Today's Message Index:
----------------------
1. 06:10 AM - Re: Re: Offset pistons in Brand "L," "C" or "F"? (FLYaDIVE)
2. 08:17 AM - Re: Re: Offset pistons in Brand "L," "C" or "F"? (Rob Turk)
3. 05:57 PM - Re: Re: Offset pistons in Brand "L," "C" or "F"? (Gary Aman)
Message 1
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| Subject: | Re: Offset pistons in Brand "L," "C" or "F"? |
Marty:
I do not know about Suzuki or Harley - But I do know about Lycoming and
Continental - They DO NOT HAVE ANY PISTON OFFSET.
I know of NO reason to have the wrist pin offset - It just does NOT make
ANY sense at all. There are Front & Rear to some pistons but that is
because of piston dome designs and valve clearances.
Think of it this way: What CENTERS the piston in the center of the
cylinder?
THE RINGS!!!
So, how or why would there be a wrist pin offset?
If there was piston pin offset, then the rings would be offset also - And
that would lead to uneven wear and loss of compression.
Whomever started this Wives Tail should be SHOT with Dumb-Dumbs because it
would match their intellect.. Always REMEMBER B.S. is spread at the speed
of an electron on the internet.
*Barry*
*"Do you know why pilots think they are mechanics? Because they can but
tools at Home Depot."*
On Thu, May 30, 2013 at 9:45 PM, Martin Hone <aerobiz1@gmail.com> wrote:
> Hi Frank,
>
> There has been a lot of discussion on the Jabiru engine list on this
> subject. It started when someone couldn't work out which way the pistons
> should be fitted. Most engines have piston pin offset, mainly to reduce
> piston slap at TDC hence noise. Some racing types reverse it to try and
> get a little more torque, while others 'desax' the bore by offsetting the
> barrels/cylinders relative to the centreline of the crank, ie. moving the
> cylinders forward or backwards a few millimetres in the same plane, not
> rotating around the crank as in a v-twin or radial. In a motorcycle
> production racing class I was involved in, a guy got caught cheating by
> doing just this. He moved the entire cylinder bank on a Suzuki 1000cc four
> cylinder engine !
>
> Marty
>
>
> On Fri, May 31, 2013 at 11:31 AM, Frank Roskind <frankroskind@hotmail.com>wrote:
>
>> Thanks for your response. I have googled offset piston with lycoming,
>> continental and franklin, but found nothing relevant except a reference to
>> the Franklin automobile having offset piston pins. After your message I
>> also googled the same three with "desaxed" and found nothing relevant. It
>> seems like a great idea, given all the fooling around with exhausts,
>> intakes and ignition, it is kind of odd that I am not reading of anyone who
>> took a shot at offsetting the pistons.
>> Maybe I just found a great retirement occupation.
>> ------------------------------
>> Date: Fri, 31 May 2013 06:58:04 +1000
>> Subject: Re: Offset pistons in Brand "L," "C" or "F"?
>> From: aerobiz1@gmail.com
>> To: frankroskind@hotmail.com
>>
>> Frank , this has been discussed at length. Many engine types use offset
>> piston pins or 'desaxed' bores. Harleys for example.
>> Try Googling either term.....
>>
>> Marty
>>
>
>
Message 2
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| Subject: | Re: Offset pistons in Brand "L," "C" or "F"? |
Barry, before lashing out like this and having people shot for sending
information, perhaps you should read up on Piston slap.
If it were an old wives tail, then no engine manufacturer would bother
to put an orientation in their manual, don't you think?
On 5/31/2013 3:09 PM, FLYaDIVE wrote:
> Marty:
>
> I do not know about Suzuki or Harley - But I do know about Lycoming
> and Continental - They DO NOT HAVE ANY PISTON OFFSET.
> I know of NO reason to have the wrist pin offset - It just does NOT
> make ANY sense at all. There are Front & Rear to some pistons but
> that is because of piston dome designs and valve clearances.
> Think of it this way: What CENTERS the piston in the center of the
> cylinder?
> THE RINGS!!!
> So, how or why would there be a wrist pin offset?
> If there was piston pin offset, then the rings would be offset also -
> And that would lead to uneven wear and loss of compression.
> Whomever started this Wives Tail should be SHOT with Dumb-Dumbs
> because it would match their intellect.. Always REMEMBER B.S. is
> spread at the speed of an electron on the internet.
