As engines age... - Page 2

Jason M · 06-07-09, 10:56

Lower RPM, stronger parts, diesel acts as a lubricant, tapered rings, etc.

Basically diesel engines are made to have a longer service life. If would be easy to build a gas engine that lasted for a million miles. Of course it would weigh a ton, rev to 2500RPM, and make 50ft/lbs or torque. You get the idea. It's a balancing act.

Change your oil, avoid detonation, maintain your fuel system and modern gas engines should have no issues going for 150-200k without losing compression.

944obscene · 06-07-09, 12:34

Quote:

Originally Posted by butchdave

One thing that hasn't been touched on but relevant to the question since most people here are petrol heads is that the fuel will also make a difference. Most diesel engines wear more slowly than gas, reaching higher mileages before suffering compression loss. Though I have to say that as I sit here and write that, any explanation for that completely escapes me!

I would assume that this is due to the lower temperatures that the motor runs at. Gasoline motors run pretty hot. Deisel on the other hand, ignites and burns at a lower temperature. Slower motor speeds might contribute, as there would be less friction involved with a motor, who's redline is 4k rpm.

944obscene · 06-07-09, 12:37

Quote:

Originally Posted by Jason M

Lower RPM, stronger parts, diesel acts as a lubricant, tapered rings, etc.

Basically diesel engines are made to have a longer service life. If would be easy to build a gas engine that lasted for a million miles. Of course it would weigh a ton, rev to 2500RPM, and make 50ft/lbs or torque. You get the idea. It's a balancing act.

Change your oil, avoid detonation, maintain your fuel system and modern gas engines should have no issues going for 150-200k without losing compression.

What he said...

butchdave · 06-07-09, 01:16

Of all that, I'd go with the lower RPM as the main contributor, after all, less movement - less wear. Yes temperature and lubrication from the diesel etc will assist, but I suspect the largest factor is simply the lower RPM.

But if that were the case then lower revving, more torquey gas engines would also last longer, and I've not noticed it being a particular factor.

Of the engines that last longer, I'm of a feeling that its more to do with drivers than design. Diesels don't attract the high revving, heavy footed drivers, and the longer lasting gas engines seem in my mind to also to be those that attract shall we say the more mature driver. Perhaps too though, the older driver tends to me a bit more affluent and able to afford regular servicing.

Interesting concept, though not exactly what the OP was asking.

Jason M · 06-07-09, 01:45

Temp has almost nothing to do with it. An engine can be designed to run at any temperature. And diesels exhaust gas temp is actually higher than most gas engines anyway. Lower RPM is also not a major factor. The main deal is that they are designed to be stronger from the start.