Slimy38
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| posted on 28/1/14 at 05:35 AM |
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quote:
Originally posted by coyoteboy
And difficulty tuning anything vaguely modern.
Really? Modern diesels just seem to need a remap to gain an instant boost, there are literally hundreds of companies offering the service. Granted
getting much further can be a challenge but getting that extra top up is a couple of hundred quid drive thru service.
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stevio73
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| posted on 28/1/14 at 11:36 PM |
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Seems I've opened a can of worms and everyone has an opinion.
I reckon with the correct forethought a 'fun' and 'efficient' mid engined car could be done fairly cheaply.
I say mid engined because let's face it everyone here likes to have oversteer, and a cheap supply of normally overlooked engines and gearboxes
are predominately front wheel drive transverse units. I dare say that the weight issue of having a 'normal' seven style car with an anvil
in the front would cause compromise to handling.
But then I hear you all saying.... Noisey rattley lump just behind my head, I should co co!! But magic can be done with dynamat.
Might be a pipe dream..... Might already be making plans....
Quick as a flash...... Nothing happens!
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blakep82
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| posted on 29/1/14 at 12:29 AM |
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yes, indeed, why ruin a sports car with a diesel engine...
quote:
Originally posted by Slimy38
quote:
Originally posted by coyoteboy
And difficulty tuning anything vaguely modern.
Really? Modern diesels just seem to need a remap to gain an instant boost, there are literally hundreds of companies offering the service. Granted
getting much further can be a challenge but getting that extra top up is a couple of hundred quid drive thru service.
correct! for some reason, it seems that most factory fresh diesels can be remapped for more power AND better economy.
ok, so mines not new, i've got a 1999 90bhp audi, saw a local company advertising diesel remaps and asked the question. he reckons he can get
115-120bhp from mine, and a 4-5mpg increase. £240 though, which i'd consider, but theres a fair bit of ground work i would have to do first, so
probably won't get around to it
he didn't give me the specifics of my dads car, but said he could do his for 240 too (if done at the same time as mine, otherwise normal price
for either is 280) and thats a 61 plate astra with 165bhp, again, more power and better mpg
[Edited on 29/1/14 by blakep82]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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mcerd1
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| posted on 29/1/14 at 08:15 AM |
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^^ thats all fair enough when your talking about 10 - 15 year old VAG engines or the 2.5 BMW one out of a vauxhall omega (or other BMW ones in the
rovers etc) - tried and tested engine swaps / installations with old fashioned controls that are fairly simple to separate from there donor car
but the more modern, higher performance ones have the ECU more and more integrated into the rest of the car - making it harder and harder to extract
all the donor bits and get it running
diesels don't really give you the option of just throwing all the OE bits in the bin and starting from scratch with a generic ECU like you can
with a petrol 
and even if you do get it running and the chip tuned as far as you can - whats you next step if thats not enough power ?
having said that this new generation of turbo'd small eco petrols is probably just as hard to deal with....
[Edited on 29/1/2014 by mcerd1]
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DH2
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| posted on 29/1/14 at 09:21 AM |
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quote:
Originally posted by mcerd1
having said that this new generation of turbo'd small eco petrols is probably just as hard to deal with....
Friend of mine has Ecoboost in an Elise running on Emerald which seems pretty happy 
DH2
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dinosaurjuice
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| posted on 29/1/14 at 10:59 AM |
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ive done nearly 8k miles in my diesel Rocket now. loved every mile.
I had it remapped 2 years ago, no idea what power its producing but its significantly more than the standard 136hp.
Economy is so good i don't even think about.
Noise isn't an issue. its a bit clunky when cold and idling but that's it.
I'm amazed that I built it 5 years ago and there arnt more diesel kitcars on the road 
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MikeRJ
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| posted on 29/1/14 at 11:49 AM |
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quote:
Originally posted by Sam_68
quote:
Originally posted by MikeRJThe Locost (and any 7 style car) is a sports car...
But it could also be an incredibly fuel-efficient lightweight commuter that also happens to offer better performance and handling than the best
current hot hatches (at the price of all creature comforts, of course).
It would be one of the most impractical commuter cars ever. The aerodynamics are tragically poor compared to most tin tops so fuel economy is always
going to be compromised, crashworthyness is negligible, most have insufficient ground clearance to deal with the ever increasing number of speed bumps
and pot holes and their very low height means visibility is compromised in traffic.
The 7 and it's clones are what they are, cheap sports cars, designed with driving pleasure way up at the top of the list of other attributes.
