I apologize in advance for falling behind on updates for the engine rebuild of the 2007 Cayman S. Summer projects and travel have taken a priority. But there is some progress to report.
As discussed here, I chose Slakker Racing Development (SRD) to perform the machine work on my 3.4L flat six Cayman engine. Broadly speaking, they performed two tasks. They machined out the bores for the cylinders and press fit proprietary cylinder liners. I say proprietary in that the liners were developed by Hartech in the UK. As discussed in previous posts, Hartech had caught my eye regarding their solid engineering work to develop M96/7 engines that could withstand the rigours of racing. Out of this effort, among other things, they have developed a “closed deck” cylinder sleeve, along with proprietery pistons, rings, and pins. If they can make them survive for endurance racing, I’m pretty sure they will meet my purposes. SRD is the authorized US shop to install the sleeves and sell the associated Hartech parts. So that was the first part of their job. The second part was to rework the cylinder heads. Basically, they tore the heads down, cleaned them, performed an inspection of wear/damage, installed new valve guides and new valve springs, and assembled everything.
Finally, I worked with Brandon at SRD to come up with a parts package that met my specifications. We started with the obvious rebuild stuff. Main bearings. Rod bearings. ARP rod big end bolts. All new gaskets. Single use “torque to yield” bolts. After you get beyond the “must replace” items, then it becomes a value assessment between cost and benefit. I leaned pretty heavily on the benefit side of things, at least from a reliability standpoint.
You may have heard of the IMS bearing? I had SRD install an OEM bearing on my intermdiate shaft but they removed the seals so it would receive splash oil. The M97 engine already was designed with a stronger bearing than that used on the M96. Removing the seals to provide splash oiling pretty much removes any future risk of failure. BTW, you do have to remove the engine and split the case to remove the old bearing and install a new one on the intermediate shaft.
I would have bought a new clutch and flywheel but I found that mine had been replaced about 25K miles ago. But pretty much anything made out of rubber or plastic in the engine compartment got replaced, within reason. I also replaced “electro-mechanical” components. Think fuel injectors, knock sensors, hall sensors, O2 sensors, and Variocam control valves. A big hit but worth it to me was a new engine wiring harness. In my thinking, things get pretty well roasted in that enclosed mid-engine compartment after several decades. It is often said that the 987.1 Cayman is one of the last analog Porsches. One way to look at this is that the engine management system still uses percentages of 12 volt signals to make critical engine management type decisions. If your wiring harness and its connectors have built up modest resistance values over the years (yes, it happens) it can confuse things for the DME engine control unit. I am also replacing the water pump and various rollers associated with the serpentine belt.
When I asked Brandon about the air oil separator (AOS) he had an interesting observation. He said that in his decades of track work, he knew a lot of folks with the stock AOS that were doing fine. He thinks the key is awareness of AOS failure symptoms and to be proactive if the AOS has failed. He recommended that I baseline the pressure drop of my new stock AOS with a simple gauge (a digital manometer) and just keep an eye on it. Versus installing the very expensive Porsche “motorsport” version. If required, it can be replaced with the engine in place.
As you may be aware, there seems to be a lot of angst over oil starvation in the M97 engine family. Brandon has actually done a lot of personal research in this regard. His recommendation in a nutshell is to use the Hartech deep sump, keep the oil full, use a low temperature thermostat, and go with a 3rd radiator to keep oil temps reasonable, along with a motorsport friendly oil. That is a vast simplification of the research and development that he has done so you might want to contact him for more details. I am going with the Hartech deep sump and the 3rd (center) radiator on my build. The 3rd radiator is stock on PDK cars so the parts used are readily available from Porsche.
Another issue was that my aftermarket exhaust system, installed by a previous owner, had developed an annoying leak at a “flex joint”. I decided to go with all new components, including the cats. Brandon said that Hartech likes the Top Gear system. That is what I am going to use.
Outside of the engine, I added some things to make the car more track reliable. In addition to the above mentioned deep sump and center radiator, I am rebuilding all the shocks/struts with OEM components. Nothing trick here, just OEM parts. I am replacing the transmission mounts. The motor mount has already been replaced. And I plan to run a data logger that I aleady own to track oil pressures and coolant temps, hopefully with a threshold warning light.
To date, as discussed in the article here, I’ve received my machined items and parts in a big box. As my parts list was extensive, I went though and double checked that I had received everything that I had ordered. We were almost perfect in that the only issue was one bearing for the serpentine belt that was overlooked. I am now reviewing my Jake Raby engine assembly videos with an eye toward getting started with the assembly shortly. It should be interesting!
A spreadsheet of the parts I received in my order from SRD is attached below. Sorry, it is a little bit of a jumble but with the part numbers and the PET, you can identify every item if you need to. FYI I am over $27K for machine work, parts, and shipping. As noted above, I have been generous in multiple areas.
Update- I’m assembling the engine, with articles coming soon. I would like to say that SRD did a very nice job cleaning up the block. My understanding from Brandon is that they use vapor blasting. As you can see in the photos, the result is fantastic. As I was looking at my valve covers, they looked so dirty, I went ahead and sent them to SRD to be cleaned up also. My recommendation would be if you are sending your block to SRD, throw in everything else and get it cleaned. You will thank yourself as you put the engine back together.
Next article in this series – Engine Re-Assembly Part 1
New Hill Garage 
Discussion
Comments are closed.