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Marcel,
Yes, if you increase rocker ratio and do not change the cam lift, the maxim=
um lift will also increase by 13%.
Richard
Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com
On Wednesday, February 12, 2020 van.mulders.marcel <van.mulders.marcel@tele=
net.be> wrote:
Richard,=C2=A0dare I answer this...Do you mean that, with the higher rocker=
ratio, the valve is moving faster in the first part of the opening phase a=
nd hence moving slower nearing the maximum lift? Suppose the cam lift of bo=
th camshafts is such that the maximum lift is 13mm for both the 1.65 and 1.=
50 ratio and duration at 0.050" is 240=C2=B0, thus the crank has to move 12=
0=C2=B0 to go from 0.050" lift to maximum lift in both cases. If the valve =
is opening 13% faster all the way from 0.050" lift untill maximum lift, the=
maximum lift will also be 13% higher! When an engine is at, say 5000rpm or=
any other speed, it takes the same time to move 120=C2=B0 (from 0.050" to =
maximum lift) : the rocker arm ratio does not change that and the valve tha=
t is opening 13% faster with the 1.65 ratio will end at a maximum lift that=
is also 13% higher.=C2=A0MarcelVan: "Richard Good" <goodparts@verizon.net>=
)
Aan: "Michael Zbarsky" <mzbarsky@yahoo.com>, gkbyrne@optusnet.com.au, "van =
mulders marcel" <van.mulders.marcel@telenet.be>
Cc: "fot" <fot@autox.team.net>
Verzonden: Woensdag 12 februari 2020 02:23:07
Onderwerp: Re: [Fot] Camshaft recommendation
=C2=A07.887
Michael,
People often seem to overlook the main performance benefit of increasing th=
e rocker ratio.=C2=A0 That is the increase in valve velocity.=C2=A0 The vel=
ocity of a flat tappet is limited by it's diameter. If you grind the cam lo=
be for too much velocity the contact patch will move out past the edge of t=
he lifter and things will self destruct.=C2=A0 So tappet velocity is limite=
d.=C2=A0 However, since tappet velocity times rocker ratio equals valve vel=
ocity, increasing the rocker ratio will increase valve velocity.
First decide what will be the optimum valve lift for your engine then divid=
e by rocker ratio to determine the net cam lift needed to achieve that valv=
e lift.=C2=A0 Yes, you can grind the cam with a large enough lobe to reach =
desired lift using stock rockers but you are limited in how fast you can op=
en the valve.=C2=A0 Now if you grind the cam with less lift then use 1.65:1=
rockers to reach that same desired valve lift you will be moving the valve=
about 13% faster. That means it will be open further in a given period of =
time.=C2=A0 Graph it out and you will see a big difference.=C2=A0 Valve vel=
ocity is a huge factor in performance.=C2=A0=20
I can understand why someone who has tried to use high ratio rockers with a=
cam that was already maxing out the valve lift with stock rockers would de=
cide that high ratio does not work.=C2=A0 Valve lift was already at max. In=
creasing it further may be a detriment.=C2=A0 If duration was also maxed ou=
t for reasonable torque then the increase in lift during the overlap period=
caused by the increase in rocker ratio may reduce the low end torque.=C2=
=A0 Properly applied with the right cam profile, high ratio rockers enable =
performance that is just not achievable with stock rockers.
