MakeEverything
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| posted on 30/12/11 at 10:04 AM |
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quote:
Originally posted by phelpsa
quote:
Originally posted by MakeEverything
Good testament to diesel power is the le mans racers produced by Audi that won a few years back. I love the Jidda, especially with some producing an
easy 200hp+ with enough torque to spin the wheels off the rims.
That was a good testament to rule changes giving diesels a big advantage 
I'd love a go out in one if someone made it work, but diesels just don't make driving exciting. A 335d might be fast, but most drivers
cars don't need to be massively fast to be fun.
Well I don't know anything about the rules or e changes, so that may well be true though it is still an impressive feat for them to have
survived the 24h race and be competitive?
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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MikeRJ
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| posted on 30/12/11 at 10:40 AM |
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quote:
Originally posted by Simon
I can't understand the arguments against diesel either - have mentioned in the past that I'd like to try a diesel in something.
As for the lack of revs and massive torque in a lightweight car, both can be overcome using a lower ration diff. This brings the effective torque at
rear wheels down and makes up the difference in lack of revs.
No they can't, whatever diff ratio you use a diesel is still a low revving engine. My argument is nothing to do with the low RPM meaning low
road speed, very clearly this is entirely dependant on gearing and is why all diesel cars have much higher gearing. This also doesn't address
the problem of peaky torque delivery whatsoever, the torque at the wheels is directly proportional to torque developed by the engine irrespective of
the overall gear ratio.
quote:
Originally posted by MakeEverything
Well I don't know anything about the rules or e changes, so that may well be true though it is still an impressive feat for them to have
survived the 24h race and be competitive?
The rules were heavily biased towards the diesel cars, they were allowed variable geometry turbos, much high boost pressure, larger inlet restrictors
and could refuel faster due to larger fueling restrictors. The rules have been changed regularly since Audi's 2006 domination to gradually
level the playing field.
I was at Le Mans in 2006, and even though the Audi sounded OK for a diesel, it was nothing like as exciting as the Pescarolo, Corvette and Aston cars.
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whitestu
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| posted on 30/12/11 at 12:51 PM |
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I'm with MikeRJ, but then I've never driven a diesel car with a decent engine. I've had modern VWs and Peugeots but the 1.3 16v
petrol in our old Toyoya is miles nicer than any of them.
I can totally understand why folks fit bike engines, but diesels just feel like the opposite end of the scale.
Stu
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Simon
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| posted on 31/12/11 at 05:02 PM |
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quote:
Originally posted by MikeRJ
No they can't, whatever diff ratio you use a diesel is still a low revving engine. My argument is nothing to do with the low RPM meaning low
road speed, very clearly this is entirely dependant on gearing and is why all diesel cars have much higher gearing. This also doesn't address
the problem of peaky torque delivery whatsoever, the torque at the wheels is directly proportional to torque developed by the engine irrespective of
the overall gear ratio.
Of course it does. If you use a petrol engine that revs to 6k, or a diesel that revs to 4, instead of using the petrols 3.9:1 use the diesels 3.14
(both Sierra for eg) then the lack of rpm is translated into a higher speed because of the gearing. Try doing a spreadsheet in excel or similar and
you'll see that the road speed/revs arguments can be lost in the final drive ratio. If I find the one I did for toy car, I'll put it up
As for the torque argument, get on a bicycle, stick it in the lowest gear you can and go ride in some mud, I bet you can spin the wheel. Stick it in
the highest gear, bet you can't.
ATB
Simon
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Danozeman
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| posted on 31/12/11 at 06:14 PM |
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Id be putting a 1.9pd vag engine in one if i was to do a derv. 150 remapped. Would shred the tyres and return 100 mpg at a guess as the car would
weigh bugger all. Especially if you could get it on a 6 speed. win win imo. For the proper pur a v6 tdi would be superb but too much agro to set
up.
