Thread: 4BD1T Defender Conversion after 380,000ks Was it worth it?

In 2007 I had a factory Turbo 4BD1T fitted to my Defender - (the conversion was covered in posts at the time). Was it worth it?

A rusty Isuzu County was purchased as a donor vehicle for all the Land Rover Isuzu parts (radiator, fan shroud, Edict, sandwich plate, Bell housing etc) the conversion looks factory and has performed extremely well. The gearbox is a late suffix R380. Total distance covered since the conversion 380.000ks. the engine had about 164,000ks on it at the time. I fitted a new turbo last year, had the fuel pump overhauled about 10 years ago, and have had new nozzles fitted to the injectors.

The Good:

1. Power. The engine pulls 1.2:1 high range with a 300Tdi R380 effortlessly fully loaded or empty. The 1.2 was fitted before the 300Tdi was replaced with the 4BD1T, and the vehicle became a hill detector particularly when fully loaded - although fuel economy improved about 10%. Off road the Isuzu works very well with better lift off torque and engine braking than the Tdi. in heavy sand eg in the desert or coastal sand hills the vehicle works well but the limited revs of the Isuzu requires careful gear selection and quick gear changes on the biggest sand hills.

2. Reliability. The engine has been extremely reliable, with none of the annoying breakages that seem to afflict the Tdi ancillaries (I have driven 300Tdis nearly 600,000ks).

3. Performance. The engine is effortless to drive, and has made the vehicle a pleasure to drive over long distances. Towing is easy, and even the heaviest trailers are not really noticeable. Headwinds slowing the vehicle down are a thing of the past.

4. Cooling. The engine runs at 80-85c on the highway and on hot days will nudge 90 or so. In the Simpson in 48C + the max temperature seen was about 93C when working hard. even when driving down wind in slow going with a strong tail wind the temps stay very stable. Radiator is a copper core in factory tanks. The Tdi would hit 105C+ on hot days, but never overheated.

5. The R380. The naysayers said that an R380 would not last behind the Isuzu. I have just fitted a rebuilt gearbox after 350,000ks on the previous one. The ratios a very well suited to the engine, and top gear is ideal for the rev range of the Isuzu, and gives effortless highway cruise. I started off with a Maxidrive 30% rock crawler TC, which has recently been replaced with a standard low range transfer case. The standard low range ratio works much better in sand. The 30% worked well in very steep country, and worked fine in the desert but there were times when you ended up in no mans land, needing either a lower 1st high or a higher 3rd low. With the standard low range 3rd low is lower that 1st high and 4th low is higher than 1st high giving a better spread of ratios. The 30% 4th low is a fraction higher than 1st high and 3rd low is significantly lower. I have decided to keep the 30% for another project.

The Indifferent.

1. Fuel Consumption. The vehicle averages 13.65 lts/100ks (20.5 mpg) (11.75lts/100s as a 300Tdi) round town and on the highway. Fully loaded on a trip average will drop to about 14lts/100ks (12.25lts/100s as a 300Tdi)cruising at 100-110, although on a recent trip economy improved about 5% dropping to around 13lts/100ks. Off road consumption increases to about 15.66lts/100ks (18mpg) (14.1lts/100s as a 300Tdi), and in the desert ranges from 16.5lts/100ks(14.1lts/100ks 300Tdi) (Frenchline in the Simpson) to 25.63lts/100ks (18.8lts/100ks 300Tdi)in heavy, slow cross country in the Simpson.

The Bad.

The engine is heavy.

Conclusion. Would I do it again? all else being equal probably yes, but I would consider an LS1 for power and performance. Was it worth it? Yes, definitely. The conversion cost about $17,000.00. The Isuzu transformed the vehicle and has been very reliable. I have travelled to very remote areas single vehicle. have travelled all over the Simpson without concerns, have done thousands of hwy ks summer and winter without a second thought, and have not been stranded once. The vehicle is fitted with Maxidrive Diff locks front and rear, is comfortable and extremely capable, goes anywhere I have ever wanted to go from extremely steep forestry fire trails to the Simpson desert and everything in between.

In short the 4BD1T transformed the vehicle and 14 years later is still going strong

FWIW
C H T

Originally Posted by Red90

Got a better turbo. I never get worse than 11 l/100 km, have lots of power and weigh over 3 tonnes.

He runs a garret tb2568, which isn't that bad a turbo, but only runs at 11psi, so could do with a bit of a tune.