LT230 1.2 in defender rev question

payydg · Mar 13, 2019

Another thread brought this back into my mind.

Put a 1.2 LT230 in my defender after a full rebuild. It seems to rev quite high, so in lower gears shoots through the rev range. In 5th doesn't seem to have made a huge reduction in revs at 60-70. I can't remember the exact numbers.

I've only done one journey in it like this as I took the engine out after but not quite what I was expecting? Fuel economy seems better. The Ashcroft calculator suggests should give an improvement with the tire size i have 235/85 R16 120 116s.

Is this normal?

windy81 · Mar 13, 2019

don't have a rev counter in mine but, with the same 1.4 to 1.2 conversion that i've also done, i can confirm that at 60-70mph the engine with a 1.4 would be reving it's nuts off !
Currently only revs it's nuts off if going 90 which sounds to me like the 1.4 sounded at 70mph.
Totally objective but the engine in mine sounds like its doing the right revs for the speed now.

edit - just to say, mine is a 200tdi with 235/85 r16's also

300bhp/ton · Mar 13, 2019

payydg said:
Another thread brought this back into my mind.

Put a 1.2 LT230 in my defender after a full rebuild. It seems to rev quite high, so in lower gears shoots through the rev range. In 5th doesn't seem to have made a huge reduction in revs at 60-70. I can't remember the exact numbers.

I've only done one journey in it like this as I took the engine out after but not quite what I was expecting? Fuel economy seems better. The Ashcroft calculator suggests should give an improvement with the tire size i have 235/85 R16 120 116s.

Is this normal?

What engine?

Did you confirm it was really a 1.2 before fitting?

A 1.2 with 235/85/R16 tyres, you should be able to top 70mph+ before shifting into 4th. If you have a rev counter you'll easily be able to see what speed vs rpm you are doing in each gear. Then just compare with a gearing calculator (one on Ashcrofts site).

discomania · Mar 13, 2019

payydg said:
Another thread brought this back into my mind.

Put a 1.2 LT230 in my defender after a full rebuild. It seems to rev quite high, so in lower gears shoots through the rev range. In 5th doesn't seem to have made a huge reduction in revs at 60-70. I can't remember the exact numbers.

I've only done one journey in it like this as I took the engine out after but not quite what I was expecting? Fuel economy seems better. The Ashcroft calculator suggests should give an improvement with the tire size i have 235/85 R16 120 116s.

Is this normal?

The idea is you are doing less revs on the 1.22 so it shouldn't feel like your doing more. The difference (calculated on a factory fit size of tyre) was 458rpm reduction at 65mph if you previously had the 1.44 and 1038rpm if you had the 1.67.

payydg · Mar 13, 2019

discomania said:
The idea is you are doing less revs on the 1.22 so it shouldn't feel like your doing more. The difference (calculated on a factory fit size of tyre) was 458rpm reduction at 65mph if you previously had the 1.44 and 1038rpm if you had the 1.67.

Well yeh exactly. Can’t quite work out why it’s like that. The engines currently out so I’ll post some numbers.

payydg · Mar 13, 2019

300bhp/ton said:
What engine?

Did you confirm it was really a 1.2 before fitting?

A 1.2 with 235/85/R16 tyres, you should be able to top 70mph+ before shifting into 4th. If you have a rev counter you'll easily be able to see what speed vs rpm you are doing in each gear. Then just compare with a gearing calculator (one on Ashcrofts site).

200tdi defender

Chalky. · Mar 13, 2019

Sounds like potentially that it may not actually have 1.22 internals then...

Muddy Vicky · Mar 13, 2019

Assuming you've got standard diff ratio and LT77 main 'box, I'd expect you to be doing around 2600-2700rpm at 70mph in 5th.

My 110 with a standard 1.4 LT230 does a little over 3200rpm at 70mph whereas the 90 with a 1.003 used to do around 2100rpm before I put the R380 in, so splitting that in half for your 1.22 I get that 2600-2700rpm figure and 500rpm reduction from where you were.

How are you figuring it's not what you expect? I'd struggle to hear a 500rpm at those revs and in the lower gears you're only talking small changes in mph for any given engine revs and if you've had the engine out and done any work on, maybe it's just pulling better and so going through the gears faster. Even oil in the transfer box can make a difference - I find EP90 takes an age to warm up and so everything in the 110 seems sluggish when cold whereas the 90's got 20/50 in her box and gets going much better.

Rougharse Racing · Mar 13, 2019

I have a 1.2:1 transfer box in my 300tdi 110, running on 750x16 tyres.
The previous transfer box was 1.6:1, so the difference was huge. The gearing on mine feels quite tall and you wouldn't want any higher ratio.
As others have said, I would check that it is actually 1.2:1, the first 3 digits of the serial number will tell you what ratios it left the factory with.

discomania · Mar 14, 2019

payydg said:
200tdi defender

Here is something to consider, if you have done a full rebuild and not been driving the Landy for a while but rather a car - the Landy will feel like a total truck when you first drive it again.

When I did the final stages of the rebuild of my 90 it was off the road for over a year I think, when I got into it early one Saturday morning to take for it's MoT and got it out onto open road I was looking about the place convinced I had left an entire floor panel out or something. Everything just felt agricultural and the engine sounded to me like it was doing 6000rpm all the time. I had been driving solely my Disco while the 90 was off the road and it had got me used to a more refined drive - now the Defender feels perfectly refined as I am just used to it - which is actually ridiculous because I know it sounds like a tractor, but I love every minute of it.

payydg · Mar 14, 2019

That’s a fair point. I’ll need to get it on the road and see what the revs are. Just thought I’d ask in case someone suggested an obvious issue I’d over looked.

payydg · Mar 14, 2019

Gottschalk said:
Sounds like potentially that it may not actually have 1.22 internals then...

Interesting. I’m fairly sure it is. 1.22 on the box.

payydg · Mar 14, 2019

Muddy Vicky said:
Assuming you've got standard diff ratio and LT77 main 'box, I'd expect you to be doing around 2600-2700rpm at 70mph in 5th.

My 110 with a standard 1.4 LT230 does a little over 3200rpm at 70mph whereas the 90 with a 1.003 used to do around 2100rpm before I put the R380 in, so splitting that in half for your 1.22 I get that 2600-2700rpm figure and 500rpm reduction from where you were.

How are you figuring it's not what you expect? I'd struggle to hear a 500rpm at those revs and in the lower gears you're only talking small changes in mph for any given engine revs and if you've had the engine out and done any work on, maybe it's just pulling better and so going through the gears faster. Even oil in the transfer box can make a difference - I find EP90 takes an age to warm up and so everything in the 110 seems sluggish when cold whereas the 90's got 20/50 in her box and gets going much better.

I’ve got a rev counter and seemed to rev high and fast. Got up to revs quickly. Like I said I’ll post some
Numbers once the engine is back in

Muddy Vicky · Mar 15, 2019

If the engine's not back in yet, suggest you put both boxes in gear (high ratio and preferably 4th) and get someone to turn the input shaft of the LT77 a specific number of times (say 20) whilst you count the number of revolutions the LT230 output does. Then you can double check that the LT230 has the correct internals.

Believe I'm right in saying that the LT77's 4th is a 1:1 ratio so 20 turns on it's input should lead to a bit over 16 on the LT230 output. Anything less and the internals have been swapped.

Remember also that speedo's are notoriously inaccurate so when you finally do run it, compare your revs with a real (say GPS) speed. I swapped the 90 from 205R16 to 265/75R16's and only then did the speedo become accurate.

LT230 1.2 in defender rev question

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