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Car Forum / UK Car Forums / General Car Topics (UK group) / July 2005What's likely to be more economical
Considering buying a new Renault Trafic van (LWB Hi-Roof), and wondered what people might think would be more economical out of these two engines: 2.5 litre dCi 140: 4-pot, 16v, 18:1 compression ratio, Peak power: 135kW ISO / 99hp DIN, @ 3500rpm Peak torque: 310Nm @ 1750rpm 1.9 litre dCi 100: 4-pot, 8v, 18.3:1 compression ratio, Peak power: 100kW ISO / 74hp DIN, @ 3500rpm Peak torque: 240Nm @ 2000rpm The van will be used for multi-drop delivery work, including about 55 miles of driving on open roads - mainly NSL A-roads/motorway, and around 40-50 drops over 30-40 miles (around 3.5-4 hours from 1st to last drop). I'm thinking that the smaller engine will probably be the better bet, as it'll use less fuel whilst idling, but with the amount of driving on open roads, would the larger engine be the better bet? I'm thinking that the fact that the 2.5 litre engine could be better as it's a 16-valve engine rather than 8-valve (so possibly more efficient?), and still a 4-pot engine, so not like it'll drink it up like something with more cylinders. Any suggestions? Or actual real-world fuel economy figures based on experience?  SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." > Considering buying a new Renault Trafic van (LWB Hi-Roof), and wondered what > people might think would be more economical out of these two engines: [quoted text clipped - 10 lines] > Peak power: 100kW ISO / 74hp DIN, @ 3500rpm > Peak torque: 240Nm @ 2000rpm You've got your KW's and Hp the wrong way about. Anyways, with that kind of driving, probably the smaller engine would be slightly more economical. If you find it abit lethargic, get it chipped- and you'll then find its better on fuel than before.- mainly due to less gear changes, and ability to pull a higher gear- less rpm. Tim.. >> Considering buying a new Renault Trafic van (LWB Hi-Roof), and wondered >> what [quoted text clipped - 13 lines] > > You've got your KW's and Hp the wrong way about. I thought that might be the case - those figures were lifted straight from Renault's site. I always thought that the figure after 'dCi' referred to the bhp of the engine. > Anyways, with that kind of driving, probably the smaller engine would be > slightly more economical. If you find it abit lethargic, get it chipped- > and > you'll then find its better on fuel than before.- mainly due to less gear > changes, and ability to pull a higher gear- less rpm. That's what I thought. 100bhp version it is then, cheaper to buy *and* cheaper to run. No-brainer really. Sounds like the more powerful one would only really be worth it if the van was regularly fully laden and doing long motorway trips day in, day out. SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." > Considering buying a new Renault Trafic van (LWB Hi-Roof), and wondered > what people might think would be more economical out of these two engines: [quoted text clipped - 18 lines] > it'll use less fuel whilst idling, but with the amount of driving on open > roads, would the larger engine be the better bet? Probably not but it'll depend on how the van is driven. Driven flat out everywhere, the 1.9 would be the better bet. Driven gently everywhere, the 1.9 would be a better bet. Driven to keep up with the flow of traffic whilst carrying a full payload, I'd put the 2.5 as a better bet - but only just. Smaller is usually better inside the speed limit. If the driver were to hoon about on the motorway beyond the Copper Tolerance Level (CTL) then the 2.5 may be a better bet. > I'm thinking that the fact that the 2.5 litre engine could be better as > it's a 16-valve engine rather than 8-valve (so possibly more efficient?), > and still a 4-pot engine, so not like it'll drink it up like something > with more cylinders. Well, maybe, it would depend on the design. > Any suggestions? Or actual real-world fuel economy figures based on > experience? SignatureThe DervMan www.dervman.com > "You're not a real UKRCMer until you've owned a Rover 620ti." *cough* How about that small engine will be thrashed to an inch of its life whereas the bigger one is not > How about that small engine will be thrashed to an inch of its life > whereas > the bigger one is not That's a bit of a broad generalisation. Would you care to read my post again, and take into account the type of driving the van will be used for? SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." > How about that small engine will be thrashed to an inch of its life > whereas > the bigger one is not How about you include some of my post so I can see what you're on about? :) One won't need to thrash the 100 PS 1.9 van. If it's given a thorough beating everywhere with a heavy payload, the less power produced (and wasted) the better. If it's driven hard with a heavy load but it spends time cruising, the 2.5 may be marginally more economical. Smaller is almost always better when it comes to vans. SignatureThe DervMan www.dervman.com >> How about that small engine will be thrashed to an inch of its life >> whereas [quoted text clipped - 11 lines] > > Smaller is almost always better when it comes to vans. In terms of engine size, maybe, but what about engine power for the same size? Take the Merc CDI engines - would a 129bhp 2.2 CDI engine (as in x13CDI Sprinters) be any worse for stop-start work than a 109bhp 2.2 CDI engine (as in x11CDI) or the 82bhp model (x08CDI - 2.2 litre again)?? In these cases, surely the lowest power one would need to be worked considerably harder than the other two, potentially using more fuel, wouldn't it? And what about the two different power levels of 1.9dCi Renault engine? 