Moto GP to go to 800cc in 2007

Now find a turbo petrol with turbo diesel comparison and you'll compare
apples with apples

Turbo 2.0 petrol, should be around 160-180 kW and probably half again
the torque, as per previous email

JL

 

Before the teams were told they *had* to run V10's, there were alot of different engine configs coming out. A few V8's still, a
coupla V10's and a few V12's. There was even an attempt at a W16 at one stage, but it lasted only about a year.

Most of the teams eventually went for the V10 config as they were easier to balance than the V12's, which tended to shake themselves
apart and suffer all sorts of reliability issues. They were also able to produce higher revs and therefore HP than the V8's.

 

Whoops, correction, there was a W12.

Some engine configs before the engine regs demanded V10's (1998 and prior)...................


AGS Ford Cosworth V8
Brabham Judd V8
Coloni Subaru flat 12
Dallara Ford Cosworth V8
Euro Brun Judd V8
Larrousse Lola Lamborghini V12
Leyton House Judd V8
Life started with their imaginative W12 but then Judd V8
Lotus Lamborghini V12
Onyx Ford Cosworth V8
Ossella Ford Cosworth V8
Arrows Ford Cosworth V8
Benetton Ford HB V8
Ferrari V12
McLaren Honda V10
Minardi Ford Cosworth V8
Tyrrell Honda V10
Williams Renault V10

 

Yes but turbo petrol engines don't work as well (fuel wise) as turbo
diesels so they don't make them except where performance is _all_ that
matters.

A turbo petrol engine with around 105kw and similar torque to the 2
above would almost certainly have worse fuel economy than the naturally
aspriated petrol above.

You need to stop looking at turbo's as an option and start looking at
engines as 'packages' within which one should use the most effective
'fuel, transmission, carberation/injection, induction, extration'
combination to achieve the stated objective. [1]


G-S

[1] OK, you can include NVH as part of the stated objective if you
really want

 

Petrol turbos suffer more from lag than turbo diesels (or at least the
lag is more noticible because of the lower torque).

I was very interested in the SAAB's a while back as a company car, but
after test driving one I changed my mind.

Look at the package Theo... how that result is achieved isn't really
relevant. If petrol turbo's are such a fuel efficient choice why are we
only seeing them in small numbers?

Oh rubbish... you can drive a turbo diesel hardish and _still_ get
decent fuel economy (fuel economy doesn't drop as fast with extra
performance as with petrol engined vehicles).

You've got that 40% extra to start with remember... so it's the petrol
engined one that's got to be grannied to stay within the budget


G-S

 

LPG? Pass... I tried that... starting issues in sub zero conditions, 10
to 15% power loss on dual fuel, and more than that loss in torque... and
torque is more important than power. LPG only (which has less power and
torque loss) isn't viable in the country... not enough filling stations).

I don't think the point about many cars not doing that sort of milage is
really relevant to this discusssion though.

It means that I am in a position to judge small fuel economy differences
closer than most people (which probably makes my experience more relevant).

So... when I say turbo diesel best for long term fuel economy I'm not
just giving you an opinion... I'm giving the the benifit of a lot of
klms of evidence ;-)


G-S

 

If we've 'pretty much got them figured out' then why are they getting so
much cleaner and better performing so quickly over the last decade or so?

If they get to the point of being 'quick, economical, good handling and
economically priced' then I'll start considering them. At this point in
time they are still inferior to good turbo diesels (like the 2 litre
golf mentioned in another thread).

That's a fair point, but it doesn't justify why we should buy hybrid
cars _now_.

I stand by my comment

Although if you insist I will say that I was talking about the current
situation (and not some hypothetical future time where hybrids may have
improved faster than diesel technology).


G-S

 

Umm would you care to explain that extremely strange comment ? I can't
even begin to fathom what "don't work as well (fuel wise" is supposed to
mean.

A turbo, whether used on a diesel or a petrol engine does a very simple
job, it's an air compressor, it makes the intake charge have a pressure
greater than atmospheric, which means you can burn more fuel air mixture
for a given capacity.

Sure, a turbo petrol engine held wide open will have worse fuel economy
than the same engine sans turbo. So what ? That's a furphy, the orginal
statement was about an apples to apples comparison between turbo diesel
and turbo petrol - if you compare apples with apples a turbo petrol
makes a shit load more power (40 to 50%) for usually a touch less torque.

Alternatively if you get a turbo petrol engine making the same HP as a
turbo diesel you'll find the petrol gets better economy (albeit it won't
have the torque so don't choose it to go towing boats with)

Diesels are best suited to heavy load situations because cc for cc they
make big torque - thats why just about every truck, coach, bus and large
motorboat runs one. If you want to shift big amounts of mass around, and
acceleration isnt all that important the diesel is the motor for the
job. In smaller lighter vehicles a petrol engine makes more sense.

Hmm, which of us is doing that again ?

Umm yes I certainly do include NVH as a parameter ! As does just about
every car tester I've ever read.

JL

 

Oh fercrissakes, any more urban myths to trot out ? Turbo petrol engines
have as much lag as you choose to build into them. In the 80s when
turbos started to go in production machines a lot of the manufacturers
didn't have much of an idea about the trade offs, and hence big turbos
got put on little motors with low compression - that's where the turbo
lag story comes from - that setup has a torque curve like an RGV250,
nothing nothing nothing HOLY SHIT !.

