Apparently on date Thu, 29 Apr 2004 15:46:04 +0100, "Dan405" <me (AT) privacy (DOT) net>
said:

A diesel engine, all else being equal, will have a thermal efficiency around
40%, while an otto cycle petrol engine will manage around 30%, these are
measures of how much of the energy in the fuel is turned into motive power and
how much is dissipated away as heat.

I said "all else being equal", and that's not normally true. Diesel engines are
noisy, which doesn't matter too much, and heavier than their petrol
equivalents. There are differences in rev range, so a comparison must include
the fact that a diesel has to be geared lower so that it doesn't redline at a
low speed, and must manage a range from minimum to maximum revs that permits it
to function as an engine in the same way as the petrol engine.

To put this in a nutshell, when a diesel engine can be made of similar weight
and power output to a petrol engine, it's fairly obvious to anyone with basic
physics skills, that it will power a car in much the same way and deliver more
or less the same performance. By merit of the shape of the power curve, it will
actually put out better figures, on the whole, due to the elevated torque and
flatter power band, but that depends on the design of the petrol engine as well
as you can make them peaky or torquier.

The main difference, in that situation, is you have of the order of a third
better mpg with the diesel, when equivalent, and have a bit less heat to get
rid of through the radiator.

Course, this assumes diesels can be made with similar output to the petrol
engine while not being heavier. I dunno how feasible that is, at present.

"Tim S Kemp" <news (AT) timkemp (DOT) karoo.co.uk> wrote

S'what i thought too.... Whats the point in an impressive space frame
superlight chassis, filled with a ridiculously heavy 5 litre diesel lump.
Summet like a Twin Turbo 3.0 petrol from a Supra would be way better...

--
Dan
http://www.danontherun.com

In article <yNakc.341$pk3.4918384 (AT) news-text (DOT) cableinet.net>,
pete.murray (AT) blue-nopressedmeat-yonder (DOT) co.uk spouted forth into
uk.rec.cars.modifications...
manage pushing about 800 kilos?
--
Carl Robson
(The poster formerly known as Skodapilot)
http://www.bouncing-czechs.com

In article <c6ra3a$1nu9$1 (AT) news (DOT) f.de.plusline.net>, scott (AT) spam (DOT) com
spouted forth into uk.rec.cars.modifications...
car, I reckon I could make something that handled.

I mean Ferrari have been sticking 5 litre 8 and 12 cylinder engines into
car for donkeys.
--
Carl Robson
(The poster formerly known as Skodapilot)
http://www.bouncing-czechs.com

"MeatballTurbo" <carl.robson (AT) bouncing-czechs (DOT) com> wrote

17 maybe 18 its American after all.

"scott" <scott (AT) spam (DOT) com> wrote

Heavy cars have greater inertia... you need more force in order to change
the direction of movement (stop, turn or whatever). Of course, the more
weight you have on the wheels, the more your tyres grip to the road but I
don't know to what extent or how the greater grip compares to the increased
inertia of the car.
All that being said, the engine is nowhere near as responsible for making a
car heavy as it is every other 'toy' that you get in a car. A massive engine
in a spaceframe chassis with very little in the way of bodywork, safety
features, electronic gadgets or windscreens would *still* make an incredibly
light car.
My Mazda RX-7 Turbo II, despite having such a small engine, weighs over
2000kgs - yet my top-of-range Peugeot 305 GTX (yes you can stop laughing
now) with a 1.9 litre 4 cylinder weighs 1050kg as standard.
...
(I said stop laughing)
....
Almost perversely though, lets say you got that *huge* V8 engine and tried
to make the lightest car you possibly could with it - you'd probably find
yourself in all sorts of trouble trying to actually get the power down on
the road.

Chris.

Chris B <lord_waymaster (AT) yahoo (DOT) com> wrote:

Are you absolutely sure about that 2 tonnes? - neither of my biggish
Alfas comes in anywhere near that!

Just checked, it's 1284kgs, which is more like it.
--
Steve H 'You're not a real petrolhead unless you've owned an Alfa Romeo'
http://www.italiancar.co.uk - Honda VFR800 - MZ ETZ300
VW Golf GL Cabrio - Alfa 75 TS - Alfa 155 TS Lusso - COSOC KOTL
BoTAFOT #87 - BoTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

"SteveH" <steve (AT) italiancar (DOT) co.uk> wrote

You know what? I have no idea where I got 2 tonnes from. I just checked as
well and my model seems to weigh in at 1315 kgs or thereabouts. I did rather
think that 2 tonnes was heavy, but I was trying to prove a point .. not
the best way to do it, trying to compare a well front-heavy FWD car with a
50/50 weight distributed RWD car, especially if I can't actually get the
weight right!

Chris.

"Chris B" <lord_waymaster (AT) yahoo (DOT) com> wrote

That's why you want wings
Not to look like a tosser, but if you're really looking for track
performance, forcing the rubber into the road without having a weighty
bodyshell is a good thing.

On the road, you're never going to be legally doing the sort of speeds
required to make moderate angles work, and severe wing angles that might do
something will really bugger up your mpg.

I quite like the 305GTX. It's got that chunkiness about it that gives it
more presence than the jellymold crap made nowadays, IMO.

If it's sheer traction that's required, having the engine in the "Wrong
Place (copyright Porsche)" would help, but for good lap times, I would
imagine having a good suspension set up and if you really must, TC, would be
better. Might not have ultimate grip in terms of getting the power down out
of a tight turn, but the balance of the car going into and around the corner
should compensate, IMO.

"Stuffed" <merde (AT) theworld (DOT) com> wrote

Yup, you're absolutely right on both counts.. my experience on prepping a
car for track performance is. ummm. nil.. Didn't even occur to me about
using wings, although of course it makes perfect sense.

Ta for that. I've kinda gotten used to making my daily transport into a bit
of a joke, but I secretly believe it looks fantastic
As I point out to people, it's Pininfarina-styled (do you think they get
some work-experience boys to design the Peugeots?) so that automatically
qualifies it as beautiful, surely?

What do you mean by TC? You've lost me there...

Chris.