Why try to force it to be something it will never be good at?
[Edited on 29/1/14 by MikeRJ]
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Sam_68
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| posted on 29/1/14 at 12:33 PM |
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quote:
Originally posted by MikeRJIt would be one of the most impractical commuter cars ever. The aerodynamics are tragically poor compared to
most tin tops so fuel economy is always going to be compromised...
The aerodynamics I addressed with my first post. You may or may not be aware, but the original Lotus Seven came after the Lotus Eleven; it was
a 'poverty spec', cut-down variant of the Eleven for poor boys, using a virtually identical chassis but without the Eleven's complex
and expensive alloy bodywork. Of course, these days, we don't need to do curvy, aerodynamic bodywork in expensive hand-rolled aluminium, a fact
that Westfield and Sylva caught on to some time ago....
The Lotus Eleven remains one of the most aerodynamically efficient cars ever built, especially in 'single seat' form and especially when
you take into account that it's CdA, not just Cd, that matters.
... though I would draw your attention to the tested fuel economy of the original Weasel; I'd say that 58mpg isn't too much
of a compromise on a car that can do 0-60 in 6.6 seconds, despite its 'tragically poor' aerodynamics and its relatively low-tech
diesel?
In any case, would you say that high aerodynamic drag is a bigger problem on a typically slowly driven commuter car, or on a typically quickly driven
sports car (clue: aerodynamic drag is proportional to the square of the speed)?
quote:
Originally posted by MikeRJcrashworthyness is negligible
The only real problem with crashworthyness on a traditional 'Seven' is lack of side impact protection. If it bothers you, fill the
sills on your nice, streamlined Eleven/Phoenix with rigid foam, and the jobs a good 'un...
But: this crashworthyness... less of an issue when driving a sports car at high speed than when driving a commuter car at moderate speed, do
you think?
quote:
Originally posted by MikeRJ... most have insufficient ground clearance to deal with the ever increasing number of speed bumps and pot
holes
Ground clearance is what you want it to be. The bigger problem is that many 'Seven' owners read (probably with their lips moving and their
finger following the words) in a book somewhere that Colin Chapman recommended stiff dampers with soft springs, so they take their springs (that are
often already 3 times the stiffness of those on the original Seven/Eleven) and crank their adjustable dampers up to 11... sure, they lose fillings and
crack the vertebrae in their back, but it must be good because formula one cars run ultra-stiff suspension, don't they?
At least the 'Seven' has a sensible wheelbase, so doesn't pitch as badly as ultra-short wheelbase cars like the Twizzy or Smart when
it has to address road humps and raised manhole covers.
quote:
Originally posted by MikeRJ... and their very low height means visibility is compromised in traffic.
Sure small vehicles (whether or not they're low... ask your friendly neigbourhood bikers) are apparently more difficult to spot, and you need to
take appropriate care and drive defensively (...ask your friendly neighbourhood bikers, again). More of a problem when commuting relatively slowly
in traffic, or when blasting at high speed down twisty country lanes with hedgerows and dry stone walls to hem you in and hide you, do you
think?
But I go back to my original question; would a diesel (and preferably streamlined) 'Eco-Seven' be any less valid as a design solution than
the Renault Twizzy and other electric micro-commuters?
Does the Twizzy (or G-wizz, or any 'heavy quadricyle'-class commuter car) score any better on any of the issues you raised?
Are any of the issues you raise less of a problem for a 'Seven' when you use it as a road-going sports car than as a road-going
eco-commuter car, or anything in between, for that matter?
[Edited on 29/1/14 by Sam_68]
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drt
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| posted on 29/1/14 at 12:39 PM |
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Good thread!
Lot's of interesting responses.
What I would like to contribute, is a choice of engine.
Despite everything the lightest option will be the best,
So I recommend the Mercedes 170/200CDI engines. (Mercedes-Benz OM668/OM640)
They have the best p2w ratio.
If you're in to aircraft... the Cessna diamond use to have 2 of these lumbs by Thielert (Centurion).
When this option came to marked the designers specifically chose the engine for the p2w
(It bit them in the backside as it was never a very good plane engine).
You can find them in A-class and (I think) C-class mercedes.
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britishtrident
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| posted on 29/1/14 at 12:44 PM |
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quote:
Originally posted by coyoteboy
What's all this nonsense about torque vs revs? Stick the right gearbox on it and you have a flat torque curve and little difference in
performance. You don't use flywheel torque to drive a car directly.
The only real issue, to me, would be noise. And weight. And difficulty tuning anything vaguely modern.
