Do engines lose power over the miles?

[dci]

As per the title really... Do engines lose power over time? For example will a 335d on 135k have the same power and torque figures as a showroom fresh example and one which has 30k miles?

Are some engines age better or worse than others? E.g the 3.0 turbo diesel from a pickup compared to a highly strung turbocharged engine from a jap import?

Cheers, Richard

[Luffehamp]

I get my car dyno'd once a year and the same place. Went up by 15bhp over 2 years but far too many variables to make a conclusion.

[willisit]

Can of worms. Some do, some don't. Depends on maintenance and the engine in question. How stressed it is, etc etc etc.

I know bigger V8s, diesels etc can actually gain power or mpg over miles and time, but it's all very subjective (the engine being a component of the car itself that can affect all those things).

Generally speaking, I'd expect a petrol engine to lose power over the years as things like valves and rings wear.

[Mr Sparkle]

I had a mk3 Honda Prelude with 150,000 miles and managed to get the same quarter mile time and speed that Autocar did 15 years earlier so a car might loose power over time but I don't think it would be anything like as bad as has been said on top gear before. Obviously I had modern tyres when I did it so could have got off the line slightly better.

[Jaaack]

My 175k mile Accord Type-R still feels very strong, and kept an even distance with a 50k mile EP3 through a couple of gears. Ran a 15.3 second quarter mile on Kumhos (not sure what the official time is meant to be). Been told by a specialist that the high mileage ATRs tend to make factory power while the S2000s and Civics don't.

I'm sure I read recently (on PH) that Honda reckoned a B18C in a DC2 Integra Type-R was at it's peak at 150k miles. Which is funny as a lot of B-series engines I've seen with that kind of mileage smoke their bag off due to abusive owners

[LocoBlade]

Old engines with carbs and mechanical distributors etc probably loose quite a bit but more modern ones with electronic injection / ignition and closed loop ECUs controlling it all will probably lose a lot less, as the combustion process will generally remain far more optimised than they would on an old school engine.

Edited by LocoBlade on Saturday 26th October 16:08

[lowdrag]

Not too sure on the last point. Modern tolerances enable old engines to keep their performance pretty well. My E-type, with 60,000 on, was tested by EVO and on a damp track managed 7.2 secs to 60. I know, not fast by today's standards but skinny tyres etc. It was tested in 1961 at 6.9 secs on a dry track, so not too far out. My Mercedes (2001) has 250,000 and feels no different to new.

[vikingaero]

Most new cars will have engines that are tight as a gnats chuff when new. 20-30k down the line and they will be performing at their peak.

[Walter Sobchak]

I was told when asking about my car that the 55K engines actually tend to make more power after some Miles, I was a bit skeptical so had it dynoed and it was making 504, not bad considering the standard output is meant to be 493 I think.

[jimbobsimmonds]

I have dyno plots of my S60 T5 pre and post remap... tthe car recorded 245 bhp at 88k miles before the map went on. Basically the car had lost no power in 9 years and 90k (providing the dyno was accurate...)

[Ozzie Osmond]

The main effect on power in the longer term is cylinder compression. As an engine wears the pistons/rings eventually fit less precisely in the cylinders and so it easier for gases to "leak" past the rings. That leakage means lower compression and less power.

This is one reason why it makes no sense to cherish a new engine with expensive oil and frequent changes yet become more casual as the engine gets older. Gases leaking past the piston rings contaminate your engine oil so older engines deserve good oil and regular changes.

(At the same time, oil leaking up past piston rings tends to make older engines burn a bit of oil. Also worn valve guides.)

[LocoBlade]

One contributor to that bore wear is over fuelling, if you get an engine running rich it will start washing the bores of oil and accelerating wear so again modern ECUs help reduce this by learning and adjusting as things wear to keep fuelling etc near optimum.

[GVK]

Really old Top Gear showing difference between a mk2 Golf GTI 16v with 60k miles vs a newer,tighter one with 5k miles on it.

http://www.youtube.com/watch?v=7sxN5GV8ywY

[Eski1991]

GVK said:

Really old Top Gear showing difference between a mk2 Golf GTI 16v with 60k miles vs a newer,tighter one with 5k miles on it.

http://www.youtube.com/watch?v=7sxN5GV8ywY

Loved the Top Gear with the 3 sub 10k Super Cars and Clarkson's Maserati was pushing out 90 BHP.

Don't think that it makes a huge difference on properly maintained modern engines.

[J4CKO]

I think they get better if run in well, I remember my mother in laws BMW 320i (24 valve, 150 bhp) E36, I was dissapointed when I drove it whilst she had it, never really went above 3000, my brother in law had it and kicked the st out of it for a couple of years, at 50k it was a different car, properly faster, until he ran it short of oil and killed it.

[stuart-b]

I remember seeing a post around here where there was a 964 dyno'd. It had done 160,000 miles and was exactly to spec, hadnt lost a single one.

[anonymous-user]

I did an engine compression test on a 115k mile e46 m3 last week. All cylinders were all but equal and making 175psi each. Bang on spec.

Pulled like startled horse too.

[GokTweed]

Wife's TT rated at 225bhp. W reg and dyno'd earlier this year at 223bhp on 95 petrol. Not bad at all I think!

[DKS]

My 1.3 Astra has been on the Janspeed rollers and made I think 55BHP at the wheels at 210k miles (should be 72 @ fly). I get ribbed for the amount of oil changes my cars get, but I don't get any smoke and they never need topping up.