies. By changing the frequency(The time the 12 volt stays on) the cam would move. On the ECU terms they talk about duty cycle.
If the duty cycle is 0% the actuator would be completely off. If the duty cycle is 100% the actuator would be on all the time. Some of these actuator can’t run 100% duty cycle as over time they would over heat and burn out.
What the manufactures also did is they increased the range of the VVT actuators. So if the lock position of the cam is the fully advanced position the the cam is past its optimum point. The same counts for the fully retarded point. So by using these VVT systems as on\off VVT does not bring the potential of the engine out. You have to run closed loop on these engines. To give you an idea, if the optimum power is at 110 Deg Cam centers on the engine then the rest position could be at 125 Deg, That is 15 Deg past the optimum. Power would have dropped off dramatically.
V & Boxer Engines with VVT
On V & Boxer engines it becomes a bit more difficult. If you want to run a aftermarket ECU you will have to get a decent one. These engines need close control outputs for each cam. You can’t use the same output on the ECU and share it between two cam. Because of where the cam is in the cycle and different friction between the cams the duty cycle will vary. You have that one intake cam needs 50% duty cycle to move to a certain angle while the other needs 55% or even 60%. So if you drive the two cams of the same signal the cams would stand at different positions. One bank would make nice power and the other bank would be off.
It would also cause that one bank would be running richer or leaner than the other causing you to through even more power out the door. So each cam does needs is own closed loop system using its own sensor for positioning. The two closed loop systems can only share the target position map.
Engines with modified aftermarket Cams with VVT
When building race engines that still uses the VVT system stuff can get interesting. Some times you find that when you retard the CAM you will reach the end stop of the actuator and the torque has not started to drop off. This means you could fit an after market actuator that allows you to retard the cam even more. You have to be careful though. As normally the valve to piston clearance is very close. You would have to check that you have deep enough valve pockets on your pistons to achieve the proper angle.
Some people do modify the standard actuators to reach the angles they need to. Your are very limited though on what you could reach.
Areas to machine to achieve more angle
When doing mods like this you need to make certain that there is enough meat for the metal seals to function properly. Also like I mentioned earlier that the valve to piston clearance allows to do that.
So what is the difference between VVT and VVL
VVT is Variable Valve timing where VVL is Variable valve lift. This is just a way that the manufactures get the engines to be super light on petrol and give good emissions results. One again there is many ways to achieve VVL. Volkswagen has an setup that there is two lobes next to one another. The one lope is a low lift lobe and the other is a high lift lobe. They have an actuator that will move the cam from side to side. So on low throttle positions they would run on the low lift cam that will allow a small amount of air into the cylinder. Doing this you need less fuel.
When acceleration and you are at a higher throttle position the cam would move so that the high lift lobe is in use. Now it allows more air to enter the cylinder which need more fuel fuel and makes more power. These type of systems is on\off systems as it is either the one lobe or the other.
Over the years running high performance cams engine got heavy on fuel. with all this new technology you could have the best of both worlds. Light on fuel and powerful.
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As we blew the radiators at the previous race it was obvious that the 2 radiators was to small for the 700 Hp beast. The problem we had is we could not get more air to go through the radiators. The only solution was to get bigger radiators. I had to maintain the coolant flow rate trough the system. I only had to get the coolant to spend more time in the radiators. This way more heat would be rejected by the radiator and cooler coolant will flow back to the engine.
This is 1 of the 2 old radiators on the Porsche.
After some phoning around I found a supplier that was willing to do 2 custom radiators for us. It was very pricey but it had to be done.
The new radiators
We had to change the design of the radiators as we could not change the space the coolers had to fit in. We reduce the tank size which meant the cores was about 40 mm longer. There was space to go slightly wider so there we gained about 30 mm. The area that we gained the most was on the thickness of the core. We went from a 40 mm core to a 50 mm core. The 2 radiators together was substantially bigger.
New Radiator with new mountings for the Porsche 917
Fitting the radiator was the easiest bit. What was a time consuming job was to get the new radiator cowls that I made a few weeks ago for the new fans to fit on the bigger radiators.
New cowls and fans for the old radiator.
After doing some design work, getting the parts laser cut and allot of grinding and welding I got the new cowls constructed and fitted on the car.
