Installing a Larger Volume Intercooler on the Range Rover P38 (BMW M51)

It took a while, but I finally got around to installing a larger volume intercooler on the Range Rover P38.

I ordered the unit as a Britpart replacement, although it appears the actual manufacturer is Serck Motorsport.

When the intercooler arrived, the weather was poor and I was short on time — which, in hindsight, wasn’t ideal. As expected, the installation turned out to be anything but straightforward, especially when done in a hurry.

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Preparation and Removal

For easier access, I decided to drain the cooling system, which is highly recommended for this job. While doing so, I also removed the right-hand radiator support bracket that bolts to the chassis. This creates much-needed space to manoeuvre the intercooler into position.

Because this upgraded intercooler is thicker and shaped differently compared to the OEM unit, the original mounting points cannot be reused. On top of that, the fit is extremely tight.

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Intercooler and Oil Cooler Installation

Once the intercooler was positioned, I reinstalled the radiator. Due to the increased thickness of the intercooler, the engine oil cooler now has to be mounted above the intercooler instead of below it.

With everything loosely in place, I marked the mounting points and drilled new holes in the side support pillars to secure both the intercooler and the oil cooler. To improve clearance, I added a 3 mm thick washer behind the intercooler.

The vertical position of the intercooler is largely dictated by the oil cooler, as it sits just below the top of the radiator. Positioned this way, the intercooler hoses line up properly with both the turbo outlet and the intake piping. One important thing to watch out for is clearance on the left-hand side near the washer bottle filler neck.

For now, I used self-tapping screws to secure everything. I may replace these with proper bolts and nuts at a later stage.

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Results and Driving Impressions

So, does it make a difference?

First of all, I discovered that the old intercooler was leaking, which meant I was losing boost pressure. That alone justified the upgrade.

I haven’t driven the car extensively yet, as the transfer case still needs attention. However, even from limited driving, the engine feels stronger at lower RPM, and throttle response seems improved.

I also noticed that the engine is running cooler. That said, I did clean the radiator while the coolant was drained, so that likely contributed as well.

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Final Thoughts

Overall, I’m very happy with the result. Once the drivetrain issues are sorted, I may experiment with a slight increase in boost pressure to extract a bit more power — nothing extreme.

But first things first:
the transfer case, ball joints, and panhard rod bushes 😏😐😂
That’s a job for another time.

Choosing the Right Tyres for a Range Rover P38: Why I Went with 265/70 R16

For quite some time, I’ve been looking for tyres that offer better off-road performance for the Range Rover P38, without committing to a full mud-terrain setup.

In my use case, mud-terrain tyres would only see limited off-road mileage. That makes them noisy, heavy and unnecessary for everyday driving. Instead, I was looking for a tyre that sits between an all-terrain and a mud-terrain: aggressive enough off-road, yet still civilised and predictable on the road.

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Initial Tyre Options Considered

My first shortlist included several well-known and proven options:

• Falken Wildpeak AT3

• Toyo Open Country AT3

• Kumho Road Venture MT51

On paper, all of these tyres are solid choices for mixed on- and off-road use. The real limitation, however, turned out to be availability and correct sizing. Either the tyres were not available at all, or not offered in the specific size I was targeting for the P38.

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Why 265/70 R16 Makes Sense on a P38

The target tyre size for this setup was 265/70 R16.

This size offers an excellent balance for a largely standard Range Rover P38:

• Increased ground clearance compared to the factory size

• No need for body trimming or suspension modifications

• Works well with the original drivetrain and gearing

• Maintains good road manners and reliability

In practical terms, moving from the original ~29-inch tyre to a ~31-inch tyre noticeably improves off-road capability without introducing the downsides that come with oversized tyres.

If you want to verify how different tyre sizes translate to real-world diameter, clearance and speedometer deviation, you can use my P38 Tyre Size Calculator here:

👉 P38 Range Rover Tire size calculator page

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Final Choice: Cooper Discoverer S/T Maxx

After searching for quite a while, I eventually found a tyre that ticked all the boxes:

Cooper Discoverer S/T Maxx – 265/70 R16 121/118Q, 10PR, M+S, POR

This tyre sits firmly in the aggressive all-terrain category and is clearly aimed at heavier vehicles like the P38. Key characteristics include:

• Strong and predictable off-road traction

• Reinforced carcass and sidewalls

• Excellent durability for mixed on- and off-road use

While it’s technically still an all-terrain tyre, it’s very much on the tougher end of the spectrum — which is exactly what I was looking for on a heavy 4x4 like the Range Rover P38.

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Fitment and Expected Results

The tyres will be mounted on the original 16-inch alloy wheels, which will first be painted black to complete the overall look.

This setup should provide:

• A clear improvement in off-road capability

• No negative impact on drivability or comfort

• A clean, factory-plus appearance

Overall, it’s a well-balanced upgrade that suits how the P38 is actually used, rather than chasing tyre sizes or specifications for the sake of it.

Ducati Desert X Rally new decals

 I'll let the pictures speak for themselves. Kind of a pain in the b*t to apply but it's good enough for me.

Range Rover P38 Transfer Case Failure – Diagnosis and Replacement Plan

After only 1,000 km, the transfer case on the Range Rover P38 started making a significant amount of noise.

Initially, I suspected an engine-related issue, as the noise appeared to come from the front of the vehicle. After further investigation, however, it became clear that the transfer case (TC) was the real culprit.

Before reaching that conclusion, I even considered the gearbox as a possible cause. To rule that out, I replaced the gearbox oil and filter twice — without any improvement.

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Confirming the Transfer Case Failure

The real confirmation came when I drained the oil from the transfer case.

The condition of the oil immediately raised red flags:

• The oil looked heavily contaminated

• Metal particles were present

• The small internal mesh filter was completely clogged

At that point, it was obvious that the transfer case was the source of the problem.

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Finding a Replacement Transfer Case

Fortunately, I managed to find a second-hand transfer case. That did require a four-hour drive to pick it up and bring it home — but sometimes that’s the price you pay for the right part.

Of course, there was still some doubt in the back of my mind:
What if I install this unit and it turns out to be just as bad?

To avoid that risk, I sent the replacement transfer case to a specialist company capable of inspecting its internal condition.

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Good News at Last

Yesterday, I received the verdict — and it couldn’t have been better.

The transfer case was described as “brand new on the inside”, showing no signs of wear and requiring no rebuild or additional work.

That was a huge relief.

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What’s Next

With a confirmed good replacement unit ready to go, the next step is straightforward:

• Remove the old, failed transfer case

• Install the replacement unit

• Finally get the P38 back on the road

After a string of setbacks, it’s great to have something go smoothly for once.

More updates soon 👊

P38 Borg Wagner
transfer case