Well what can I say, an (|) I am not!
I don't think incredible rubbish is a strong statement compared to the use of
expletives and such. Sometimes I don't like typing long replies either.
What I do get tired of is some of rot that gets produced as FACT when it is
far from it.
BUT
Shorter is not the same as smaller in my understanding but if you meant
shorter then I apolgise for my lack of American/English understanding. I do
think that generally on a Sprite the use and shape of any particular ram on
any given carb on a Spridget will make more difference than the length alone.
I stand on my comments about a restrictive exhaust - I cannot understand why
this would work so can't respond to something that plain doesn't make sense
to me. I think one of the biggest myths of all time is that an engine needs
back pressure. A 2 stroke engine doesn't need back pressure either and
having experimented with removing the exhaust baffles from the exhaust system
of my Yamaha RD 250 LC my limited practical experience support my view. What
a two stroke does need is exhaust pulse tuning, shock waves and all that
stuff to produce extraction of gases etc. Also a big performance gain on two
stroke motors is the use of expansion chamber type exhaust systems.
Generally the thing with exhaust systems is tuned length and diameter and not
restriction.
I don't agree that modifications that produce low rpm torque sacrice power at
the top end and my own and others experience using carburettor ram pipes to
mention a single modification bears this out.
Obviously there are tuning modifications that reduce low rpm torque at the
expense of top end power (bhp) but the reverse is not true.
In a message dated 16/11/00 05:16:30 GMT Standard Time, sfooshee@home.com
writes:
<< Daniel1312@aol.com wrote:
>
> I have heard of some rubbish in my time but this is incredible - absolute
> rubbish.
>
> In a message dated 15/11/00 04:20:16 GMT Standard Time, sfooshee@home.com
> writes:
>
> << The generalization
> is that you want a more restrictive exhaust and a smaller carb/intake for
> higher
> velocity at low engine speeds. >>
Okay, so besides your subtle disagreement, what's the answer? I qualified
it as
a wide sweeping and incomplete generalization because I didn't feel like
typing
that much.
In my experience, engines with smaller and/or longer intake tracts have
made
better low end torque versus high speed power. Mazda's Le Mans winning
prototype
used a variable intake (copied, I believe, by Ferrari's F1 program) in which
the
intake would shorten as engine rpm increased. This allowed the longer (and
more
restrictive) runners to increase the velocity of the intake charge at lower
engine speeds while still allowing the short runners required for higher rpm
power. Mazda has also used this with the '89-'91 normally aspirated car's
variable dynamic intake effect system, and Porsche's variable intake is very
similar. If the intake charge is stagnant (too big an intake for a given
engine
speed) then the fuel doesn't mix well and doesn't burn well.
I don't pretend to understand all the physics of engine design, but my
short
experience has shown me many people make their cars slower by simply opening
up
the exhaust. I know that 2-stroke engines are desperately dependent on
backpressure for torque, and rotaries are very similar to this. My old SAAB
was
in dire straits when the manifold flange rusted off, it wouldn't discuss
power
until 3500 rpm or so.
Assuming that the questioner is limited to modifications below
fabricating some
means of variable cam timing, most any change which will increase low end
torque
will sacrifice top end power.
Even if I'm wrong, why call it _incredible_ rubbish with no evidence or
opinion
of your own? If I'm wrong, correct me, but don't be an ass.
--
~
-Xavier Onasis.
'87 RX-7 TII: Live fast.
'90 GS-500E: Die young.
MCMLXIX Sprite: And leave an exquisite corpse.
If God dropped acid, would he see people? >>
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