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Old 08-06-2021, 01:13 AM   #273
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Join Date: Oct 2015
Location: Cardiff, UK
Posts: 106
Originally Posted by strombomb View Post
Looking great Escy, I canít wait to see those rs6 turbos in action. Itís going to rip!

According to my measurements on the mock engine in the Boxster bay, the charge coolers should fit, but it will be tight for sure (the coolant fittings stick out towards the front and will be close to the front of the bay). With the air-water intercoolers, how big of a heat exchanger are you running up front? Are you satisfied with its size/capacity?
Yeah, hopefully it'll make good numbers. It's on the dyno the 13th of August but I'm not overly optimistic.

I've copied and pasted a bit on my build thread on another forum about my charge cooler radiator. It was a Chinese special, off ebay, it's large and only just fits. It's really heavy. I don't think it's particularly good at cooling. Compared to OEM stuff the core design doesn't look as good, plus it's so thick I couldn't mount it with as much angle I wanted for the air to easily escape behind it. I feel like with this stuff you are better off using OEM parts where possible, cheap aftermarket is typically ****************e.

I monitor the inlet and outlet temperatures of the coolant (pre and post turbos), I thought my system was performing quite well but since I had my engine out recently I'm not so sure. My current usage isn't ideal, it's currently about 20c ambient and I'm tuning it which means make a pull, then pull over for 5 minutes while I go through the logs making changes. The whole lot heat soaks. I've got no fan on the radiator at the front but I do turn off the pump when the car isn't under positive boost pressure or at low speed to try and stop heat soak. During a pull I'm typically seeing between 30 - 35c for the coolant entering my charge coolers, so 10-15c over ambient, not awful but I think room for improvement with a better radiator. The coolant temperature coming back from my charge coolers can go as high as 65c but there is a lag on it, during the pull it's similar numbers to the inlet temperatures (my sensors aren't that close to the coolers). It seems to show the Mercedes charge coolers are doing their job, putting heat into the coolant (the ones you are using will be more efficient than mine). Constant throttle around a track, I think this system get's overwhelmed fast but it's alright for street driving. My IAT's aren't brilliant typically around 50c at the top of a pull, did see one where I turned the boost up to 28psi which is probably past the efficiency of the turbos and saw 90c which is crazy.

Am I happy? Not really, think there is room for improvement in all aspects of my system but the gains are marginal and not worth re-doing everything for. I think the reality is air to water systems disappoint in nearly all applications I've seen. Even OEM systems over-heat and end up in reduced power modes. One thing I've looked at are systems like the interchiller which uses A/C to cool the liquid. It looks good but I think the same rules apply, you'll over heat the system with hard use, you just start from a lower base temperature.

I've got water/methanol injection (not used it properly yet), this should take care of my charge cooler shortfalls. I sometimes wonder if I'm better off with just this and ditch all the weight of the charge coolers.


I fitted the radiator up front. Everything on the 987 is slightly different so like pretty much the rest of it, I had to start again with mounting this and making brackets. One benefit of the differences are the radiator ducts on each side are smaller so I didn't need to cut them like on the 986.

The pump hidden away and mounted nice and low. After having the radiator inlets and outlets mounted on the passenger side I realised there wasn't enough space to run the coolant lines down the sides and behind the wheel arch liner/down the side of the fuel tank like it'd done before on the 986 so I had to work it out a different route.

The charge cooler tank is going to be mounted inside the front boot, there was a handy rubber blanking plug just above the radiator so the hose feeding the radiator runs through there. Then it goes through the rad, to the pump, back over the top of the rad and down the drivers side chassis rail and into the engine bay. On the way back there was another handy little blanking plug, I hadn't noticed it before as it was covered in seam sealer, the hose comes back into the front boot through that and back into the tank. I do my best to not cut holes all over the place, I'm pleased with the pipe routing.

Here is the tank mounted in the front boot. I spent a bit of time making up some brackets to raise it up and angle it slightly. I raised it as the higher it is the better in terms of any trapped air making it's way back into the tank. I angled it slightly so it looks better under the cover.

All hidden away, you'd never know.

The next big job was the tank for the meth injection. Having fitted the charge cooler tank where I initially planned to mount a meth tank I could now put the meth tank on the battery tray where the charge cooler tank was on the 986. I added in the fitting for the meth line.

My meth tank and the little race battery both fit on the battery tray. There were no mounting points on the tank so I used a battery clamp I'd bought years ago and never needed. The battery is held in place with a metal bracket. I bought another of those Battery Brain's the first one I had seemed to be playing up so I returned it. It took a bit of fiddling to get it all in place without needing to cut the battery cables which I wanted to avoid. I had to move the alarm siren to the other side where the original earth point used to be.

All hidden away. I'm happy with how it's turned out, it's been really time consuming planning where to put things and make the best use of the available space but I think it's worth the extra effort.

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