Diesel or Petrol power - which is best?

[FridgeFreezer]

Funny that none of the current JLR engines count as worth a look so far - I thought as modern, powerful, efficient engines suited to land Rover use went they might at least warrant a mention.

Never mind project iceberg, they actually made the TDV8 and as far as I can tell it's not bad?

[tacr2man]

If fuel cost isnt a factor then a simple (relatively ) V8 ala chev , for the sound , torque from go, and lack of noise , but as soon as fuel is a factor then a 6 in line cylinder diesel has to be the answer. Thats why i went to the M57 BMW , but not the later type , same reasons as JLR V6 was discounted . Too fussy !

[discomikey]

Funny that none of the current JLR engines count as worth a look so far - I thought as modern, powerful, efficient engines suited to land Rover use went they might at least warrant a mention.

Never mind project iceberg, they actually made the TDV8 and as far as I can tell it's not bad?

i had the bonnet up on dads D4 the other week (no it hadnt broken down lol) and decided that the TDV6 would sit quite well space wise inside a series engine bay. the engine is shorter than a TDI!

F* quick in a nearly 3T discovery so must be incredible in a RWD 1.3T series 3......

mind you it goes sideways enough already!

[qwakers]

TDV8 for the win. drove one last week. want one this week

[Tanuki]

Funny that none of the current JLR engines count as worth a look so far - I thought as modern, powerful, efficient engines suited to land Rover use went they might at least warrant a mention.

They're all hampered by emissions/economy/green programming [as are their transmission-ratios]. A month or three back my local JLR-pimper lent me a TDV6 Disco Commercial for a weekend. I totally couldn't get on with it - it always seemed to be in 3 or 4 gears higher than I wanted [it was an auto] despite so-called 'sport' mode - and tended to run out of puff horribly once you winded it up past 4000RPM. Just when you thought the fun was about to begin the autobox forcibly changed-up!

[Scotts90]

In a car, petrol. A defender or disco...diesel.

I loved the sdv6 in my d4. The gearbox (8sp ZF) was so much better than the 9speed fitted to the evoque. You shouldn't expect to be able to drive a diesel in the same way as a high revving petrol...both have their merits. The sdv6 in a defender sounds like great fun though.

So, for a land rover the heavy oil gets my vote

[Shackleton]

Have this argument on an ongoing basis with a automotive pal. He's on the petrol side. I'm on both. But a large part of his argument is the things that go wrong on diesels arising from efforts to make them run in a refined way; dual mass flywheel replacements, bonded crank pulleys stuff like that.

Internal combustion wise, I've no need for anything but a diesel these days, and I've had petrol V8's in my RR. But give me a race tuned Ford cross flow, BDA, or Mini A-series - basically a classic old world petrol engine and I'd love it like my own child, in between bouts of trashing it.

[Adam001]

I'm sure a TDV6 or TDV8 in a defender would be great...if you could afford to fit it.

[Chicken Drumstick]

Guys, remember what this would be used for (see the op).

Personally I like, own and have owned both.


But apart from availability and mpg I'm not sure what other attributes the diesels really have.


Even keeping it simple:

Rover V8 = higher usable rev range, better throttle response, no turbo lag, does not need an intercooler, lighter than a Tdi/Td5, more torque from idle, easy 200-250hp, smooth, refined, sounds good.

Tdi/Td5 = heavier, turbo lag, low off idle torque, unrefined, noisey, poor throttle response by comparison. And easy 120-160hp, but difficult to really get 200hp. Intercooled thus requiring moving air flow when working the engine to maintain output.

I admit an old tired 3.5 RV8 with low CR and twin SU's/Strombergs isn't much of an improvement apart from throttle response and refinement. But a 3.9, 4.0+ with some more modern bits would seem to have any Defender diesels pretty much beat on most accounts bar mpg.

[FridgeFreezer]

Guys, remember what this would be used for (see the op).

Well, as this is a thinly disguised "which engine should I fit?" thread, and the criteria are vague enough, fit whatever you prefer and are more familiar with. No point fitting an EFI V8 if you hate electrics, no point fitting a TDi if you hate cambelts/injection pumps, no point fitting a big powerful lump if you hate paying for fuel and no point fitting a small efficient one if you hate pottering about slowly.

I vote fit a 2.25 N/A diesel, it's simple, reliable, and you'll never break a halfshaft through lead footed exuberance.

[Dave W]

In my "fleet" I have a Defender powered by an LS1/6, a Defender powered by a TD5 and a Range Rover powered by a 4.0 RV8.

I love them all and they each have their own purpose, benefits and compromises. If MPG isn't a consideration then the LS1/6 is by far the best engine of the three. Flexible, powerful and sounds beautiful.

