Fan shroud design and installation

Pictured on the left is the front of the car, specifically the radiator as viewed from standing just behind the left front tire. The car comes with this custom radiator essentially installed, but the fans just come on their own without any brackets to mount them. That’s a where a fan shroud comes it. It serves as a mounting point for the fans and it also more or less forces air to go through the fans and not around them.

Enter a piece of aluminum, a jigsaw and some very precise measuring. In the end not a very difficult task, but you have to get a lot of measurements exactly right. Below are the simple steps after purchasing a piece of aluminum cut to the width of the radiator and high enough so that I could screw it into the top and bottom radiator cross-brace.


Step 1: Find the center of rectangle and the center of each fan. Also note that full circles on each fan would make the outside strip between the fans and the outer edges quite narrow, so I kept that a little straighter.
Step 2: Ghetto compass for drawing circles. I held the center in place with a screwdriver and had a hole big enough on the other end to fit a marker pen.


Step 3: Start cutting. I just used a jigsaw. Does the trip you can hide the slight scarring on the inside if you really care. (I did). Note the wider straight strip on the outside.


Step 4: Finish product, holes drilled to mount the fans from the inside.
Step 5: Mount the fans. I used stainless 1/4″ allen key button head screws with lock nuts.
Step 6: Drill the radiator. Aaaaah! Actually, it’s not that bad. There’s nothing but air behind that cross-brace. I had previously put mounting holes in the shroud, so I just aligned using those and then drill-tapped allen key button head screws in.
And the finished product… excuse the wiring mess. That’s since been cleaned up obviously.



9 thoughts on “Fan shroud design and installation

  1. Is the radiator have rubber mounts ? Also put some kind of gasket/rubber or even silicone where your fans mount to radiator in my experience there is some vibration with road use and also fans will vibrate . Are noisy and will amplify thru solid mounts

    • Not yet, but that’s the plan. I hadn’t really considered it, but was talking to a few folks last week and they all are quite concerned about galvanic corrosion. Good thought on reducing vibration as well – thanks.

  2. Tim, you should space out the fans from the radiator more than that. About 30% of your radiator flow is blocked by the shroud being right up against it.

    • Dave, very valid point. I checked to see what the spacing is and right now it’s somewhere just more than 1/4″ all around so I should get some air flowing across. I’ll probably keep for now and see where my engine temps net out and how frequently the fans turn on. The Porsche flat-six doesn’t run terribly hot and it will “only” make 380-400 HP probably. But thanks for checking in, always happy to hear your thoughts.

  3. Enjoyed reading your blog, it brought back many memories for me. In the late 80’s I built one of the first Beck 550 spyders. I had worked on a few sports cars, but had never built anything like that before. For two years I worked away during the evenings, most of my friends wondered where I went 🙂 When finished the car had a 145 HP engine and weighed about 1600 lbs loaded, it was very fast and alway a lot of fun to drive. Fond memories blasting down HWY 9 eating up the turns. The quality of the SLC looks very good and after a conversation with Fran I may use the chassis for my next project. I look forward to your future posts.


    • Hey Mike,

      Glad you liked the posts! I’m woefully behind on putting more stuff up. I’ve been getting bugged about it though, so hopefully soon. Great project you did there. That’s true Colin Chapman-style power-to-weight ratio stuff. SLC is of a similar concept. Feel free to reach out if you have any more questions:

      Happy Holidays,


  4. Good afternoon. 16-year-old student who lives in South Korea.
    I like to model this (with soild works), making your own car. but was unable to get any accurate sizes.
    I tried filling those lines by just guessing, and ended up with a huge amount of errer.

    I’m sorry, but. have a precise size (X x Y x Z) of the square pipe and / or a entire schematic,
    please offer me a help. I’ll be very, very thankful if you do so.

    I do not speak English. Rude, but please read.

    • Hi Kuenwoo,

      Unfortunately, I do not have any plans since the chassis itself is made at the factory. I can tell you all the tubing is 2″ x 2″, but beyond that, I don’t know. Sorry…


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