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Discussion Starter · #1 ·
As I am Stage 2, the general opinion is to upgrade the charge cooling system. This is more so in warmer climates.

I have done 2 rolling road sessions, both in 20+ degrees, one being when the car was remapped to Stage 2. I sufferred from high IATs, the max 80 C when the ECU pulls timing/boost and ultimately power, like down to 440bhp. It should be somewhere around 460/470.

So after this RR sesh and the warm summer, even though on the road the car goes like stink, I decided to upgrade the charge cooling, but on a budget as I didn't to spend £1000 on a kit for something that only causes a power drop in a small number of occasions.

I actually did this upgrade a couple of months ago, but only now getting round to posting a thread on it.

Anyway, I looked at the Jag heat exchanger, but I think it is only a single pass and wanted a multi pass unit to give the best effect on cooling. Also these were out of stock at time of searching. So I opted for a universal rad.

I have, prior to fitting the heat exchanger fitted a FIS Control and made mental logs of the IATs. They weren't too bad, after full warm up, hovering around the 60 degree mark.

I spent a couple of days modifying the rad to accept brackets and put a top bleed screw in. Making brackets, checking pipe routing etc. I have kept the OEM rad in place and placed the uni rad above it. So the pipe work goes into the bottom of the OEM rad, out of the top, then U turns into the bottom of the uni rad, out of the top.

I only managed to get 2 litres of coolant out of the std system and this was removing the OEM rad and tipping it up, plus pressure blowing the supercharger intercoolers through, so this will warm up pretty quickly on a stage 2! The Uni rad holds just under 1.5 litres, so it has added a decent amount of coolant to the charge cooling system.

But it is quite a neat install and so far it is keeping the IAT down. On average I would say around 10-15 degrees over just the OEM rad.

I also removed the OEM rad and gave it a clean by blowing it with compressed air in reverse of the normal air flow to blow out flys, dirt and dust. As you will see in the photos, is was a like peppered, so possibly not even as efficient as when new!

When refilling I used 30:70 antifreeze mix and DEI charger chill (like Water Wetter), to get a better temperature transfer in the intercoolers and rads. Not sure what difference it made, but it should help.

I have done some redline pulls through 3 gears and the IATs have only managed to just about touch 55 degrees!

I haven't done any scientific data logs or controlled experiments, I just know that the temps are not as high. :)

Before fitting the uni rad, the IATs would follow the oil temp up at the same rate as the engine warms, until about 50-60 degrees. Now with the additional uni rad, the IATs rise more slowly and follow the oil temp but at around 10 degrees lower.

I think it is a worth while mod and not worth spending a grand on a full tuner's kit, unless you going for all out power and stage 3 etc. :)

Tire Vehicle Wheel Automotive lighting Automotive tire

Trial fit before aluminium welding mounts, top bleed screw and painting black + removed half a tree of dead leaves.

Automotive tire Grille Road surface Wood Door

Protective plastic guard still lets debris pepper the rad.

Automotive fuel system Automotive tire Hood Motor vehicle Vehicle

Several hose clips, bit of joining hose and a U bend connect it up.

Hood Grille Automotive tire Automotive design Motor vehicle

Stainless hardware.

Automotive tire Grille Automotive exterior Bumper Motor vehicle

Grille Motor vehicle Hood Automotive tire Automotive design

Overall surface area is pretty close to a full replacement Merc racing rad! just doesn't hold as much water.

Urban design Building Rolling Engineering Track

The top of the uni rad is near level with the top of the grille.

Automotive parking light Vehicle registration plate Vehicle Tire Grille

Whilst I had the bumper off, I chucked an RS grille in too! :)
 

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Audi S5 sportback
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Great write up mate, and looking good
 

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Blimey mate that is one hell of a good job and great write up and pics, thanks!!!! You will surely have plenty more power even in the summer days cos the cooler we can run an engine then the better she will perform!!! Well done.
 

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Audi S5 sportback
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What did this mod cost?
 
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Discussion Starter · #6 ·
What did this mod cost?
It was around £190 + consumables like aluminium welding wire, coolant, paint.

Once you add everything up, you are nearly halfway to a Merc racing rad and subtract the time it takes to make everything from scratch like brackets, pipe bending etc would I do it again? Erm, I may be tempted to just buy the Merc racing rad and chuck it straight on! :D Depends if you're really tight on budget and don't want to spend the extra £250 or prefer the satisfaction of saving money and designing & making a kit from scratch all by yourself!? :) If we didn't have Merc racing in the equation, then yes I would do it again rather than spend £1000 on a kit!
 

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Fair play mate, hats off to you.


If you have the time, tools, and skills, why not put them to use and save money
 

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Audi S5 Black Edition Mrc Stage 2
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Hi Dave, good job and excellent write up from you as usual.
This is something I have thought about upgrading for nearly the last 2 years but have never had a genuine reason to do it. I have discussed this countless time with my tuner and while I am staying at stage 2 - there advice is there no need to upgrade unless I change the throttle body and push for more power.

My car has been on MRC's rolling road 6x in 3.5 years and as far as I am aware not suffered with high intake temperatures during mapping or health checks.
Initially when I took the car for a stage 1 in May 2018 the air temperature was 21 degrees and the car made 453bhp. I took it back to Mrc for a health check in January 2019 and the air temps were 7 degrees and the car made 450 bhp but the torque had increased slightly.
I have flushed the entire cooling system twice since owning the car and refilled with genuine G13 coolant on both occasions and the results have been the same since going to stage 2 whether it was on the Martec rolling road or the Dynojet rollers.
Please keep us posted with the results when you revisit your tuner
 

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Discussion Starter · #9 ·
Thanks Aide! :)

Yeah, the only reason to fit, is because 2 runs on the rollers in the summer has thrown up high IATs, not had an issue or noticed at any other time! :)
Hence why I didn't want to spend loads on it.

Will do! Will wait for the cool autumn weather first to make sure! :D
 
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