Project S2000: Part 30 – Cooling Upgrades and Packaging Improvements

In deciding to go with an air-to-water intercooler setup, there are extra component and packaging challenges compared to a typical air-to-air setup. The S2000 already has a tight engine bay as Honda did an excellent job at optimization. In order to make some more package space, we needed to make a couple upgrades.

If you recall from our initial packaging trials, the air-to-water intercooler didn’t fit quite as nicely as I’d like.

Way back in the day, around a decade ago, we installed a Koyo radiator that was 53mm thick. Koyo’s newer variant is only 36mm thick. So that gets us back 17mm, or ~0.67 inch.

Koyo makes a high quality 1.3bar radiator cap. I recently handled another aftermarket shiny radiator cap and the internal gasket fell out. What a piece of garbage. And it was more expensive. Project S2000 AP1 inherited my old Koyo and the original Koyo cap is just fine.

Koyo says 36mm thick. 36.12mm is pretty damn close. A typical sheet metal bending tolerance is 1/32nd of an inch which is ~ +/- 0.8mm. So being +0.12mm is way under typical tolerance.

The stock fans bolt right up. The smaller left fan is the A/C fan and the right is the radiator fan.


  1. I strongly disagree that the s2k has a tight engine bay… with the front of the engine being aligned with the axle line its got tons of space in the front end. its prolly got the most engine bay space of any similar car of similar vintage or newer… only thing I can think of with more are full size pickups with V6’s… and a Challenger with a V6, and those aren’t in a similar class.

    -bitter NC owner (thats jealous of all that space you have) (and amazing engine)

    1. You make a fair point! Uh… It’s very tight on the sides of the engine but lots of space in front? I think I’m still in cram in manifold mindset.

      1. its still not bad, its a longitudinal 4, so kinda best case scenario… any V config has less space (except Challenger and trucks). Maybe we should all get Challengers and have all that engine bay space, haha

          1. That engine is not hard to drop and so are most things working on it. Only working on the turbos is a fucker with the engine in the car.

  2. I give that fan mounting 1/2 a track day life span. The fan cover screws are not meant to do any more than hold a piece of thin stamped sheet over a hole. Those are just screws threading into plastic and you have lost a fair bit of that thread depth due to the thickness of the aluminum strap. I’d suggest you find a solution that mounts to the fan frame as designed. If that holds the fan in place for a while it is still going to bounce against the radiator and do some damage.

    1. Appreciate the feedback. I actually have good confidence in the durability of the strap setup because the screws are surprisingly long and the fan is pretty light. The screws are about 10mm long if my memory still works, and the strips are 1/8″ thick, so about 3mm. About 1mm for the cover, so there still should be about 6mm of tread engagement. That all said, I did google SPAL fan mounting brackets after your comment and SPAL makes some plastic pieces with metal straps that slide into the slots on the perimeter of the fans.

      How I didn’t find these things before, I have no clue. Way back, I was familiar with the zip-tie things that pull through the heat exchanger to hold the fan on and they suck. And these metal strap bracket combos are under $3 each. Well, time to upgrade.

  3. That fan mounting does look sketchy, but it’s not really any different than there being a shroud that extends to those bolt holes. As long as the aluminum has sufficient stiffness against bending I’m sure it’d be fine. Having something decide the bottom of the fan would make me sleep better as I assume the problem would be the fan bouncing around and possibly ripping the aluminum strap.

    Can’t wait to see this project come to a ‘finished’ state – sounds like it’s going to be an amazing do it all kinda machine.

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