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Hi Ian,
Thanks for responding. I am not going to another piston manufacturer; the
older AE pistons are excellent quality and have a good reputation. You
can't judge the quality of castings and machining from an illustration, and
half the time what is illustrated is not exactly what is sold anyhow. Omega
pistons are also excellent and I have fitted them to classic BSA and
Velocette motorcycles when I was doing a complete balance, Carrillo rods,
bench flowing the head; the whole nine yards. However, with the Healey,
unless you are building a performance engine, I do not see the need for
forged pistons. That said, if I did not have the AE pistons, then I would
have gone with the Omegas.
I would still like to hear about the purpose/wisdom behind the change in
piston design that led to the introduction of the 5th ring. They would not
have spent the extra money to switch up the machining if there was not a
good reason.
From: Healeys <healeys-bounces@autox.team.net> On Behalf Of Ian Hey via
Healeys
Sent: April 16, 2021 2:09 PM
To: healeys@autox.team.net
Subject: [Healeys] To fit or not to fit
In a recent engine rebuild of a standard BJ7 engine which was fitted with
four ring pistons, when I looked at replacement pistons they were pictured
with five rings, which did not seem good to me.
I fitted Omega pistons from Denis Welch. These have three rings with a
total width of 3.2mm compared with 9.8mm for the four rings. (For the oil
rings only the width contacting the cylinder bore is measured)
Since friction is in proportion to ring width (possibly due to the lower
pressure required to make thinner rings seat against the cylinder wall) this
represents a reduction in losses to heat and a power increase (small).
Another, much more expensive, option for consideration. I also have no
doubts about the quality of the pistons, whereas I am not sure about the
four or five ringed replacements. They seem very cheap to me.
Ian
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link=3D"#0563C1" vlink=3D"#954F72" style=3D'word-wrap:break-word'><div =
class=3DWordSection1><p class=3DMsoNormal>Hi Ian,<o:p></o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>Thanks for =
responding. I am not going to another piston manufacturer; the =
older AE pistons are excellent quality and have a good reputation. =
You can’t judge the quality of castings and machining from an =
illustration, and half the time what is illustrated is not exactly what =
is sold anyhow. Omega pistons are also excellent and I have fitted =
them to classic BSA and Velocette motorcycles when I was doing a =
complete balance, Carrillo rods, bench flowing the head; the whole =
nine yards. However, with the Healey, unless you are building a =
performance engine, I do not see the need for forged pistons. That =
said, if I did not have the AE pistons, then I would have gone with the =
Omegas.<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p =
class=3DMsoNormal>I would still like to hear about the purpose/wisdom =
behind the change in piston design that led to the introduction of the =
5<sup>th</sup> ring. They would not have spent the extra money to =
switch up the machining if there was not a good =
reason.<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p =
class=3DMsoNormal><o:p> </o:p></p><div><div =
style=3D'border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm =
0cm 0cm'><p class=3DMsoNormal><b><span lang=3DEN-US =
style=3D'mso-fareast-language:EN-CA'>From:</span></b><span lang=3DEN-US =
style=3D'mso-fareast-language:EN-CA'> Healeys =
<healeys-bounces@autox.team.net> <b>On Behalf Of </b>Ian Hey via =
Healeys<br><b>Sent:</b> April 16, 2021 2:09 PM<br><b>To:</b> =
healeys@autox.team.net<br><b>Subject:</b> [Healeys] To fit or not to =
fit<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal><span =
lang=3DEN-GB>In a recent engine rebuild of a standard BJ7 engine which =
was fitted with four ring pistons, when I looked at replacement pistons =
they were pictured with five rings, which did not seem good to =
me.<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB>I fitted Omega pistons from Denis Welch. These have =
three rings with a total width of 3.2mm compared with 9.8mm for the four =
rings. (For the oil rings only the width contacting the cylinder =
bore is measured)<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB>Since friction is in proportion to ring width (possibly due =
to the lower pressure required to make thinner rings seat against the =
cylinder wall) this represents a reduction in losses to heat and a power =
increase (small).<o:p></o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB><o:p> </o:p></span></p><p class=3DMsoNormal><span =
lang=3DEN-GB>Another, much more expensive, option for =
consideration. I also have no doubts about the quality of the =
pistons, whereas I am not sure about the four or five ringed =
replacements. They seem very cheap to me.<o:p></o:p></span></p><p =
class=3DMsoNormal><span lang=3DEN-GB><o:p> </o:p></span></p><p =
class=3DMsoNormal><span =
lang=3DEN-GB>Ian<o:p></o:p></span></p></div></body></html>
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