I have had thoughts of various strut tower brace designs bouncing around the head a few times. A couple of those ideas would require removing the big piece of plastic up top which covers the battery among other things. I went to a DIY car wash place and the high-pressure spray definitely gets a lot of water under the hood. I would not recommend removing the plastic cover unless the car never sees rain or high-pressure water jets. I used the high-pressure jets to get into the side intakes and when I got home, I noticed the back of the driver’s side GT4 scoop had popped out.
So off went the side rocker panels so that I could screw the GT4 scoops to the panels. Another pile of dirt and gravel came off the car for weight reduction.
There are some OEM Porsche screws, but I just went to McMaster and spec’d my own. I went with stainless steel (to prevent rust over time), thread-forming in plastic, M4s that are 8mm long with a T20 torx head. And I got some white masking tape which you’ll see why in a few.
On the passenger side, all the clips were still fully engaged.
Porsche uses three screws to secure the scoop to the panel; top, middle, and bottom locations. I had a bag of 25, so I used five on each side by adding two more screws in the middle section that attach the trailing edge of the scoop to the panel. I drilled pilot holes slowly with the scoops clipped in, first going through the panel layer and then through the scoop layer. Then I installed the screws using a torx bit on a socket extension, tightening by hand to avoid stripping the holes. I eyeballed the locations while referencing pictures to make sure there was material on the scoop where I was drilling. Do at your own risk!
8 comments
Khiem-
I have admired your many articles, and enjoy reading and rereading them. The title of this one sounded interesting, and the explanations, pictures, etc. were keeping me engaged, and then you casually drop that “a certain Mr. Coleman” drove your car. With you along for the thrilling ride, I assume. I’ve been onboard with Mr. Coleman’s writing, storytelling, and engineering prowess since I picked up my first issue of Sport Compact Car in late 1998. Yes, a 200-plus-page tangible magazine; remember those? I’m currently shopping for a car (a tree fell on the current ride), and that same certain Mr. Coleman is a major factor in considering the Mazda3 that I’ve been eyeing. Sorry to hijack the comments, Khiem, but I really wanted to give a shoutout to him. I hope that was alright. Thanks again for the always enjoyable and educating articles. Enjoy the drive!
I loved reading all things Dave Coleman as well! I wrote a question into SCC when I was in college and he answered it! I love Mazdas; I have a base model 2016 CX-5 that just turned 90k miles. I recently took it on a road trip with one of my dogs hitting up some of the best roads in California and it was still fun. I had to put the auto transmission in Sport mode on some sections and the transmission shift strategy was great for the twisty roads. Of course in manual mode, it has the proper sequential shifter orientation of downshift forward, upshift rearward. Lifetime average of 27mpg driving around LA. I literally just had a brand new Mazda3 sedan for a rental car and got almost 39mpg over 350 miles of mostly two-lane cruising. A lot of new cars have lane keep assist which is very annoying. Dave helped make the system be as minimally annoying as possible. The only thing that’s not optimal is the brake pad compound which doesn’t have a ton of initial bite. Though it is an improvement over a CX-30 I drove a couple years ago, but not as good as my 2016. Seems to be a bean counter change. Dave can’t fix everything. I’ll recommend anything in the Mazda lineup if you’re looking for a driver’s car.
Doing some research suggests these vanes improve front downforce and don’t do much for the rear diffuser.
https://images.squarespace-cdn.com/content/v1/5d7cfd7b13f6f06e8b55ed5c/1609096469910-BUNFCV10FN32JTZGA418/graphs.jpg
I’d found that before too. I do think it is vehicle/overall package dependent. The only thing I know for certain is that they direct air from the middle of the car outwards. I vaguely remember reading somewhere they also interact with the air swirl coming off the front tires which helps clean up the underbody airflow. I think acting as an air curtain to prevent the dirty air off the front tires from going under the rear.
This link is to an artist representation of the airflow under the GT4RS with the more extensive turning vanes array underneath the car. It does show the vanes redirecting the air outward right into where my rocker panels got hammered. Huh.
https://press.porsche.com/prod/presse_pag/PressResources.nsf/Content?ReadForm&languageversionid=1289808&hl=modelle-cayman-718_cayman_gt4_rs
My 718’s rocker panels aren’t as peppered with rocks like your is. But the under panel definitely is.
Never understood why my 718S water pump started leaking at 20,000 miles and 3 years. Makes sense. Thanks for your 718 articles, they’ve been great reading! PS I have the APR tune and wish I tried the AP…
If the car is bone stock, I think APR is a best option. It’s when you start modifying things where the pro-tune has benefits.
Very good article post. Thanks Again. Keep writing.