Re: Daks & rotaries

From: Andy Levy (andylevy@yahoo.com)
Date: Wed Oct 17 2001 - 19:45:46 EDT


I was hoping you meant a rotary in your Dak (that'd be a wild swap!), then
I saw your sig.

Eric Carter wrote:

> Might work alright, but you have to consider RPM range too... Rotaries
> have
> very high rev ranges when compared w/ piston engines. Dakotas and
> rotaries
> are the best combo to own... Just check out my website
>
> www.digitex.net/ecarter
>
> Eric
> 2001 Dakota QC 4x4
> 1985 Rx7 Gsl-Se
>
>
> Date: Tue, 16 Oct 2001 21:15:01 -0500
> From: Tom Slick North <prodog@swbell.net>
> Subject: Re: DML: Re: RE: Now - Turbo Dakotas-Tom
>
> 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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-- 
-andy
andylevy@yahoo.com
Maintainer, DML FAQ - http://www.dakota-truck.net/faq/
http://home.twcny.rr.com/andylevy/dakota/
'99 CC 4x4 318 auto



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