Running In Engines
Discussion
cymtriks said:
Does running in really make any difference at all?
Has someone actually stripped and inspected a run-in and a non-run-in engine after, say 3 years/30000 miles and found a real difference?
Experts have found that depending on how you run it in effects the subsequent power output. In other words, you need the rings to bed in properly. Some Jap motorbikes are fired up at the factory and given full throttle.
Boosted.
My dad works for Triumph, and he says they open the bike up full throttle at the end of the production line. Seems they do it now as the engine block & head are the same metals so they can, if they're different (cast block, alloy head) like they used a couple of years ago then they had to do something else to ensure the differnt head & block heat cycle didn't deform the cylinders, valve seats or cams and lead to an unbalanced engine later.
>> Edited by jitsukadave on Monday 9th January 10:05
>> Edited by jitsukadave on Monday 9th January 10:05
Very interesting reading people,
I have finished the engine rebuild (at last) for my TVR, it's a 2.8 V6 ford, with quite alot of mods.... Lightenend, ballanced, big valve heads with hard seats, custom ground cam (JW Developments), turbocharged, intercooled, forged pistons, modified K jetronic injection, modified ignition and so the list goes on.
During the rebuild most was replaced.... Cam, followers, pushrods, rockers, rockershafts, heads, valves, valve guides, cam drive gear, pistons (overbored cylinders), big end bearings, main bearings, oil pump, high tensile big end bolts, main studs, head studs. Wire ringed the new heads (as per old items). The turbocharger was overhauled about 500-1000 miles ago, so nothing to that except ceramic coating the exhaust and wastegate housing along with the manifolds and system.
I have run it up to bed in the cam/followers with a 20/50 oil, dumped the oil and filter and refilled it with 20/50 and fitted a fresh filter. My question is on oil types for the next step/remainder of the running in period and then running in anger, I have concerns about a 20/50 mineral and carbon build up in the turbocharger bearing housing, in the wealth of PH knowledge, has anyone have any experiance or advise for me?
I have finished the engine rebuild (at last) for my TVR, it's a 2.8 V6 ford, with quite alot of mods.... Lightenend, ballanced, big valve heads with hard seats, custom ground cam (JW Developments), turbocharged, intercooled, forged pistons, modified K jetronic injection, modified ignition and so the list goes on.
During the rebuild most was replaced.... Cam, followers, pushrods, rockers, rockershafts, heads, valves, valve guides, cam drive gear, pistons (overbored cylinders), big end bearings, main bearings, oil pump, high tensile big end bolts, main studs, head studs. Wire ringed the new heads (as per old items). The turbocharger was overhauled about 500-1000 miles ago, so nothing to that except ceramic coating the exhaust and wastegate housing along with the manifolds and system.
I have run it up to bed in the cam/followers with a 20/50 oil, dumped the oil and filter and refilled it with 20/50 and fitted a fresh filter. My question is on oil types for the next step/remainder of the running in period and then running in anger, I have concerns about a 20/50 mineral and carbon build up in the turbocharger bearing housing, in the wealth of PH knowledge, has anyone have any experiance or advise for me?
I ran my newly built engine in with a days mapping on the rolling road. Also drive it hard up to sensible revs then back off, keep driving that way and then as the miles start to add on increase the revs your going up to. Its the compression that beds the rings in.
I orginally had used a semi synth oil and a week after mapping and driving round as above, i was still getting a bit of white smoke - changed to a halfords 'special' cheap cheap oil, ran for only a few days and then no smoke at all. Not skipped a beat or smoked since.
I will always use cheap oil for any subsequent builds.
I orginally had used a semi synth oil and a week after mapping and driving round as above, i was still getting a bit of white smoke - changed to a halfords 'special' cheap cheap oil, ran for only a few days and then no smoke at all. Not skipped a beat or smoked since.
I will always use cheap oil for any subsequent builds.
Is it just me being of a nervous disposition or are there others who find the thought of revving the nuts off a freshly built engine rather disconcerting?
Even though I will have been as careful as possible and turned the engine by hand to make sure everything is smooth, upon first start, I will be letting my rebuilt engine idle for some time. I'll be checking for untoward noises, oil-pressure, leaks, air-locks in the cooling system etc. I'll probably then switch off and allow to cool and recheck all levels before going on a first short and gentle drive. If all seems satisfactory, I will change the oil and make some longer, more exuberant runs.
I find it hard to believe that the above approach will be to the detriment of my engine. Obviously the more load on the engine, the quicker items will bed in but what's wrong with taking it easy at first? How would this harm my engine?
Even though I will have been as careful as possible and turned the engine by hand to make sure everything is smooth, upon first start, I will be letting my rebuilt engine idle for some time. I'll be checking for untoward noises, oil-pressure, leaks, air-locks in the cooling system etc. I'll probably then switch off and allow to cool and recheck all levels before going on a first short and gentle drive. If all seems satisfactory, I will change the oil and make some longer, more exuberant runs.
I find it hard to believe that the above approach will be to the detriment of my engine. Obviously the more load on the engine, the quicker items will bed in but what's wrong with taking it easy at first? How would this harm my engine?
tr7v8 said:
Idling kils camshafts especially modified ones. Explicitly condemned in
Camshaft instructions, Pipers for my V8 cam said "Do NOT let the engine run below 2000RPM for the first 20 minutes, if you need to make adjustments or it starts to run hot
then switch off, DO NOT let it idle".
Why is that? I can imagine that as the revs increase, the forces on the up-slope of the cam lobes must increase and those on the down-slope decrease. Does that matter?
tr7v8 said:
No forces on the cam decrease as revs increase hence why no tickover running!
Providing everything else has oil the 2,000rpm won't hurt it.
The function of the cam lobe is to depress the valve. The force opposing this is the tension in the spring (constant with revs) and the acceleration of the valve assembly. Since Force=mass*acceleration and the greater the revs, the greater the acceleration of the valve, then it seems to me that force on the up-slope of the cam will increase with revs and that on the down-slope decrease. Also, whatever the revs, the down-slope force will always be less than the up-slope force (unless the engine has stopped).
Still
! >> Edited by jap-car on Tuesday 14th February 12:41
>> Edited by jap-car on Tuesday 14th February 14:19
jap-car said:It must depend how aggressive your cam is and what springs you are running. The more highly tuned the engine the heavier springs you are likely to be running, and the higher lift. Both these things increase the load on the cam follower at full lift. Maybe this is why mass production engines can get away without, by designing a valve train and cam profile than has cam loads low enough to survive the bedding-in period at low revs. Or maybe they just assume that every new customer is going to spend the first twenty minutes revving the nuts off it, well the company car drivers anyway.
Quite how important this is in reality, I'm not sure.
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