I've seen bearings now offered with a coating for less friction along with uncoated ones. Has any one bought these or had their bearings coated? How about thermal barriers on piston tops? I'm giving thought to a forced induction engine that I want to last. Seems with what loads are incured it would be beneficial.
Coatings for performance
- Thread starter kaboom10
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Depending upon the intended application I would have to say yes they are very helpful. I had my main and rod bearings coated and my piston crowns on a 1,000HP custom turbocharged camaro. I have not had the motor apart ( thank god) but I feel better about having done this in my application. Anything you can do to prolong the life of a FI motor like cryo or coatings is worth the extra $$$.
manufacturers are starting to use coatings in OEM applications. the main and rod bearings on Ford GT's have tri-metal coatings.
Trick coatings are being used more and more is there a benefit I do not know but if you are spending big bucks on an engine why not!!!
where you can use them, ceramic roller bearings are the choice.
Hi,
Ceramic coatings have been used in heavy diesel engines for around 15-20 years. The Japanese were the first to use ceramic piston caps - unfortunately the learning curve for some maufacturers was longer than others. Adhesion was an issue in many cases
Detroit Diesel have had ceramic (silicon nitride)valve/injector actuation rollers for around 20 years now. These are under enormous loads due to the injection pressures (and engine brake) required. At one stage the metal bearing shaft was a problem as was the friction modifiers in ceratin lubricants that caused the roller to only rotate intermittently or not at all - of course the camshaft suffered
I never needed to replace any rollers in many millions of miles of engine use!
Mercedes use Eaton superchargers (and others) and these also have special coatings for flow and noise abatement reasons
IMHO various coatings will overwhelm some factors in engine design as will completely sealed lubrication system components along with such things as electric oil pumps etc
Ceramic coatings have been used in heavy diesel engines for around 15-20 years. The Japanese were the first to use ceramic piston caps - unfortunately the learning curve for some maufacturers was longer than others. Adhesion was an issue in many cases
Detroit Diesel have had ceramic (silicon nitride)valve/injector actuation rollers for around 20 years now. These are under enormous loads due to the injection pressures (and engine brake) required. At one stage the metal bearing shaft was a problem as was the friction modifiers in ceratin lubricants that caused the roller to only rotate intermittently or not at all - of course the camshaft suffered
I never needed to replace any rollers in many millions of miles of engine use!
Mercedes use Eaton superchargers (and others) and these also have special coatings for flow and noise abatement reasons
IMHO various coatings will overwhelm some factors in engine design as will completely sealed lubrication system components along with such things as electric oil pumps etc
Originally Posted By: sunruh
where you can use them, ceramic roller bearings are the choice.
I'll agree. Expensive, and if your crank is in a plain bearing set up, well, it's even better as there should be no physical contact like even a ceramic roller bearing. Then the coatings can retain or shed oil depending on the application.
where you can use them, ceramic roller bearings are the choice.
I'll agree. Expensive, and if your crank is in a plain bearing set up, well, it's even better as there should be no physical contact like even a ceramic roller bearing. Then the coatings can retain or shed oil depending on the application.
I have had Calico coat my Main bearings on my BBC for years. Wit use of methanol fuel it sure helps improve the life. Before that after 100 runs fatigue issue could be seen.
I'd say on a well built gas engine, using them is a wast of cash as the normal oil wedge should be all that's needed.
I'd say on a well built gas engine, using them is a wast of cash as the normal oil wedge should be all that's needed.
Since plain bearings should never touch the crank, what good is coating them?
Improved oil flow from the sheeting effect. The crank does come in contact with the bearing upon startup so it's a protective coating. Less friction allows easier starting by lessening the load. Improved thermal dynamics by transferring heat to the oil. The amount of friction that must be overcome to crank is substantial.
In addition, very high HP or very high rpms can potentially squeeze out the oil film and result in bearing journal contact.
In general though, engine bearing coatings are more of an added safety factor than for significant efficiency increases. There's an article floating around on the net of a Nascar team that had their bearings coated by Swaintech. Lost oil pressure during a race and the driver kept going for another few laps till a caution was called and he went into the pits, they rectified the problem and he managed to finish the race.
I had my main and rod bearings coated for this very reason. I'm using bi-metal bearings which are superior to tri-metal bearings in embedding any foreign material in the oil and have superior high temperature resistance (the lead babbitt top layer of tri-metals can be completely removed at lower heat than the silicon aluminum in the bi-metals), but they have poorer friction characteristics than the lead babbitt on tri-metal bearings.
These means that in the event of oil pressure loss, the bi-metal bearings could potentially weld to the journals much easier, so I had the bearings coated. The engine is a twin turbo 6G72 in a 3000GT VR4 that I run on tracks in the summer. Under very high sustained cornering loads on R-compound tires (the sump design is especially susceptible to long left-handers), it's possible to pull oil away from the pickup and potentially have the oilpump suck air, resulting in a loss of oil pressure. This is one of the reasons most dedicated race cars use a drysump system, but the cost to modify the car to install one has thus far been prohibitive. So far, the coated bearings + Accusump + larger capacity oilpan have worked.
Max
In general though, engine bearing coatings are more of an added safety factor than for significant efficiency increases. There's an article floating around on the net of a Nascar team that had their bearings coated by Swaintech. Lost oil pressure during a race and the driver kept going for another few laps till a caution was called and he went into the pits, they rectified the problem and he managed to finish the race.
I had my main and rod bearings coated for this very reason. I'm using bi-metal bearings which are superior to tri-metal bearings in embedding any foreign material in the oil and have superior high temperature resistance (the lead babbitt top layer of tri-metals can be completely removed at lower heat than the silicon aluminum in the bi-metals), but they have poorer friction characteristics than the lead babbitt on tri-metal bearings.
These means that in the event of oil pressure loss, the bi-metal bearings could potentially weld to the journals much easier, so I had the bearings coated. The engine is a twin turbo 6G72 in a 3000GT VR4 that I run on tracks in the summer. Under very high sustained cornering loads on R-compound tires (the sump design is especially susceptible to long left-handers), it's possible to pull oil away from the pickup and potentially have the oilpump suck air, resulting in a loss of oil pressure. This is one of the reasons most dedicated race cars use a drysump system, but the cost to modify the car to install one has thus far been prohibitive. So far, the coated bearings + Accusump + larger capacity oilpan have worked.
Max
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