Top mount vs side mount vs front mount

Alright just wondering if anyone can give advice on pros and cons for each setup. I googled it but the internet is awash with personal opinion rather than science.

Im asking because i was looking for options for my future turbo plans. Originally i was going to run a side mount in the drivers side fender as theres lots of unused space, it saves all the ass farting around cutting the bumper to make a front mount fit and should be fine for a mild 7psi setup.

The turbo i have (IHI RHB5) is setup so that the outlet faces upwards which would suit a top mount, shortening the piping needed making it far easier to work with and reduce lag i guess. Also suits the direction of the inlet manifold opening being on top too. The bonnet could be cut open leaving the support frame in tact and a small non wanky bonnet scoop could be installed to dorect airflow to the top mount.

I had a look around the front bumper when i was doing my major service and it seems there is basically no room at all for a front mount without cutting alot of it away.

Thoughts?? Any experiance from some subaru owners maybe?

I used to have a twin turbo Subaru Legacy which is same IC setup as WRX etc. Top mount is good for short pipe runs and giving reduced lag but it's very easy to suffer from heatsoak at which point the IC becomes essentially useless. On a hot day, in traffic or driving hard it WILL heatsoak, how long before it's useless depends on the temps and how hot your engine bay as a whole is as well. This can be countered somewhat with waterspray setups though but that only works when on the move and you have the added complication of setting it all up. For a fun daily driver though a top mount would work fine and be easiest. You can also look at a water to air intercooler for top mount... slightly more work than a straight top mount but substantially more effective.

Your side mount idea could be easy but you're going to have no air flow and a long and complicated piping setup = lag.

Front mount is ideal but again custom piping, lack of space etc.

IMHO a top mount or a nice water-air setup would be best bet for what you want.

TX Autosport's IC kit for the Z20LET conversions is actually designed to sit behind the bumper without the need for cutting it away. Well, I guess I'll be able to tell you more soon enough anyway.

As Chris said, you can get one designed for it albeit a bigger engine. May just find you'll need brackets that will push back the radiator and a/c

The Corsa C TX cooler isn't that much bigger than the factory Astra unit, it's just mounted in a more optimal position. Does help if you have a facelift front bumper too :D

To add to my previous comment about the TX intercooler kit, they also include a pair of 9 or 10 inch fans, so if you removed the original AC fan (the one on the front of the condenser), you could put these two in above the intercooler and wire them up to the AC fan connector. In my case, they'd be drawing air straight in from the grille area (which again, airflow is helped by the facelift grille and more so with the Irmy grille), where the intercooler draws 100% of it's flow from the lower grille area.

So there is an IC kit for the C that could be modified to fit the 1.8 :) that would be awesome. Im not really fussed about lag so to speak, just space concerns.

On a different note i saw a patrol the other day with a thermo fan on top of the top mount, dont know if it would make it better in any way though. Personally id love to not have to cut holes in my bonnet to make it work. Ill suss out that front mount kit. The other option i was going to look at was a small rectangular IC like those thin bar looking ones. I think thats what the dbilas kit comes with.

Just checked out the TX kit and it wont work as on the z18 unfortunately due to where the exhaust goes under the engine the turbo would be mounted the opposite way to a z20let engine. :(

But it gives me hope as it means theres room for a front mount. Checking now to see if they do jist the intercooler with brackets and no piping.

If you are going that way look into just a cheap core off fleabay.

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Originally Posted by SilentShout

On a different note i saw a patrol the other day with a thermo fan on top of the top mount, dont know if it would make it better in any way though

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Most factory intercooled Patrols and Pajeros have thermo fans mounted on the underside of the TMIC from factory. They're not awesome but they certainly increase flow through the cooler when you're offroad and only cruising around at 5km/hr.

top mounts really need to have good airflow to them, would you put in a scoop?
Note that a lot of aftermarket scoops are really just for looks and not actually getting air into a TMIC - they need to be ducted too, and with space underneath for the air to escape.

Alternatively you can try and make a WTA top mount, they are good, particlarly on a street driven car.
Still need to run water lines and a radiator and pump for it though.


side mount is basically a smaller front mount, usually only done due to space reasons, or to ensure the radiator isnt blocked off.
FMIC is always the best.

I'm sure that with a top mount Cooler, there's something to do with pressure in the engine bay, so on our cars that aren't designed for them, it won't work very well.

Best sticking with a front mount, as good gains are always the result 👍