Richard Good
Good Parts Inc
Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com
On Tuesday, February 11, 2020 Michael Zbarsky via Fot <mzbarsky@yahoo.com> =
wrote:
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
=C2=A06K. I=E2=80=99d also like to keep the 1.65 setup rather than invest i=
n a 1.55 so keep the intel and=C2=A0suggestions coming. The GP3 is a defini=
te contender.=C2=A0
Mike=C2=A0
On Monday, February 10, 2020, 4:07 PM, Geoff Byrne <gkbyrne@optusnet.com.au=
> wrote:
Ditch the 1.65 rockers no good for racingGeoff ByrneTR6 racer down under
Sent from my iPhone
On 11 Feb 2020, at 12:52 am, van.mulders.marcel--- via Fot <fot@autox.team.=
net> wrote:
I also once bought a Goodparts 1.65 rocker roller assembly for a TR6 engine=
, but in the end I had to use a 1.55 roller rocker assembly, also from Good=
parts, because, with the 1.65, it is difficult to find a race camshaft with=
a=C2=A0 lobe lift that is low enough. With lobes of 8mm or higher, I could=
not find valve springs to cope with the high valve lift. I bought a G5 cam=
shaft from Schneider, they call it=C2=A0 the 320-F grind (duration is 268=
=C2=B0 at 0.050", timing is 57-83=C2=A0 =C2=A0 87-53 , installation figure =
is then 103=C2=B0 :is that the same as the G5 grind?) with 0.340"/8.6mm cam=
lift and that makes for a=C2=A0 valve lift of 12.9mm with the 1.55 rocker =
arms. With 1.65 rockers , valve lift would be 14.2mm and I could not find v=
alve springs for that lift. The valve springs I used are part no 281003-063=
.20 from Summit (Isky), 320lb/inch spring rate. They recommend 0.45"/11.43m=
m=C2=A0 (1.250" - 0.800"from closed to full open position, so it is about 1=
.4mm more in my engine, but there is no problem concerning=C2=A0 coil bindi=
ng : the installed height is a 1mm more than 1.250 , the pressure in closed=
position is lower=C2=A0 of course, but still 34kgs (105kgs at full lift) a=
n that seems to be enough till 7500 rpmRacetorations have a race cam with 7=
.6mm cam lift, probably that would work with 1.65 rocker arms. I still have=
the 1.65 rocker assembly, it is new and it could work with a road cam or a=
ny camshaft with a maximum of 8mm cam lift.Marcel
Van: "fot" <fot@autox.team.net>
Aan: "fot" <fot@autox.team.net>
Verzonden: Maandag 10 februari 2020 02:34:27
Onderwerp: [Fot] Camshaft recommendation
Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.65 ratio=
roller rockers from Goodparts. Any recommendations for a suitable camshaft=
? I will be putting in cam bearings.=C2=A0
Thanks, Mike
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
arcel@telenet.be
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
home.com.au
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
izon.net
------=_Part_1418617_319219693.1581524710562
Content-Transfer-Encoding: quoted-printable
<p dir=3D"ltr">Marcel,</p>
<p dir=3D"ltr">Yes, if you increase rocker ratio and do not change the cam =
lift, the maximum lift will also increase by 13%.</p>
<p dir=3D"ltr">Richard</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br>
Get the new AOL app: mail.mobile.aol.com</p>
</br></br><div class=3D"device_aol_et_org_dt_dd_quote"></div><hr style=3D"b=
order:0;height:1px;color:#999;background-color:#999;width:100%;margin:0 0 9=
px 0;padding:0;"></hr><span style=3D"font-size:14px; color:#999999;">On Wed=
nesday, February 12, 2020 van.mulders.marcel <<span style=3D"color:#000=
0A0">van.mulders.marcel@telenet.be</span>> wrote:</span><br></br><div i=
d=3D"yiv9741220511"><html><div><div style=3D"font-family:Verdana, Arial, He=
lvetica, sans-serif;font-size:10pt;color:#000000;"><div>Richard,=C2=A0</div=
><div>dare I answer this...</div><div>Do you mean that, with the higher roc=
ker ratio, the valve is moving faster in the first part of the opening phas=
e and hence moving slower nearing the maximum lift? Suppose the cam lift of=
both camshafts is such that the maximum lift is 13mm for both the 1.65 and=
1.50 ratio and duration at 0.050" is 240=C2=B0, thus the crank has to=
move 120=C2=B0 to go from 0.050" lift to maximum lift in both cases. =
If the valve is opening 13% faster all the way from 0.050" lift untill=
