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1.5 ohm coils are typically used with a ballast resistor to make the overall=
resistance about 3 ohms except when starting the engine. A total resistanc=
e of less than 3 ohms may damage an electronic distributor switching unit un=
less it is specifically designed for low resistance coils. =20
I think that some racing applications, particularly 8 cylinder engines may u=
se a lower resistance ballast, or none at all. But at low revs like 2500 on=
a 4-cly, the peak current is too high for points and the usual electronic d=
istributor. =20
-Tony
Sent from my iPhone
> On Sep 19, 2015, at 2:45 PM, Jason Sukey <jsukey@gmail.com> wrote:
>=20
> I don't have all the specs on me at the moment, but from memory, the "hott=
er" red coil has a primary resistance of about 1.5 ohm, and the "colder" coi=
l had a primary resistance of 3 or 3.5 ohm. My understanding is this is the=
typical situation where the lesser coil can't develop enough voltage at hig=
h rpm when the charge time is the shortest, thus needing the increased volta=
ge of the lower resistance coil.
> Jason
>=20
>> On Sep 19, 2015 2:35 PM, "Anthony Rhodes" <spamiam@comcast.net> wrote:
>> That is can interesting question of why one coil was failing at high RPM w=
hile the other didn't.
>>=20
>> Assuming both are in proper operating condition, then I would expect that=
the one that can't sustain high RPM has a lot more inductance than the one t=
hat worked ok
>>=20
>> As a matter of fact, the "high voltage" coils probably get that extra oom=
ph by having higher inductance. The price you pay for high inductance is th=
at it takes longer to "charge" the magnetic field of the coil. So, there is=
a steeper drop off of output voltage vs RPM.
>>=20
>> Do you have the specs on the two coils? Btw the resistance of the second=
ary windings also has an influence. So does the resistance of the primary w=
indings though I am assuming both are 3 ohm.
>>=20
>> -Tony
>>=20
>> Sent from my iPhone
>>=20
>> > On Sep 19, 2015, at 1:00 PM, triumphs-request@autox.team.net wrote:
>> >
>> > Message: 1
>> > Date: Fri, 18 Sep 2015 14:26:04 -0400
>> > From: Jason Sukey <jsukey@gmail.com>
>> > To: auprichard@uprichard.net, triumphs@autox.team.net
>> > Subject: Re: [TR] TR3 coil question
>> > Message-ID:
>> > <CAMmo4o-UUO+VMFaKgUCjZiOEQHs1zfsV6fArUq9C+eKQ8s-Mzw@mail.gmail.com>=
>> > Content-Type: text/plain; charset=3D"utf-8"
>> >
>> > Andrew,
>> > Not TR3 related, but I've had to play around with coils on my modifi=
ed
>> > GT6 using the 123 distributor (USB tune model). After a lot of fiddlin=
g, I
>> > found that with the recommended Bosch "blue" coil, it would "go flat" a=
t
>> > high rpms when I was accelerating hard. (this is compared to points di=
zzy
>> > with a hot coil).
>> > I ended up with the Bosch "red" coil (made in Brazil model, I'm told th=
e
>> > made in Mexico version is of lesser quality). This solved my problems a=
nd
>> > it once again is happy to pull strong up to 7,000 RPM's.
>> >
>> > My theory is that the lower voltage "Blue" coil is fine for stock
>> > applications, but isn't enough for higher performance use.