It is more complex than that because of the restricted rpm range a diesel needs more gears, also a small petrol engine is much more free revving in
response to accelerator pedal input that an equivalent output turbo diesel.
In a heavy Mondeo/Jag/BMW/Rover saloon weighing 1.5 tons how fast the engine can increase rpm has very little impact on how fast the car
accelerates, but in a very low weight Seven style the impact on performance is much bigger.
To give comparison using the highly regarded and very tweakable BMW diesel, the 131ps BMW 2litre diesel in the Rover 75 gives exactly the same
performance figures as the 118ps na petrol version, the extra 13ps power compensating for the 90-100kg weight increase.
Put the same engines in a Seven style car car weighing 510kg with a petrol engine and with diesel version at 600kg and the combined effect of
the extra weight and the petrol engines ability to zap up the revs will give the petrol unit a very considerable advantage especially in the lower
gears.
Then we have of course to consider the effects on handling and extra 90kg mainly on the front wheels of a light car will not improve things.
[Edited on 29/1/14 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mcerd1
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| posted on 29/1/14 at 01:34 PM |
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quote:
Originally posted by Sam_68
But I go back to my original question; would a diesel (and preferably streamlined) 'Eco-Seven' be any less valid as a design solution than
the Renault Twizzy and other electric micro-commuters?
Does the Twizzy (or G-wizz, or any 'heavy quadricyle'-class commuter car) score any better on any of the issues you raised?
if you want to talk about commuter car's then yes the Twizzy's and smarts are more practical:
1 - this is Britain - we have weather - these cars have a roof ! (assuming you buy the doors for your twizzy of course)
2 - they are easier to get in and out of
4 - being short enough enough to park almost anywhere is no bad thing
if central london is your area then electric cars with zero congestion charge is a bonus
personally I'd have none of the above - give me a series 1 Pug 106 anyday 
I could get 65mpg out of mine on the motorway - and that was petrol with a carb!
and the 1.5D's are meant to be quite a bit better than that - not bad for 20+ year old cars with 5 seats and a roof!
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dinosaurjuice
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| posted on 29/1/14 at 01:37 PM |
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Ive never had a problem with my engine not building revs fast enough.
If I had the time I would really like to build a fully enclosed kit car, probably with the 1.6 PSA hdi/tdci engine, and use it as an everyday
commuter.
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Sam_68
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| posted on 29/1/14 at 02:30 PM |
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quote:
Originally posted by mcerd1...if you want to talk about commuter car's then yes the Twizzy's and smarts are more
practical...
Fair points on practicality, and I did earlier acknowledge that a diesel 'Seven' would give a unique blend of performance and economy
at the cost of all creature comforts.
That would be the price you pay for driving something that's more fuel efficient than the best conventional diesels or hybrids, but offers
better performance and handling than the best hot hatches.
On the flip side for EV commuter buggies...
1) The limited range of EV's remains a serious issue for many. I live in a rural area; it would take the entire range of a fully charged Twizzy
to take me shopping, and if I'd tried the commute I had to undertake on my last job, I'd have found myself on the hard shoulder of the M5
looking for a charge point every morning (that is if I'd been allowed on the M5, which I wouldn't have been, so it would have been
somewhere on the A38 instead...).
2) Heaters and air-con are an issue for EV's, 'cos they eat juice and reduce range still further; the Twizy has no heater and demist is
limited to a heated screen, so you may be dry (if you spec the doors as an optional extra) but you'll still probably be cold and have
limited visibility in winter.
3) The Twizy is flat out at 50mph (which makes it rather difficult to compare 0-60 times against the Weasel's 6.6 seconds, of course... can we
agree that it's not quite as sprightly?)
4) I'd rather eat my own entrails than live in London, so congestion charge doesn't really bother me, but if I lived in central
Hell I'd use public transport to commute, anyway - it's quicker and less stressful.
Smarts are quite good fun: my girlfriend has one, and I have owned a Brabus Roadster Coupe in the past, myself, but again, they're a different
compromise... comfortable, but neither performance nor fuel economy are spectacular (the Brabus gave me about 45mpg), and the pitching of the short
wheelbase on the ForTwo over bumps does, personally, drive me nuts... so the advantage of being short enough to park in little spaces has to be
balanced against being made to feel like a nodding dog every time you hit a bump or pothole.
FWIIW, I used to drive conventional petrol-engined Sevens (a Westfield, then a Caterham) as my only car, all year round, commuting into a major city
(Leeds) every morning when I was younger, so I do believe I'm in a position to properly appreciate their shortcomings.
