In article ,
says...
If a car's torque peak is at 5000 rpm (typical of a modern petrol engine),
would it really get better mpg doing 5000 rpm in 1st gear at 25 mph, than
say 2000 rpm in 3rd gear at the same speed? Er, don't think so...


TBH, I'm not sure of any car with a reasonable sized engine that has
peak torque at 5krpm.

Peak torque is usually arround 3500-4000rpm, while on a diesel usually
arround 1700-2500rpm.

peak BHP on a normal family car with a petrol engine is normally arround
the 5-6krpm unless it is a VTEC/VVTi variable timing type engine in
which case it is higher.
--
The poster formerly known as Skodapilot.
http://www.bouncing-czechs.com

In article ,
MeatballTurbo wrote:
TBH, I'm not sure of any car with a reasonable sized engine
that has peak torque at 5krpm.

Peak torque is usually arround 3500-4000rpm, while on a diesel
usually arround 1700-2500rpm.

My Honda Jazz CVT, one of the most economical petrol hatchbacks,
has peak torque at 2800rpm, peak power at 5700rpm. Round town on a
good level road, light foot, it will drift along at around 30mph
with the engine doing little more than 1000rpm.

--
Tony Bryer

In article ,
says...
In article ,
MeatballTurbo wrote:
TBH, I'm not sure of any car with a reasonable sized engine
that has peak torque at 5krpm.

Peak torque is usually arround 3500-4000rpm, while on a diesel
usually arround 1700-2500rpm.

My Honda Jazz CVT, one of the most economical petrol hatchbacks,
has peak torque at 2800rpm, peak power at 5700rpm. Round town on a
good level road, light foot, it will drift along at around 30mph
with the engine doing little more than 1000rpm.


Exactley like I said, only I got the peak torque higher than reality,
but far below the other posters suggestion.
--
The poster formerly known as Skodapilot.
http://www.bouncing-czechs.com

"MeatballTurbo" wrote in message
t...

TBH, I'm not sure of any car with a reasonable sized engine that has
peak torque at 5krpm.

peak BHP on a normal family car with a petrol engine is normally arround
the 5-6krpm unless it is a VTEC/VVTi variable timing type engine in
which case it is higher.

The 2.0 Vtecs seem to have peak power and torque at
normal revs, and the Type S and S2000 are higher.

On Thu, 1 Apr 2004 14:35:41 +0100, "Nick Finnigan" wrote:

"MeatballTurbo" wrote in message
et...

TBH, I'm not sure of any car with a reasonable sized engine that has
peak torque at 5krpm.

peak BHP on a normal family car with a petrol engine is normally arround
the 5-6krpm unless it is a VTEC/VVTi variable timing type engine in
which case it is higher.

The 2.0 Vtecs seem to have peak power and torque at
normal revs, and the Type S and S2000 are higher.

Same technology, widely different implementations for different design
goals. The S2000 is something outrageous like 220bhp, normally aspirated...
I think these and the Type S engines are the ones supposedly hand-built by
just two guys in Japan.

--
Diplomacy: the art of letting someone else have your way.

Mail john rather than nospam...

"John Laird" wrote in message
...
On Thu, 1 Apr 2004 14:35:41 +0100, "Nick Finnigan"
wrote:

"MeatballTurbo" wrote in message
et...

TBH, I'm not sure of any car with a reasonable sized engine that has
peak torque at 5krpm.

peak BHP on a normal family car with a petrol engine is normally
arround
the 5-6krpm unless it is a VTEC/VVTi variable timing type engine in
which case it is higher.

The 2.0 Vtecs seem to have peak power and torque at
normal revs, and the Type S and S2000 are higher.

Same technology, widely different implementations for different design
goals. The S2000 is something outrageous like 220bhp, normally
aspirated...
I think these and the Type S engines are the ones supposedly hand-built by
just two guys in Japan.

With a diesel engine you actually get the peak in the torque (which governs
the ability to accelerate out of a bend/roundabout and when changing lanes
on a motorway) at normal engine speeds (eg around 2000 rpm), so you don't
have to change down to accelerate. Driving a petrol-engined car is a real
faff now I'm used to my Peugeot 306 HDi - I tend to forget that other cars
can't take roundabouts in third with smooth progressive acceleration right
back up to 30 or 40 again without the need to change gear mid-way.

What *is* the point in designing an engine whose torque and power peaks are
at even *higher* rpm than normal? I'd have thought that the Holy Grail was
an engine that had as much low-end torque as possible to minimise
gear-changes, especially around town. Is it my imagination or are modern
petrol-engined cars lower-geared that older ones? When I borrowed a petrol
Peugeot 306 while my car was in for a service, the poor thing's engine was
screaming away at about 4000 rpm at 70 on the motorway, whereas my car
manages about 2500 rpm: much quieter. And the poor petrol-engined car ran
out of puff at motorway speed: its 50-70 acceleration was very poor. This
was a top-range 1800 engine, not some under-powered 1300. Give me a diesel
(preferably the 130 bhp one used in the Golf GTI!!!) any day.

