Blueprint 103 - Connecting Rods
Connecting rods are the crux of the engine. They're responsible for
carrying the force of the explosions that occur in the combustion chamber
and using it to turn the crankshaft. Oil clearance specifications of the
"big end" and "small end" are crucial to maintaining consistent oil
In this video we take 3 measurements:
Rod Journal (also called Crank Pin) Diameters
"Big End" Bore diameter
Using the Journal diameters and the "Big End" Bores, you can calculate your
oil clearances of each bearing. The process is illustrated here. Anyone
rebuilding an engine who doesn't know its history should check all of these
clearances whether or not they're re-using the rods. If the crank,
bearings or connecting rods are going to be replaced, it's imperative that
you measure the new parts as well to ensure they're in spec.
Connecting Rod Balancing
See how connecting rods are balanced by John Edwards @ Costa Mesa R&D,
BMW Connecting Rod Modifications
John Edwards discusses how he machines BMW connecting rods to reduce weight
for increased RPM for naturally aspirated and forced induction engines.
Fiat X1/9 Pistons & Connecting Rods
This video will show some of the modifications that are made by John
Edwards @ Costa Mesa R&D Automotive Machine on a 1500cc Fiat X1/9 (Punto
Marea) connecting rods and new forged JE pistons. www.engine-machining.com
Connecting Rod Weight Reduction
Here's another weight reduction method used by John @ Costa Mesa R&D
Automotive Machine. Check it out!
Con Rod Mods-01.wmv
Here's another connecting rod modification that John Edwards of Costa Mesa
R&D Automotive Machine performs to reduce reciprocating weight.
www.engine-machining.com (949) 631-6376
Engine rebuild part 2
Here is the link for the series on a DVD
setting the crank in place and checking to be sure everything clears
Atomic Performance Products - XR6T High Performance Conrods
Atomic billet steel conrods were designed from scratch with one principle
in mind; use aerospace quality materials and sophisticated manufacturing
processes to produce an extremely strong, light and durable connecting rod
for the popular inline 6 cylinder Ford SOHC/DOHC engines, at an affordable
The Design and Evaluation Process
The Atomic engineering team set out to address these parameters by
designing what many performance engine builders are now calling the finest
conrod on the market for the Ford DOHC 6 cylinder engine.
Extensive CAD/CAM computer modelling was employed and produced a H-Beam
design, which has an extremely high stiffness-to-mass ratio. The next step
was to pick the correct materials, heat treatment and surface treatment
processes to ensure durability under rigorous performance applications.
Next came FEA modelling (Finite element analysis) to simulate stresses on
the conrods. This also entailed weighing every piston, gudgeon pin and ring
set on the market and loading this information, plus stroke, rotating and
reciprocating conrod values into our computer modelling software to
calculate the stresses.
The greatest load exerted on a conrod in an engine producing 600 comes not
from the force of normal combustion but from the tensile force exerted by
the piston at top dead centre (TDC). At 5250 RPM the piston exerts a
tensile load on the conrod of 1908 gs (-1693 kgs) at split overlap TDC
reversal. If you increase maximum engine speed by only 1000 RPM to 6250
RPM, the TDC tensile load rises by 50.4% to 2870 gs. At 7500 RPM the
tensile loading increases to 4132 gs, clearly demonstrating the Atomics
design strength of 8000 gs means it has plenty in reserve.
Excessive loads at TDC are brought about by a high reciprocating mass
and/or by increasing engine RPM, so it is essential to design reciprocating
engine components with the lowest mass possible to minimize premature lower
bearing shell bearing failure. This is particularly relevant to our
customers who are turning their engines to 7500RPM+.
For more information, visit
Allis-Chalmers WD engine piston/connecting rod damage
This shows the damage in the Allis-Chalmers 201 CID engine when the rod cap
got loose. The piston fell down and parts of it got busted off...the rod is
actually still attached to the piston. It looks like somebody left the
cotter pins off some of the rod bearing bolts and the nuts may have
vibrated loose. Any advice will be much appreciated...I really want to get
my tractor running again!
An Animation Of How A Piston Operates, To Generate Gradual Speed
Comparison of MIVEC, VTEC and VVT
Comparison of the variable valve timing systems Mitsubishi MIVEC (2 cam
profiles), HONDA VTEC (3 cam profiles) and Toyota VVT (4AGE black/silver
top engine with adjustable cam gear).
Found on mivec.co.nz