why diesel engines are having hight torque comparing with the same size of Petrol Engines ??

Well , im trying to have your opinons buddies , im doing a small search
bout this subject . so anyhelp . i got a lot of stuff but still
wondering how the torque can have direct effect on the engine .

waiting al ur replies .

10x advance ,

On 2 Nov 2006 02:54:54 -0800, [email protected] wrote:

>
>Well , im trying to have your opinons buddies , im doing a small search
>bout this subject . so anyhelp . i got a lot of stuff but still
>wondering how the torque can have direct effect on the engine .
>
>waiting al ur replies .
>
>10x advance ,


THere is a couple of reasons. THe first ishow the energy is extracted
from fuel in that it has very high compresion (16 or 18 to one or
better) which increases the amount of power extracted. Next there is
how the fuel purns more slowly with a lower expansion cycle which asle
extract more energy over a lower period of crank rotation. (it also
greatly limits the efective RPM of engine too) Last and most
importantly, there is the boost as modern diesel run between about 17
and 30 PSI boost which increases effective displacement. Example, a
400 cu inch motor running about 15 lb of boost uses the same amount of
air as a 800 cu in motor without it and a 800 cu gas motor would have
awesome torque. Take away the boost from a CTD, a PS or a Dmax and it
would be pretty gutless. By same token run the same amout of boost on
a gas engine and the power would be downright scarey at times. The
main reason that you do not see boosted gas motor is the publics
affinity for 87 octane fuel which would destroy a gas motor when
boosted. Had it not been for high performance super and/or turbo
charged gas engines that powered allied aircraft in WW2, the world
would be a different place today. Also had it not been for germany's
affinty for diesel tanks , the russain front battle may have gone
differently because they soon found them to be next to useless in
really cold weather. True, the fuel was less volitule in combat damage
but it did not much matter if it will not run. There is pluses and
minuses to both engine types but cu in for cu in, a gas motor will
make far more HP power than any diesel will at the same relative
manifold pressure. Witha 400 cu gas motr you can easily make 300HP
with no boost plus but same size diesel with out boost might make 160
or so if you are lucky. To compare engines effectively, you need to
consider tha amount of air they use because as stated earlier, boost
changes its "effective" displacement. too. Furthermore if you design a
gas engine from scratch to run on better fuel than 87 octane you can
increase CR a lot and boost output and efficency as well. 87 octane is
more of a hinderance to gas engine efficency than most people want to
except because were it not for it, we would have main stream engine
with 11 and 12 to 1 CR like we did in 60's and better power and use
less fuel doing it too.
-----------------
TheSnoMan.com

[email protected] proclaimed:

> Well , im trying to have your opinons buddies , im doing a small search
> bout this subject . so anyhelp . i got a lot of stuff but still
> wondering how the torque can have direct effect on the engine .
>
> waiting al ur replies .
>
> 10x advance ,

Check the compression ratio and peak combustion pressure on a diesel and
a typical gasoline engine.

Everyone is all hot on torque, but what matters is power. You just have
to shift down to get the power you need. Look at the rock crawlers,
they have gears so low they can go 1 mph at 5000 rpm! Power is what you
need. Torquey motors give good power at low rpms, which is a kick I
guess.

Diesel fuel has more btus (watts) per gallon than gasoline. Diesels
engines can be run at higher compression ratios because engines wont
ping with the diesel fuel. I think just about all diesel engines are
fuel injected (but so are gas now). Anyway, both work. Personally I
don't like the noisy, dirty, stinky diesel (prefer gasoline), but they
do work well. Make an engine with really big cylinders and big flywheel
and you will have a torqy sob no mater what fuel you use.

On 7 Nov 2006 13:23:04 -0800, "Doug" <[email protected]>
wrote:

>Diesel fuel has more btus (watts) per gallon than gasoline. Diesels
>engines can be run at higher compression ratios because engines wont
>ping with the diesel fuel. I think just about all diesel engines are
>fuel injected (but so are gas now). Anyway, both work. Personally I
>don't like the noisy, dirty, stinky diesel (prefer gasoline), but they
>do work well. Make an engine with really big cylinders and big flywheel
>and you will have a torqy sob no mater what fuel you use.