"Martin Underwood" wrote in message
s.com...

With a diesel engine you actually get the peak in the torque (which governs


Or petrol turbo engine...

the ability to accelerate out of a bend/roundabout and when changing lanes
on a motorway) at normal engine speeds (eg around 2000 rpm), so you don't

Most petrol cars are well above 2,000rpm on motorways,
and are driven around 1,500rpm in town.

have to change down to accelerate. Driving a petrol-engined car is a real
faff now I'm used to my Peugeot 306 HDi - I tend to forget that other cars
can't take roundabouts in third with smooth progressive acceleration right
back up to 30 or 40 again without the need to change gear mid-way.

Maybe, but why specify 'in third' ?

What *is* the point in designing an engine whose torque and power peaks are
at even *higher* rpm than normal? I'd have thought that the Holy Grail was
an engine that had as much low-end torque as possible to minimise
gear-changes, especially around town.

Why don't people stay in second gear then?

Is it my imagination or are modern
petrol-engined cars lower-geared that older ones? When I borrowed a petrol
Peugeot 306 while my car was in for a service, the poor thing's engine was
screaming away at about 4000 rpm at 70 on the motorway, whereas my car

Top speed 119mph, peak power at 5,500 rpm,
so 70 should be 3,300 rpm (or less).

Martin Underwood wrote:
"John Laird" wrote in message
...
On Thu, 1 Apr 2004 14:35:41 +0100, "Nick Finnigan"
wrote:

"MeatballTurbo" wrote in message
t...

TBH, I'm not sure of any car with a reasonable sized engine that
has peak torque at 5krpm.

peak BHP on a normal family car with a petrol engine is normally
arround the 5-6krpm unless it is a VTEC/VVTi variable timing type
engine in which case it is higher.

The 2.0 Vtecs seem to have peak power and torque at
normal revs, and the Type S and S2000 are higher.

Same technology, widely different implementations for different
design goals. The S2000 is something outrageous like 220bhp,
normally aspirated... I think these and the Type S engines are the
ones supposedly hand-built by just two guys in Japan.

With a diesel engine you actually get the peak in the torque (which
governs the ability to accelerate out of a bend/roundabout and when
changing lanes on a motorway) at normal engine speeds (eg around 2000
rpm), so you don't have to change down to accelerate. Driving a
petrol-engined car is a real faff now I'm used to my Peugeot 306 HDi
- I tend to forget that other cars can't take roundabouts in third
with smooth progressive acceleration right back up to 30 or 40 again
without the need to change gear mid-way.

Perhaps you should get an automatic?

What *is* the point in designing an engine whose torque and power
peaks are at even *higher* rpm than normal? I'd have thought that the
Holy Grail was an engine that had as much low-end torque as possible
to minimise gear-changes, especially around town.

errm, because you don't want maximum torque while driving around town?? I'd
rather have more control while around towns and be able to floor it up to
maximum torque when out of town. I don't want my car to lurch into a shop
window by tapping the accelerator! In fact, a friend of mine commented on
this fact when she drove a diesel hire car for the first time, she didn't
like all the torque!

Is it my
imagination or are modern petrol-engined cars lower-geared that older
ones? When I borrowed a petrol Peugeot 306 while my car was in for a
service, the poor thing's engine was screaming away at about 4000 rpm
at 70 on the motorway, whereas my car manages about 2500 rpm: much
quieter.

But you're happy to wake everyone up at 6am in the winter when you start up
your car :-) Have you driven a modern petrol car? I can't say I've noticed
any engine screaming at normal motorways speeds, even very fast motorway
speeds.

And the poor petrol-engined car ran out of puff at motorway
speed: its 50-70 acceleration was very poor.

I imagine you were trying to do this in 5th gear?

This was a top-range
1800 engine, not some under-powered 1300. Give me a diesel
(preferably the 130 bhp one used in the Golf GTI!!!) any day.

In general an 1800 petrol will be much quicker than a 1800 diesel, just look
at 0-60 (or 50-70) times in magazines. Just because *you* can't drive a
petrol, doesn't mean nobody else can either!

John Laird wrote:

Same technology, widely different implementations for different design
goals. The S2000 is something outrageous like 220bhp, normally
aspirated... I think these and the Type S engines are the ones
supposedly hand-built by just two guys in Japan.

Hand built, hand assembled or hand finished? VERY unlikely to be the
first!