82bhp and 100bhp. Surely when idling the higher power unit isn't pumping extra fuel through - it's only used when requested by the right foot, right? So the higher power version of the same size engine would be a much better bet, no? In fact, apart from cost to buy, is there any justifiable reason why someone would actually go for the lower power version of the same size engine? SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." >>> How about that small engine will be thrashed to an inch of its life >>> whereas [quoted text clipped - 14 lines] > In terms of engine size, maybe, but what about engine power for the same > size? That would depend on how it the more powerful engine achieves more power. If it achieves it through being intercooled, having improved aspiration (more valves, say), or higher turbocharger boost, that makes a difference. An intercooler is good news if the donk doesn't have one since that improves efficiency across the range. Improved aspiration may improve matters under a high load, but then if the engine needs to produce a given amount of power then it'll produce that amount of power and burn that much fuel. The key difference may be through gearing. If the 2.5 is able to produce sufficient acceleration in fourth gear rather than third, at a given loading it'll be at lower engine speed, so there's less friction... maybe. > Take the Merc CDI engines - would a 129bhp 2.2 CDI engine (as in x13CDI > Sprinters) be any worse for stop-start work than a 109bhp 2.2 CDI engine > (as in x11CDI) or the 82bhp model (x08CDI - 2.2 litre again)?? In these > cases, surely the lowest power one would need to be worked considerably > harder than the other two, potentially using more fuel, wouldn't it? But only if you drive to use full power in the lower powered engine. That would depend on loading. From all of the vans I've driven, when driven reasonably light, all have been quick enough to keep up with the general flow of driving. It's when you add 600 kg of junk that there's a bigger difference. > And what about the two different power levels of 1.9dCi Renault engine? > 82bhp and 100bhp. Surely when idling the higher power unit isn't pumping > extra fuel through - it's only used when requested by the right foot, > right? In theory - is the 82 PS version non-intercooled and the 100 PS engine intercooled? Or does the ECU just provide more boost. The PSA HDI 2.0 engine is a great example. The 90 PS has no intercooler. The 110 PS has an intercooler (and various detail changes). All things being equal (car, weight, gearing) the 110 PS version is more economical than the 90 PS version for most people under most circumstances. Lots of idling or when running without turbocharger boost (how?!), there shouldn't be any difference in consumption. Our 110 PS Peugeot 406 was noticeably more economical on a long motorway run, but around and about Norwich there was no difference between the two. > So the higher power version of the same size engine would be a much better > bet, no? In fact, apart from cost to buy, is there any justifiable reason > why someone would actually go for the lower power version of the same size > engine? It could be cheaper servicing or cheaper insurance. Also, the less stressed version will have a broader power band. It may have shorter gearing, so provide the equivalent performance over the usual run. The 2.2 turbodiesel Lagunas had very, very tall gearing, which made them feel especially sluggish compared to (say) the Mondeo or Peugeot 406 1.8 / 1.9 turbodiesels. The LDVs I used to ride about in all used the Ford Duratorq 2.4 turbodiesel, mostly in 80 PS version, with suitably short gearing. The 120 PS "flying machine" Transit had taller gearing, so only felt quicker above 50 mph. And this evening some git in a "Trafic 1.9" repeatedly flashed me as I overtook a HGV on the A64 dual carriageway before zooming off into the distance. Made me think of you... <Astravanman, your email arrived just as I was poking off home, I'll have a think about it tomorrow.> SignatureThe DervMan www.dervman.com >>How about you include some of my post so I can see what you're on about? :) Like this! >>>One won't need to thrash the 100 PS 1.9 van. If it's given a thorough >>>beating everywhere with a heavy payload, the less power produced (and >>>wasted) the better. You sure - whenever I have driven a van I have found them underpowered - try the Bedford Midi Diesel, hence they get driven flat out With petrol engines it is rare that a small engine is any more economical than a bigger one when driven at similar speeds. >>Smaller is almost always better when it comes to vans. Sounds boring >>>How about you include some of my post so I can see what you're on about? > :) [quoted text clipped - 8 lines] > try > the Bedford Midi Diesel, hence they get driven flat out Have you driven anything made in, say, the last 5-10 years? Diesel engines have come a *long* way since then. > With petrol engines it is rare that a small engine is any more economical > than a bigger one when driven at similar speeds. SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." >>Have you driven anything made in, say, the last 5-10 years? Diesel engines >>have come a *long* way since then. A few cars! >>>Have you driven anything made in, say, the last 5-10 years? Diesel >>>engines >>>have come a *long* way since then. > > A few cars! Any diesels? It's just that your statement that all vans you've driven have been underpowered implies that all vans still are. Certainly not the case. SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." >>Any diesels? It's just that your statement that all vans you've driven have >>been underpowered implies that all vans still are. Certainly not the case. No diesels recently - all petrols from 1l 3cyl to 3.5l I6 >>>Any diesels? It's just that your statement that all vans you've driven >>>have >>>been underpowered implies that all vans still are. Certainly not the >>>case. > > No diesels recently - all petrols from 1l 3cyl to 3.5l I6 That's hardly *all* petrols. There are much bigger petrol engines out there y'know :-) SignaturePeter "You're not a real UKRCMer until you've owned a Rover 620ti." > > No diesels recently - all petrols from 1l 3cyl to 3.5l I6 > > That's hardly *all* petrols. No, but it *is* all from the range that he specified... SignatureLordy.UK |
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