New radiator fitted with cowls and fans
Everything fitted like a glove. At this stage of the fight I fitted a extra Jabsco water pump to the system. We were running 3 pumps in parallel. I did a flow test on the engine and could not see an increase in water flow with the extra water pump. As the 3 pumps was in parallel they were fighting each other for water. I added a tank in the car so that all three pumps get an equal chance to pump water. With the 3 pumps piped up like this I got round about 160 Liters a min. I would not be able to improve that without changing to other pumps. The cooling system was done.
Checking out the motor
Because the engine ran so hot and blew the radiators I was worried that the engine my have gotten damaged. I did a full compression check on the engine. Everything thing looked fine. I let the car idle till it was at working temp which is 85 Deg C. I re did the compression check and it was still good.
Once again we were ready for the track.
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I just started back at the company after working at another company for 3 years. Mike was so glad to have me back and he was more into racing than ever. The Porsche 917 has been out for a few races after the upgrade to 700 Hp. The car was very problematic. It hasn’t finished one race. The car kept breaking down. If it wasn’t the one issue it was the next.
One of the issues the car had it kept on shredding the supercharger belt. It was so bad that the belt won’t survive one race weekend. Mike entered another race but this time I was going as well. I just needed to see what is going on with the car. Testing the car at work and testing the car at the track is completely different.
So we got to the race track the Friday. We were just in time for afternoon practice session. The car was running well and there seemed to be no issues. Later the car went out again for qualifying and the car came in again. When getting to the garage Mike said that the oil light come on when the revs goes to low and then go off again as the revs pickup again.
This didn’t sound to good. I checked everything I could check and everything was fine. I added a bit of oil to the drysump system and the car was ready to go out again.
The next day arrived and we were all set and ready to go. It was race time and the Porsche went out. The car did a few laps and then we saw the yellow flag go out. We wondered what was going on. The green flag went out again and the race continued. The issues was the Porsche wasn’t between the car.
The race ended and the Porsche was towed to the pit garage. The oil light came on during the race and the the car lost power. We loaded the car and took it back to the workshop.
Inspecting the car
Back at work we started looking at what the issue could be. It turned out that the standard adapter that sits on the crank that turns the OEM oil pump broke and the pulleys stop turning, This stopped all the pulleys turning. The oil pump, supercharger and alternator all lost drive. That is why the dash lit up like a Christmas tree.
Broken adapter next to standard adapter
Crank without adapter
As a piece of the adapter had broken out that was still inside the engine. The engine had to come out. We had to inspect the engine to see if everything is ok and then get the broken piece of adapter out the crank case. Upon stripping I found that there was way to much free play between the supercharger lobs and the drive pulley of the supercharger as well. There was a plastic drive disc in the nose of the supercharger that was completely disintegrated. This was because the supercharger did not have a bypass valve. The breakage of the crank adapter was also because the wasn’t a bypass valve on the supercharger. The load on the everything was just way to high.
With the 50 mm tooth belt we were running there was no forgiveness in the system and the crank adapter and drive disc in the supercharger was seeing all the loading when coming off throttle.
Oil pressure issue
I also decided to take the Moroso oil pump apart and see what the condition of the pump is looking like. I found 2 issues with the pump, there was a seal between pressure side and the scavenge side that was damaged.
Damaged oil seal.
The other problem I found was the pump was badly worn. There was about 0.15mm clearance between the sides of the rotors and the housing. The clearance should be 0.05mm, if it is more than that then you will loose oil pressure. When the oil is cold and thick the pressure will be fine but as soon as the oil is on temp the pressure will drop out of spec. This is exactly what we were seeing.
Starting with the fixes…
My first priority was to get the Moroso pump up and working again. I ordered the new seal with spares from Moroso as I could only get the seals from them. I got the machine shop to machine the pump housings to get the surface true for the rotors to run against. Next I made a steel disc the diameter of the pump housing and got is surface ground to a flat surface. I used this disc with fine valve lapping paste to lap the housing surfaces. After that I used some Autosol to get a smoother finish. This was very time consuming but this needed to be right.
I measured up all the stages and got the pump clearance on all the stages to be 0.05 mm. After washing everything I assembled the pump with the new seal. I through some oil down the ports of the pump and turned it over by hand. The pump had a nice and tight feel to it. The pump wasn’t sticking it just felt right.
