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Full Version: Mk2 Focus Rs Intercooler To Fit Into A Tdci
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I don't suppose anyone would know whether a intercooler from a focus rs mk2 ( aftermarket ) would fit into a 1.6tdci. Looking at them the inlet and outlet are not the same as the original one. They are both facing aft of the cooler instead of to the sides. Would this pose a threat into not being able to fit. Only I'm not sure how flexible the original cooler hose are to make it it? Much appreciated if anyone could shed some light on this? Many Thanks Ryan
Theres not really alot of give in them hoses plus incrase pressure of any type could blow them off, split them etc.

Best get a aftermarket intercooler for your engine or a custom made one. Or get a metal shop to custom fit yours

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It can be made to fit but there may be no technical advantage, in fact you may actually reduce power/ increase lag  


As this is a non-technical forum, the reasons are outside the scope of the forum, but here is a brief simplified  rundown of intercooler basics/ choosing an intercooler  and the difference between petrol / diesil applications


1 - a petrol Focus RS mk2 intercooler is not nessisarily better than the one already fitted to your diesel car    


2 - If your original intercooler has a specific inlet/ outlet size (say 2-1/4" / 57mm) if you go down in size (say to 50mm) this can "choke" the airflow, restricting revs & power, if you go up in size, (say to 2-1/2" 63mm) by using an adaptor, this can cause a sudden loss of velocity in the airstream, causing turbulence, the hose design may have to be modified, if you increase the pipe/ hose diameter it can increase volume,  reduce airstream (gas flow) velocity, potentially  reducing pick-up from lower revs and increasing latency/ lag


3 - if you increase the size of the intercooler, the internal volume is liable to be bigger, the bigger the internal volume, the longer the intercooler takes to fill up with air, the longer it takes to fil up with air, the more lag you get


4 - if you fit a much larger intercooler, the front of it may not be in the direct, cooling airstream, and "hidden" or "masked" behind things, on Fords there is often a bumper bar running right through, if part of the intercooler is sitting behind the bumper, it is not in the airstream, and as it is right in front of the radiator, can suffer from increased heatsoak - some aftermarket intercoolersare are  fitted like this  (eg- Airtech on a ST-TDCI) 


5 - now it gets a bit more technical -  A larger intercooler has a larger mass of metal, and more thermal inertia this means it takes longer to heat up (good) but longer to cool down (bad) a smaller intercooler ften has a lower thermal inertia so cools down quicker


6 - turbo petrol and diesel engines are different, a diesel tends to run a lot of boost for sustained periods (petrol turbo tend to run less boost for shorter periods) - so if you have a large intercooler with a high thermal inertia it might work better as the intercooler acts as a "heat sink" and then is allowed to cool down (due to the longer periods of low boost compared to a diesel) - so what works on a petrol turbo may not work on a diesel turbo


7 if a larger intercooler is stuck on a stock engine, it may not increase power, but it can increase lag and raise the boost threshhold, (so making the power band narrower, reducing effective power at low revs - a larger intercooler must be optimised with a map, or the boost pressure increased to take advantage of the better cooling capacity


8 - if a larger intercooler is fitted to a petrol engine, a little bit of lag/ latency does not matter, as long as it increases power (is optimised to increase power) in the midrange / top end, because a petrol engine revs a lot higher than a diesel engine, on a deisel engine that only revs to/ has peak power at 4k, (or 3.5k in some cases) you cannot afford to lose any bottom end power/ torque that you may loose by fitting a larger intercooler - that would make the power band narrower - making the car slower. - (reducing the bottom end power can give the illusion of more mid/top, but the car may actually be slower)      


9 - so the intercooler must be very carefully chosen for the application, get it wrong and you will raise the boost threshold  (), increase lag and reduce power, and make the effective power / torque band narrower - even well-known brands like Airtech can get it wrong, with large intercoolers designed for petrol turbos stuch on diesels, partly "masked" behind bumpers, and slower in-gear acceleration figures due to increased lag (ST-TDCI)


10 - a very large intercooler can add a significant weight to the extreeme front of the car - this can affect acceleration, especially on lower powered cars and handling on all cars, and if it increases lag as well....


11 - in a hot country, you may need a bigger intercooler than in a colder country, on a sprint/ hillclimb, a smaller intercooler for less lag, etc etc the intercooler is matched to the car, engine, state of tune, event and temperature, the stock intercooler may outperform a larger one in some situations, like on the road



i would recommend just leaving the original intercooler on, if you must fit another intercooler, fit one that fits in the space, (is not "masked"/ hidden behind bumpers etc, fit one that has the same size fittings / hoses, one that is not massively bigger than stock, and take expert advice from the likes of myself, and it is for those that have already done the remap, extensive exhaust mods etc, already                  

Wow thanks for that I wasn't expecting a write up about that. I'm not planning going huge as I know it will be bad and the engine has limits like they all do before you make it worse than what it was. I'm after something like stage one sort of size. Very similar size to original as I don't want to cut away anything. Mainly just better flow as I am trying to remove as many restrictions as possible. The car will be mapped soon enough. The car has an enclosed induction. It's a kn57s so it's all in the airbox and nothing showing to avoid heatsink. Egr blanked about 20,000 miles ago. Just need exhaust sorted and Dpf gutting and I should have a fairly healthy car with better overtaking ability and more economical. I woukdnt mind sorting out the oil breathing system as I get oil in the intake pipe leading to the turbo. Perhaps a catchment tank but I have been looking and not much luck. Because if there's oil there then the chances of oil in the intercooler will be present. Not sure if it's entirely a good thing though.

Heatsoak can occur not just into the intake but straight onto the back of the intercooler as well (from the radiator as well as just the heat from the engine bay) - if the intercooler is bigger than the opening below the bumper it suffers worse as that happens and there is no direct cooling airsstream onto the parts of the intercooler masked behind the bumper, the fact the bonnet is sealed makes things worse


venting the bonnet helps and on some race and "seriously" modded cars they put the radiator fan(s) between the radiator and intercooler - this helps to insulate the intercooler from the heat off the radiator - the fans can often be switched on manually before a run to help cool the intercooler (say sitting on the start line of a drag strip) - it wont overcool the engine as the temperature is controlled by the thermostat


(Pic to come)


these are acceleration figures for a regular, road-going ST-TDCI, in black are the standard times, in green standard with a bluefin remap only (otherwise stock) and in red with the Bluefin and a £300 Artech intercooler, supposedly specially designed for the car/ engine -     


30-50in 3rd - 3.2 - 3.1 - 3.4


40-60in 4th - 4.4 - 4.3 - 4.7


40-60in 5th - 7.2 - 6.1 -6.7


50-70in 5th - 6.3 - 5.9 - 6.0


As you can see the quickest times are with the stock intercooler and bluefin, and with the larger Artech intercooler the car is slower


you might just be better of leaving the standard intercooler on and going just for the remap  


has anyone managed to relocate the I/C into the lower recess of the focus bumper? obviously with a bit of cutting here and there?

I've seen it been done but I'm not sure how though. I see well my car would custom mapped to suit what I'm putting on it. A bluefin is just a generic map and it won't work on my car because of it's age. They done cover it I've been there to try it with no luck. So custom map it will be. I may see about getting a custom cooler made but I wouldn't know where to look for that. Any advice? And I'm sure you wouldn't need to put the cooler right into the front of the bumper. Subject to more damage. I'd rather keep the grille perhaps changing it to an st honeycomb type for better flow and still have some sort of protection for the cooler right?

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