OEM cold engine testing - just curious really

[Plate spinner]

Put this here rather than GG as I’m looking for more than just opinions.

I’m curious about OEM engine testing from cold ie start up a stone cold engine and put it straight to max revs and just hold it there. I know this is not a good idea, but it must have been done to cater for the most unsympathetic owner scenarios?

Will it kill the motor? Is it a standard test that modern engines are designed to cope with?

Any engineers care to divulge the sort of tests that are actually run? Just curious really. My lad is interested in cars and asked me, I didn’t really know and google doesn’t bring up much. My gut feel is that manual downshift over revs are one of the few ways to actually kill a modern ecu engine, all other factors have been tried and tested. Enlighten me

Thanks.

[GreenV8S]

Plate spinner said:

My gut feel

All the things that used to be bad for engines are still bad for them. Rapid temperature changes, heavy load when too cold or too hot, lack of maintenance and so on are all harmful and will reduce the engine's life.

[stevieturbo]

In some cases the ecu may be programmed to prevent that behaviour in the first place.

Try it and see.

[Piersman2]

As above... my old 4.2 XJRs used to limit the revs to 3000 when in park IIRC.

[anonymous-user]

Plate spinner said:

Put this here rather than GG as I’m looking for more than just opinions.

I’m curious about OEM engine testing from cold ie start up a stone cold engine and put it straight to max revs and just hold it there. I know this is not a good idea, but it must have been done to cater for the most unsympathetic owner scenarios?

Will it kill the motor? Is it a standard test that modern engines are designed to cope with?

Any engineers care to divulge the sort of tests that are actually run? Just curious really. My lad is interested in cars and asked me, I didn’t really know and google doesn’t bring up much. My gut feel is that manual downshift over revs are one of the few ways to actually kill a modern ecu engine, all other factors have been tried and tested. Enlighten me

Thanks.

The science of internal combustion engine durability is mature and well understood. The OEMs have developed over the last 50 years a series of durability tests designed to validate the effective life time durability of any ICE tested. These tests are generally well in excess, in terms of aggressiveness, of any actually use profile, as they are intended to evaluate an engine on an accelerated type cycle.

Thermal shock type tests are broadly split into two main categories:

1) Deep thermal shock tests on a running engine designed to establish that engines overall resistance to thermal fatigue effects, ie how changes in temperature cause the engine to wear, age or fail

and

2) Specific component thermal tests, designed to establish the resistance of any particular component to thermal effects over the life of that component



The "Deep thermal shock" test is a test sequence used to establish 1). An engine is connected to a special dynamometer cell, which has the capability to supply that engines coolant loop with cooling water that undergoes rapid, and huge changes in temperature. Usually this is done with a large tank (several thousand litres) of coolant that is chilled to around -25 degC and dumped into the engines coolant loop suddenly. The engine is run, allowed to warm up to max operating temp (typically 120 degc) and then the cold dump occurs:



Everything on and in the engine experiences a very sudden contraction. This causes running clearances to change, and mechanically stresses parts due to that thermal shock. Depending on the manufacturer, this test may be run at a range of loads and speeds, and usually lasts until something breaks (typically an excessive crank case blow by limit is breached)


The "piston scuff" test is a sequence specifically looking at the piston, ring and bore, and is designed to establish their robustness to operation under load and non-optimum operating temperatures. Here, the entire engine is soaked down to around -25degC when off, and is then started at immediately taken to full throttle and peak power speed. The engine is allowed to warm up normally (ie until the thermostat opens and normal coolant temp is reached) and then it's turned off and re-soaked down for the next cycle. Again, this us run until certain limits are breached (or catastrophic failure like rods poking out of blocks etc!)


These tests are both very severe, and realistically unlikely to occur on a repetitive basis in the real world, but give an indication of the robustness of the engines mechanical systems to that sort of event. I've seen engines fail on the first cycle, and engines that are still going 500 cycles later! It also is a good way of looking at things like oil dilution, because cold starts result in fuel getting past the rings and into the oil etc. With a poor cold start calibration that effect can reduce the oil lubricity and result in eventual failure, which would reproduce months of driving short distances in a cold climate (ie a 3 mile commute in Northern finland for example)


The important fact is that despite none of these test reflecting any likely real world scenario, the OEs have build up a history of using the results of these tests as a very good indicator as to the short and long term durability of their engines in the real world, over real time spans. It gives them confidence after say a 3 year development program to release a product to their customers with a good level of confidence that the product is indeed fit-for-purpose

[anonymous-user]

I should also add that in all cases these basic engine dyno tests are of course backed up by vehicle durability programs, in all climates. Accelerated vehicle durability programs will be run for example on a complete vehicle (usually vehicles plural) at an Arctic proving ground, where those vehicles will accrue test mileage day in, and day out for months, sometimes years depending on the cycle and test requirement, in real world extreme environments.

[Boosted LS1]

Good stuff Max.

Older saabs are pretty hard to destroy. The same may apply to volvos as well.

[tapkaJohnD]

This might beof interest to the OP and his son. Outside test laboratories, the place where vehicles meet similar conditions is Antarctica. This is an interview with the operations manager of the US Antarctic Program, about the vehicles they run, and the problems they face: https://www.caranddriver.com/features/a15122649/po...

There are probbaly other pages out there on the same subject.

John

[Sardonicus]

stevieturbo said:

In some cases the ecu may be programmed to prevent that behaviour in the first place.

Try it and see.

This ^ many are inc the Honda S2000 for obvious reasons you will always have some numpty what all the revs before the fluids are up to temp , like mentioned working a motor hard from cold is bad always was always will be cold high oil pressure does not indicate high/suitable lubrication for starters

[Krikkit]

Totally anecdotal, but I believe Mercedes run 100 consecutive scuff tests and expect a particular amount of wear before they'll sign off on an engine... But they seem to be pretty conservative with durability.

[Plate spinner]

Really interesting insights, thanks all particularly Max_Torque for a great post