Next up I designed a new adapter for the crank. As we were running an external drysump pump we didn’t need all the detail on the adapter. The adapter was now going to be a steel billet part instead of a cast steel part.
Design of new crank adapter
Fixing the belt issues
After some investigation I found a issue with the steel supercharger pulley. The pulley didn’t machine very well due to the fact that the steel is very hard and a small cutter had to be used to cut the pulley. I check this on a previous pulley setup we had on the shelf that we used for the development of the engine. The belt did not naturally sit nicely in the grooves. The belt had to be stretched into the grooves.
Machining that did not work out right.
I ended up redoing the profile and added in some more clearance so that we could re machine the profile so that the belt could sit properly in the groove by itself. Having to have had pulled the belt into the profile will cause excessive wear on the belt and cause it to prematurely fail.
Well machined pulley.
Now for some updated
As we had issues with stuff breaking due to not having a bypass valve on the supercharger I made a plan. We just needed one and I was not going to take no for a answer. I designed the parts needed and ordered everything. Some of the parts we could make in our own machine shop.
Bypass valve with actuator
It was round about this time as well that my boss designed a now intake housing for the Supercharger as the one on there was restricting the air flow into the charger. I adapted his design to take the bypass valve. The setup worked out very nicely.
I decided that while everything was open now that I would do some extra mods, this is a race car so every bit counts. I had a look at the charger cooler setup on the engine. This how it was designed for production engines. It had to be a easy machining operation.
The standard Charge cooler on this engine
I got the machine shop to machine round on all the edges so that there is no turbulence over the sharp edges. After that I polished the casing around the aria were it was machined to have a nice and smooth transition area.
After casing was machined and polished
I also checked out the height between the cooler cartridge and the base plate, I found that the cooler was running to close to the base plate. At higher air flow this could cause a restriction. So I made a spacer flange to lift the cooler up by 10 mm. This would give the more than enough area for the air to flow through.
Cooler housing on top of the base plate.
There was another thing I noticed. The guys was running 2 K&N filters one on each of the throttles. The were not looking that good. It almost looked like the filters was sucked in. I calculated the volume of air this charger pumped at 7000 RPM. What I found was that the 2 filters could not cope with 41250 liters of air per minute. The filter was choking the engine. When we ran the engine on the dyno we didn’t have any filters on the engine as it was a clean environment.
I found 2 big cone filters from BMC that would do the job. All I had to do was to make a box that would connect on the 2 throttles and the the 2 throttle will share the 2 filters. Space was my biggest issue but everything worked out well.
Big filters for big charger
Now that all the issues was addressed the engine could go back into the car.
Ready to race
The engine went back in and everything connected back up. On startup the oil pressure was nice and high and as soon as the engine got to temp the pressure still remained high. I was happy, they engine sounded healthy. We were once again ready to go race.
At the next event the Porsche 917 went out for qualifying, the car ran really well.
Porsche 917 Replica - Qualifying session - YouTube
The 917 doing its Qualifying for the race.
The car ran really well the whole weekend. The Porsche finished a race for the first time since the new motor went in. When Mike got back to the pit garage with the car he said that he had to though water in the cooling system when he came off the track, The coolant gauge was standing on 130 deg C. We opened up the back end of the car and the one radiator was blown up like a balloon. The one tube had a hole in it. The car ran a bit hot and build up to much pressure and blew the radiator. Well at least we finished the race. We could not expect the cooling system to cope with all the extra power.
The Porsche 917 went back to the workshop so we could see what we could to to make it cope with the extra power.
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My Ex boss Mike, through another new engine in the works. The issue with the remote oil filter housing was sorted out and all the pipes has been cleaned. At some stage we bought Whipple W200AX supercharger for one of the engine projects at work. When we got the supercharger it was physically just way to big for the engine. The supercharger ended up on a shelf and almost forgot about.
I got a phone call from Mike, he asked me what ever happened to the bigger supercharger we bought. When I left the company that was one of the things I put in his office. The charger stood underneath my desk for months. One of the guys at work found it in the graveyard. The graveyard was a section in the building that all the old parts of project went to. If you needed something for a prototype or for a project you could go in there and look for stuff.
