--===============1745200097140871837==
Content-Transfer-Encoding: 7bit
--Apple-Mail-4372FEC4-1EE4-4F9A-9A74-F2CA053A367C
charset=utf-8
Content-Transfer-Encoding: quoted-printable
Sent from my iPhone
> On Aug 24, 2020, at 9:13 PM, Peter Vucinic via Fot <fot@autox.team.net> wr=
ote:
>=20
> =EF=BB=BF
> Hi Tim,
> Good explanation. And 100% right on the effects of the flywheel weight. No=
t to discount the pulley at the front of the crank and its effect also.
> =20
> What you are feeling at around the 5200 mark is the 2nd harmonic of the cr=
ankshafts natural frequency. The 2nd harmonic is usually the most destructiv=
e harmonic and this is the crankshaft bending the most during rotation. Usua=
lly, but not always around the mid distance crank. But can be around the 2nd=
crank journal in the 4 Cyl engine. You will see that a lot of people will f=
it billet, machined, large main bearing cap around mid-crank length as they h=
ave had issues with either bearing =E2=80=98wipe=E2=80=99 of broken cap bolt=
s. They are trying to counteract the 2nd harmonic by making the bearing jour=
nal stiffer.
> =20
> You don=E2=80=99t need to complete a complex calculation to understand wha=
t RPM=E2=80=99s you should minimise holding your duration at. The crank is s=
uspended and =E2=80=98struck=E2=80=99 and the natural frequency that the cra=
nk vibrates/resonates at will give you it=E2=80=99s harmonic characteristics=
. Just like a tuning fork. This is the basis for setting your RPM=E2=80=99s a=
nd multiples of that RPM to stay away from. OR you need to reduce the effect=
at those RPM=E2=80=99s. Say, using a harmonic balancer design to reduce the=
harmonic effect at certain RPM=E2=80=99s.
> =20
> Just as Joe Alexander describes, the first harmonic is in the 2800 RPM ran=
ge, but it is the least destructive so you almost miss feeling it.
> =20
> Hope that helps?
> Have a great day
> =20
> =20
> "You can Make a Small Fortune =46rom Motor Racing. As long as You Started W=
ith A Lage Fortune!"
> Kind Regards
> Peter Vucinic
> TR4 - TR7 V8 - Spitfire MkII
> _______________________________________________
> fot@autox.team.net
> =20
> http://www.fot-racing.com
> =20
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> =20
> =20
> =20
> =20
> From: Fot [mailto:fot-bounces@autox.team.net] On Behalf Of timmmurphh--- v=
ia Fot
> Sent: Friday, 22 May 2020 9:08 AM
> To: fot@autox.team.net
> Subject: [Fot] FW: Flywheel wt & crank harmonics -TR3/4
> =20
> =20
> =20
> From: timmmurphh@gmail.com <timmmurphh@gmail.com>=20
> Sent: Thursday, May 21, 2020 6:06 PM
> To: 'TeriAnn J. Wakeman' <tjwakeman@gmail.com>
> Subject: RE: [Fot] Flywheel wt & crank harmonics -TR3/4
> =20
> The weight of the flywheel will definitely affect the harmonic frequency. =
The heavier the flywheel, the lower the harmonic frequency will be. The fl=
ywheel contributes a significant amount to the total rotating inertia due to=
its weight and that the weight is at greater radius than the other rotating=
masses. Inertia increases as the square of the radius. It is not a linear=
function of the radius.
> =20
> An RPM of 5200 was mentioned as the harmonic resonance. I had always hear=
d that it was more like 6300 RPM. I have never seen a calculation for it. I=
t would be complex. Note that lighter pistons and connecting rods would ten=
d to lower the harmonic frequency as they would reduce the inertia in the en=
gine.
> =20
> Tim Murphy
> =20
> From: Fot <fot-bounces@autox.team.net> On Behalf Of TeriAnn J. Wakeman via=
Fot
> Sent: Thursday, May 21, 2020 2:44 PM
> To: FOT <fot@autox.team.net>
> Subject: [Fot] Flywheel wt & crank harmonics -TR3/4
> =20
> Something I have wondered about for years.
