Subject: [Fot] racing rod design

From: "Enquiries Road & Track" <[email-masked]>
Date: Fri, 24 Jul 2015 07:02:45 +1000

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i've been rebuilding race and street  engines for decades and have never
seen a conrod fail in the beam , that was not caused by another item
failing first.
In nearly every case its the rod bolt. Either it fails dramatically from a
defect, or it fails "progressively" , usually because the builder set the
stretch/torque wrongly.
In the latter case, its common to see the bearing commence spinning as the
cap slowly looses its crush on the bearing shells , the oil system cannot
hold up the pressure and typically the shell backing seizes onto the rod.
of course, all this can  happen in a matter of seconds
we have had apart modern 500-700hp turbo engines that have  cheap chinese
rods in them and they look like new provided they were installed correctly
In amateur racing, the discussions about rod shape are mostly academic. The
are truly valid pros and conds for all shapes of rods, but i would be
staggered if any that discussions was really a consequence in any triumph
engine as they simply are not at the cutting edge of engine technology
of far more importance are fundamental issues like, rod twist &
straightness (rarely an issue with new rods of any brand), big end tunnel
size and shape (notoriously bad on cheap rods) , oil level in service, BUT
most importantly, assembly practises

Terry  (engine shop owner)

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<div dir=3D"ltr">i&#39;ve been rebuilding race and street =C2=A0engines for=
 decades and have never seen a conrod fail in the beam , that was not cause=
d by another item failing first.=C2=A0<div>In nearly every case its the rod=
 bolt. Either it fails dramatically from a defect, or it fails &quot;progre=
ssively&quot; , usually because the builder set the stretch/torque wrongly.=
=C2=A0</div><div>In the latter case, its common to see the bearing commence=
 spinning as the cap slowly looses its crush on the bearing shells , the oi=
l system cannot hold up the pressure and typically the shell backing seizes=
 onto the rod.</div><div>of course, all this can =C2=A0happen in a matter o=
f seconds=C2=A0</div><div><div>we have had apart modern 500-700hp turbo eng=
ines that have =C2=A0cheap chinese rods in them and they look like new prov=
ided they were installed correctly</div><div>In amateur racing, the discuss=
ions about rod shape are mostly academic. The are truly valid pros and cond=
s for all shapes of rods, but i would be staggered if any that discussions =
was really a consequence in any triumph engine as they simply are not at th=
e cutting edge of engine technology</div><div>of far more importance are fu=
ndamental issues like, rod twist &amp; straightness (rarely an issue with n=
ew rods of any brand), big end tunnel size and shape (notoriously bad on ch=
eap rods) , oil level in service, BUT most importantly, assembly practises<=
/div><div><div><div><div class=3D"gmail_signature"><br></div></div><div cla=
ss=3D"gmail_signature">Terry =C2=A0(engine shop owner)</div>
</div></div></div></div>

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