Aerochargers are better than (insert compressor)

[lance]

OK, I understand that part of it.  I was being nice saying 200 hp, and I
was implying that the turbo system was properly sized, cam properly
selected, running on the right fuel, correctly timed, etc., etc.  I
don't understand how an engine that is capable of 200 hp (or much more)
is going to be restricted by a turbo housing when it is only being asked
to produce something in the 15 to 20 hp range.  That's a pathetically
small amount of airflow compared to WOT, so the gas load will be
relatively tiny.  Surely I could build a naturally aspirated engine with
a much smaller exhaust than 1.5" that makes 20 or even 30 hp, there are
LOTS of bikes that do it, so I'm still not getting the restriction
concept.

The other concept that is a little confusing to me, a turbo certainly
isn't operated by flow volume, if that were the case, diesels could all
have full boost just off of idle.  No throttle plate, full gulp of air
each cycle, constant gas load only varying with rpm.  It's the waste
heat expanding the exhaust gases (according to my understanding) that
makes boost happen.  No heat, no boost.  Same example, our diesel under
full load.  Driver lifts to shift, boost drops off until he steps down
on the loud pedal again, boost jumps back up as soon as the exhaust heat
hits the turbine.  You hear it everyday on the freeway when driving near
a boosted tractor-trailer.

Maybe we are saying the same thing, but when I studied aircraft turbine
engines the basic concept of operation was based on the premise that the
expanding exhaust gases push the rotors against the stators and cause
the whole system to generate thrust.  Still suck, squeeze, bang, but
more like a turbocharger than a piston engine.

Lance

P.S.  I liked McInnes's book, but it left out a lot of the nitty gritty,
and doesn't address the current technologies (of course it was written
some time ago, so it couldn't).

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org] On
Behalf Of Bruce
Sent: Thursday, October 21, 1999 8:16 PM
To: diy_efi at diy-efi.org
Subject: Re: Aerochargers are better than (insert compressor)





Think self EGR'ing.
Some EGR can help, too much and mileage will drop.
There is two sides to these statments, while you might think that you'll
get better cruise, remember the statement is for a 200 HP engine so you
also have to make 200 HP thru that pipe.  That will take a fair sized
cam, and really make the self EGR'ing an issue. Bruce


----- Original Message -----
From: "clayb" <clayb at sbcglobal.net>
To: <diy_efi at diy-efi.org>
Sent: Sunday, October 21, 2001 11:01 PM
Subject: RE: Aerochargers are better than (insert compressor)


> > Do you really think you will get optimum cruising fuel mileage if 
> > you
are
> > exhausting a 200 plus HP engine through a 1.5" diameter single 
> > exhaust
pipe
> > ??
>
> Of course you will. The larger pipe is of no use when the engine is 
> making 30 HP. Most engines have no objection to slight backpressure 
> under light loads, anyway. Some even run better that way.
>
> So, by your logic, zoomie pipes would be the optimum setup for part 
> throttle efficiency? Do you put large headers on a small engine, 
> because that means less backpressure and it will work better? Don't 
> they make different size headers for a reason?
>
> - Clay
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