>> >
>> > Jason
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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>1.5 ohm coils are typically used with a=
ballast resistor to make the overall resistance about 3 ohms except when st=
arting the engine. A total resistance of less than 3 ohms may damage a=
n electronic distributor switching unit unless it is specifically designed f=
or low resistance coils. </div><div><br></div><div>I think that some r=
acing applications, particularly 8 cylinder engines may use a lower resistan=
ce ballast, or none at all. But at low revs like 2500 on a 4-cly, the p=
eak current is too high for points and the usual electronic distributor. &nb=
sp;</div><div><br></div><div>-Tony<br><br>Sent from my iPhone</div><div><br>=
On Sep 19, 2015, at 2:45 PM, Jason Sukey <<a href=3D"mailto:jsukey@gmail.=
com">jsukey@gmail.com</a>> wrote:<br><br></div><blockquote type=3D"cite">=
<div><p dir=3D"ltr">I don't have all the specs on me at the moment, but from=
memory, the "hotter" red coil has a primary resistance of about 1.5 ohm, an=
d the "colder" coil had a primary resistance of 3 or 3.5 ohm. My under=
standing is this is the typical situation where the lesser coil can't develo=
p enough voltage at high rpm when the charge time is the shortest, thus need=
ing the increased voltage of the lower resistance coil.<br>
Jason</p>
<div class=3D"gmail_quote">On Sep 19, 2015 2:35 PM, "Anthony Rhodes" <<a h=
ref=3D"mailto:spamiam@comcast.net";>spamiam@comcast.net</a>> wrote:<br typ=
e=3D"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8=
ex;border-left:1px #ccc solid;padding-left:1ex">That is can interesting ques=
tion of why one coil was failing at high RPM while the other didn't.<br>
<br>
Assuming both are in proper operating condition, then I would expect that th=
e one that can't sustain high RPM has a lot more inductance than the one tha=
t worked ok<br>
<br>
As a matter of fact, the "high voltage" coils probably get that extra oomph b=
y having higher inductance. The price you pay for high inductance is t=
hat it takes longer to "charge" the magnetic field of the coil. So, th=
ere is a steeper drop off of output voltage vs RPM.<br>
<br>
Do you have the specs on the two coils? Btw the resistance of the seco=
ndary windings also has an influence. So does the resistance of the pr=
imary windings though I am assuming both are 3 ohm.<br>
<br>
-Tony<br>
<br>
Sent from my iPhone<br>
<br>
> On Sep 19, 2015, at 1:00 PM, <a href=3D"mailto:triumphs-request@autox.t=
eam.net">triumphs-request@autox.team.net</a> wrote:<br>
><br>
> Message: 1<br>
> Date: Fri, 18 Sep 2015 14:26:04 -0400<br>
> From: Jason Sukey <<a href=3D"mailto:jsukey@gmail.com";>jsukey@gmail.=
com</a>><br>
> To: <a href=3D"mailto:auprichard@uprichard.net";>auprichard@uprichard.ne=
t</a>, <a href=3D"mailto:triumphs@autox.team.net";>triumphs@autox.team.net</a=
><br>
> Subject: Re: [TR] TR3 coil question<br>
> Message-ID:<br>
> <<a href=3D"mailto:CAMmo4o-UUO%2BVMFaKgUCjZiOEQHs1zfsV6=
fArUq9C%2BeKQ8s-Mzw@mail.gmail.com">CAMmo4o-UUO+VMFaKgUCjZiOEQHs1zfsV6fArUq9=
C+eKQ8s-Mzw@mail.gmail.com</a>><br>
> Content-Type: text/plain; charset=3D"utf-8"<br>
><br>
> Andrew,<br>
> Not TR3 related, but I've had to play around with coils on=
my modified<br>
> GT6 using the 123 distributor (USB tune model). After a lot of fi=
ddling, I<br>
> found that with the recommended Bosch "blue" coil, it would "go flat" a=
t<br>
> high rpms when I was accelerating hard. (this is compared to poin=
ts dizzy<br>
> with a hot coil).<br>
> I ended up with the Bosch "red" coil (made in Brazil model, I'm told th=
e<br>
> made in Mexico version is of lesser quality). This solved my prob=
lems and<br>
> it once again is happy to pull strong up to 7,000 RPM's.<br>
><br>
> My theory is that the lower voltage "Blue" coil is fine for stock<br>
> applications, but isn't enough for higher performance use.<br>
><br>
> Jason<br>
</blockquote></div>
</div></blockquote></body></html>=
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** triumphs@autox.team.net **
Archive: http://www.team.net/archive
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