2006-2008 Porsche Cayman S Engine Health- Establishing a Baseline “3500-7000” Value

I am going to write a series of articles exploring how to use the Durametric diagnostic tool to establish the health of a Cayman engine, in this case the engine for a M97.1 car. The information that I am collecting will come from an “S” engine but the concepts directly apply to the “Base” engine and to the previous and subsequent engine series for the 911, Boxster, and Cayman.

I purchased the Durametric diagnostic tool many years ago. At the time, it seemed to be the only game in town, which I imagine was not true, but it was the one being mentioned on the forums. I know there are other products out there but I have the Durametric and am very happy with it. Some of the concepts will apply to other products that have similar functionality.

I could not find a lot of “how to” articles out there for the Durametric. I am basically learning as I go along and posting my findings to hopefully save other folks some time and aggravation. I’m sure there are some experts out there. I welcome any feedback.

OK- a very high level overview of the Durametic device. You go to their website. You purchase the product. They send you a cable in a box, probably referred to as a “dongle” or maybe a “security device”. One end connects to the OBD port under the dashboard. The other end is a standard USB plug. You download their software from their website to a suitable device. See their website for details. I am using Windows 11 on a bog standard laptop. The software download is free. You plug in the USB end of the cable to your laptop. You launch the software. You select your car from a menu. And it launches on your laptop. There is more detail on these steps in the Durametric Users Guide.

So, let’s talk about “Engine Health”. That can mean a host of things to different folks. Some of you may have arrived here because you have a Check Engine light and need to make it go away. The Durametric can be very useful in this regard but that is not what I want to talk about. I want to talk about establishing a baseline of operation of your engine, mainly using the Durametric, but also other tools, so when things don’t seem quite right you have a basis for comparison.

ZERO TO 60 TIME – ANOTHER APPROACH

Almost all new performance related cars seem to come with a published zero to 60 time. This can be a pretty good indicator of how well a “healthy” engine will accelerate when all systems are operating correctly. Thus, an indicator of engine health. But awkward I think. There is a lot of technique involved to dump that clutch and get the car going. If you have a PDK with Launch Mode, not so bad. But as a mechanical engineer, the whole idea of “launches” makes me feel guilty about what is happening to the poor drive train. So I am proposing a different parameter: 3500 rpm to 7000 rpm. In 2nd gear. And yes, my cars have manual transmissions but the concept should work with PDK. With this test, there is no launch. There is no gear shift. On my car, 7000 rpm gets you to about 113 km/hour or about 70 mph. Normally not enough to get you arrested. The starting point is around 56 kph or about 34 mph. It should be pretty easy to find a stretch of road where you can do this. Interesting that the mph numbers are basically the same as the rpm numbers, divided by 100. That probaby tells you something about the overall gear ratio while in 2nd gear. In english units, we can call this the 35 to 70 time.

So the idea is to get your car good and warmed up. Find a clear stretch of road. Tip in full throttle say around 3000 rpm. Throttle to the floor until you reach 7000 rpm. Back off. You may hit the rev limiter just past 7000, which is entirely fine. While doing this, you have to get a start time at 3500 rpm and a stop time at 7000 rpm. As we will see, this will be in the area of 4 seconds. But whatever you get, that is the baseline for your (hopefully) healthy car. That, in a nutshell, is the premise of this article. Establish your number and file it away. Hopefully the day will never come but if you sense that your engine isn’t running as well as it used to, you can perform this test again and see if you are correct or are imagining things.

3500 TO 7000 – WHAT SHOULD I BE SEEING

My tests were done on a 2006 Cayman S, purchased new by my wife, with approximately 75000 miles on it. All maintenance done by me. Bone stock. As far as I know it is a healthy engine. I will get into the details of data collection below but as a general statement, 3500-7000 in that car is around 4 seconds. Let’s not worry about the 1/10ths. The intake air temp for the test runs was 21 degC or 70 degF. 93 octane gas. The air temp, fuel on board, driver weight, ect. will all have small effects.

As an experiment, I also did 35-70 mph in 3rd and 4th gears. In 3rd gear, the elapsed time was 5.6 seconds. In 4th gear it was 7.3 seconds. Yes, I throwing in the 1/10ths. But if starting in 4th gear is a proxy for an engine that is not developing full power, there is a noticable falloff time that you should be able to capture, even using a handheld timing device.

DATA COLLECTION

I used my Durametric to “log” time, rpm, vehicle speed, and intake air temp. How to get the data is one area of the Duramentric that was not totally obvious to me initially. I understand the steps now and have made a video, linked below. The output is a .csv file, which is shorthand for comma separated variables. I simply open this file with Excel, scan down to find the cluster of rpm values that go from 3500 to 7000, denote the Start and Stop times, and subtract to get elapsed time. If your car is geared the same as mine, as noted above there are corresponding speeds but rpm is rpm so I like to use that to get the baseline.

You do not need a Durametric to do this. Hopefully, a passenger can use a stopwatch or a cellphone to measure your elapsed time. That should be close enough. But the video below shows you how to use the Durametric. If you have a Durametric, this is a good starting point to do a simple data collection activity.

WONKY STUFF

All modern cars sold in the US have to have an OBD diagnostic plug. It is used in many jurisdictions to measure vehicle emissions. But the “computers” in modern cars, and there are many of them, generally talk to each other using a CAN bus. Google it, I will not attempt to explain it but the CAN bus helpfully tracks a bunch of vehicle data. It is basically a local area network, with packets of information being moved around. Most of the CAN bus data is available at the OBD plug, amazingly in a single pair of wires. The magic of digital commuications. The Durametric (and other devices) reads the data and presents it in a usable fashion in their software interface. They and I call these Actual Values. There are a lot of Actual Values available. See my article here. It is initially overwhelming but one goal of these articles to learn how to use this data to document Engine Health.

I plan to request others to try their hand at getting 3500 to 7000 times on their cars, so hopefully I can then post the results here. Remember, it is not a race! We just want to get some values that indicate typical engine health.

UPDATE- I have the luxury of owning both a 2006 and a 2007 Cayman S. As noted above, the 2006 car has around 75K miles on its engine. The engine on the 2007 car has been recently rebuilt, as documented by a series of articles starting here. I have been holding off on a 3500 to 7000 until that engine was broken in. I am now past break-in mileage and I took the oportunity to make a data collection run. My elapsed time was 3.7 seconds. I have stated above that I am not really interested in 1/10ths of seconds and I still hold that position. The 2007 car has a new, tight engine and less weight due to the installation of Recaro Pole Position seats so I would expect it to be quicker. The takeaway is only that now, based on a sample size of 2, around 4 seconds is a reasonable time for a 987.1 Cayman S.