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
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karlak
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| posted on 31/12/11 at 06:29 PM |
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Got a Diesel 3litre V6 A4 Avant with Quattro, Love it 
With a remap, it is a quick motor
MK Indy - 2litre Duratec - Omex 600 - Jenvey throttle bodies - ETB DigiDash2
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NS Dev
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| posted on 31/12/11 at 10:04 PM |
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My main (one of a few) issue with diesels, modern ones included, is lack of torque spread. Sure they make big peak numbers, but apart from in-gear
overtaking they are very unrewarding to drive. Don't make the mistake of applying paper numbers to a hobby car. You'd have more fun with
an old fashioned petrol with half the power I'm afraid!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Simon
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| posted on 1/1/12 at 01:27 AM |
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Those peak numbers come in with the turbo and once they are in, are very flat (a bit like the V8 in toy car). Use the bit before the turbo comes in,
and that's where the economy comes from (not like in the toy car)
ATB
Simon
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Mr C
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| posted on 1/1/12 at 12:31 PM |
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There's been a few posts mentioning the peakiness of the torque as Simon mentions they are very flat and also on modern engines are early and
smooth in the delivery. On the road this does equate to good in gear acceleration and overtaking, My Daily Driver is good for 30mph to 100mph in
fourth in a seamless manner delivered at a fair rate of knots (in the right places) Which IMO is ideal for pressing on, suiting the roads of today.
Swmbo has the 200bhp petrol version of my daily driver (170bhp Common Rail). The cars are identical in every respect except the engine and
drivetrain. I still opt for mine each time as its no slower point to point and I can cane it and still get over 40mpg (swmbos drops to low 20's)
and lets face it the high fuel prices do factor in to this. It is a close call between the two versions, this is no doubt reflected in the debate
taking place here
My idea and experience of a peaky engine is an early VTEC in a CRX which I found difficult to drive very quickly, always stirring the gearstick and
arriving at a corner with the engine off cam or revving away franticly.
As I posted previously its everyone to their own.
Girl walks into a bar and asks for a double entendre, so the barman gave her one
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NS Dev
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| posted on 1/1/12 at 12:39 PM |
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Re. "very flat" delivery, what is the rpm range?!
Re. Comparison with v8, I have the same issue with many of those as fitted to lightweight cars, I.e. Torque curve at odds with traction!
These diesels may have a flat delivery for, say 3000 rpm, but that's all.
Diesel with lots of torque in lightweight car = accelerate, bang, boost, wheelspin, gearchange, bang, wheelspin, and so on, while you get driven round
by someone with a nice duratec, vauxhall xe or big bike engine. A mildly tuned xe pulls from 3000 revs to 8000 revs very linearly, meaning you can
actually use your gears properly, duratec is similar.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Paul Turner
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| posted on 1/1/12 at 06:18 PM |
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Been driving Turbo Diesels now since the mid 90's and absolutely love them, on my 5th. They get better with every new generation and a modern 16
valve normally aspirated petrol of the same capacity, although probably as powerful on paper is a poor drive due to the lack of torque. Only cars I
have driven recently that I would buy instead of a TD is one of the modern low pressure Turbo Petrols, the VW I drove was particulary good (only the
simple 1.4 122bhp turbo only model), keep meaning to try the new BMW 1.6 turbo petrol with 140 bhp, gets great reviews. They fall down on fuel
consumption of course but are a bit chepaer to buy, down to mileage.
With regards to a forced induction Seven, no thanks. Whether petrol or diesel I would not want the type of power delivery they provide, drove one many
years ago, 1.6 supercharged CVH, owner had spent a fortune on it to get BDA type performance, sounded rubish, he could have bought a proper BDA and
still had change. Over the past 23 years I have had Sevens with N/A petrols and I honestly belive they are the engine that suits the car best, in a
car weighing 600kg the lack of torque relative to a turbo is meaningless and even if you only have 130 bhp its still a supercar power to weight ratio.
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dinosaurjuice
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| posted on 1/1/12 at 09:03 PM |
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some very good points raised here, all of which i was concerned about when i pulled my finger out and took on the diesel challenge. im still amazed
nearly 4 years later not many others have.
The power range is different. I currently have about 180hp at 4000rpm, and max torque of 300lb'ft at 2000, so basically i can double my speed in
every gear. Works fairly well in practise. 2nd gear pulls strong to 50, then 3rd to 70 and after that 4th is quite happy between 40 and 90. I have
quite a lazy driving style and find theres not much benefit changing up and down too often.
weight is an issue, my complete drivetrain (engine, box, driveshafts) is 240kg's. Certainly know its there, and think far to often i could be
going round corners 5mph faster if it wasnt. But its just how it is unfortunately. its only a passenger away from a lightweight petrol engine, at
least thats what i keep telling myself.
