Came across a forum recently based on overseas(U.S.) farming equipment and such.
Bloke there wrote that Caterpillar no longer make an INDIRECT injection engine, probably one of the better known brands that persisted with pre-combustion chamber technology for many years even after a lot of others went to direct injection.
Put up a good argument in saying that what with modern materials available, the fuel itself being used, turbo/supercharging/ variable cam timing, intercooling and whatever else, the basic engine has far outstripped its modest beginnings.
Couple of others joined in citing various makes well known to us here in road transport, GM, Crummins just to name a couple.
I am not sure just when Cummins introduced their 855 cu in NH series engines, but for many years they were one of the mainstays in road tpt. Everyone remembers the beloved NH250, along with the likes of P motor Mack, 6/71 and 8V71, you couldn't kill them with an axe and I'll bet some of these engines are STILL puttering along!
As with all forums, you are going to get differing views (This one here is no exception), a few blokes wrote that the Yanks had a tendency to "overbuild" their engines and it wasn't until the constant chase for ever increasing HP that longevity and reliability began to suffer. Personally I can't form an opinion on that as have been away from the game too long now.
No doubt there would be blokes who could claim they got millions of miles out of their Signature engines, or their trusty DD12's, whatever, without putting a spanner to them.
BUT, what caught my attention was the claim and the follow up discussions of how more than quite a few of these forum writers had DERATED their engines, with no apparent harm and increased an already impressive lifespan. Admittedly a few of these blokes were talking agricultural/farm use i.e. tractors, pumps, sprayers, lighting plants etc, but also a couple of them had "hobby" trucks that they trundled around to State fairs etc.
Counter-argument was that the engine manufactures know how far they can go and if they can double the output of a known size, and maintain some sort of reliability, then these blokes shouldn't be tampering with them.
One bloke cited he had bought a reconditioned Cat 6 cylinder engine way back when, on some sort of sled he dragged around, so guessing was some sort of irrigation pump. Once the initial engine warranty expired he had them (Cat) come out, take the turbo and intercooler off, recalibrate the injector pump and put it back to work but derated. He said he used the engine/pump for 12 hrs a day, every day of the week, for 9 months of the year and other than changing the oil and filter "when it got as black as sin".m Had been doing this for well in excess of twenty years, never had the Cat blokes have to come out.
Plenty of replies to this from blokes operating screening machines, rock crushers, timber jacks, you name it, who agreed that by derating the engine that they "hadn't had to touch an engine in years".
I know it's a different kettle of fish to road transport requirements, as well as use. But can't help thinking about some of those massive old engines (both petrol and diesel) built so many years ago, and although they may well have been gas guzzlers then, may still be ticking over today.
In another forum topic we have heard of twin power straight eight Lycomings in Relays, we know quite well the Rhodes-Ridley, Clippers (and Whites with straight 8 Buick and flat 12's respectively).
These seemed to be either the need for high HP just wasn't able to be filled with what was available OR special applications.
I an just wondering if we have got away from the high cu-in capacity engine (but low HP rated) where we had known lifespan and maybe the manufacturers started at the other end. Build a smaller capacity (or in some cases like the 855) just keep increasing the output with all these you-beaut add on devices. Certainly you couldn't really compare todays engines with those same cubic capacities of the past, If you got 4mpg out of your Cummins or GM you would have been smiling. Todays engines although the same cubic capacity are putting out TWICE as much HP AND giving an increase in MPG. (Also some of this increase would be related to improvements in tyres, drive trains, aerodynamics etc, cant pin it down to one single component).
However this is digressing from the discussion these blokes were promoting. "Is derating an engine a worthwhile proposition"
In their case, taken over a lifetime and taking into consideration the actual use of the engine, probably yes. For a bloke who is engaged in road transport who may be turning his trucks over regularly, and wants the maximum utilisation, probably not.
A lot of people seem to be of the opinion that as far as engines are concerned, if you go to a larger capacity and then cut back on the manufacturers ratings, you get a lot longer life out of it than trying to get the same longevity of a smaller volume engine and try and maintain the same output with all sorts of addons, possibly stressing the engine and thereby decreasing engine life.
I am certainly no engineer, but that part at least makes some sort of sense to me. wonder what you blokes reckon?
Dave_64
