"The horses have escaped over the years..."
Discussion
Example:
My question is this- 'horses escaping', fact or fiction?
I know how an engine works and I know that the condition of piston rings, bores, valve seats, injectors, ignition systems, filters etc will deteriorate over time and decrease performance- but is it generally accepted that performance decreases in a linear way over the miles?
My thought are that a new engine in a road car is tight and requires 'breaking in' (by which I mean normal use to bed in the metal/metal surfaces, bearings, bores and valvetrains). So the engine will probably acheive it's maximum performance in the first few thousand miles. However, I don't see why power should then linearly decrease until it dies- surely if it has compression and the right amount of fuel, electricity and oil, it should perform pretty well until quite late in life?
It is often said amongst some car fanships that their engine is still producing greater-that-spec power at XX,000 miles because they are 'great engines', is this possible?
Let's not turn this into a power vs torque, diesel vs petrol, 'all rolling roads are inaccurate', 'my car has XXXbhp' sort of convo, I'm more interested in the theory.
Justin Cyder said:
The TT QS is 240 out of the factory. By now, they'll all be around the 220 mark what with the escaping horses - the youngest one of those will be 6 years old now.
Personally, I think I first heard the 'horses escaping' analogy from a Mr. Clarkson- and although entertaining, he can't often be treated as a reliable source for technical information!My question is this- 'horses escaping', fact or fiction?
I know how an engine works and I know that the condition of piston rings, bores, valve seats, injectors, ignition systems, filters etc will deteriorate over time and decrease performance- but is it generally accepted that performance decreases in a linear way over the miles?
My thought are that a new engine in a road car is tight and requires 'breaking in' (by which I mean normal use to bed in the metal/metal surfaces, bearings, bores and valvetrains). So the engine will probably acheive it's maximum performance in the first few thousand miles. However, I don't see why power should then linearly decrease until it dies- surely if it has compression and the right amount of fuel, electricity and oil, it should perform pretty well until quite late in life?
It is often said amongst some car fanships that their engine is still producing greater-that-spec power at XX,000 miles because they are 'great engines', is this possible?
Let's not turn this into a power vs torque, diesel vs petrol, 'all rolling roads are inaccurate', 'my car has XXXbhp' sort of convo, I'm more interested in the theory.
I have before and after dyno plots of my S60 T5. Bearing in mind the car was 9 years old at this point it was producing 246 and 243 bhp on the day running the standard map. Bearing in mind I think they quoted 246 bhp out of the factory I think the car has done a decent job...
However, a similar S60T5 that has been treaten like s
t and never seen a service in its life probably wouldn't fare so well...
However, a similar S60T5 that has been treaten like s
t and never seen a service in its life probably wouldn't fare so well...Years ago, Autocar often used to 'figure' cars twice if they had them as long-termers.
The first time was when they ran the original road test figures on them, often with the cars only having 1000-> 2000 miles on the clock.
They they'd sometimes re-do the standing start acceleration, in-gear times and top speed figures again, towards the end of their test. After reading literally dozens of these LT/RT type comparisons I can say that some cars actually posted faster times once they'd done a fair few thousand miles.....whilst others posted slower times. The in-gear times would be harder to 'fudge' I'd guess.
The first time was when they ran the original road test figures on them, often with the cars only having 1000-> 2000 miles on the clock.
They they'd sometimes re-do the standing start acceleration, in-gear times and top speed figures again, towards the end of their test. After reading literally dozens of these LT/RT type comparisons I can say that some cars actually posted faster times once they'd done a fair few thousand miles.....whilst others posted slower times. The in-gear times would be harder to 'fudge' I'd guess.
Bear in mind that the italian cars in question in the "Can you buy a supercar for the price of a secondhand Mondeo challenge" would have had their figures 'massaged' by marketing departments when they were released in the 1970s/80s. In those days less people had access to dyno equipment, so the manufacturers could claim anything.
Not only that, all three of the presenters bought pups anyway which didn't look to be in a good state of repair.
Not only that, all three of the presenters bought pups anyway which didn't look to be in a good state of repair.
Esseesse said:
It's crap, the Alfa V6's I've seen dyno'd on 100k+, 10 year old+ make as much or more than they were originally meant to.
this. about 13 months ago i saw the dyno of a BMW E34 535i with 231k on the clock, was still producing 207bhp after 20-21 years and that many miles.if a car is well serviced, it won't really lose anything.
Without looking at recent data I couldn't say for sure. But I work in power-train development, running what we call design verification tests (I focus on diesel atm). Two that stick to mind are XXXX+ hour mixed use high-load system durability tests = basically everything from idle to max power speed+10% and XXX hour high-speed tests (which are timed based on a sufficient number of engine cycles to demonstrate that effectively all base engine parts; crank, rods, bearings, pistons, cams, valves et. that spin/move per cycle, are fit for "infinite fatigue life" (which depending on the material in question you'd like between 1 and 100 million cycles per part).
