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Originally Posted by falcon
(Post 634999)
I think there is a bit of misunderstanding as to how I will break the engine in. I'm not going to baby the hell out of it for that long. I've broken in a few engines before as well as motorcycles, I know that you need a lot of engine braking/compression braking and accelerations through the gears, not staying int he same gear/RPM for long periods of time etc.. All I said was there will be an RPM limit for a predetermined time... that's it. And no boost until he gives me the go ahead. Which is fine considering he is the one building and tuning the engine.
You know, just on a similar note, i've heard of people cutting open their oil filters after that first 50 or so miles. I still dont understand the point of this. |
I don't know either... but it's what's required to ensure he stands behind the motor.
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Originally Posted by falcon
(Post 635010)
I don't know either... but it's what's required to ensure he stands behind the motor.
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All this bologna makes me wanna just use stock pistons lol
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What is stock piston/wall clearance? Just out of curiosity.
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I think its like 0.0015-0.0020" or something very close to that.
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Originally Posted by wayne_curr
(Post 635009)
I'm just curious what this extra long time period of a low rev-limit is suppose to accomplish. If I hear some good reasoning i'll possibly stop taking my engines to redline within 15 minutes of the first start.
You know, just on a similar note, i've heard of people cutting open their oil filters after that first 50 or so miles. I still dont understand the point of this. |
Originally Posted by falcon
(Post 635001)
Yes.
I'm running .004 according to my builder who just replied to my email. |
Have you talked to other customers?
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Originally Posted by falcon
(Post 635020)
What is stock piston/wall clearance? Just out of curiosity.
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Exactly Sav.... you would agree that is the concern. How much larger is his than stock? Not enough?
Just think about it for a sec, I'm not sure if he was implying that when he posed the question but thats how I took it. |
It doesn't really matter how much larger it is vs. stock - you're drastically changing the design of the piston, which requires that you appropriately alter the environment that piston will be living in. Mazda could use unobtanium pistons that do not expand at all with heat, thus requiring a wall clearance that would approach zero - but it wouldn't matter at all if you're replacing them with Supertechs that require a minimum of .0028" wall clearance.
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Originally Posted by wayne_curr
(Post 634992)
The reason is that increased pressure/vacuum pushes/pulls the rings against the cylinder bore with a greater force than just their "springiness". Thusly, the cross-hatch is able to wear the rough spots off of the rings more quickly. Supposedly over time the rings will wear the cross hatch down rather than shave the imperfections off of the rings so they are perfectly in match with the cylinder bore.
This is how I understand it anyway. Someone smarter than me will likely correct me. I'm no injuneer. But using this logic, it makes sense that breaking it in like a man will get those rings in shape rather quickly. I like to think of this as setting the pace for the type of life the engine will be living. I also have piece of mind in knowing that if anything horrible is going to go wrong, it'll go wrong in that first 20 miles of absolute abuse. Full-blown abuse is not good, since it produces too much pressure and thus too much heat, which will glaze the walls - too little abuse will not produce enough pressure and the rings will glaze the walls as well. The deceleration part is important as well since it draws oil up onto the walls, cooling the rings/walls and carrying away the small metal particles the ring is shaving off. |
Originally Posted by falcon
(Post 634686)
I don't really care what others have done. I did my research and brought it forward to him when I dropped the engine off with the parts. I'm not an expert at building engines, and can only regurgitate what I see online. When I told him what others were running for clearance he basically laughed at me and said if I run the same the motor will not last very long. There's a reason I pay others to do things I don't know about... for their experience/skill/knowledge on the subject. And I'll take his word on what needs to be done over a few guys on the internet. I'm sure yours, Sav's and Snowboarders engines run great...
Originally Posted by hustler
(Post 634687)
I want to know how this badass breaks-in motors for racecars. Does he make the owner strap the car to a dyno for 9-years?
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I have played the horsepower game for a lot of years, and have learned 2 things that are important.
Loose piston wall clearance makes horsepower, tight takes it away. There are trade-offs, but loose usually wont squeak pistons. I do hope with clearance as tight as Ocean wants, he at least uses deck plates to bore and hone, if not, I hope he has a warranty fund! |
Very interesting thread. If I were you, just follow what supertech specifies or at least listen to the people on this thread. I came to know about SuperTech on this forum, so many members talk good about them. Why do it differently? If what you want is test a different route good as well. Have the balls to put pictures on how the engine looks when it cracks in half and shitty dyno charts.
Looking forward for a Miata part-out thread... |
Holy shit, can some mod please delete the numbfuckskullery that is every single thing falcon has posted in this thread?
---- As for the theory behind this stuff, I am still not really convinced. Are rings softer than the cylinder or is it the other way around? Or are they the same? If they are same I'd think they'd wear at the same rate. I think this matters. |
I might be wrong about this as well, but here is how I understand it. The rings are softer than the block. The cross hatch acts kind of like sand paper to create a tight seal on a microscopic level. But over time, the rings get work hardened from the heat and pressures. So you only have a limited window in which to do perform the seating. If you push the engine too hot too fast, the rings harden and will never seat. Same deal if you don't push it at all because you don't get the force to press the rings into the cylinders before they are hardened. Again, I could be quite wrong with my limited knowledge of materials sciences.
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I'm interested in how this is turning out.
The spec sheet, that came with my supertech 85.5 9:1 pistons that I bought from emilio said this: Application: Factor: Street Performance 0.0045 Moderate turbo / Nitrous 0.0050 Drag/oval track 0.0055 Turbo/nitrous race only 0.0065 My builder and I decided to go with "Moderate turbo / Nitrous" 0.0050. He is not a miata guy, but does high HP subies and evos. I hope we didn't swing to far the other way. Well, thats if I ever get my motor back. I'll save this story for it's own thread. :( |
I think too hard break-in could deform the honed peaks into the valleys while a softer break-in rips off the peaks into the oil gradually. I would go gradually harder on the throttle and revs with occasional blips up even higher in the rev range in neutral to eliminate the formation of ridges on the wall by incomplete conrod stretch.
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