Actually diesels ?ping/knock" all the time, that is where noise comes
from. while there is about a 12% difference in BTU content the biggest
thing limiting gas engine power and efficency is low octane fuel
because there are those that think 87 octane is the wonder fuel which
it is not and detriot has to do a LOT of trickery with timing curves
and CR ratios to control knock from it which reduces power and MPG. In
the 60's and early 70's you knew when you were not feeding your engine
right because it would knock big time but today they mask it with
knock control that quietly steals your power from you.
-----------------
TheSnoMan.com

SnoMan proclaimed:

> On 7 Nov 2006 13:23:04 -0800, "Doug" <[email protected]>
> wrote:
>
>
>>Diesel fuel has more btus (watts) per gallon than gasoline. Diesels
>>engines can be run at higher compression ratios because engines wont
>>ping with the diesel fuel. I think just about all diesel engines are
>>fuel injected (but so are gas now). Anyway, both work. Personally I
>>don't like the noisy, dirty, stinky diesel (prefer gasoline), but they
>>do work well. Make an engine with really big cylinders and big flywheel
>>and you will have a torqy sob no mater what fuel you use.
>
>
>
> Actually diesels ?ping/knock" all the time, that is where noise comes
> from. while there is about a 12% difference in BTU content the biggest
> thing limiting gas engine power and efficency is low octane fuel
> because there are those that think 87 octane is the wonder fuel which
> it is not and detriot has to do a LOT of trickery with timing curves
> and CR ratios to control knock from it which reduces power and MPG. In
> the 60's and early 70's you knew when you were not feeding your engine
> right because it would knock big time but today they mask it with
> knock control that quietly steals your power from you.

High pressure direct cylinder injection appears to be giving a lot of
the benefits of diesel in gas engines.

"Doug" <[email protected]> wrote in news:1162934584.258573.35140
@m73g2000cwd.googlegroups.com:

> Everyone is all hot on torque, but what matters is power. You just have
> to shift down to get the power you need. Look at the rock crawlers,
> they have gears so low they can go 1 mph at 5000 rpm! Power is what you
> need. Torquey motors give good power at low rpms, which is a kick I
> guess.
>
> Diesel fuel has more btus (watts) per gallon than gasoline. Diesels
> engines can be run at higher compression ratios because engines wont
> ping with the diesel fuel. I think just about all diesel engines are
> fuel injected (but so are gas now). Anyway, both work. Personally I
> don't like the noisy, dirty, stinky diesel (prefer gasoline), but they
> do work well. Make an engine with really big cylinders and big flywheel
> and you will have a torqy sob no mater what fuel you use.
>

Even *if* you have a slushbox with high stall-ratio, you *will* have to put
your high-power/low-torque engine through that gutless range from idle to
peak-power.
Or do you jam your slushbox into Drive after you revved up the engine?....)


--
Bye,

Willem-Jan Markerink

The desire to understand
is sometimes far less intelligent than
the inability to understand

<[email protected]>
[note: 'a-one' & 'en-el'!]

On Tue, 07 Nov 2006 17:17:23 -0800, Lon <[email protected]>
wrote:

>High pressure direct cylinder injection appears to be giving a lot of
>the benefits of diesel in gas engines.


It holds a lot of promise because it eliminates fuel being lost during
scanvanging which improves MPG and also allows for higher CR ratios
for a given fuel octane because the injection of fuel into cylinder
just before ignition cools the mixture as fuel vaporizes rahter than
being lost to intake port walls and such and higher CR ratio ment
better power and MPG too. In theory you could run about 13 to 1 CR
with a gas motor with direct injection and 94 octane and get a nice
power and MPG boost too. I look for DI on gas engines to be main
stream by 2010and for diesel to start loosing their luster after that
because the MPG difference will be a lot less and the diesel will
still cost a lot more to buy and fuel. DI will alos make it easier to
supercharge gas motors too.
-----------------
TheSnoMan.com

Horsepower is torque times speed (and maybe a constant to get the right
units). If your torque is in ft. lbs and you multiply by the rpm of the
engine, you get your horsepower. You can look at the torque curves and
horsepower curves for engines in car magazines that review the cars.