>=20
> Does the weight of the flywheel affect the RPM and intensity of harmonics i=
nherent in a TR3/4 stock crank? I've never found an answer to that question.=
>=20
> TeriAnn
>=20
> _______________________________________________
> fot@autox.team.net
>=20
> http://www.fot-racing.com
>=20
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
> Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/vfracing@aol=
.com
>=20
>=20
--Apple-Mail-4372FEC4-1EE4-4F9A-9A74-F2CA053A367C
charset=utf-8
Content-Transfer-Encoding: quoted-printable
<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><br><br><div dir=3D"ltr">Sent from my iPhon=
e</div><div dir=3D"ltr"><br><blockquote type=3D"cite">On Aug 24, 2020, at 9:=
13 PM, Peter Vucinic via Fot <fot@autox.team.net> wrote:<br><br></bloc=
kquote></div><blockquote type=3D"cite"><div dir=3D"ltr">=EF=BB=BF<meta http-=
equiv=3D"Content-Type" content=3D"text/html; charset=3Dutf-8"><meta name=3D"=
Generator" content=3D"Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
@font-face
{font-family:"Adobe Garamond";
panose-1:0 0 0 0 0 0 0 0 0 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext=3D"edit">
<o:idmap v:ext=3D"edit" data=3D"1" />
</o:shapelayout></xml><![endif]--><div class=3D"WordSection1"><p class=3D"Ms=
oNormal"><span style=3D"font-size:14.0pt;color:#1F497D">Hi Tim,<o:p></o:p></=
span></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#1F497=
D">Good explanation. And 100% right on the effects of the flywheel weight. N=
ot to discount the pulley at the front of the crank and its effect also.<o:p=
></o:p></span></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;col=
or:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal"><span style=3D=
"font-size:14.0pt;color:#1F497D">What you are feeling at around the 5200 mar=
k is the 2<sup>nd</sup> harmonic of the crankshafts natural frequency. The 2=
<sup>nd</sup> harmonic is usually the most destructive harmonic and this is t=
he crankshaft bending the most during rotation. Usually, but not always arou=
nd the mid distance crank. But can be around the 2<sup>nd</sup> crank journa=
l in the 4 Cyl engine. You will see that a lot of people will fit billet, ma=
chined, large main bearing cap around mid-crank length as they have had issu=
es with either bearing =E2=80=98wipe=E2=80=99 of broken cap bolts. They are t=
rying to counteract the 2<sup>nd</sup> harmonic by making the bearing journa=
l stiffer. <o:p></o:p></span></p><p class=3D"MsoNormal"><span style=3D"font-=
size:14.0pt;color:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal=
"><span style=3D"font-size:14.0pt;color:#1F497D">You don=E2=80=99t need to c=
omplete a complex calculation to understand what RPM=E2=80=99s you should mi=
nimise holding your duration at. The crank is suspended and =E2=80=98struck=E2=
=80=99 and the natural frequency that the crank vibrates/resonates at will g=
ive you it=E2=80=99s harmonic characteristics. Just like a tuning fork. This=
is the basis for setting your RPM=E2=80=99s and multiples of that RPM to st=
ay away from. OR you need to reduce the effect at those RPM=E2=80=99s. Say, u=
sing a harmonic balancer design to reduce the harmonic effect at certain RPM=
=E2=80=99s.<o:p></o:p></span></p><p class=3D"MsoNormal"><span style=3D"font-=
size:14.0pt;color:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal=
"><span style=3D"font-size:14.0pt;color:#1F497D">Just as Joe Alexander descr=
ibes, the first harmonic is in the 2800 RPM range, but it is the least destr=
uctive so you almost miss feeling it.<o:p></o:p></span></p><p class=3D"MsoNo=
rmal"><span style=3D"font-size:14.0pt;color:#1F497D"><o:p> </o:p></span=
></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#1F497D">H=
ope that helps?<o:p></o:p></span></p><p class=3D"MsoNormal"><span style=3D"f=
