Thread: 4BD1 into Defender

Originally Posted by Dougal

Serious question. For $AU3-4k for an adapter & gear/TC linkage set (buy your own gearbox and LT230) what is the demand?

$3k AUD is the upper limit of what I'd pay - but for a proven product I'd pay it.

Originally Posted by workingonit

And I'm not sure of availability of msa 5 speeds to replace lt95. Competition between those converting Lrovers and those wanting to keep their NPR trucks running may see the eventual end of this conversion option? By way of example I believe I may have got the only engine and box in Darwin after ring all wreckers.

They used to be available brand new for a surprisingly modest cost. My RRC allegedly got a new MSA-5P in 1994 for $1k. I'd expect about triple that now.

Kicking this thread in the guts again because some progress has been made. If you had '97 Defender axles (front standard, rear Hy-Tuff) and Perentie axles, which would you use and why?

My thinking was Perentie front (stronger CVs) and Defender rear (already Hy-Tuff and disk brakes). Any reason that isn't a good option?

Defender fine spline front centre would be better with earlier county CVs.

You could leave the perentie Salisbury in place esp if has less km and swap over stubs shafts brakes and hubs.

Thanks Pete (again), that sounds like the way to go.

To justify this conversion in my head – and because work is slow - I’ve run some numbers comparing 4BD1T to 300Tdi performance in real world situations. These graphs assume a 2.5 tonne vehicle, 235/85r16s, Cd of 0.65, frontal area of 2.89m squared, a driveline efficiency of 65% (probably too high, but the same for each vehicle) and a bag of other things.

Firstly, driving up an incline. If you’ve attempted this in a loaded 300Tdi Defender, you’ll know what a horrible thing it is to do. Running the numbers, a 300Tdi Defender travelling at 110km/h is flat out scaling a whopping 3% grade. At a 9% grade you’ll be back in 3rd doing 70km/h. An Isuzu powered Landy will still be travelling at 100km/h, still in 4th. In these first two graphs, the solid lines are Isuzu - dotted are 300Tdi (it's hard to see the dotted light blue lines in these graphs, but they are the 300Tdi's fourth gear).



The next real world situation; overtaking. If you are stuck behind a caravan at 100km/h, your ability to overtake is limited by your ability to accelerate. A 300Tdi is capable of accelerating at 2.5km/h/s from 100km/h while the Isuzu can manage 4 km/h/s. Any time saved on the other side of the road is an absolute godsend.



So I don't think I'll be spending any more money on the 300Tdi

I also took some time to compare 4BD1-T with LT95 to a 4BD1-T with r380 and an LT230 with Disco gearing as that was an option put forward by KLR. The gearing between the two options works out almost identical, except that the r380 lands a gear between the LT95’s 3rd and 4th. You can see how that affects the vehicle’s performance in the following graphs:



Again, it's hard to see the dotted light blue line (LT95 fourth gear) but it follows the solid purple of the r380's fifth.



It seems as though the extra gear could help overtaking on 80km/h streets and climbing some very steep highway stretches, but aside from that wouldn’t add much. Which is something most of you have said already, of course

Look out, we've got another Dougal

Brilliant. Now if someone can just pay me to stay at home and work on my County instead of going to work, I'd be set.