On 2 Nov 2006 02:54:54 -0800,
yunustaboglu@gmail.com 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.
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