4.0 v8 or 4.6 v8

hi all right im getting shot of my dse because its doing my nut in now, im thinking of getting v8 but whats best (and most reliable) a 4.6 or 4.0 also what mpg will i get on each (dont worry ill be getting a lpg one)

12mpg most of the time, 22 on motorways! Both are same engine just diferent piston and con rods

gavbriggs said:

12mpg most of the time, 22 on motorways! Both are same engine just diferent piston and con rods

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some people say stay clear off 4.6 as head gaskets go alot is that true

they are higher compression so i would imagine theres more strain on em, the thing to watch is the liners slipping, this happens on both engines, also porous block, although i have only experienced slipped liners myself. the head gaskets are an easy job to replace and can be done comfortable in a w/end but you will need to have the heads skimmed which obviously depends on the machine shop. the place i used was very good and did them in the day!! they are friends/contacts of uncle tho so it was more of a favour than a job!!!

Well the advice I was given 5 years ago when I bought my 4.6 was that the 4.6 was a (much) better performer, but that it tended to run "hotter" and was thus potentially likely to have problems with LPG conversions, due to the low tolerances - in other words, if you want to run a P38 on LPG, I was advised not to do it on a 4.6 as it would just be a metter of time before major engine problems arose UNLESS you do a complete engine refit like tophat liners or a Coscast block, at the time of fitting the LPG system.

So loads of people on this forum may shout "bollocks" at the advice I was given, but then I've had the Rangie over 5 years now and over 120 000 miles and the engine has stayed sweet, so perhaps the proof of the pudding is in the eating as the saying goes.
At nearly 150 000 miles I suppose she could pop her clogs any time and is using a bit of coolant now, but the rad is a bit suspect, but I am eternally grateful I resisted the temptation to fit LPG - the "saving" from the LPG would have cost me a fortune in a new engine etc and the 4.6 Special Edition I have has a very high interior spec which I believe the 4.0S don't have.

Horses for courses, but good luck with whatever choice you make.

mines on at least its second lump and its lpg 4.0, its a top hatted block so should last a lifetime!!! prolly not tho!!!!!

from this i might stay clear of the v8, cant afford probs on them, i spent well over £1000 on the dse

thems yer options, doozel or v8!! there are many people who have never had issues with thier v8, i saved alot of cash by doing all the work myself, the block only cost 250 quid and to be honest i reckon i ripped the fella off but thats what he wanted for it so thats what i paid!!!

skippy22 said:

hi all right im getting shot of my dse because its doing my nut in now, im thinking of getting v8 but whats best (and most reliable) a 4.6 or 4.0 also what mpg will i get on each (dont worry ill be getting a lpg one)

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seems to be luck of the draw with r/r engines petrol or diesel, but seems to more have probs with the petrol than diesel but like i said luck of the draw

the disco v8 (which is the older range rover engine) is essentially the same as the classic/p38 but i dont hear much about them going tits up!

prolly cos i dont go in the disco section!

gavbriggs said:

the disco v8 (which is the older range rover engine) is essentially the same as the classic/p38 but i dont hear much about them going tits up!

prolly cos i dont go in the disco section!

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thats cos its the feckin g/boxes that pack up

Both being 94mm bore engines, either can slip a liner (as can a 3.9) but the 4.6 appears to be the most prone, something to do with the fuelling & the torque band leading to higher combustion temperatures (as does LPG) I'm not an engineer & whilst I see how a 'top-hat' design can prevent liner movement, I fail to see how engines built this way can prevent the block cracking behind the liner.

norseman said:

Both being 94mm bore engines, either can slip a liner (as can a 3.9) but the 4.6 appears to be the most prone, something to do with the fuelling & the torque band leading to higher combustion temperatures (as does LPG) I'm not an engineer & whilst I see how a 'top-hat' design can prevent liner movement, I fail to see how engines built this way can prevent the block cracking behind the liner.

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The top hat liner has 2 functions,first the head gasket can actually seal against it - look at the original liner and you will see that the gasket only seals against the alloy of the deck face.Second is that ridge at the top of the liner prevents it moving up and down like the originals could when the block cracked/lost strength or the interference fit was not good enough.
The top hat liner cannot prevent the cracking,but it does not matter as the liner cannot move nor can the combustion chamber pressurise the cooling system.
The only improvement on this is done by Turner enginering,which is fitting an O ring around the lower part of the liner to prevent coolant escaping into the sump - rare but can happen.
The bit about lean fuel maps on the petrol injection systems is rubbish and easily disproved.Lean mixture on LPG are VERY common,often due to poor components,poor adjustment,lack of maintenance or a combination of all of them.

to add to that, it should be easier to seal against the water pressure escaping past the liner than it would the combustion pressure should the alloy and liner seperate.

i'm sure stuff like the ceramic sealer could cope with this situation!!!

nathan5346 said:

thats cos its the feckin g/boxes that pack up

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i reckon if we got one of every land rover and drove them all at speed into a single central point, the resulting fusion of midlands engineering could just produce a car that works!! well at least for longer than 10 feckin minutes!!!!