Subject: Re: [TR] Electric Fans: Something Different

From: TERRY SMITH <[email-masked]>
Date: Tue, 11 Sep 2018 09:27:08 -0400 (EDT)

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So what exactly is the energy co-efficiency of heavy vs. light flywheel?  Heavy means more torque to take you up a steeper hill in higher gear, whereas light means less mass to move on acceleration so prompter speed?  Something like that?

Terry Smith, TR3A  TS 58667

New Hampshire

> On September 10, 2018 at 2:01 PM Rye Livingston <[email-masked]> wrote:
> 
>     For what it's worth, I switched to the 9lb alloy flywheel on my TR3.  I believe the stock one is 32 lbs.  I don't notice any difference getting started in 1st gear, and it does spin up nice and fast. 
> 
>     Rye
>     PH: 530-FIND-RYE
> 
>     On Sep 10, 2018, at 06:26 AM, John Macartney <[email-masked]> wrote:
> 
> 
>         > >         I think I'm correct in saying one of the reasons for the heavier flywheel is
> >         that the wet liner four engine was originally designed for the Standard
> >         Vanguard with a two speed (low and high) gearbox with overdrive and also the
> >         Ferguson tractor - both of which engines needed to develop shedloads of
> >         torque at very low engine speeds. In both instances, much heavier flywheels
> >         were required. Even if the early TR's could have got away with lighter
> >         units, that would have meant having two different units. In those early post
> >         WW2 days, iron and steel in the UK was in such short supply that having a
> >         'common' flywheel across the range made economic sense from a production
> >         cost viewpoint. Just an opinion
> > 
> >         Jonmac
> > 
> >         -----Original Message-----
> >         From: Triumphs <[email-masked]> On Behalf Of
> >         [email-masked] mailto:[email-masked]
> >         Sent: 23 July 2018 00:38
> >         To: 'TERRY SMITH' <[email-masked]>; Randall <[email-masked]>;
> >         Andrew Uprichard <[email-masked]>; George Haynes
> >         <[email-masked]>; [email-masked] mailto:[email-masked]
> >         Subject: Re: [TR] Electric Fans: Something Different
> > 
> >         I believe the TR2/3/4 was more or less "balanced" internally. The flywheel
> >         weighs about 3x what it needs to. I believe they used the flywheel to
> >         smooth it out.
> > 
> >         Jonas Payne
> >         PBR Consulting Services, LLC
> >         702.882.6711
> > 
> > 
> > 
> >         ** [email-masked] mailto:[email-masked] **
> > 
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<!DOCTYPE html>
<html><head>
    <meta charset=3D"UTF-8">
</head><body><p style=3D"font-size: 12pt; font-family: helvetica, arial, sa=
ns-serif; color: rgb(51, 51, 51);">So what exactly is the energy co-efficie=
ncy of heavy vs. light flywheel?&#160; Heavy means more torque to take you =
up a steeper hill in higher gear, whereas light means less mass to move on =
acceleration so prompter speed?&#160; Something like that?<br></p><p style=
=3D"font-size: 12pt; font-family: helvetica, arial, sans-serif; color: rgb(=
51, 51, 51);"><br></p><p style=3D"font-size: 12pt; font-family: helvetica, =
arial, sans-serif; color: rgb(51, 51, 51);">Terry Smith, TR3A&#160; TS 5866=
7<br></p><p style=3D"font-size: 12pt; font-family: helvetica, arial, sans-s=
erif; color: rgb(51, 51, 51);">New Hampshire<br></p><blockquote type=3D"cit=
e">On September 10, 2018 at 2:01 PM Rye Livingston &#60;[email-masked]&#62; w=
rote: <br> <br><div>For what it&#39;s worth, I switched to the 9lb alloy fl=
ywheel on my TR3. &#160;I believe the stock one is 32 lbs. &#160;I don&#39;=
t notice any difference getting started in 1st gear, and it does spin up ni=
ce and fast.&#160;</div><div><br></div><div class=3D"ox-46ae33b836-x-apple-=
signature">Rye <br>PH: 530-FIND-RYE</div><div><br>On Sep 10, 2018, at 06:26=
 AM, John Macartney &#60;[email-masked]&#62; wrote: <br> <br>=
</div><div><blockquote type=3D"cite"><div class=3D"ox-46ae33b836-msg-quote"=
><div class=3D"ox-46ae33b836-_stretch"><span class=3D"ox-46ae33b836-body-te=
xt-content">I think I&#39;m correct in saying one of the reasons for the he=
avier flywheel is<br>that the wet liner four engine was originally designed=
 for the Standard<br>Vanguard with a two speed (low and high) gearbox with =
overdrive and also the<br>Ferguson tractor - both of which engines needed t=
o develop shedloads of<br>torque at very low engine speeds. In both instanc=
es, much heavier flywheels<br>were required. Even if the early TR&#39;s cou=
ld have got away with lighter<br>units, that would have meant having two di=
fferent units. In those early post<br>WW2 days, iron and steel in the UK wa=
s in such short supply that having a<br>&#39;common&#39; flywheel across th=
e range made economic sense from a production<br>cost viewpoint. Just an op=
inion<br><br>Jonmac<br><br>-----Original Message-----<br>From: Triumphs &#6=
0;[email-masked]&#62; On Behalf Of<br><a href=3D"mailto:jp=
[email-masked]">[email-masked]</a><br>Sent: 23 July 2018 00:38<br>To: &=
#39;TERRY SMITH&#39; &#60;[email-masked]&#62;; Randall &#60;tr3driver@=
ca.rr.com&#62;;<br>Andrew Uprichard &#60;[email-masked]&#62;; Geo=
rge Haynes<br>&#60;[email-masked]&#62;; <a href=3D"mailto:triumphs@auto=
x.team.net">[email-masked]</a><br>Subject: Re: [TR] Electric Fans:=
 Something Different<br><br>I believe the TR2/3/4 was more or less &#34;bal=
anced&#34; internally. The flywheel<br>weighs about 3x what it needs to. I =
believe they used the flywheel to<br>smooth it out.<br><br>Jonas Payne<br>P=
BR Consulting Services, LLC<br>702.882.6711<br><br><br><br>** <a href=3D"ma=
ilto:[email-masked]">[email-masked]</a> **<br><br>Donate:=
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From: "Randall" <[email-masked]>
Date: Tue, 11 Sep 2018 12:14:12 -0400

