I trimmed off most of the upper section of the foam using a box cutter. I left the ends on which clamp the foam to the metal beam.
With the foam trimming completed, I reinstalled the bumper, again. Here you can see the airflow path leading to the top of the radiator. I will note that removing and installing the bumper on the Cayman is easier than the S2000; there are more steps on the Cayman, but the S2000 bumper has annoying clip features around the headlights that are difficult.
I suspect most of the airflow will only exit out the upper half of the vent as the metal beam underneath restricts flow out of the lower half. If you want the vent to be functional, I would not mount it any lower down the bumper.
The fitment of the 997 GT3 vent matches the shape of the 718 Cayman bumper very well. I didn’t check if there were any gaps before clamping the vent down to the bumper, but the fitment is pretty flush in the final install.
There are four of these openings on the bottom of the bumper which are the standard radiator airflow exits on the non-GT cars. This is also why the third radiator for the non-GT 718s is angled with the top tilted back. The 718 GT4 gets a wider third radiator with the top of the radiator tilted forward to make it easier for the air to exit out the bumper vent. The 718 GT4 bumper vent is integrated into the GT4 bumper which has unique features for the vent, so it wasn’t possible to try to install the GT4 vent into my base Cayman bumper. The downside to the bottom airflow exit is more frontend lift, but I left them open as I’m going for maximum cooling. I figure the GT3 vent will help reduce some of the lift compared to the stock setup anyway.
11 comments
What a cool mod!
That’s not punny. You’re going to get punished by being sent to the punintentary.
Cool and rad. Nice article. I think I’ve accepted the fact that I will never be cool enough to understand Porsche life.
Just modding for more cooling for better track reliability like my other cars. Just happens Porsche has more factory parts to use!
Nice! I’m surprised you didn’t just buy the replica or OEM GT4 front bumper! You get the top vent, larger lower vent openings, and a more aggressive front splitter for maybe more front downforce. Plus you wouldn’t have had to hack up the stock front bumper. AFAIK, a GT4 front bump is pretty much a plug and play solution. Can’t wait to see even more progress on this build!
Maybe it’s just me but I would not want to put an aftermarket fiberglass bumper on a Porsche daily driven street car. An OEM GT4 bumper is pretty spendy. This is a nice compromise.
The reason for not doing a GT4 front end is that it would get destroyed around where I live. Lots of steep driveway entries in shopping plazas, gas stations, parking lots, etc. As it is, I scrape the air strake in front of the front tire every time I leave my complex. A couple people have done the full GT4 frontend conversion.
The center vent really looks factory – great job!
Great job and beautifully documented!
Fantastic final result.
It’ll be interesting to compare temperatures with a stock car with common “control” ambients and driving, at a track day.
I 100% agree with the perfect compromise of repurposing the stock bumper, on the grounds of cost and ground clearance. I have a 981 GT4 and conscious of the limited approach angle.
I live in the UK where local town councils instal traffic speed calming with “sleeping policemen”, which I negotiated at an angle and crab over.
Hotels in Europe tend to have underground car parks and on road trips I check if they are ok for low sports cars!
The 997 GT3 vent looks pretty good on the 718. But, why not just use the actual GT4 radiator kit instead of the GTS?
To do the GT4 center radiator right, either have to do the full GT4 front end conversion or make a custom center section to go from the base bumper opening geometry to the GT4 radiator. Neither are easy or low cost options.