The Supercharger was still rapped up as the day I left the company. One of my good friend was assigned the job to make the supercharger fit on VK45DE. This was a full custom one off job. He cut a set of supercharger casing up for this build. He used the intake runners and had to do some mods to them to make the charger fit between the. It wasn’t long and they contacted me to design new drive pulleys for the supercharger and crank.
Getting the build ready
I got a call from Mike, he asked me if I could come through and assist with the mapping of the engine. The aim with this engine was to get 1000 Hp. This was a tall order as the engine still had standard rods and pistons. I told Mike I would try and get as much power out of the engine as I can.
Mike trough a spanner in the works. He wanted to use the new ECU’s that they were getting from a new supplier in Sweden. The company was called NIRA. We have been using there ECU’s for a while and I knew my way around the software.
Supercharged VK45DE on the engine dyno.
So let the tuning begin
It took me a good few hours to get the ECU setup before we could crank the engine. The Supercharger was bigger, we had fitted a 4 bar map sensor on the car as well. It has a set of 1000 cc injectors. Everything was different from what we have run before. Eventually I got the engine started. You could hear that beast of a charger from far away. To give you an idea of the physical size difference here is a comparison.
Left is the 2.3 liter supercharger the Porsche had on and on the right is the 3.3 liter supercharger
To get to a 1000 Hp we would need about 2 bar gauge boost. I didn’t want to stress the system this hard. To start with I did a charger ratio that would give us round about 1.3 bar boost. I started to map my way up from Idle. The boost levels was looking really good. At 2500 RPM the engine was making well over 500 Nm of Torque. This engine was insane. At 1500 RPM the engine was making 0.75 bar boost already. Every 500 RPM the boost was climbing 0.05 bar.
Looking at this figures the engine was going to make good power. We got to 4000 RPM and the belt went on the supercharger. We were running a PK8 Multi groove belt. It looked like the belt was just not up to it. So what now?
How to fix this
I had a look at what the guys with the dragsters run, they all run toothed belts. I designed new pulleys to take a HTD 8M belt, 50mm wide. This is a serious belt on this motor now. If this doesn’t work there is bigger issues. After all the new bits was fitted I was back behind the PC mapping the engine.
I worked my way up the maps and got to 4000 RPM where the belt went last time. The belt worked great but we ran into a wall. The boost climbed all the way to 4000 RPM and the boost stabilized at 1 bar. This was unusual as a supercharger is a positive displacement pump, the faster you spin it the more it pumps. I was baffled, something was wrong. I spoke to Dustin at Whipple superchargers and he said that we had a restriction on the inlet or a big miss match of the inlet and the supercharger.
What was wrong now
What I found was when the bigger supercharger went on the guys used the old chargers inlet. The inlet was fitted with a adapter plate as the bolt holes was different. This made a step from the smaller inlet manifold to the bigger charger inlet. I phoned Dustin again at Whipple and he said that was my problem. Air does not like to bend. At slower air speed it does bend. As soon as the air speed goes past a certain point it just goes straight.
Air at lower air speeds. Charger filling up fully.
Blue is good air into supercharger, red is unfilled area of rotors.
In the above pic it does not look like allot less air but if you view it from the inlet side it is a different story.
Red is the unfilled area of the supercharger rotors at high air speeds.
I showed this to Mike and he said there is no time to redo the inlet of the supercharger. I must finish the mapping so that the engine can go back into the car. He just wanted to race. I must see what I can get with the setup as is. I told him that they still needed to fit a bypass valve to the supercharger as there was non. He said he doesn’t need one and don’t want one.
The Maximum boost that I was seeing as 1 bar of boost, all the way from 4000 RPM to 7000 RPM. It was a bit annoying as we know what the issue was but could not fix it. The engine ran really well. We didn’t have any more issue for the rest of the mapping session. We ended up getting 700 HP and 850 Nm of torque with this engine. Mike was extremely happy with this. I knew it could go more but thought we could fix this at a later stage.
Supercharged Nissan VK45DE - YouTube
Supercharger VK45DE engine on engine dyno
I did some acceleration testing on the dyno to make certain the engine is running the best it could. This was a beast of an engine and I just could not wait to see this engine in action.
Engine going back in
It was about 2 days later and I got a call from the guys at the workshop. The Engine is in the car and ready to start. I went through that evening to go setup the engine in the car. The throttles and pedal had to be calibrated. I also had to sort out a gremlin or two.