You don't have to build them like that, go drive a saab turbo, if you
can tell that it's a turbo and spot the turbo lag, well, I won't
question your veracity, but....ever other tester on the planet says you
can't tell.. how ? Very simply, the combination of turbo size, boost
level, compression ration, ecu map, intake length and diameter,primary
exhaust tract diameter etc determines both the maximum amount of HP you
generate and the shape of the torque curve.

Smaller turbos give boost from idle, bigger turbos need more gasflow to
spin up, you can even get fancy like some of the japanese manufacturers
and run sequential turbos, a small one to create boost in the low rev
range and a big one that creates boost at higher revs.

<shrug> I don't like FWD so I won't have one either, but they've done a
good job of creating a range of engines with a range of different
driving attributes.

Oh rubbish.. you HAVE to drive a turbo diesel hardish to get there this
week !

JL

 

next week huh, if ya lucky

 

Umm yeah, but as I said earlier, there's still no pressing reason for
99.99% of the country to justify swapping to diesel from petrol at the
moment.

To get a car with the same performance requires a diesel with
equivalently bigger engine than the petrol, hence to obtain your fuel
savings you have to give up performance, not a trade off I personally
appreciate. While ever I can afford it I will always buy the highest
performance option within the vehicle package I've chosen, and if you
look at the sales numbers of the Ford and Holden V8s and turbo V6s,
there's a very significant portion of the population who agree.

Turbo diesel passenger cars sell in miniscule numbers in Oz, and will
continue to do so until fuel prices get high enough to make the fuel
economy/performance trade off worth it.

JL

 

So there was. In 1966 (driven by Hill and Stewart) and 1967 (Stewart).

http://www.nationmaster.com/encyclopedia/Image:Rntbrm3litergp.jpg

 

1953 Formula One BRM 1.5 litre V-16 Supercharged racing car
The short-stroke, high-revving Vl6 had its cylinder banks at an included
angle of 35 degrees, with alloy cylinder heads and block, and tiny cast-iron
liners (a weak point, as they broke up when coolant leaked into the
cylinders). The engine could be regarded as a pair of 744cc V8s with a
common two-piece, 10-bearing crankshaft. There was a half speed power
take-off at its centre, with trains of gears operating the twin overhead
camshafts. The drive for the supercharger was taken from the front of the
output shaft, forward via a gear train.

Boxer

 

OK, I admit that wasn't worded well.. I'd had a long day ok

What I meant was that turbo'd petrol engines tend to be performance
based, not economy based.

Well yes... one promising area of development is the supercharged and
turbocharged small diesel.

Your apples with your apples by you definition. My definition of apples
with apples is 'current mass market engines' compared with other
'current mass market engines'.

Proof please? Which petrol engine with turbo compared to which diesel
engine (and I'll ignore the power is more important than torque
assumption you've made for the moment

Ahh... well now we are getting to the hub of it! For good economy small
engines shifting larger amounts of mass are used. For maximising power
turbo charging or supercharging are used.

Using small diesels to shift the (comparitivly) large weight of a full
sized passenger car and 4 adults is a 'heavy load situation' relative to
the size of the engine.

That would be you... seriously... you keep saying 'apples vs apples' and
ignoring the 'package'.

Sure, but the question becomes _where_ you include it, and how
significant it is.

I strongly suspect I rate it's importance well under fuel economy, and
from what I've seen you probably don't

G-S

 

Yes now that's an interesting comment, and has at the core of it one of
the real reasons that petrol turbo's haven't caught on. History shows
that they aren't as reliable as non turbo charged petrol engines.

Whereas history shows that turbo charged diesels _are_.


G-S

 

Exactly my point!

Bugger... this is a me too post isn't it...


G-S

 

At a guess, I'd say around 1986. And it would have been one of the last of the turbo cars.

Some of those donks were producing around 1500 HP !!!

 

Whilst they have gotten better petrol turbo engines _still_ have more
lag than diesel engines because diesel engines simply have more
compression! You can minimise the lag of course, but diesels inherently
have less of it.

Have you driven a turbo 2.0 golf?


G-S

 

Saving money isn't a pressing reason?

Cars are for point A to point B transport for 99% of the population (and
for most of the motorcyclist population).

I'm pleased you find 'performance' cars fun, but you are in the minority
here John, if you look at the sales numbers of cars you'll find that
most holdens and fords are sold as company cars, and that the most
popular private sale cars are medium 4 cylinders.

Have a look at the ramping curve exhibited by the sales of the Turbo
Diesel golf range and realise that there is a pent up demand for this
sort of vehicle.

There are lots of people out there for whom this sort of car meets thier
criteria.


G-S

 

I would also add that there is no evidence (your assertions are not
evidence you know) that hybrids will _ever_ catch up to or exceed the
performance/cost/economy ration of small forced induction diesel engines.

And personally I'd bet that by the time they even get close we will have
full fuel cell vehicles available.

At which point the issue becomes moot... which is why I regard these
hybrids as a necessary engineering test bed for full electric or fuel
cell cars, but _not_ as something one would buy in preference to a fully
functional forced induction diesel.

G-S