The TD5 is nice to drive and has a reasonable power output over a comparatively narrow range. Having driven it on a lap around Australia earlier this year I have to say that I only missed the LS a couple of times but then in those temperatures I also know that the LS would have been thirsty and the heat in the cab would have been uncomfortable to say the least. I've simplified the fuel supply system so it's more akin to an EFI now and that has, in my mind, removed a great deal of the complexity that might otherwise have given reliability concerns.

The RV8, especially the Thor version in my Range Rover is good at it's job and is a good compromise between the TD5 and the LS - more flexibility than the TD5 but without the fuel consumption (or the power/torque) of the LS.

Just like comparing a draft horse with a racing thoroughbred, there is no single "best" it all comes down to which compromises you are happier to live with for your particular use. In my case I have resolved this by having one of each on the drive so I can choose the best vehicle/engine for a specific journey. If I had to plump for one it would be the LS simply because, MPG aside, it's the most fun, the most power and the most flexible engine I've ever owned in a LR.

Electric has the potential to be a good option, if they ever figure out a practical way of storing the electricity that allows it to be quickly recharged and predictable in use over it's life time. The biggest failing of electric at the moment is the inability to "instantly" recharge it to full like you can with a petrol or diesel vehicle on the forecourt.

I dislike "revvy" engines, mainly because all my vehicles are expected to head off tarmac at some point and low down torque is important to me. I dislike the transit engine Defenders for that reason but the TDV6 or, even better, the TDV8 would appeal to me if there was a practical way of shoehorning them into a Defender.

[Chicken Drumstick]

Well, as this is a thinly disguised "which engine should I fit?" thread, and the criteria are vague enough, fit whatever you prefer and are more familiar with. No point fitting an EFI V8 if you hate electrics, no point fitting a TDi if you hate cambelts/injection pumps, no point fitting a big powerful lump if you hate paying for fuel and no point fitting a small efficient one if you hate pottering about slowly.

I vote fit a 2.25 N/A diesel, it's simple, reliable, and you'll never break a halfshaft through lead footed exuberance.

Nah, nothing of the sort. Just a general discussion.

Currently in Landy's I have a 2.25 petrol and a moderately tweaked 200Tdi. But also have access to a 3.5 V8 one. Not currently looking at engine swaps, but was interested in what others thought.

[studmuffin]

I am not a big fan of new technology but maybe an interesting direct comparison would be the new JLR Ingenium engine being made at the i54.

2 Litre (4 x 500cc cylinders). Same block for both petrol and diesel models, made to fit transverse or straight, and I understand front,rear or 4x4 drive.

Just a thought

Barry

[Chicken Drumstick]

If fuel cost isnt a factor then a simple (relatively ) V8 ala chev , for the sound , torque from go, and lack of noise , but as soon as fuel is a factor then a 6 in line cylinder diesel has to be the answer. Thats why i went to the M57 BMW , but not the later type , same reasons as JLR V6 was discounted . Too fussy !

Slightly off topic. But do you have a build thread for you M57 conversion? Would you recommend it or did it require a lot of bespoke work?

[carlosbeldia]

I've just came from a short but intensive rally (1.000 km of mud and water). All diesel vehicles came out in good conditions, everyone had attached a gasoline car, UTV or ATV in the back. Mine was an almost new Defender 90 NAS with the 4.0 V8. All except one of the Toyotas in our team were gasoline... guess which car was the best among them? it was the only one that didn't need to be rescued all the time. At least in most of the terrains you find here in Colombia, a diesel is by far the best option. It's not only a reliability or strenght dilemma... problem with gasoline are all those horsepower not matching well with a too high torque band. In all the road, we could see how those 250+ HP cars were stucked all the time no matter how good was the pilot where we went in 4 Low at really low speed. Even the NAS with it's "low" output (190 HP) had to be towed lots of time, despiting it's rear locker (was the only Land Rover with locker. All the Toyotas and one Jeep had lockers)...... all this not mentioning about all the time they spent loading fuel.... not, just let me be with my diesel car (have a Series petrol 2286, but it works closer to an old diesel than to a modern gasoline).

[mad_pete]

I think if you look at the engine line ups and the sales figures the market thinks diesel is best by a long way. Although I guess US market is all petrol.

[Boydie]

In Oz, for long distance touring - is there any other type ??? - you have to give the nod to diesel, for exaple quite a few outback roadhouses dont sell petrol and those that do charge an arm and a leg, diesel is from the bowser, if they have opal petrol (opal is a variety of unleaded petrol that is sold outback as it has no fumes so it cannot be "sniffed" - its from a 200 litre drum and has to be hand pumped. I'd guess if you were a city lad, then convenience wise petrol would be the go.

[CwazyWabbit]

....(opal is a variety of unleaded petrol that is sold outback as it has no fumes so it cannot be "sniffed" ....