It was good to see the car back together again. I was still light outside so I took the car out onto the apron for a quick test. This car was insanely powerful, the car actually scared me. It could be because I haven’t driven this car in a good while now. It was fun though to get the adrenaline pumping.
One thing I did notice something. When you start braking coming down from acceleration the car felt like it was still under power for a few seconds. This was due to the fact that there was no recycle valve on the engine. The boost had only one way to go and that was through the engine. This was not a ideal setup but Mike was happy with this.
The Porsche 917 was now once again ready to go race.
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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 brakes at a race we can just swap it out. What I found was the toothed belt pulleys profiles wasn’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 hours of running.
To the next race
We got everything ready and loaded for the next race weekend. Till 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 my have become a little loader due the the exhaust damping material burning out but still. The exhaust can’t be that much loader 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 a exhaust shop and asked them what they could do to. After a few days they called us to come fetch the Porsche. The Porsche was allot 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 is 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.
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 a 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 load bang and the car started loosing 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 every where. 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 to much.
Opening up the motor
At this stage I wasn’t working for the company anymore but kept contact and new everything that was going on. The guys took the motor out and opened it up. The bearings started seizing onto the crank, 2 rods was broken and one piston was missing, it was laying in pieces in the drysump 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 second and the 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 or tow and suddenly the engine just locked up. They 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 allot more power. Enough is never enough…
So one day my boss calls me up to his office. He told me that I need to get the Porsche 917 ready as we are going to the Knysna Hill climb. The hill climb is called the Simola Hill Climb of Knysna. We didn’t really know what to expect or how big the event was.
We got everything together. I didn’t know what tires to fit on the car. Will we run the slicks, or will we fit the wet tires. There isn’t much time to get the tires hot for a run and the run doesn’t last that long. It was a bit of a difficult decision to make so we took the wets and the slicks with.
Loading the car to take it to the Hill Climb.
We left for Knysna the Thursday afternoon, it is about a 5 hour drive from Cape town to Knysna. We got to Knysna late afternoon. Everybody stayed over at the house my boss had on Thesen Island. The Porsche was in tip top shape.
The Simola Hill climb is part of the Speed Festival that is held in Knysna every year. It is a very big event and it draws a big crowed of people to Knysna. The hill climb started the Friday and carried on till the main event on the Sunday.
Let the fun starts
We had to take the Porsche 917 to the waterfront for a show and shine. All the cars that was going to compete the weekend had to be on display in the parking lot of the Waterfront. There was a really big crowed of people that came to look at all the cars.
Next up the organizers told us that there is going to be a parade lap through the town. My boss told me I can go ahead and do the parade lap with the Porsche. He would be behind me with his Aston Martin DB9 and his friend behind him again with his Ferrari 458 Italia. The engines started up and one for one the cars was leaving the waterfront parking lot. Mos of the cars that competed in the event wasn’t road legal but no one cared.
The traffic department tired to control the traffic so that we could do a seamless lap without to many passenger cars between the competitors. At one stage one of the traffic officials showed me to accelerate a bit as there was an opening in front of me. I put my foot down and beast started screaming. The crowds next to the road loved it. It was quite a adrenaline rush to drive the Porsche 917 on a public road. We Ended up back at the waterfront after which we loaded the Porsche back onto the trailer to take the car up the Simola Hill were the event is held.
Lets start to make some noise.
The Porsche in the pit tents
The Saturday was mostly practice sessions up the hill. Everybody got multiple chances to run up the hill. There was a few cars that didn’t come down the hill in one piece. This was an insane event, with allot of nice cars and allot of noise.
Lamborghini and Ferrari that competed
Track car that competed.
High Horse Power GT-R that competed.
McLaren that tried his luck.
Check the wheel on this car.
Another Mclaren that competed.
There was allot of beautiful cars and allot of them was really high horse power cars. The battle was between the 2 wheel driven cars and the 4 wheel driven cars. There wan’t much that could compete with the Nissan GT-R’s. They were the fastest up the hill. The one 1000 HP Mitsubishi EVO 8 wasn’t far behind the GT-R’s. There was some really quick cars here.
