When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have spent the last three months maintaining and up-fitting a 2015 F55 base cooper with the front bumper and cooling components from a LCI 2 JCW and just had the chance to push the car recently. I did this because the Forge intercooler for the B38 cars is quite expensive and for around the same price I could swap the entire cooling system over. Here are the findings.
Fitment: The radiator, intercooler, evaporator, charge pipe, boost pipe, and auxiliary radiator from the F56 JCW all fit on a B38 car (with some custom fitment required for the aux rad if you don't buy the JCW support rail)
Performance: IAT's on the base intercooler package (for a 20c ambient day) would have a delta T of 25-35c over ambient under heavy acceleration in the 40-70 mph range for a fully warmed up car. The JCW intercooler drops IAT delta T down between 8-15c above ambient which I was very surprised about. Caveat being the GP3 intercooler I have is nearly new and the stock unit was 10 years old and quite dirty. The rad + aux rad combo kept coolant temperatures around 98-105c pretty consistently and the 850w fan brought temperatures down a lot faster if I stopped quickly after a hard run.
While you're in there: Because of the age and mileage of my car (10 years 82k miles) I elected to replace: the oil filter housing with a URO metal unit, Rein Metal coolant outlet fitting, all EPDM coolant hoses, Oil feed & return o-rings for the turbo, GP3 upper engine mount, and many more things.
A chip tuner might be a good thing: I have a Racechip GTS that I always found harsh on the factory setup as it would create a surging power delivery feeling. With the larger volume intercooler it seems to buffer this condition and make it feel more like factory power delivery but with a higher top end.
If you have any questions about the build, let me know and I can elaborate. I am dumping picture from many different parts of this process. If you're interested in doing this to your own B38 car, I have another set of JCW cooling parts that I would like to sell.
First drive back together
Factory Cooling System
JCW/GP3 Parts installed
Size comparison
GP3 Charge Pipe
X1/Clubman/Countryman front BBK, Stainless Lines, Koni FSD Shocks
Blocked intake snorkel before being opened up and resealed
AC line and evaporator flush
New Oil Cooler and other parts
Replaced a badly dented transmission pan and resealed
Aux rad duct
Last edited by UnderWaterAce; Dec 26, 2025 at 04:10 PM.
Love it! Reminds me of the Civic guys who back in the day would buy the cheapest DX hatchback and throw all sorts of Integra parts at them
I think it’s pretty cool that all those GP3 parts fit right up. The “Justa” is a cool platform, I think - even though I drive a JCW.
What handling mods have you thrown into the car? I see the Koni Reds… Sway bars? Springs? Bracing? I think the car could be a great daily driver. Frugal with the 3-cylinder, but fun with all the upgrades.
Love it! Reminds me of the Civic guys who back in the day would buy the cheapest DX hatchback and throw all sorts of Integra parts at them
I think it’s pretty cool that all those GP3 parts fit right up. The “Justa” is a cool platform, I think - even though I drive a JCW.
What handling mods have you thrown into the car? I see the Koni Reds… Sway bars? Springs? Bracing? I think the car could be a great daily driver. Frugal with the 3-cylinder, but fun with all the upgrades.
So far I just have the Koni’s on stock springs and WMW braces. Going to be getting Continental ECS 02 tires on soon to replace the Pilot Sport AS3+’s I have on right now. Considering doing the MMX forward brace and WMW 25mm rear bar at some point as well once the wallet can support it.
The Koni Reds do a good job of keeping the car refined for the daily commute and reasonably stable under more aggressive conditions. At some point I would like to see if KW V3 street comforts could strike a similar balance but that set is well out of the reasonable budget range for now.
Impressive swap and data. Huge IAT improvement. Curious about long term reliability and daily drivability changes.
I have around 300 miles on the car post swap and thus far no abnormal behaviors. I am most concerned about all the resealing I did on the car lol. At some point I will test the car without the racechip to see if the higher volume intercooler introduces more turbo lag on the factory tune.
It is within my plan to code in the 2TB transmission parameter at some point to see how it interacts as well.