Sniffed? Do people sniff petrol to get high? Thought I'd heard of most things but that's a new one on me (over here they had to change the buttons on payphones from plastic to metal as people were burning them with lighters and sniffing the fumes)

EDIT: Seems it's quite common in lots of places around the globe .... apart from here

[FridgeFreezer]

I think if you look at the engine line ups and the sales figures the market thinks diesel is best by a long way. Although I guess US market is all petrol.

Some people buy Nissan Jukes, that doesn't mean they should be encouraged or emulated.

[discomikey]

They're all hampered by emissions/economy/green programming [as are their transmission-ratios]. A month or three back my local JLR-pimper lent me a TDV6 Disco Commercial for a weekend. I totally couldn't get on with it - it always seemed to be in 3 or 4 gears higher than I wanted [it was an auto] despite so-called 'sport' mode - and tended to run out of puff horribly once you winded it up past 4000RPM. Just when you thought the fun was about to begin the autobox forcibly changed-up!

try winding any diesel up past 4000RPM and see what happens? much more than that and youll be replacing rockers left right and center haha! diesels like to work rather than rev. never had any issued with our TDV6 D4, or the previous. they certainly dont lack in torque or a kick in the back thats for sure!

[Ed Poore]

For some reason always preferred diesels to petrols but then not actually driven a big petrol V8. Currently got a 3.6TDV8 Range Rover and by god that's a good engine - the 4.4's supposed to be even better (although a large portion of that may be attributed to the gearbox). It does like to hold high gears in normal mode but flick it into Sport for a 2.7 tonne car it's surprisingly spritely.

I think that engine coupled to a big alternator and electric drive to all four wheel in a Defender shell and the Range Rover's interior. Now that would be a vehicle - 110 obviously. 90's just too impractical. Maybe just bit a slightly bigger Defender shell onto an L322 as a start...

[Tanuki]

try winding any diesel up past 4000RPM and see what happens? much more than that and youll be replacing rockers left right and center haha! diesels like to work rather than rev. never had any issued with our TDV6 D4, or the previous. they certainly dont lack in torque or a kick in the back thats for sure!

Plenty of designed-this-decade Diesels are happy-revvers: Audi and Honda seem to get it right. I guess it all depends if your design-mindset originates with commercial vehicles or cars.

Start with an intrinsically short-stroke design - which gains you two important things - plenty of room to fit enough valves to give good volumetric efficiency, and lower intrinsic vibration because the piston mass/velocity product is low.

Then - add lots of smallish cylinders together. . Gaining you more smoothness, and a reduction in the sort of horrible maximum-to-average ratio of torque-delivery over the rotational cycle that high-output Diesels inevitably create if you have a small number of big-bang cylinders doing the work. That in turn means your need for balance-shafts, DMFs, rubber-bonded multipiece harmonic-damper pulleys on the crank-nose etc can be minimised - your transmission will live longer too.

I seem to recall Sir Harry Ricardo working out that the best cylinder-volume for thermal efficiency was somewhere around 450cc.

Top it all off with a cams-operating-valves-directly [no clattery rockers or interposed fingers needed: look at the 1950s Jaguar XK engine] separate-camshafts-for-intake-and-exhaust-valves 4-valves-per-cylinder OHC setup (allowing you to use adaptive valve-timing like BMW VANOS or Honda's VTEC) and camshaft-operated injectors [TD5-style] and things can be engineered to produce wide, flat torque and power curves. Belt-driven camshafts create less NVH and suffer less 'timing-drift' compared to chains.

Thinking of Ricardo, and electrics - many years ago whrn I was down at their Shoreham place, they had a version of the 4.2 Jag XK engine (whose use was already well established in military vehicles) where they had replaced the flywheel, alternator and starter-motor with a combined unit. It was about 3 inches thick and completely sealed within the bellhousing. From memory the alternator-part could produce 500Amps, 400Hz at 24/28V continuous, with 1000A 'overload' for 5 minutes. They were investigating use of electrical power to replace the more-traditionally used hydraulics in armoured personnel carriers etc.

The 28V 400Hz was derived from military-aircraft ground power requirements of the day.

Why do I mention this? Well, that 28Kilowatts peak could easily also be fed to in-hub motors for a hybrid mechanical/electric 4x4 setup.

[elbekko]

A TDV8 is definitely a dream of an engine, and would be brilliant in any Land Rover.

I've been driving my dad's Audi A4 with a 1.9 TDI (~130hp tune) for the past week, and while it's not bad, I've gotten so used to the 4.6 pulling and pulling that I seem to be missing a few thousand RPM. Just when it starts to feel fun, I have to shift.

So in general, a petrol is very nice, a big V8 has plenty of torque low down just like a diesel, but can also rev nicely and will sound nice. But a TDV8 is definitely a contender.