Project Cayman T: Part 1 – Intro and Must-Do Mods

You know, my bro-in-law had a bugeye WRX wagon with the EJ20 and that thing was a tank. Many people I know with STIs and EJ25s… not so much. Regardless of Subaru designs, the Porsche 2.0L has a smaller bore than the 2.5L version which translates into lower stresses. They both have a 76.4mm stroke with 91mm and 102mm bores respectively.

Another difference between the 2.0L and 2.5L is the pulley design. They have different vibration dampers due to the different harmonics of each engine. The 2.5L engine requires more stuff in the pulley for extra damping along with a lot more mass to smooth out the greater vibrations of the bigger engine. That implies to me the 2.5L has more stresses compared to the 2.0L. I was a bit worried about the engine free-revving a bit sluggishly because it has a dual mass flywheel, but this 2.0L actually revs pretty quickly. Smaller and lighter pistons compared to the 2.5L should be a factor along with the lower mass pulley. There are aftermarket lightweight flywheels for the Cayman, but I am content with how quickly this setup free revs such as doing a throttle blip for downshifting. It is about the same as Project S2000 with the AP1 flywheel.

In Project S2000, I installed a baffled oil pan to reduce the likelihood of oil starvation during track use. The Cayman engine comes with an ‘integrated dry sump’ according to their marketing material. The 4-banger has three oil scavenge pumps pulling oil from the pan, cylinder heads, and turbo drain. The oil pan being quite wide and flat should contribute to keeping oil at the pick-up to prevent starvation too. The oil system is pretty much good to go for serious track use.

A most-do modification is to reprogram the dash to show proper coolant temperatures. On the S2000, I had to install the ARK Design MFD2 to plug into the OBD2 port to display the coolant temperature. I also had to install the oil filter sandwich plate to get the oil temperature and pressure. The Cayman already comes with coolant temperature, oil temperature, and oil pressure displayed. And boost pressure of course. Oh yeah, the 2023 Cayman has as old school of an interior as you can get in a new car. Analog tach right in the middle of the dash? The Miata is the only other car I can think of that you can buy that has an analog tach in the middle.

Back to the displayed coolant temperature issue, Porsche programmed the coolant gauge to show a constant 90degC when the actual coolant temperature varies between 80.3-110.3degC. In US inch/slug/weird units, the gauge shows a constant 194degF while the actual temperature various between 176.5degF to 230.5degF. I guess too many people asked questions or think something is wrong with the car if the coolant temperature moves. So instead of educating people, automotive companies find it easier to just make the gauge stupid. My old Nissan SE-R with a needle indicator didn’t budge The S2000 bar indicators didn’t move bars from 178F-225F. On my 2016 Mazda CX-5, they just made it simple, there’s a light for when the engine is cold and the light goes out when the engine is warm.

I do see some logic in the range of temperatures Porsche chose at least. In Normal mode, the coolant temp runs up to 220degF and the oil to around 235degF in order to reduce fuel consumption. In Sport/Sport Plus mode, the coolant runs about the 184degF and oil around 200degF on the street. Therefore, regardless of the mode the car is in, the coolant temperature will show the constant 194degF value in order to avoid complaints from customers. Hmm, very similar to the S2000 fixed range. To fix the coolant temperature gauge readout to show the actual temperature, I bought a Launch X-431 Pro V4 to do some coding and fix the coolant gauge along with many other things. I also rescaled the coolant temperature and oil temperature bar graphs. Their max values were 155degC, but I adjusted them down to 115degC for coolant and 130degC for oil with their red zones starting at 105degC and 115degC respectively. All the info on how to do it can be found on forums.


    1. I auto-x’d a C6 when it first came out way back when. I didn’t care for it; it felt bigger than it was whereas the Cayman feels smaller.

      1. I hear you. I cycled through an AP2 S2000, C6 Z06, F80 M3, and now TTRS daily and 991.1 GT3 track car. between these cars and rentals and driving friends’ cars, realized I valued a smaller lighter car and mid/ rear engine feel over other factors. There’s always someone richer/ smarter/ faster, go the route that makes you happy.

    2. Except Khiem has a car he can drive to and from the track comfortably and also drive on a daily basis. A Cayman is far more comfortable than a C6 on a day to day basis. More interior and trunk space as well. Plus he doesn’t have to put up with a god awful early 2000s GM interior.

      More money, but you get what you pay for.

  1. I have solid trans mounts in my base 718. I think I bought the 981 models from tarett engineering. With the standard mounts a floor jack under the back end of the trans could move it 1.75 inches before the car moved. That was with 20k miles. Didn’t notice much change in nvh. Improved shifting a lot.

    1. Good to know on the compatibility! I was hoping Porsche would carry over parts as OEMs do to save money. I still need to figure out how to disable any potential error codes because of the active mounts. I hopefully can code out the active mounts as they are an optional feature.

    1. It’s a digital tach. But at least one of the display options is round like an analog tach. Other options include a bar…. graph, I guess you could call it. Which I did not particularly care for on the S2000.

  2. Thank you for the explanations of how the switched water pump works to reduce temp in sport mode! I do have the same idea of leaving it open all the time for cooler operations. I like the idea of plugging the control vacuum line. Do you know where that pump is? I have a 23′ CGTS 4.0. It has the same enhanced cooling feature, and I’d think it has the similar cooling components. Thanks!

    1. I don’t know where it is on the 4.0L 6-cyl, but on the 4-cyl turbo, it’s on the side of the engine next to the passenger compartment bulkhead. I’ve found pictures of where the vacuum line goes and it’s not easy to get to.

      For now, I’m content with just running the car in Sport + mode all of the time. I need to ask someone to see if the water pump still stays closed for faster warm-up from a cold-start even in Sport + mode. I imagine it would in order to reduce emissions. In Sport +, even during track use, I only saw the coolant temp get up to 87C max. I’ll see it fluctuate between 82-86C during everyday driving.

      EPDM rubber is very commonly used in cars for gaskets, o-rings, and coolant tubes. Anything related to the coolant system, EPDM is typical. It commonly comes in two grades, cheaper that is good for 120C and more expensive that is good for 150C. Having worked for a long time in the auto industry and also observing the frequency of water pump failures on modern Porsches, I have it a very high likelyhood the cheaper rubber is used in the water pump. I mean, there’s even a plastic impeller instead of metal. OEMs are looking to save a dollar anywhere they can.

      In Normal mode, it seems the coolant runs between 100-105C. Which is a lot closer to that 120C limit. So my hypothesis is running in Normal degrades the seals and gaskets in the water pump much faster. Plus the engine runs much warmer oil. So after a drive and doing a shutdown, everything is just going to be hotter. But running in Sport + with the coolant only around 85C and oil around 90-95C, the seals should last much longer. Fingers crossed.

  3. Thanks again for sharing your knowledge! I’d think the thermostat should take care of the faster warming up mostly, as it opens up typically at 180-195F (not sure about Porsche cars)? The open water pump will circulate the coolant continuously, but might not affect the oil warm-up much…at least, that’s my theory :).
    Aside from the vacuum controlled water pump you mentioned, there looks to be a vacuum control valve for the coolant going into the engine oil cooler. I don’t know how to add picture here, but if you google ‘718 BOXSTER ENGINE OIL COOLER INLET LINE OEM 98130707500’, you will likely find used parts that show the picture. It looks to be controlling the amount of coolant, or maybe just on/off, going into the engine oil/water exchanger (located on top of the engine, driver side, by the oil filter in the 4.0L)
    I’ll make a spring project to play with vacuum lines and see what happens 🙂

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