Long-rod BP build underway
02-29-2012, 09:56 AM
#41
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Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
maybe a block heater is your best option...
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02-29-2012, 10:42 AM
#42
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
The 2.0L race motor we just built with Supertechs is silent.
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02-29-2012, 11:24 AM
#43
Emilio and Sav, I understand you both have done extensive sonic measuring of the BP blocks. I would like to know if boring to 85mm would be acceptable in a turbo build if boost pressures were kept to about 18-20 psi. How thin were the readings at 85 mm? Did they vary much block to block? Did one year of engine block happen to be better than another?
Thanks
Thanks
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02-29-2012, 12:52 PM
#44
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More geeky deets, this time on the JE pistons. FSR, yo.
http://blogs.insideline.com/roadtest...the-house.html
http://blogs.insideline.com/roadtest...the-house.html
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02-29-2012, 01:01 PM
#45
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Emilio and Sav, I understand you both have done extensive sonic measuring of the BP blocks. I would like to know if boring to 85mm would be acceptable in a turbo build if boost pressures were kept to about 18-20 psi. How thin were the readings at 85 mm? Did they vary much block to block? Did one year of engine block happen to be better than another?
Thanks
Thanks
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02-29-2012, 04:42 PM
#47
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
Cast pistons are probably not a bad idea for a long term DD
.
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02-29-2012, 07:08 PM
#49
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Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
Are rings really that much harder than the cylinder walls?
My Weisco's squeak when hot. Or kinda moan.
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03-01-2012, 01:38 AM
#50
The biggest thing is you lose oil control when the gudgeon pin intersects the oil control groove like that. Thats why FM has everyone delete their oil squirters on their stroker kits. 
I don't really feel like checking the difference in g-loading, but a longer rod should theoretically only reduce piston G's by maybe 1 to 2 percent by increasing the amount of dpistondisplacement/dtheta around TDC. This also theoretically increases engine breathing by a small amount by allowing more time for intake valves to open before the piston begins traveling down the bore.
Maximum gain? 1% higher RPM limit? 2-3% in output, but not exceeding previous knock limits?
Innovation is good, but value is calling. Then again I could be missing something. Who knows?
4032
2618
I don't really feel like checking the difference in g-loading, but a longer rod should theoretically only reduce piston G's by maybe 1 to 2 percent by increasing the amount of dpistondisplacement/dtheta around TDC. This also theoretically increases engine breathing by a small amount by allowing more time for intake valves to open before the piston begins traveling down the bore. Maximum gain? 1% higher RPM limit? 2-3% in output, but not exceeding previous knock limits?
Innovation is good, but value is calling. Then again I could be missing something. Who knows?
4032
- 2.68 g/cc
- 52ksi yield
- 16ksi fatigue
- 38ksi shear
- 10.8uin/in F* CTE
2618
- 2.76 g/cc
- 54ksi yield
- 18ksi fatigue
- 38ksi shear
- CTE 13.4uin/in F*
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03-01-2012, 06:08 PM
#52
Question on the 2618 alloy. Since it has a higher rate of thermal expansion, and thus requires larger clearances, doesn't this mean that on a "daily" engine, were the engine spends a significant amount of time in cold condition, the cylinder walls will wear down a lot quicker, promoting an oval-like shape and losing compression in no time at all?
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
This seems like an alloy ideal for racing applications, where you don't actually expect an engine to last more than 10,000-20,000 racing miles.
Historically, the slap noise really has been the biggest driving factor on whether to use 2618 or not, and that's why they designed the FSR forging to accomodate pin offset if so desired. Pin offset essentially preloads the major thrust side skirt so that it doesn't rock over and slap. The tradeoff to pin offset is a bit more side loading.
Last edited by JKav; 03-01-2012 at 06:24 PM.
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03-01-2012, 07:52 PM
#53
The only reason I said that I said is because of my experience with 347 V8 Ford strokers. Every kit that intersected the oiling groove burnt oil. Every kit that didn't controlled the oil. This is the actual reason FM has you delete the oil squirters. The additional oil is not able to be controlled by a compromised oil groove.
Its well known within the V8 community that compromising that ring groove makes life hard.
And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons.
The belief that every stroker engine uses oil is a myth. There are several factors to consider when building an engine in order to have proper oil control. But it's especially critical with stroker engines where the lower oil ring is in the wristpin hole.
Read more: http://www.mustang50magazine.com/tec...#ixzz1nuqA0HSN
Read more: http://www.mustang50magazine.com/tec...#ixzz1nuqA0HSN
And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons.
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03-01-2012, 09:55 PM
#54
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So if I recall from back in the day in sport compact car, they did a big shtick on Swain coatings--particularly ceramic piston top coatings.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too.
I didnt re-read this since I read it originally in print but here's the article:
http://www.modified.com/projectcars/...vii/index.html
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too.
I didnt re-read this since I read it originally in print but here's the article:
http://www.modified.com/projectcars/...vii/index.html
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot.
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03-02-2012, 12:55 AM
#55
The only reason I said that I said is because of my experience with 347 V8 Ford strokers. Every kit that intersected the oiling groove burnt oil. Every kit that didn't controlled the oil. This is the actual reason FM has you delete the oil squirters. The additional oil is not able to be controlled by a compromised oil groove.
Its well known within the V8 community that compromising that ring groove makes life hard.
And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons.
Its well known within the V8 community that compromising that ring groove makes life hard.
And consequently the deletion of the oil squirters increase piston temperature and decrease piston life. The same 2618 alloy at 600*F has just 2030 psi of yield strength. While that same piston at 300*F has 49000 psi of yield strength (a 96% reduction in strength in just 300*F of change). Now considering combustion temperatures can easily exceed 1500F in these high output combos you need every bit of help you can get to maintain the strength of the aluminum in the pistons.
Something else is going on if consumption increases. With a proper support rail for the oil control ring, there's no difference compared to ordinary pistons.
Agreed 100% that deleting the squirters is a horrible idea.
So if I recall from back in the day in sport compact car, they did a big shtick on Swain coatings--particularly ceramic piston top coatings.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too.
I didnt re-read this since I read it originally in print but here's the article:
http://www.modified.com/projectcars/...vii/index.html
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot.
The intent was to keep heat out of the piston if I recall. I guess both to reduce thermal expansion and help maintain tensile strength. I think they even said they ran slightly tighter clearances too.
I didnt re-read this since I read it originally in print but here's the article:
http://www.modified.com/projectcars/...vii/index.html
edit: I have a minor issue with Swain using a "Jesus Fish" in their magazine ads but there are quite a few other coating companies out there now so it is mostly moot.
That said, I do like dlc coating esp on valve buckets. Nice on wrist pins too, since you can then delete the bushing and save some more rod mass. Spendy, though.
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03-02-2012, 09:32 AM
#57
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I saw that fish on cars for 20 years before I learned what it meant. By that time though, I was already a Satinist.
Hmm, so you mean it goes into the valves and the um, valve dome? Wouldn't some of that heat also be pushed out when the valves open?
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