maximum lift, the maximum lift will also be 13% higher! When an engine is =
at, say 5000rpm or any other speed, it takes the same time to move 120=C2=
=B0 (from 0.050" to maximum lift) : the rocker arm ratio does not chan=
ge that and the valve that is opening 13% faster with the 1.65 ratio will e=
nd at a maximum lift that is also 13% higher.=C2=A0</div><div>Marcel</div><=
hr id=3D"yiv9741220511zwchr"><div><b>Van: </b>"Richard Good" <=
goodparts@verizon.net>)<br clear=3D"none"><b>Aan: </b>"Michael Zbar=
sky" <mzbarsky@yahoo.com>, gkbyrne@optusnet.com.au, "van mu=
lders marcel" <van.mulders.marcel@telenet.be><div class=3D"yiv97=
41220511yqt0090589858" id=3D"yiv9741220511yqtfd74605"><br clear=3D"none"><b=
>Cc: </b>"fot" <fot@autox.team.net><br clear=3D"none"><b>Ve=
rzonden: </b>Woensdag 12 februari 2020 02:23:07<br clear=3D"none"><b>Onderw=
erp: </b>Re: [Fot] Camshaft recommendation<br clear=3D"none"></div></div><d=
iv class=3D"yiv9741220511yqt0090589858" id=3D"yiv9741220511yqtfd30775"><div=
>=C2=A07.887</div><div><p dir=3D"ltr">Michael,</p>
<p dir=3D"ltr">People often seem to overlook the main performance benefit o=
f increasing the rocker ratio.=C2=A0 That is the increase in valve velocity=
.=C2=A0 The velocity of a flat tappet is limited by it's diameter. If y=
ou grind the cam lobe for too much velocity the contact patch will move out=
past the edge of the lifter and things will self destruct.=C2=A0 So tappet=
velocity is limited.=C2=A0 However, since tappet velocity times rocker rat=
io equals valve velocity, increasing the rocker ratio will increase valve v=
elocity.</p>
<p dir=3D"ltr">First decide what will be the optimum valve lift for your en=
gine then divide by rocker ratio to determine the net cam lift needed to ac=
hieve that valve lift.=C2=A0 Yes, you can grind the cam with a large enough=
lobe to reach desired lift using stock rockers but you are limited in how =
fast you can open the valve.=C2=A0 Now if you grind the cam with less lift =
then use 1.65:1 rockers to reach that same desired valve lift you will be m=
oving the valve about 13% faster. That means it will be open further in a g=
iven period of time.=C2=A0 Graph it out and you will see a big difference.=
=C2=A0 Valve velocity is a huge factor in performance.=C2=A0 </p>
<p dir=3D"ltr">I can understand why someone who has tried to use high ratio=
rockers with a cam that was already maxing out the valve lift with stock r=
ockers would decide that high ratio does not work.=C2=A0 Valve lift was alr=
eady at max. Increasing it further may be a detriment.=C2=A0 If duration wa=
s also maxed out for reasonable torque then the increase in lift during the=
overlap period caused by the increase in rocker ratio may reduce the low e=
nd torque.=C2=A0 Properly applied with the right cam profile, high ratio ro=
ckers enable performance that is just not achievable with stock rockers.</p=
>
<p dir=3D"ltr">Richard Good<br clear=3D"none">
Good Parts Inc</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br clear=3D"none">
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"yiv9741220511device_aol_et_org_dt_dd_quote"></div><hr style=
=3D"border:0;min-height:1px;color:#999;background-color:#999;width:100%;mar=
gin:0 0 9px 0;padding:0;"><span style=3D"font-size:14px;color:#999999;">On =
Tuesday, February 11, 2020 Michael Zbarsky via Fot <<span style=3D"color=
:#0000a0;">mzbarsky@yahoo.com</span>> wrote:</span><br clear=3D"none"><d=
iv id=3D"yiv9741220511"></div><div>
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
=C2=A06K. I=E2=80=99d also like to keep the 1.65 setup rather than invest i=
n a 1.55 so keep the intel and=C2=A0suggestions coming. The GP3 is a defini=
te contender.=C2=A0<div><br clear=3D"none"></div><div>Mike=C2=A0<br clear=
=3D"none"><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><div cla=
ss=3D"yiv9741220511yqt2182859488" id=3D"yiv9741220511yqt21880"><p class=3D"=
yiv9741220511yahoo-quoted-begin" style=3D"font-size:15px;color:#715ffa;padd=
ing-top:15px;margin-top:0;">On Monday, February 10, 2020, 4:07 PM, Geoff By=
