[DeTomaso] Speaking of (crankshafts)

Thomas Tornblom thomas at hax.se
Wed Feb 29 09:28:45 EST 2012


2012-02-29 14:52, Will Kooiman skrev:
> The Ferrari Testarossa 12 cylinder (flat not V) does not have a flat crank.
> I was surprised the first time I saw one.  I thought it would be flat.
>
> There must be a pretty good reason.  I was never curious enough to do the
> math.  Getting lazy.

Yes, the reason is that it is a 12 cylinder engine.

With a flat crank you would have to fire three cylinders at the same time :D

A flat crank would require half of the pistons to be at TDC at the same 
time, and with a four stroke engine, that means half of those would be 
on the compression stroke.

Had it been a 12 cylinder boxer, with a flat crank, it would have had 
all 12 pistons at TDC, and thus you would have had to fire six at the 
same time. That would have been an interesting engine. :D

Thomas



>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> Behalf Of Tomas Gunnarsson
> Sent: Wednesday, February 29, 2012 6:32 AM
> To: Thomas Tornblom; detomaso at realbig.com
> Subject: Re: [DeTomaso] Speaking of (crankshafts)
>
> Nope, the Corvair crank has six separate throws where the pairs are 180 deg
> apart, e.g. boxer.
>
> Tomas
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com
> [mailto:detomaso-bounces at realbig.com]On Behalf Of Thomas Tornblom
> Sent: den 29 februari 2012 12:55
> To: detomaso at realbig.com
> Subject: Re: [DeTomaso] Speaking of (crankshafts)
>
>
> And the Corvair engine is strictly speaking not a boxer either, it is a
> 180 degree V engine.
>
> Thomas
>
> 2012-02-29 12:01, Tomas Gunnarsson skrev:
>> True, but what I wanted to point out was that neither crank is flat, they
>> are both 120 degree cranks it seems.
>>
>> Tomas
>>
>> -----Original Message-----
>> From: Roland Jaeckel [mailto:pantera874 at t-online.de]
>> Sent: den 29 februari 2012 11:48
>> To: Tomas Gunnarsson; detomaso at realbig.com
>> Subject: Re: [DeTomaso] Speaking of (crankshafts)
>>
>>
>> Porsche 917 is a V engine, the Corvair is a boxer. These are totally
>> different constructions and not compareable.
>>
>> Roland Jaeckel
>> ----- Original Message -----
>> From: "Tomas Gunnarsson"<guson at home.se>
>> To:<detomaso at realbig.com>
>> Sent: Wednesday, February 29, 2012 10:11 AM
>> Subject: Re: [DeTomaso] Speaking of (crankshafts)
>>
>>
>>> Porsche 917 crank:
>>>
>>> http://www.pbase.com/917carl/image/21844549
>>>
>>> Corvair crank:
>>>
>>> http://www.n56ml.com/corvair/flexplate/problem.html
>>>
>>> Neither looks particularly flat. I've a hard time imagining any inline
> six
>>> with a 180 deg crank too.
>>>
>>> Tomas
>>>
>>> -----Original Message-----
>>> From: detomaso-bounces at realbig.com
>>> [mailto:detomaso-bounces at realbig.com]On Behalf Of JDeRyke at aol.com
>>> Sent: den 29 februari 2012 09:13
>>> To: kenn_green at yahoo.com
>>> Cc: detomaso at realbig.com
>>> Subject: Re: [DeTomaso] Speaking of (crankshafts)
>>>
>>>
>>> In a message dated 2/28/12 9:34:54 PM, kenn_green at yahoo.com writes:
>>>
>>>> Dies the crank have to be flat for a12 cylinder boxer?
>>>>
>>>
>>> Obviously not re your example. Porsche flat-12 race engines used flat
>>> cranks, as did their boxer-4s (&   VWs too) and -6s. My Corvair boxer-6
> had
>>> flat
>>> cranks from GM. Most 4 vertical cylinder engines use flat cranks as do
>>> many
>>> straight 6s. THey're not rare except in modern passenger V-8s.
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>
>
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-- 
Real life:   Thomas Törnblom             Email:	   thomas at hax.se
Snail mail:  Banvallsvägen 14            Phone:    +46 18 32 31 18
              S - 754 40 Uppsala, Sweden  Mobile:   +46 76 209 8320




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