And like you, I take a more conventional route at present for my 'shopping' car: a petrol Toyota Aygo, which gives 68mpg on the motorway
and about 55mpg overall, but doesn't have any performance that you'd notice.
[Edited on 29/1/14 by Sam_68]
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mcerd1
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| posted on 29/1/14 at 04:17 PM |
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quote:
Originally posted by Sam_68
And like you, I take a more conventional route at present for my 'shopping' car: a petrol Toyota Aygo, which gives 68mpg on the motorway
and about 55mpg overall, but doesn't have any performance that you'd notice.
i don't think 'conventional' applies to my reasons...
the old 106 had no fancy bits to get broken - in fact my old carb'd one only had 2 electronic things on the whole car - the ignition amp (on the
side of the dizzy) and the radio
I think I'd still rather have an old 106 over any of its replacements - I actually like little tin boxes with manual steering and no frills
if I could get a 106 rallye 1.3v8 on carb's I think that would be very close to my perfect tin-top
[Edited on 29/1/2014 by mcerd1]
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Sam_68
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| posted on 29/1/14 at 04:33 PM |
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quote:
Originally posted by mcerd1i don't think 'conventional' applies to my reasons...
You liked it because it was cheap to run and simple (hence cheap) to maintain and repair? Seems fairly conventional to me?
I like little tin boxes, too (hence the Aygo, and the appearance of several Imps and Minis in my motoring history), but I'm not resistant to
more offbeat solutions - I think that a lot of what makes lightweight kit cars appealing as a budget high performance car could also make them
appealing as an ultra-economy vehicle (with excellent handling and pretty good performance as a bonus), with just a slight change in emphasis?
The fact that they're idiosyncratic is not necessarily a disadvantage in either case, as both would be appealing to the lunatic fringes of the
motoring public, to some extent!
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mcerd1
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| posted on 29/1/14 at 04:39 PM |
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getting back to diesel vs petrol...
I've driven diesel tin-tops with far more power than my petrol ones - but somehow they all feel dead to me
and yet I know people that love the modern diesels... so I guess its another BEC vs CEC at the end of the day
quote:
Originally posted by mcerd1
quote:
Originally posted by Sam_68
And like you, I take a more conventional route at present for my 'shopping' car: a petrol Toyota Aygo, which gives 68mpg on the motorway
and about 55mpg overall, but doesn't have any performance that you'd notice.
i don't think 'conventional' applies to my reasons...
the old 106 had no fancy bits to get broken - in fact my old carb'd one only had 2 electronic things on the whole car - the ignition amp (on the
side of the dizzy) and the radio
I think I'd still rather have an old 106 over any of its replacements - I actually like little tin boxes with manual steering and no frills
if I could get a 106 rallye 1.3 8v on carb's I think that would be very close to my perfect tin-top
[Edited on 29/1/2014 by mcerd1]
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Simon
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| posted on 29/1/14 at 08:32 PM |
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Diesel revs slower, and spin up slower, but has more torque. Therefore, if you use a lower ratio final drive the "revs slower" becomes
revs the same at the rear wheel. The spinning up slower is also countered by the lower f/d ratio. The low f/d also reduces the effective torque at the
wheels. I had an injected Rover 3.9 V8 in toy car, but a Jag/BMW 2.7/3l diesel would offer similar performance (- a slight weight penalty), but prob
twice as many mpg and, as I stated elsewhere, most of the time you'll be pootling along with the rest of the traffic. And sound is lost behind
you at anything more than about 40mph, so who cares what it sounds like. Oh yeah, and use an auto box with diesel
I know what I'm trying to say and an analogy might be something like this (which is true).
We have a bloke in the local mtb club I belong to, he's less than 2/3's my weight, and has Bruce Lee's physique. He can spin the
pedals very fast. Being the petrol engine with high ratio final drive.
I don't have the physique of Bruce Lee (weighing in at 17st), and like to turn a big gear, being the low f/d. Luke cannot get away from me
(until after the first 100 yards when 20 odd years of smoking catch up and I need to fill my lungs up again, but that's an aside) or we get to a
bend.
Once I've lost 5 stone, I'll still turn a big gear, he'll still turn a little one, and I'll out run him with far fewer pedal
stokes
If I still had Deimos it might well have either of the above engines in by now.
ATB
Simon
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stevio73
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| posted on 30/1/14 at 03:01 PM |
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This is certainly interesting....
