Project 718 Cayman T: Part 6 – Third Radiator, Center Grill, and GT3 Vent Installation

I did say I was going to tackle the suspension next in order to optimize tire usage, but life threw me a bit of a curveball. So, I decided to go back to the previous plan of improving the thermal capacity of the engine coolant system and push back the suspension upgrades until later. For the cooling upgrades, there are relatively affordable parts available by raiding the Porsche parts bins.

The beauty of having a ‘lower’ model Porsche is you can get parts from the higher performance variants for OEM+ upgrades. The higher trim GTS Cayman comes with a centrally mounted third radiator for additional cooling to supplement the thermal system for the higher power engine; more power equals more heat to reject. The third radiator is also packaged with the optional Sport Design front bumper and on cars sold in hot climates like the Middle East. Suncoast Porsche puts together everything you need in their 718 Third Radiator kit to make this a plug and play install. Before tackling this job, I used this post as a guide to plan out my install. Step one for me was installing these rubber bushings on the two hose barbs of the radiator.

This plastic bracket is used to support the radiator to the chassis. Two round rubber bushings which locate the bottom of the radiator mount onto this bracket.

In my recent free time, I’ve dusted off the ole bike and racked up 130 miles in the last three weeks. That matches my total for all of last year. And my resting heartrate while sleeping has decreased from 67 bpm to 60 bpm. And I used the chain lube on the rubber bushings to make it much easier to install the radiator to the support bracket.

To install the radiator to the bracket, the lower portion of the radiator pushes up onto the bushings mounted to the support bracket. The upper section with the bushings on the hose barbs push down into their mating bracket locations. Without lube on the rubber bushings, it’s very difficult to force the bushings into their final installed locations. With lube, the effort is minor. The chain lube I used is designed to be compatible with the rubber o-rings in the chain and it is critical here to ease the installation. Is it possible to install the radiator without lube? Sure, but why struggle if you don’t have to. You can probably use soapy water, hand soap, Armor All, or olive oil for lube if you want.

On each side of the support bracket, a wedge-shaped end-cap snaps in to seal off the airflow path.


    1. Cool and rad. Nice article. I think I’ve accepted the fact that I will never be cool enough to understand Porsche life.

      1. Just modding for more cooling for better track reliability like my other cars. Just happens Porsche has more factory parts to use!

  1. 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!

    1. 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.

    2. 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.

  2. 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!

  3. The 997 GT3 vent looks pretty good on the 718. But, why not just use the actual GT4 radiator kit instead of the GTS?

    1. 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.

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