We tend to stay within a few % start to finish, and have much bigger variation from exhaust condition (old exhaust cat/dpf blocking up) or deterioration of installation (charge coolers etc. - not vehicle fit parts). And sometimes pre-programmed in wear counters for certain parts (exhaust, fuel system, turbo's etc.) limiting peak performance after a number of hours at full-load (depending on operating conditions, speed and time). Currently have a test running that started good, lost a few % at 100 hours, was up at 200, even at 300 etc. pretty consistent to within <3% - we target.
Some conditions for certain engines can be particularly wearing on pistons (high loads/temperatures at constant speed. and 200 hours can lead to a lot of oil consumption and noticably (still not the 10-20% extra that clarksonists would have you believe...) - we would try to catch these before serious catastrophic failure monitoring, performance, oil consumption and crankcase pressure.
so. yeah, modern diesel - not really in "normal" operation, bar wear protection for exhaust or fuel system things (could get them "re-mapped" out) - not alot happens on tests that prove their fit for ~5 years worst case customer usage without failure OR constant max power usage.
We tend to stay within a few % start to finish, and have much bigger variation from exhaust condition (old exhaust cat/dpf blocking up) or deterioration of installation (charge coolers etc. - not vehicle fit parts). And sometimes pre-programmed in wear counters for certain parts (exhaust, fuel system, turbo's etc.) limiting peak performance after a number of hours at full-load (depending on operating conditions, speed and time). Currently have a test running that started good, lost a few % at 100 hours, was up at 200, even at 300 etc. pretty consistent to within <3% - we target.
Some conditions for certain engines can be particularly wearing on pistons (high loads/temperatures at constant speed. and 200 hours can lead to a lot of oil consumption and noticably (still not the 10-20% extra that clarksonists would have you believe...) - we would try to catch these before serious catastrophic failure monitoring, performance, oil consumption and crankcase pressure.
so. yeah, modern diesel - not really in "normal" operation, bar wear protection for exhaust or fuel system things (could get them "re-mapped" out) - not alot happens on tests that prove their fit for ~5 years worst case customer usage without failure OR constant max power usage.
I think it is a load of rubbish. Most of the cars I have had that have been down on power are due to components around the engine failing or as i commented in the Audi9 thread the OP refers to vacuum leaks and split boost pipes account for most 20vT power losses - both cheap/easy and not the fault of the engine.
Newer cars are better at keeping the horses in. 
In the olden days with rubbish lubricants, iffy metallurgy and poor tolerances, engines had a tiny bit of "piston slap" designed in to stop the pistons seizing in bores when they got hot and expanded. It meant a little bit of compression was lost since there would be a tiny gap between the ring and bore at certain parts of the stroke.
That gave a fairly gentle failure mode - as the piston slapped around it wore the bores bit by bit, making the compression, and power loss, gradual.
In the olden days with rubbish lubricants, iffy metallurgy and poor tolerances, engines had a tiny bit of "piston slap" designed in to stop the pistons seizing in bores when they got hot and expanded. It meant a little bit of compression was lost since there would be a tiny gap between the ring and bore at certain parts of the stroke.
That gave a fairly gentle failure mode - as the piston slapped around it wore the bores bit by bit, making the compression, and power loss, gradual.
davepoth said:
Newer cars are better at keeping the horses in.
In the olden days with rubbish lubricants, iffy metallurgy and poor tolerances, engines had a tiny bit of "piston slap" designed in to stop the pistons seizing in bores when they got hot and expanded. It meant a little bit of compression was lost since there would be a tiny gap between the ring and bore at certain parts of the stroke.
That gave a fairly gentle failure mode - as the piston slapped around it wore the bores bit by bit, making the compression, and power loss, gradual.
Not to mention carbs with worn jets, cracked diaphagms and leaking bodies. Worn distributor shafts and tired rotor arms would send randomly timed sparks through old HT leads reducing the spark intensityIn the olden days with rubbish lubricants, iffy metallurgy and poor tolerances, engines had a tiny bit of "piston slap" designed in to stop the pistons seizing in bores when they got hot and expanded. It meant a little bit of compression was lost since there would be a tiny gap between the ring and bore at certain parts of the stroke.
That gave a fairly gentle failure mode - as the piston slapped around it wore the bores bit by bit, making the compression, and power loss, gradual.
Definately on older cars the horses escaped unless the engine was maintained to the very highest standards.
Edited by balls-out on Friday 20th July 16:18
Forums | General Gassing | Top of Page | What's New | My Stuff