rne <gkbyrne@optusnet.com.au> wrote:</p><blockquote class=3D"yiv97412=
20511iosymail"><div id=3D"yiv9741220511"><div>Ditch the 1.65 rockers no goo=
d for racing<div>Geoff Byrne</div><div>TR6 racer down under<br clear=3D"non=
e"><br clear=3D"none"><div dir=3D"ltr">Sent from my iPhone</div><div dir=3D=
"ltr"><br clear=3D"none"><blockquote>On 11 Feb 2020, at 12:52 am, van.mulde=
rs.marcel--- via Fot <fot@autox.team.net> wrote:<br clear=3D"none"><b=
r clear=3D"none"></blockquote></div><blockquote><div dir=3D"ltr"><div style=
=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-serif;font-size:10=
pt;color:#000000;"><div>I also once bought a Goodparts 1.65 rocker roller a=
ssembly for a TR6 engine, but in the end I had to use a 1.55 roller rocker =
assembly, also from Goodparts, because, with the 1.65, it is difficult to f=
ind a race camshaft with a=C2=A0 lobe lift that is low enough. With lobes o=
f 8mm or higher, I could not find valve springs to cope with the high valve=
lift. I bought a G5 camshaft from Schneider, they call it=C2=A0 the 320-F =
grind (duration is 268=C2=B0 at 0.050", timing is 57-83=C2=A0 =C2=A0 8=
7-53 , installation figure is then 103=C2=B0 :is that the same as the G5 gr=
ind?) with 0.340"/8.6mm cam lift and that makes for a=C2=A0 valve lift=
of 12.9mm with the 1.55 rocker arms. With 1.65 rockers , valve lift would =
be 14.2mm and I could not find valve springs for that lift. The valve sprin=
gs I used are part no 281003-063.20 from Summit (Isky), 320lb/inch spring r=
ate. They recommend 0.45"/11.43mm=C2=A0 (1.250" - 0.800"from=
closed to full open position, so it is about 1.4mm more in my engine, but =
there is no problem concerning=C2=A0 coil binding : the installed height is=
a 1mm more than 1.250 , the pressure in closed position is lower=C2=A0 of =
course, but still 34kgs (105kgs at full lift) an that seems to be enough ti=
ll 7500 rpm</div><div>Racetorations have a race cam with 7.6mm cam lift, pr=
obably that would work with 1.65 rocker arms. I still have the 1.65 rocker =
assembly, it is new and it could work with a road cam or any camshaft with =
a maximum of 8mm cam lift.</div><div>Marcel</div><div><br clear=3D"none"></=
div><hr id=3D"yiv9741220511zwchr"><div><b>Van: </b>"fot" <fot@=
autox.team.net><br clear=3D"none"><b>Aan: </b>"fot" <fot@au=
tox.team.net><br clear=3D"none"><b>Verzonden: </b>Maandag 10 februari 20=
20 02:34:27<br clear=3D"none"><b>Onderwerp: </b>[Fot] Camshaft recommendati=
on<br clear=3D"none"></div><div><br clear=3D"none"></div><div>
Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.65 ratio=
roller rockers from Goodparts. Any recommendations for a suitable camshaft=
? I will be putting in cam bearings.=C2=A0<div><br clear=3D"none"><div>Than=
ks, Mike<br clear=3D"none"><br clear=3D"none"><br clear=3D"none"></div></di=
v>
<br clear=3D"none">_______________________________________________<br clear=
=3D"none">fot@autox.team.net<br clear=3D"none"><br clear=3D"none">http://ww=
w.fot-racing.com<br clear=3D"none"><br clear=3D"none">Donate: http://www.te=
am.net/donate.html<br clear=3D"none">Archive: http://autox.team.net/archive=
http://www.team.net/pipermail/fot<br clear=3D"none">Unsubscribe/Manage: ht=
tp://autox.team.net/mailman/options/fot/van.mulders.marcel@telenet.be<div c=
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r=3D"none"></div></div></div><div class=3D"yiv9741220511yqt5723059911" id=
=3D"yiv9741220511yqtfd38997">______________________________________________=
_<br clear=3D"none">fot@autox.team.net<br clear=3D"none"><br clear=3D"none"=
>http://www.fot-racing.com<br clear=3D"none"><br clear=3D"none">Donate: htt=
p://www.team.net/donate.html<br clear=3D"none">Archive: http://autox.team.n=
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lockquote></div></div></div><blockquote></blockquote></blockquote></div></d=
iv>
</div><div class=3D"yiv9741220511yqt2182859488" id=3D"yiv9741220511yqt54816=
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http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
--===============3550129795550633399==--
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