>
>
> *Barry*
>
> *"Do you know why pilots think they are mechanics? Because they can
> but tools at Home Depot."*
>
>
> On Thu, May 30, 2013 at 9:45 PM, Martin Hone <aerobiz1@gmail.com
> <mailto:aerobiz1@gmail.com>> wrote:
>
> Hi Frank,
>
> There has been a lot of discussion on the Jabiru engine list on
> this subject. It started when someone couldn't work out which way
> the pistons should be fitted. Most engines have piston pin
> offset, mainly to reduce piston slap at TDC hence noise. Some
> racing types reverse it to try and get a little more torque, while
> others 'desax' the bore by offsetting the barrels/cylinders
> relative to the centreline of the crank, ie. moving the cylinders
> forward or backwards a few millimetres in the same plane, not
> rotating around the crank as in a v-twin or radial. In a
> motorcycle production racing class I was involved in, a guy got
> caught cheating by doing just this. He moved the entire cylinder
> bank on a Suzuki 1000cc four cylinder engine !
>
> Marty
>
>
> On Fri, May 31, 2013 at 11:31 AM, Frank Roskind
> <frankroskind@hotmail.com <mailto:frankroskind@hotmail.com>> wrote:
>
> Thanks for your response. I have googled offset piston with
> lycoming, continental and franklin, but found nothing relevant
> except a reference to the Franklin automobile having offset
> piston pins. After your message I also googled the same three
> with "desaxed" and found nothing relevant. It seems like a
> great idea, given all the fooling around with exhausts,
> intakes and ignition, it is kind of odd that I am not reading
> of anyone who took a shot at offsetting the pistons.
> Maybe I just found a great retirement occupation.
> ------------------------------------------------------------------------
> Date: Fri, 31 May 2013 06:58:04 +1000
> Subject: Re: Offset pistons in Brand "L," "C" or "F"?
> From: aerobiz1@gmail.com <mailto:aerobiz1@gmail.com>
> To: frankroskind@hotmail.com <mailto:frankroskind@hotmail.com>
>
> Frank , this has been discussed at length. Many engine types
> use offset piston pins or 'desaxed' bores. Harleys for example.
> Try Googling either term.....
>
> Marty
>
>
> *
>
>
> *
Message 3
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| Subject: | Re: Offset pistons in Brand "L," "C" or "F"? |
http://www.motorcycleproject.com/motorcycle/text/cows-offset.html
You might try this page for some insight into pin off set before you start
calling people names.
-----Original Message-----
From: FLYaDIVE <flyadive@gmail.com>
Sent: Fri, May 31, 2013 9:10 am
Subject: Re: JabiruEngine-List: Re: Offset pistons in Brand "L," "C" or "F"
?
Marty:
I do not know about Suzuki or Harley - But I do know about Lycoming and Con
tinental - They DO NOT HAVE ANY PISTON OFFSET.
I know of NO reason to have the wrist pin offset - It just does NOT make AN
Y sense at all. There are Front & Rear to some pistons but that is because
of piston dome designs and valve clearances.
Think of it this way: What CENTERS the piston in the center of the cylinde
r?
THE RINGS!!!
So, how or why would there be a wrist pin offset?
If there was piston pin offset, then the rings would be offset also - And t
hat would lead to uneven wear and loss of compression.
Whomever started this Wives Tail should be SHOT with Dumb-Dumbs because it
would match their intellect.. Always REMEMBER B.S. is spread at the speed
of an electron on the internet.
Barry
"Do you know why pilots think they are mechanics? Because they can but too
ls at Home Depot."
On Thu, May 30, 2013 at 9:45 PM, Martin Hone <aerobiz1@gmail.com> wrote:
Hi Frank,
There has been a lot of discussion on the Jabiru engine list on this subjec
t. It started when someone couldn't work out which way the pistons should b
e fitted. Most engines have piston pin offset, mainly to reduce piston sla
p at TDC hence noise. Some racing types reverse it to try and get a little
more torque, while others 'desax' the bore by offsetting the barrels/cylin
ders relative to the centreline of the crank, ie. moving the cylinders forw
ard or backwards a few millimetres in the same plane, not rotating around t
he crank as in a v-twin or radial. In a motorcycle production racing class
I was involved in, a guy got caught cheating by doing just this. He moved
the entire cylinder bank on a Suzuki 1000cc four cylinder engine !
Marty
On Fri, May 31, 2013 at 11:31 AM, Frank Roskind <frankroskind@hotmail.com>
wrote:
Thanks for your response. I have googled offset piston with lycoming, cont
inental and franklin, but found nothing relevant except a reference to the
Franklin automobile having offset piston pins. After your message I also g
oogled the same three with "desaxed" and found nothing relevant. It seems
like a great idea, given all the fooling around with exhausts, intakes and
ignition, it is kind of odd that I am not reading of anyone who took a shot
at offsetting the pistons.
Maybe I just found a great retirement occupation.
Subject: Re: Offset pistons in Brand "L," "C" or "F"?
From: aerobiz1@gmail.com
Frank , this has been discussed at length. Many engine types use offset pi
ston pins or 'desaxed' bores. Harleys for example.
Try Googling either term.....
Marty
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