Intercooler and radiator setup

So over a month has passed since I got the car and really at this stage nothing at all has happened! This time of year I was attending a lot of car shows so my current car, a Subaru WRX (you’ll find some information on that here somewhere), was my main focus. However I spent some time looking over everything I had and everything I needed then started to plan how the hell I was going to make all of this work. I’d taken the time to look over all of the work that had been done to the car too and at this stage, although I was happy with what had been done, I realised how much more there was to do!

I feel I should remind you that this SR20DET RX-7 literally just has an SR20DET in it. This process involved a modified front subframe, modified gearbox mount and a modified bulkhead. The modified bulkhead probably wasn’t needed (nobody else seems to go to this extent) but I was informed this was done in order to achieve a nearer 50/50 weight balance. As the engine now sits entirely behind the “front axles” I guess it is now considered a front-mid engine car! Kinda cool, though this didn’t make things any easier whatsoever.

Immediately tasks were starting to become a cause for concern. For example;

  • How would I route an exhaust on the wrong side of the car?
  • How do I make a clutch pedal work on a bulkhead that is now not only 20cm into the cabin but curved?
  • Which looms do I use?
  • What about the lack of a PPF (Power Plant Frame)?

… To name but a few. The list kinda went on and on from there… I felt I had hit brick walls already but persevered and tried as best as I could to plan all of these hurdles one-by-one.

Photo showing bulkhead modification.

Mmm seam sealer galore. This photo shows the extent of the modification to the bulkhead.

Well in the meantime I decided to start with some easier jobs like tidying up the bay. First port of call was to ditch the dodgy radiator and intercooler setup that came with the car. This was propped up with random bits of metal and the radiator, which I believe originally came from an RX-8, has been modified in a way that I believed would cause problems with bleeding air from the system. Not to mention it wasn’t very aesthetically pleasing. The intercooler that came with the car would probably be better suited on an MX-5 (in fact, it is a very similar size to the intercooler I ran on my turbocharged MX-5 which again, you’ll find on here somewhere). The mismatch of different pipework and silicone joins really bugs me too!!

Intercooler and pipework provided… No thank you.

With all of this removed I realised just how much room I would have in the engine bay. It would be rude not to go for a v-mount setup right? As much as the viscous is an undeniable beast in the way it can keep an SR at optimal temperature, it wasn’t going to work for me anymore.

I spent a lot of time measuring up and even more time scouring the internet for appropriately sized intercoolers and radiators. The first setup involved an intercooler from an Evo… Which unfortunately ended up being too big. If I had access to a tig welder I probably could have modified the end tanks and made this one work, but decided not to bother and sold this on.

Evo intercooler a little too large…

… It has potential. If only I could modify the end tanks.

Next up I tried this intercooler, which I believe was intended for an RX-7 anyway. Unfortunately I can’t find any information on where to purchase this particular intercooler… I guess I was just looking at the right time. Hopefully I won’t need to replace it ever! This ended up being PERFECT for what I wanted to achieve. The inlet and outlet were a decent size and the overall size of the intercooler and its core placed it perfectly in front of the SR.

This intercooler is a much better fit!

I started ordering new silicone hoses now that I was happy with measurements and with a general idea on pipework routing. See how short and direct the pipes are? I should experience no lag at all from this setup using the stock Garrett T28 turbo. Sweet!

Time for pipework! That odd elbow had to go back…

Nice and short pipework.

At this stage I’d also ordered a couple of radiators that were immediately sent back for various reasons. One of those was a Toyota MR2 radiator which was going to be the perfect setup… until I realised it was too wide. Literally wouldn’t fit between the frame rails so back that went. 🙁
In the end I settled for an aluminium radiator designed for a Mini Cooper S. The overall size and the positioning of the inlet and outlet made this ideal, especially when angled back for my v-mount setup.

Mini Cooper R52 aluminium radiator perfect for the job.

In case you’re wondering what the hall a v-mount setup is, its a way of ensuring clean equal airflow through both your intercooler and radiator to maximise efficiency. The intercooler and radiator are angled in such a way that they create a V with the largest part being the open mouth of the bumper. This requires a lot of ducting and a bonnet vent to ensure the air flows where you need it to but with the amount of space I had up front this isn’t a problem. Generally intercoolers are stacked in front of radiators and can also be combined with oil coolers and even power steering coolers. As the air passes through each of these heat exchangers…. Well, they exchange heat. As the air reaches the last item in the setup its not cooling as effectively as it should be. Everything heat soaks and you end up with an inefficient system.

Diagram borrowed from

At this stage I’m happy with the mock setup of the intercooler and radiator, though it obviously needs work in the form of effective ducting and a solid mounting frame to hold everything together.

Published as 8th July this process actually took almost the entire month until I was happy! Very slow progress so far but as I said at the start, this was a busy period with a lot of car shows with my current car and this requiring attention as the modifications came to an end.

This will do for now. Much happier than before.

You can also see the inline filler neck I added as not only does this radiator not have a filler but the position of it would mean this would have to be modified anyway. This new position should be high enough for bleeding and is easily accessible without looking ugly. Ideally I’d like to replace this and the 90-degree silicone with a swirl pot but the lack of being able to weld aluminium means I’d have to get this custom made by somebody else (£££). I’ll revisit this in the future as I think a swirl pot here, along with a slightly higher filler neck, will be very beneficial.

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