Bonneville Engine:
- Thread starter McRat
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Pat i'd talk to these guys, maybe they have a better coating solution?
http://www.swaintech.com/
maybe the weight penalty would be worth using Mahle Monotherm steel pistons if they have D-max slugs yet
http://www.swaintech.com/
maybe the weight penalty would be worth using Mahle Monotherm steel pistons if they have D-max slugs yet
I guess the only way to know for sure is ask Eric. I know you spent some time in his shop helping out (at least around Spring Fling 07), maybe you could give him a call and ask him as you have an "in".
Don't want it to shed oil. You want it to stick. Otherwise, you would need to arrange the spray pattern so it covers the entire surface adiquitly to cool each section.
JMO
JMO
So the piston underside isnt being adiquitly sprayed with oil? I know the squirters are aimed at the hole in the underside of the piston, but is there not any splashing going on.
You know what happens when oil sticks in a hot place too long.
You know what happens when oil sticks in a hot place too long.
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First, I'm not an oil cooling expert. Just some of what I have read and seen other applications do. Though most of the non-oil chambered applications are for gassers. Most heavy duty Diesels pistons use an oil chamber of some sort if they can manage it.
IF you don't have a oil chamber to inject oil into, you don't use a stream. You use a mist or other pattern that will coat the whole underside of the piston. Frequently the underside of these pistons are convoluted to both increase the surface area and direct the oil spray.
Diesel pistons suffer from their crown thickness which, almost regardless of the amount of oil sprayed under the piston, can't keep the upper surface cool.
To answer the question of oil in one place to long. Don't care about the oil. Care about the metal under it. If the oil isn't there the metal overheats. You want it to stick to everything.
At least that is how I understand it.
But what do I know.
IF you don't have a oil chamber to inject oil into, you don't use a stream. You use a mist or other pattern that will coat the whole underside of the piston. Frequently the underside of these pistons are convoluted to both increase the surface area and direct the oil spray.
Diesel pistons suffer from their crown thickness which, almost regardless of the amount of oil sprayed under the piston, can't keep the upper surface cool.
To answer the question of oil in one place to long. Don't care about the oil. Care about the metal under it. If the oil isn't there the metal overheats. You want it to stick to everything.
At least that is how I understand it.
But what do I know.
What I was saying is heat doesnt transfer to hot oil rapidly, the cooler the oil the better the heat will transfer. But with the thickness of these pistons I doubt if it would make a difference, like you said. In most racing applications you don't want oil to stick you want it to get in absorb heat and get out so the cooler oil behind can get in, IMHO. But, as you pointed out that only works when their is enough oil being sprayed on the underside of the piston.
you want the oil to be warm, believe the dispersant coatings just help oil flow, don't reflect it, should still have some cling. were the tops of just thermal coated or did they have dispersant also, that may help water injection vapor stay in cylinder and work against ignition front. just out of curiosity the cylinders that have white coating seem like the cylinders thats ports are close to intake, wonder if water injection is not breaking up and dispersing evenly with air. did you use distilled water or other water, white makes me think chlorides from water transfering to piston tops during combustion cycle. if you notice the range of clean to carbon tracing tapers off to rear cylinders. have you thought about manifolds like banks has, either do port injection of superfine mist water or last chance intercooler. noticed injector spray errosion on piston crown and tops might gain by adjusting spray pattern, number of injection ports may burn pull burn zone closer into piston hat or maybe delay injection pulse. the fuel injection pressure and heat moving with it during combustion is like taking torch to piston tops and will remove any coating eventually. wonder how actual ceramic(like porcelan) would work like they used originally in nascar, think they called it henium coating. these coatings were banned, not automotive, the newer stuff is made to be nonidentifiable for the most part, I.E.: camoflaged. think that the water may have cooled the cylinder walls and not the piston tops faster and pulled into piston, instead of piston out to cylinder wall.