My Boss took the Porsche 917 up the hill, and we were amazed at the good times the car was doing. The Porsche 917 ended up being one of the fastest 2 wheel driven cars at the event.
Knysna Hillclimb Porsche 917 Replica - YouTube
One of the runs up the hill at the Simola Hill climb.
This turned out to be a great event. The people and spirit was great. This is a must see event. We didn’t go home empty handed, we got a trophy for the fastest car in out class.
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So we are back at the workshop with the Porsche 917. We were quite disappointed that the car broke down and the test was cut short. We have never had an issue like this. The only way to find out what is wrong is to start stripping the back of the car again.
What did I find?
It was a mission stripping the side shafts out again. The tripod joints needs to be dismantled as the inner’s in solid mounted to the drive shafts. It was about a hour later and the gearbox was laying on the floor. The issue was the input shaft for the gearbox was still in the clutch spline. The shafts snapped off clean.
What we didn’t do or even think off with the rebuild was to get the input shaft of the gearbox crack tested. What we found was the shaft made a stress crack from the crash impact. With the testing and the load on the shaft was just enough to finish the shaft off.
The issue now was to get a new shaft. Xtrac makes there own steel combinations for there gearbox parts. This could mean the shaft was made from “unobtainium”. As we don’t have the exotic steels they use we copied the design of the shaft but improved the thickness. The input shaft on this gearbox is sacrificial, so if anything happens to the shaft it is a quick job to replace the shaft without opening the gearbox.
We got 2 new shafts made up and got them heat treated. Now we have a spare encase we brake another shaft. It was about a week later and we had the new shaft complete and the gearbox was back in. The Porsche was once again ready for the track. As I had some time I decided to address the cooling system issue as well.
As I have mentioned, we had a issues with the coolant temp spiking to 125 deg C on the back straight on the track. As soon as start braking for the turn meaning allot let power from the engine the engine cools down quickly. This could only be due to 3 reasons. Either the radiators is not big enough, not getting enough air to the radiators or the flow rate of the water pump is not sufficient.
Due to space constraints the radiator size was fixed. Well we could have made the radiators a bit bigger but didn’t want to spend the money if that is not the problem. At this stage we were running a Craig Davies EWP 80 pump on the cooling system. I did some research and it turned out the pump was way to small for the power output of the engine. The more power you make the mare heat gets absorbed into the cooling system. On lower RPM the cooling system is fine it is when you hit the high power then it does not cope.
I fitted two JABSCO 100 liter per min pumps in parallel. This gave me a combined flow rate of 140 liters per minute. Running pumps in parallel you never get the full combined flow rate. I was now happy and the car could go back to the track.
Next track session
We once again took the Porsche 917 to the race track as we booked the track for our selves. It was a really nice and warm day and the car looked great. I was really confident that this was going to be a good day. My boss could not make it for the test due to meetings but he said I could run the car and see if there is any other issues.
I took the car out on lap 1 just getting the car up to temp. Everything was going well. On the second lap I opened up the throttle unleashing the beast. The car was running rally great. We were actually timing my laps to see what times I was running. My best time was 1 min 21 sec. This wan’t to bad as my boss was doing 1 min 18 sec around the track. With more track time this would be able to be reduced dramatically.
On lap 7 something started to feel off. The car was battling to shaft gears, coming down the back straight I lost all shift ability once again and I had to lock the brakes up again to get the speed down for the turn. I know what was wrong just not why it happened again. It was identical to the previous break.
Back to the shop
We took the Porsche back to the shop and took the gearbox out again. The input shaft was off like suspected. The difference was this time the shaft was twisted like a pretzel. The outside skin of the shaft looked like it was shattered glass. I sent the shaft in for hardness testing on my suspicion was right. The outside of the shaft was nice and hard but the inside was soft. When the outside cracked up the inside could not handle the torque and just twisted the shaft off. This was a error made by the people hardening the shafts. We sent the second shaft back and they annealed the shaft and re harden the shaft to spec.
This was almost like second nature now, taking the gearbox out and putting it back. It wasn’t long and the gearbox was back in. I set up the car on car stands without the wheels on the car. I ran the car up to 6000 RPM ans started to shift my way up to 6 gear. The car sounded insane inside the hanger. I knew my boss was in a meeting in the boardroom but I did the test anyway. It was not even 2 minutes and my boss was standing next to the Porsche with a smile on his face.
