Original submission by T Jan 16th 2007:
- 1 The Factors That Determine Long Engine Life:
- 2 Driving Style:=
The Factors That Determine Long Engine Life:
Routine Maintenance:It's no secret that Engines thrive on routine maintenance. The efficiency
of the Engine effects both its Performance and Economy so routine Tuneups
and Oil and Filter Changes are a must if an owner is to see the best Performance
and Fuel Economy from any investment in a car.
Other Factors:After that some other factors come into play which have been covered in other
pages at the site.
In addition to those factors, how the Engine is loaded is a critical factor.
Contrary to popular belief the little old person who only drove their car to the
supermarket on Sunday did more to ruin the Engine than almost any other driver.
Not only did the short runs contribute to all the negative effects covered
in those other pages it left the Engine underloaded.
Engines need to work to load up the Compression Rings. This not only makes
the Rings seal properly but it keeps the Bore Faces (the surfaces of the Cylinders) work hardened. Since the bores are made of soft Cast Iron something has to be working for them to give them long life. That something is the effect of a Natural Bearing.
Gas Pressurisation of the Piston Rings:The animation shows how the Compression Rings are forced against the Bore Faces
when the Engine is driving the ideal load. There is enough resistance to the downward
force applied to the Piston to force the Compression Rings against the Bore Faces.
The animation also shows what happens when the Engine is not working hard enough. The Compression Rings are not forced against the Bore Faces and the Piston Ring Grooves
clog up with Carbon.
The Natural Bearing:Throughout an Old Holden Engine there are many Natural Bearings. These are formed
when a soft metal runs in contact with a hard metal. Examples are ...
| Material One|| Material Two|
| Hard Valve Stems||Soft Cast Iron.|
| Hard Piston Rings|| Softer Cast Iron|
| Soft Alloy Pistons||Harder Cast Iron|
| Hard Big End Journals (Bearings) || Soft White Metal Big End Bearings.|
| Hard Crankshaft Journals (Bearings)|| Soft White Metal Main Bearings|
|Hard Rocker Arms|| Soft White Metal Saddle Bearings|
|Hard Camshaft Bearings|| Soft White Metal Cam Bearings|
|Hard Rockers (non-adjustable)||Soft Alloy Bridges (non-adjustable)|
These bearings run in hot Oil and with friction. As a consequence a bearing surface
is made where the two different metals make contact.
When it comes to the Bores, these are dependent on hard Piston Rings to wear a work hardened face onto them. They are also affected by the Oil Scraper Ring which has the job of pulling Oil back into the sump so that only a tiny amount
makes it into the Combustion Chamber.
The fact that the bores have Compression Rings whose natural action is to work harden the bores and the opposing action of the Oil Rings to scrape them clean means that under certain circumstances either the Compression Rings or the Oil Rings can gain the upper hand.
The Oil Rings As the Bore Wear Culprit:
The Oil Rings can gain the upper hand and start tearing down the work hardening on the bore faces if the Compression Rings get too easy a time. That situation would occur if the Engine were running too light a load. Too light a load will occur if the Differential Ratio permits an excessive number of Engine turns for any speed of the car.
The Compression Rings as the Bore Life Extender:The Compression Rings can gain the upper hand and keep the work hardening on the bore faces if put to work properly. That situation would occur if the Engine were running the correct load. The correct load will occur if the Differential Ratio permits an appropriate number of Engine turns for any speed of the car.
The way a car is driven can also determine the Engine life. In a Manual Car, changing up to the next gear early and flooring the Accelerator loads the Engine correctly, makes the mixture burn more completely and gives the best gas mileage.
Revving the car out in each gear burns up the bores as well as a lot of fuel.
In short, keeping the revs down and making the Engine work gets the best results.
Diff Ratios in Old Holdens:
Looking across the model range of Holdens from 48/215 to HQ some interesting info appears.
