Re: Re: RE: Now - Turbo Dakotas-Tom

From: Tom Slick North (prodog@swbell.net)
Date: Tue Oct 16 2001 - 22:15:01 EDT


I really doesn't matter, The twin-turbo setup from a rotary should still be
fine for a 1.3L piston engine...

Later,
Tom "Slick"

----- Original Message -----
From: "Carl" <carldavis@mac.com>
To: <dakota-truck@buffnet.net>
Sent: Tuesday, October 16, 2001 8:40 PM
Subject: Re: DML: Re: RE: Now - Turbo Dakotas-Tom

> Umm, not sure I agree with you analogy. Not to bring rotary stuff to
> the Dakota List, but, the rotary displaces 654cc per face, times 2
> rotors, for a total of 1308cc, or 1.3 liters (if you round down).
> Rotary engine displacements and Piston engine displacements are measured
> the same way. Displacement is the sum total of positive combustion
> chamber volume increases for one complete revolution of the main shaft
> (crank or eccentric). In a piston engine, this means the total amount of
> space swept by its pistons. In a rotary, it is easiest to think about
> the difference between the maximum and minimum volumes for a single
> chamber multiplied by the number of rotors (where each rotor has 3
> chambers).
>
> Remember that the rotor actually revolves at one third the speed of the
> eccentric shaft, which is the reason only one chamber's displacement is
> used in the calculation. The difference in power is due to the fact that
> the rotary uses its full displacement to produce power for each
> revolution of the eccentric shaft while only half the displacement of
> the piston engine is producing power for each revolution of the
> crankshaft. When you consider the facts above, you will see that on a
> rotary, each rotor fires once per eccentric shaft revolution. In a
> piston engine, only half of the combustion chambers fire for a given
> revolution.
>
> This means that a 2-rotor engine fires as often as a 4-cylinder engine.
> However, the power stroke duration in a rotary is 50% longer, it being
> 3/4 of a main shaft revolution to the piston engine's 1/2. This makes a
> 2-rotor engine similar to a 6-cylinder.
>
> A 20B displaces 654cc times 3 rotors, or 1962 cc, or 2.0 liters (if you
> round up)
>
> This is not meant as a flame war, but a clarification. Please send any
> responses off list to me.
>
> Carl
> 99 Dakota
> 88 Rx7 GXL
> 84 Rx7 Base
>
> On Tuesday, October 16, 2001, at 12:47 AM, Crit Bennett wrote:
>
> > The twin Hitachi units on the 93+ RX-7s are a real pain in the ass,
> > plus a sequential twin setup wouldn't be the way to go. The
> > compressors are too small for a parallel twin V8. Also, the 1.3 is a
> > little misleading. Rather than displacing 1.3 liters for every two
> > revs, like conventional reciprocating engines do, the rotary displaces
> > 1.3L per face and two faces pass per rev. It's essentially a 5.2L
> > engine but doesn't burn as effectively. I'm a rotary nut and would
> > gladly drop a Mazda 20B into the Dak if I could, but it's not a fair
> > analogy.



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