Next Track session
We took the Porsche back to the race track for a test again. This time my boss drove the car in anger. This was the first outing since the first track test that we did not have any issues. My boss came in and told me I can take the Porsche out again. Every time I took this car out on the track it blows my mind. This is one serious piece of machine, the way it pushes you down into the seat. You becoming one with the car. Feeling every bump in the road. Through the turns it feels like you face is busy tearing off your scull from the G forces. There just isn’t any words to describe the feeling the rush.
Now that we had a successful track test we could enter the car for the next race. Back at the workshop I will have to run though the car again to see if there is any issues lurking around. This was a really good day.
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The Porsche 917 had been ready for a few days. I was happy that we could go do the shake down test at the track. My boss called me in and said that he booked a slot for the next day. We got everything together and loaded so we could leave for the track early the next day. Let the fun and games begin.
Porsche 917 ready for the track.
The next morning we hooked up the car trailer and left for the track. We got to the track and it was fairly misty. I got a phone call from my boss saying that he is running late. He said that I could take the car around the track and just check that the car is behaving. Luckily I remembered to bring my race kit with. I strapped myself into the seat of the 917. It is a weird feeling sitting in the 917. It is more like laying down than sitting. Because the car is so low down on the ground and the roof of the car isn’t very high you just could not sit up straight in the car.
The first outing
I was a bit worried about the damp track, but because this was only a shake down test I wasn’t going to run under full power. Usually I take the first lap even slower, I first have to calm down and breath normally. I told Riaan that was with me at the track, that if the car goes quiet he must come and look for me. Pulling out of the pits I started hyper ventilating. This carried on for the complete first lap out until I calmed down. The Porsche was an absolute beast.
The next lap I started to give it as bit of gas, just to get some heat in the tires and to see that the cooling system is working properly. I found that going down the back straight of the track the coolant temp would spike to 125 deg C and when I am braking for the turn it would drop down to 80 deg C. Wasn’t to stressed about that as the cooling system recovered well.
I came down the main straight towards turn one, I wasn’t pushing the car hard yet. Starting to turn I just felt the back end skid out sideways. I tried to correct the car with the steering and it helped a bit. The car just kept on skidding and I braked hard as I was approaching the wall. The wheels just locked up solid and the car was just getting closer and closer to the wall. I wen’t through the loose sand, and that slowed down the car and I came to a stand still after a knock against the wall.
What have I done, did I break it again?
I switched the engine off and just sat there for a minute or two. You will not believe what went though my thoughts. It the nose of the car all messed up? What am I going to tell my boss when he gets there? I got out of the car and I saw Riaan driving towards me with his car. After a quick look I could not see anything that is broken. We tied a rope onto the towing eye on the Porsche on the back and pulled the car out of the loose and with Riaan’s car.
The only damage on the car was a small patch of paint that scraped off. We said we are going to call that Clinton’s mark. I drove the car to the pits so we could have a good look if there wasn’t any other issues. When we were done the track had dried out nicely. My boss arrived and he took the Porsche out for a good few laps. The car was running really well.
My turn again.
My boss came in off the track and said I could take the Porsche out again. The tires was nice and sticky and I knew the car would sit really well on the track. I did my first lap again just to get the felling of the car. After the first lap I started driving in anger. This was the best feeling ever. All that adrenaline pumping through my system. The faster you go the faster you want to go. I did about 4 laps and I was feeling comfortable in the car. Well as comfortable as you could get in the car driving while laying down.
I came down the back straight doing approximately 250 km/h, and started to down shift and brake for the turn. Shifting from 5th to 4th was fine but as I tried to shift from 4th to 3rd there was no engine braking and the car didn’t what to shift down. I had to brake really hard and I locked up all 4 wheel. I could see the smoke pumping out the wheel arches. As I entered the turn I let the brakes go as I didn’t want to let the car step out from the brakes.
It felt like my face was going to be ripped off my skull as I went through the turn. The car freed all the way to the entrance of the pit lane and it stopped there. I tried to pull away with the car but there was no drive.
Back to the drawing board
We loaded the car up and took it back to work so I can try and find out that is going on with this car. There was a few thing that I wanted to address before we could attempt to come back to the track again.
This was a really fun day, but is was also very stressful.
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