Sports car or commuter car, neither really matters in today's "modern" British motoring conditions. Let's face it, the state
of the road surface on most highways is enough to shake your fillings unless driving the equivalent of a queen size mattress. The other factor is that
the government have cottond on to the easy revenue produced by those of us in a hurry or enjoying a "spirited" drive by way of sneaky
bastards in vans with cameras.
So it's fair to say that for the masses who enjoy the handling of a sports car on a day to day basis and don't want lots of points and
fines for excessive speed because it isn't silverstone, oh and also don't want to give Mr tax man their left arm because of fuel
costs..... Diesel may be an option.?
There's no mass produced diesel management systems out there that would work on multiple engines, BMW, Vauxhall, VAG, because of a) demand and
b) all have different ways of doing the same thing. A generic management 'box' ain't gonna happen. Which does mean tuning will
always be an issue. But then.... If we are all sheep and all drive at the speed limit to avoid fines (and the sneaky bastards in vans with cameras)
why do we need to tune?
I guess I like the idea, because I like the 'look' of the seven. I enjoy the technical side of building something I can then use. And yeah
I like driving fast, but on that one I'm maybe getting old and sensible. I want an everyday driver, I want economy, I want the
'look' I want to be able to say I built that. I've had bikes, and got wet, but always had a smile on my face. I've had a
smart car, and always been worried about how much oil it used. I've had bangers and lots of fun in them. I've made money on some,
I've lost money on most. I've commuted in vans, cars and bikes. I've yet to complete a seven build and, ashamed as I am to say this
having had so many different cars over the years, I've never yet actually driven a seven. Shocking isn't it! I am almost worried that
when I complete my current ZZR1100 haynes build I won't like it. But it doesn't stop me looking for what I'd like to do next!!
Quick as a flash...... Nothing happens!
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stevio73
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| posted on 30/1/14 at 03:26 PM |
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Just happened across a video on zcars website where he's talking about a diesel powered grass track car. Worth a look for the 1:25 length of it.
Quick as a flash...... Nothing happens!
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Simon
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| posted on 30/1/14 at 04:53 PM |
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There is a stand alone diesel ecu available but it's about £2500. Way out of reach of most sensible people's pockets
ATB
Simon
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Beardy
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| posted on 1/2/14 at 06:12 AM |
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bit off topic, but what about something like a GT70 with a V6 tdi lump?
this is a less dramatic shift than a petrol engined 7. Looking at the GT40/Lola T70/Cobra type cars which have a big chunk of iron and a slow, heavy
gearchange and are in general powerful torque monsters. Here a diesel might not be such a bad fit. Mid engined would put the additional mass in the
centre of the axis of rotation and therefore minimize its affect. Loads of grunt and reasonable fuel economy would be a good replacement to a small
block chevy for example.
as noted - a bit off topic.
I'm in California and the availability of diesels is poor, otherwise something more modest (3 cylinder Lupo Tdi?), in a J15/Riot might be a
laugh.
Mike
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drt
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| posted on 3/2/14 at 03:12 AM |
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quote:
Originally posted by Beardy
bit off topic, but what about something like a GT70 with a V6 tdi lump?
this is a less dramatic shift than a petrol engined 7. Looking at the GT40/Lola T70/Cobra type cars which have a big chunk of iron and a slow, heavy
gearchange and are in general powerful torque monsters. Here a diesel might not be such a bad fit. Mid engined would put the additional mass in the
centre of the axis of rotation and therefore minimize its affect. Loads of grunt and reasonable fuel economy would be a good replacement to a small
block chevy for example.
as noted - a bit off topic.
I'm in California and the availability of diesels is poor, otherwise something more modest (3 cylinder Lupo Tdi?), in a J15/Riot might be a
laugh.
Mike
Agreed, the 1200tdi lumps are peaches... some custom and factory build dieselBikes use them
link; http://thekneeslider.com/thunder-star-1200-diesel-by-star-twin/
Oh, not to be a pain, but you ment the 'polar moment of inertia' as a car turns around the COG.
Also, a rover v8 is often states as weighing in at 220kg? Give or take.
Most 4 cilinder diesel will struggle to go below the 200kg mark.
And these are 'almost bare' block figures.
On top of , a diesel pump (injection system) of any design will weigh more then it's petrol cousin etc...
However I am a fan of the idea ^^
But instead of reaching for performance... make a hypermiler!
3 wheels, 2 seats, minimise weight at all cost, spacesaver tyres.
And a small modern diesel with coasting ability.
Get you inspration here;
http://www.shell.com/global/environment-society/ecomarathon.html
As I was involved with a car for this competition I am a bit biased
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