When people talk about an engine that "has a lot of torque" what they
mean, usually, is that it has a lot of torque at low rpm.

The design of the engine, the bore and stroke and size of the pistons
and weight and size of the crank and flywheel all play a part in how
much torque and horsepower an engine has. I don't really think that a
diesel engine has more torque by being a diesel. It's just that these
are usually truck engines and they want it to have good pull at lower
rpm, so they make it so it has good torque at low rpm. However, I'm no
expert.

[email protected] wrote:
> Well , im trying to have your opinons buddies , im doing a small search
> bout this subject . so anyhelp . i got a lot of stuff but still
> wondering how the torque can have direct effect on the engine .
>
> waiting al ur replies .
>
> 10x advance ,

On 12 Nov 2006 15:16:27 -0800, "Doug" <[email protected]>
wrote:

>Horsepower is torque times speed (and maybe a constant to get the right
>units). If your torque is in ft. lbs and you multiply by the rpm of the
>engine, you get your horsepower. You can look at the torque curves and
>horsepower curves for engines in car magazines that review the cars.
>
>When people talk about an engine that "has a lot of torque" what they
>mean, usually, is that it has a lot of torque at low rpm.
>
>The design of the engine, the bore and stroke and size of the pistons
>and weight and size of the crank and flywheel all play a part in how
>much torque and horsepower an engine has. I don't really think that a
>diesel engine has more torque by being a diesel. It's just that these
>are usually truck engines and they want it to have good pull at lower
>rpm, so they make it so it has good torque at low rpm. However, I'm no
>expert.
>


The burning properties of diesel fuel developes good low RPM power but
it has its limitations and with proper gearing a gas motor can do a
fine job. Most gas motors are just getting started when oil burners
are running out of breath and if you gear a gas motor a lot
differently than a deisel to use its power curve properly it will pull
well. Most do not because people have a mental block on what a good
axle ratio is for a gas motor and gear them wrong. BTW, 600 ft lbs of
torque at 2000 RPM is the same HP as 450 ft lbs at 3000 or 300 ft lbs
at 4000 RPM. Als remeber that a diesel needs a lot more size to exceed
the torque output of a gas motor either via more displacement or
boosting with increases its effective displacement. Take the turbo of
a CTD, PS or Dmax and it will be quite gutless.
-----------------
TheSnoMan.com

I couldn't disagree more... The engine in my Blazer is cammed so that
it makes peak power (horsepower) at 5100rpm. It's practically useless
in that truck. Sure, it can make power, but only at such a high rpm
that it'd be screaming down the road. Even with 3.73 gears and 31"
tires, I only turn around 2000rpm at 80mph.

The truck would run much better if it made it's peak torque at a much
lower engine speed. I would not have to turn it as fast. As it stands
now, there's no low-end acceleration, it runs incredibly rich at low
speeds, and the gas mileage is horrendous (11mpg on the interstate).

Horsepower is a derived value...it's not measured, it's determined.
It's used to describe how much work is done over a period of time. The
truth is, I have no need for that much "work" to be done in that short
of a time period. I need torque, and lots of it, and will need even
more once the lift kit is installed with the bigger tires.

Horsepower could not be any more irrelevant to me than it is right now.
Buying into the idea of more HP for the money is what got me into this
mess with my truck.

~jp

Doug wrote:
> Everyone is all hot on torque, but what matters is power. You just have
> to shift down to get the power you need. Look at the rock crawlers,
> they have gears so low they can go 1 mph at 5000 rpm! Power is what you
> need. Torquey motors give good power at low rpms, which is a kick I
> guess.
>
> Diesel fuel has more btus (watts) per gallon than gasoline. Diesels
> engines can be run at higher compression ratios because engines wont
> ping with the diesel fuel. I think just about all diesel engines are
> fuel injected (but so are gas now). Anyway, both work. Personally I
> don't like the noisy, dirty, stinky diesel (prefer gasoline), but they
> do work well. Make an engine with really big cylinders and big flywheel
> and you will have a torqy sob no mater what fuel you use.