> So what exactly is the energy co-efficiency of heavy vs. 
> light flywheel?  Heavy means more torque to take you up a 
> steeper hill in higher gear, whereas light means less mass to 
> move on acceleration so prompter speed?  Something like that?

Heavier means the engine has more resistance to sudden changes in speed (aka
inertia).  So you get less drop in rpm when you let the clutch out
(especially on a hill).  Acts like more torque, but isn't really since it
only applies to sudden changes in engine rpm.

But more inertia also limits how quickly the engine can spin up.  It takes
power to accelerate that heavy flywheel, so a lighter flywheel acts like
more power when accelerating (but again isn't really more power, just less
resistance).

A heavier flywheel also tends to damp out the vibration from each cylinder
firing, so the engine seems smoother.

-- Randall

---

From: "Randall" <[email-masked]>
Date: Wed, 12 Sep 2018 11:53:28 -0400

>  Is there a mathematical middle ground in terms of ounces that can be
removed to optimize all variables?

Not really.  As is usually the case with engineering, you have to strike a
balance between desirable but conflicting qualities.  The optimum balance
depends heavily on how much you value each quality.

All I can say is that, given the easy choice of remaining stock (already in
place), one of Joe's billet steel flywheels (already on the shelf, about 14
lbs IIRC), and the Fidanza alloy (about 9 lbs again IIRC,  hanging on the
back of another motor); I did not hesitate to move the Fidanza from the
wrecked 3A to my current TR3.  Even though I was in a hurry to get the car
back together for TRfest 2009.

YMMV

-- Randall

---

From: TERRY SMITH <[email-masked]>
Date: Wed, 12 Sep 2018 09:09:35 -0400 (EDT)

Hmmmm.  Interesting.  Thanks, Randall.  So I guess how much one takes off a flywheel depends on the effect desired.  More off gives faster acceleration but can make for finicky stalls and engine vibration.  None off means slower acceleration.  Is there a mathematical middle ground in terms of ounces that can be removed to optimize all variables?

> On September 11, 2018 at 12:14 PM Randall <[email-masked]> wrote:
> 
>