Date: Mon, 15 Jul 2002 18:13:31 -0700
Reply-To: Jim Arnott <jrasite@EONI.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jim Arnott <jrasite@EONI.COM>
Organization: http://WetWesties.org
Subject: Re: tiico's, subies and diesels oh my...
Content-Type: text/plain; charset=us-ascii; format=flowed
To quote Akin's Laws of Spacecraft Design:
"Engineering is done with numbers. Analysis without numbers is, at best,
only an opinion.
Not having all the information you need is never a satisfactory excuse
for not starting the analysis.
When in doubt, estimate. In an emergency, guess. But be sure to go back
and clean up the mess when the real numbers come along."
Pay particular attention to the last one....
Jim
Christopher Berchin wrote:
>>Chris wrote: "Note that all are approximations."
>>--------------------------------
>>Stan replys: Then why bother?
>
>
> Chris counter-replies: Because approximations are the best you can ever
> hope to have, even in the engineering world, until you actually build a
> prototype and test it. It's good for A-to-B comparisons and prediction of
> trends, if not exact numbers. For example, it shows how changing your tire
> size will affect your accelerations, though not at the *exact* number of
> g's. It will show you graphically how hugely a 240-hp Vanagon would stomp a
> 1.9 WBX like mine, and so on. Most of the world's creations were simulated
> using approximations first. : ) Basically if you're thinking about
> spending a lot of money on some sort of engine, this can help show you how
> much bang you'd get for your buck.
>
> Chris
>
>
> ----- Original Message -----
> From: "Stan Wilder" <wilden1@juno.com>
> To: <ctb1@PEOPLEPC.COM>
> Cc: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, July 15, 2002 7:26 PM
> Subject: Re: tiico's, subies and diesels oh my...
>
>
>
>>Chris wrote: "Note that all are approximations."
>>--------------------------------
>>Stan replys: Then why bother?
>>
>>Stan Wilder
>>
>>On Mon, 15 Jul 2002 18:55:13 -0400 Christopher Berchin
>><ctb1@PEOPLEPC.COM> writes:
>>
>>><< I'm just curious if there is a definitive place to look for
>>>comparisons on these engine conversions? >>
>>>
>>>I wouldn't call it "definitive," but I'm currently working on
>>>finishing a
>>>spreadsheet with graphical analysis of the 2.2 Subie, 3.3 Subie, 1.9
>>>and 2.1
>>>WBX engines. Basically I've plotted the thrust curves for each
>>>engine in
>>>each gear over the entire rev range. What I'm working on now is
>>>adding the
>>>effects of powertrain losses (i.e. frictional losses that are
>>>internal) and
>>>aero drag. I have it figured out, I just haven't finished it yet.
>>>Once
>>>done, I can post the graphs - right now, the only thing that really
>>>"has it
>>>all" is my comparison of the 2.1 WBX to the Subaru 2.2, but only for
>>>top
>>>gear. I have drag and powertrain loss effects only for fourth gear
>>>for
>>>those engines - what's left to do is to do the rest of the gears
>>>and
>>>engines.
>>>
>>>The whole thing is an Excel spreadsheet, so you can play with tire
>>>sizes,
>>>gear ratios, and dyno cuves to see what happens. Note that all are
>>>approximations, but so far my 1.9 WBX chart says that I should top
>>>out at
>>>about 91 mph, and since the top speed is really 88 mph in reality,
>>>that's
>>>close enough for gov't work.
>>>
>>>If anybody wants the final results, drop me a line and I can send it
>>>along
>>>to you. Once I have something close to complete, I can upload the
>>>graphs at
>>>my Imagestation albums.
>>>
>>>To add more engines, all you would need is dyno data and gear
>>>ratios. Punch
>>>it in on the spreadsheet, do a little Excel work, and bammo - a new
>>>comparison is born.
>>>
>>>Chris
>>>
>>
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>
>
> .
>
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