ont-size:14.0pt;color:#1F497D">Have a great day<o:p></o:p></span></p><p clas=
s=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#1F497D"><o:p> </=
o:p></span></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:=
#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal"><b><span lang=3D=
"EN-US" style=3D"color:#7030A0">"You can Make a Small Fortune =46rom Motor R=
acing. As long as You Started With A Lage Fortune!"<o:p></o:p></span></b></p=
><p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"color:#1F497D">Kind Re=
gards<o:p></o:p></span></p><p class=3D"MsoNormal"><span lang=3D"EN-US" style=
=3D"color:#1F497D">Peter Vucinic<o:p></o:p></span></p><p class=3D"MsoNormal"=
><span lang=3D"EN-US" style=3D"color:#1F497D">TR4 - TR7 V8 - Spitfire MkII<o=
:p></o:p></span></p><p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"col=
or:#1F497D">_______________________________________________<o:p></o:p></span=
></p><p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;f=
ont-family:Consolas;color:#1F497D"><a href=3D"mailto:fot@autox.team.net";><sp=
an style=3D"color:blue">fot@autox.team.net</span></a><o:p></o:p></span></p><=
p class=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-fa=
mily:Consolas;color:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNorm=
al"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Consolas;colo=
r:#1F497D"><a href=3D"http://www.fot-racing.com/";><span style=3D"color:blue"=
>http://www.fot-racing.com</span></a><o:p></o:p></span></p><p class=3D"MsoNo=
rmal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Consolas;co=
lor:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal"><span lang=3D=
"EN-US" style=3D"font-size:10.5pt;font-family:Consolas;color:#1F497D">Donate=
: <a href=3D"http://www.team.net/donate.html";><span style=3D"color:blue">htt=
p://www.team.net/donate.html</span></a><o:p></o:p></span></p><p class=3D"Mso=
Normal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-family:Consolas;=
color:#1F497D">Archive: <a href=3D"http://www.team.net/archive";><span style=3D=
"color:blue">http://www.team.net/archive</span></a><o:p></o:p></span></p><p c=
lass=3D"MsoNormal"><span lang=3D"EN-US" style=3D"font-size:10.5pt;font-famil=
y:Consolas;color:#1F497D">Forums: <a href=3D"http://www.team.net/forums";><sp=
an style=3D"color:blue">http://www.team.net/forums</span></a><o:p></o:p></sp=
an></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#1F497D"=
><o:p> </o:p></span></p><p class=3D"MsoNormal"><span style=3D"font-size=
:14.0pt;color:#1F497D"><o:p> </o:p></span></p><p class=3D"MsoNormal"><s=
pan style=3D"font-size:14.0pt;color:#1F497D"> <o:p></o:p></span></p><p class=
=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#1F497D"> <o:p></o=
:p></span></p><p class=3D"MsoNormal"><span style=3D"font-size:14.0pt;color:#=
1F497D"><o:p> </o:p></span></p><div><div style=3D"border:none;border-to=
p:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class=3D"MsoNormal" styl=
e=3D"margin-left:36.0pt"><b><span lang=3D"EN-US" style=3D"font-size:10.0pt;f=
ont-family:"Tahoma","sans-serif"">From:</span></b><span l=
ang=3D"EN-US" style=3D"font-size:10.0pt;font-family:"Tahoma","=
;sans-serif""> Fot [mailto:fot-bounces@autox.team.net] <b>On Behalf Of <=
/b>timmmurphh--- via Fot<br><b>Sent:</b> Friday, 22 May 2020 9:08 AM<br><b>T=
o:</b> fot@autox.team.net<br><b>Subject:</b> [Fot] FW: Flywheel wt & cra=
nk harmonics -TR3/4<o:p></o:p></span></p></div></div><p class=3D"MsoNormal" s=
tyle=3D"margin-left:36.0pt"><o:p> </o:p></p><p class=3D"MsoNormal" styl=
e=3D"margin-left:36.0pt"><span lang=3D"EN-US"><o:p> </o:p></span></p><p=
class=3D"MsoNormal" style=3D"margin-left:36.0pt"><span lang=3D"EN-US"><o:p>=
</o:p></span></p><div><div style=3D"border:none;border-top:solid #E1E1=
E1 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class=3D"MsoNormal" style=3D"margin-l=