Model/6 Cyl Engine/Diff Ratio Comparison:
|Model||Engine Size|| Standard Diff Ratio ||Wheel Size||15" Wheel Size GMH equiv Diff|
|VB||173/202 Cubic Inches (2850/3300cc)||3.08 A (appropriately-geared)|| 14 inch|| 3.36 A|
|HZ|| 173/202 Cubic Inches (2850/3300cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch||3.89 M 3.55 A|
| HX||173/202 Cubic Inches (2850/3300cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch|| 3.89 M 3.55 A|
| HJ|| 173/202 Cubic Inches (2850/3300cc) || 3.55 M 3.36 A (under-geared)|| 14 inch||3.89 M 3.55 A|
| LJ|| 138/173/202 Cubic Inches (2250/2850/3300cc)|| 3.08 M 3.08 A (appropriately-geared)|| 13 inch|| 3.55 M 3.55 A|
| HQ||173/202 Cubic Inches (2850/3300cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch|| 3.89 M 3.55 A|
|LC||161/186 Cubic Inches (2600/3050cc)||3.08 M 3.08 A (appropriately-geared)||13 inch|| 3.55 M 3.55 A|
| HG|| 161/186 Cubic Inches (2600/3050cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch|| 3.89 M 3.55 A|
| HT|| 161/186 Cubic Inches (2600/3050cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch|| 3.89 M 3.55 A|
| HK|| 161/186 Cubic Inches (2600/3050cc)|| 3.55 M 3.36 A (under-geared)|| 14 inch|| 3.89 M 3.55 A|
| HR|| 161/186 Cubic Inches (2600/3050cc)|| 3.55 M 3.36 A (under-geared)||13 inch|| 4.41 M 3.89 A|
|HD|| 149/179 Cubic Inches (2440/2935cc)||3.55 M 3.36 A (under-geared)||13 inch||4.41 M 3.89 A|
| EH|| 149/179 Cubic Inches (2440/2935cc)|| 3.55 M 3.36 A (under-geared)|| 13 inch||4.41 M 3.89 A|
| EJ|| 138 Cubic Inches 2250 cc|| 3.89 (under-geared)||13 inch||Nothing High Enough Available|
| EK|| 138 Cubic Inches 2250 cc|| 3.89 (under-geared)||13 inch|| Nothing High Enough Available|
| FB|| 138 Cubic Inches 2250 cc|| 3.89 (under-geared)||13 inch||Nothing High Enough Available|
|FE|| 132 Cubic Inches 2150 cc|| 3.89 (under-geared)||13 inch|| Nothing High Enough Available|
| FJ|| 132 Cubic Inches 2150 cc|| 3.89 (critically-geared)||15 inch|| 3.89|
| 48/215/FX|| 132 Cubic Inches 2150 cc||3.89 (critically-geared)|| 15 inch|| 3.89|
The subsequent drop to 13" wheels (FE - HR) saw 3.89 diffs for
the remaining grey motor sedans and 3.55 for the red motor manuals.
If the 48/215 and FJ diffs are extended from their wheels sizes
they would have been running 3.36 diffs into 13" wheels and
still handled the gearing fine.
When red motor Holdens appeared with 3.55 diffs for the manuals it
was surprising how fast these cars started pumping blow-by gas
from their "umbrella handle" Engine breathers. The issue was far
more noticeable than on grey motor Holdens and became less prevalent
when the HK and later appeared with 14" wheels because the larger wheel
size placed better loading on the Engines.
My point here is that 6 cylinder Torana's came standard with
3.08 diffs and 13" wheels meaning that EH - HR was chronically
VB Commodores appeared with red 202's (3300cc) Engines, Trimatic gearboxes,
14" wheels and 3.08 diffs. In FX/FJ terms this would be the equivalent of replacing the
3.89 diff with a 3.36 diff making good sense considering the Engine is 1 litre larger in capacity.
Undergearing sold well in an era that was keen to get extra
performance on largely goat-track roads. Overtaking was made
much easier by just flooring the throttle and letting the low
diff ratio take care of things.
With the advent of expressways these original red motor ratios
burn up engines.
Is My Engine Really Worn Out?:Blocked Piston Ring Grooves cause Compression loss and Oil Burning as demonstrated in the animations.
Undergearing in 6 Cylinder Toranas:
Undergearing is a direct cause of Oil Leaks in main stream 6 Cylinder Toranas (excludes
XU1's). A 3.08 diff and 13" wheels is not enough load for a red six
that might equally have been fitted to a Kingswood with 14" wheels.
Steaming out the cylinders periodically is a cure if a diff ratio change cannot be effected.
Rescheduling the driving style can help. Changing up early and flooring it in a manual
will make the compression rings bite in harder. Fitting a Power/Economy Switch
can increase the Engine's workload in a Trimatic.
Late Model Cars:
These run quite tall diffs with gearboxes that have more ratios than Old Holdens.
Since Late Model Cars also have changes to the Engines to allow them to produce power more
efficiently they are able to drive tall gearing and still give good performance.
These are covered under the Economy page.