Noise is an odd one. I love how it sounds.... some hate it. Definately has a satisfying grumble when giving it some stick...
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MikeRJ
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| posted on 1/1/12 at 10:00 PM |
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quote:
Originally posted by Simon
quote:
Originally posted by MikeRJ
No they can't, whatever diff ratio you use a diesel is still a low revving engine. My argument is nothing to do with the low RPM meaning low
road speed, very clearly this is entirely dependant on gearing and is why all diesel cars have much higher gearing. This also doesn't address
the problem of peaky torque delivery whatsoever, the torque at the wheels is directly proportional to torque developed by the engine irrespective of
the overall gear ratio.
Of course it does. If you use a petrol engine that revs to 6k, or a diesel that revs to 4, instead of using the petrols 3.9:1 use the diesels 3.14
(both Sierra for eg) then the lack of rpm is translated into a higher speed because of the gearing. Try doing a spreadsheet in excel or similar and
you'll see that the road speed/revs arguments can be lost in the final drive ratio. If I find the one I did for toy car, I'll put it up
As for the torque argument, get on a bicycle, stick it in the lowest gear you can and go ride in some mud, I bet you can spin the wheel. Stick it in
the highest gear, bet you can't.
ATB
Simon
You miss my point (which I thought was quite clear?), the gearing does not change the fact that the diesel is inherently a low revving engine which
develops most of it's torque in a narrow RPM range. Gearing simply means you can still achieve a reasonable road speed at the low RPM which
diesels run at, it does not mean the diesel can rev any higher and it does not smooth out torque peaks (by which I mean the shape of the torque curve,
which tends to peak at low RPM, not the absolute peak torque value).
No amount of playing with Excel will work around these fundamental limitations.
[Edited on 1/1/12 by MikeRJ]
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Ninehigh
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| posted on 2/1/12 at 03:11 AM |
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Go for it, my 2 litre mondeo has a good chunk of go to it when driven "properly" and that's the 115 bhp version.. Tops out at just
under 130 too in such a heavy car. As for everyone complaining about that narrow band and lack of grunt I find slipping the clutch slightly when
upshifting keeps the turbo spinning and keeps you in that power band.
And if you want more power there are bigger turbos available, I'm sure you could go to Iveco and fit one to a Ford engine
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NS Dev
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| posted on 2/1/12 at 01:24 PM |
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Paul turner and dinosaur juice both hit the nail on the head. For all my anti diesel comments on here my daily driver has one in it!
In the future I am sure that we can really make a diesel deliver the goods......the answer is a good cvt, in fact two of them, one from rotrak for the
supercharger drive and one in the transmission from tototrak. I would also make it a two stroke diesel as well.......
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Volvorsport
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| posted on 2/1/12 at 01:45 PM |
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with a properly geared transmission , i see no reason why a diesel cant be as quick as a petrol variant .
you just dont get the throttle response associated with a petrol engine , which makes the drive more interesting .
www.dbsmotorsport.co.uk
getting dirty under a bus
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MattStorey
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| posted on 8/1/12 at 09:08 PM |
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My daily driver is a BMW 535d m sport twin turbo. 286bhp - 1660kg : 0-60 in 6.7 seconds.
With a chip another 40hp is possible.
The lag takes some getting used to. Sounds like a bag of spanners tho....
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blakep82
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| posted on 8/1/12 at 09:12 PM |
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quote:
Originally posted by MattStorey
My daily driver is a BMW 535d m sport twin turbo. 286bhp - 1660kg : 0-60 in 6.7 seconds.
With a chip another 40hp is possible.
The lag takes some getting used to. Sounds like a bag of spanners tho....
had a shot of a diesel alpina a few years ago, VERY fast, didn't realise it was a diesel til i got out and the owner told me, did wonder what
the engine sound was all about though, as said, bag of spanners, well, gas turbine running like a bag of spanners. it was quite something
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