eft:36.0pt"><b><span lang=3D"EN-US">From:</span></b><span lang=3D"EN-US"> ti=
mmmurphh@gmail.com <timmmurphh@gmail.com> <br><b>Sent:</b> Thursday, M=
ay 21, 2020 6:06 PM<br><b>To:</b> 'TeriAnn J. Wakeman' <tjwakeman@gmail.c=
om><br><b>Subject:</b> RE: [Fot] Flywheel wt & crank harmonics -TR3/4=
<o:p></o:p></span></p></div></div><p class=3D"MsoNormal" style=3D"margin-lef=
t:36.0pt"><span lang=3D"EN-US"><o:p> </o:p></span></p><p class=3D"MsoNo=
rmal" style=3D"margin-left:36.0pt"><span lang=3D"EN-US">The weight of the fl=
ywheel will definitely affect the harmonic frequency. The heavier the f=
lywheel, the lower the harmonic frequency will be. The flywheel contri=
butes a significant amount to the total rotating inertia due to its weight a=
nd that the weight is at greater radius than the other rotating masses. =
; Inertia increases as the square of the radius. It is not a linear fu=
nction of the radius.<o:p></o:p></span></p><p class=3D"MsoNormal" style=3D"m=
argin-left:36.0pt"><span lang=3D"EN-US"><o:p> </o:p></span></p><p class=
=3D"MsoNormal" style=3D"margin-left:36.0pt"><span lang=3D"EN-US">An RPM of 5=
200 was mentioned as the harmonic resonance. I had always heard that i=
t was more like 6300 RPM. I have never seen a calculation for it. =
; It would be complex. Note that lighter pistons and connecting rods w=
ould tend to lower the harmonic frequency as they would reduce the inertia i=
n the engine.<o:p></o:p></span></p><p class=3D"MsoNormal" style=3D"margin-le=
ft:36.0pt"><span lang=3D"EN-US"><o:p> </o:p></span></p><p class=3D"MsoN=
ormal" style=3D"margin-left:36.0pt"><span lang=3D"EN-US">Tim Murphy<o:p></o:=
p></span></p><p class=3D"MsoNormal" style=3D"margin-left:36.0pt"><span lang=3D=
"EN-US"><o:p> </o:p></span></p><div><div style=3D"border:none;border-to=
p:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class=3D"MsoNormal" styl=
e=3D"margin-left:36.0pt"><b><span lang=3D"EN-US">From:</span></b><span lang=3D=
"EN-US"> Fot <<a href=3D"mailto:fot-bounces@autox.team.net";>fot-bounces@a=
utox.team.net</a>> <b>On Behalf Of </b>TeriAnn J. Wakeman via Fot<br><b>S=
ent:</b> Thursday, May 21, 2020 2:44 PM<br><b>To:</b> FOT <<a href=3D"mai=
lto:fot@autox.team.net">fot@autox.team.net</a>><br><b>Subject:</b> [Fot] =
Flywheel wt & crank harmonics -TR3/4<o:p></o:p></span></p></div></div><p=
class=3D"MsoNormal" style=3D"margin-left:36.0pt"><span lang=3D"EN-US"><o:p>=
</o:p></span></p><p style=3D"margin-left:36.0pt"><span lang=3D"EN-US" s=
tyle=3D"font-size:13.5pt;font-family:"Adobe Garamond","serif&=
quot;">Something I have wondered about for years.</span><span lang=3D"EN-US"=
><o:p></o:p></span></p><p style=3D"margin-left:36.0pt"><span lang=3D"EN-US" s=
tyle=3D"font-size:13.5pt;font-family:"Adobe Garamond","serif&=
quot;">Does the weight of the flywheel affect the RPM and intensity of harmo=
nics inherent in a TR3/4 stock crank? I've never found an answer to that que=
stion.</span><span lang=3D"EN-US"><o:p></o:p></span></p><p style=3D"margin-l=
eft:36.0pt"><span lang=3D"EN-US" style=3D"font-size:13.5pt;font-family:"=
;Adobe Garamond","serif"">TeriAnn</span><span lang=3D"EN-US">=
<o:p></o:p></span></p></div><span>__________________________________________=
_____</span><br><span>fot@autox.team.net</span><br><span></span><br><span>ht=
tp://www.fot-racing.com</span><br><span></span><br><span>Donate: http://www.=
team.net/donate.html</span><br><span>Archive: http://autox.team.net/archive h=
ttp://www.team.net/pipermail/fot</span><br><span>Unsubscribe/Manage: http://=
autox.team.net/mailman/options/fot/vfracing@aol.com</span><br><span></span><=
br><span></span><br></div></blockquote></body></html>=
--Apple-Mail-4372FEC4-1EE4-4F9A-9A74-F2CA053A367C--
--===============1745200097140871837==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
--===============1745200097140871837==--
|