Bore Tech JE pistons in Maney sleeve alloy?
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Re: Immediate request on Maney sleeve alloy?
Ok thanks Jim the bore plater wanted to know before ~$400 process committed to but will have to sacrifice Swain's Black Body exterior cylinder coating but easy enough to spray on some thin weapons grade stuff or leave raw for interesting contrast. Now need to tell em how much piston bore clearance to leave. I'm guessing .060" for first set of JSM pistons.
https://www.mt-llc.com/cylservice.php
Ok thanks Jim the bore plater wanted to know before ~$400 process committed to but will have to sacrifice Swain's Black Body exterior cylinder coating but easy enough to spray on some thin weapons grade stuff or leave raw for interesting contrast. Now need to tell em how much piston bore clearance to leave. I'm guessing .060" for first set of JSM pistons.
https://www.mt-llc.com/cylservice.php
lcrken
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Re: Immediate request on Maney sleeve alloy?
.060" might be a little much, maybe .006" would be better.
Seriously, I just checked the clearance today, and right now the pistons have about .002" clearance in the bore, and I was planning hone them to .0055" - .006" clearance. With your blower plans, I'd vote for .006".
Didn't realize the bore plating companies did the honing, but that sounds reasonable now that I think about it. Saves me the work, too. I'll wait to hear from you on details.
Ken
.060" might be a little much, maybe .006" would be better.
Seriously, I just checked the clearance today, and right now the pistons have about .002" clearance in the bore, and I was planning hone them to .0055" - .006" clearance. With your blower plans, I'd vote for .006".
Didn't realize the bore plating companies did the honing, but that sounds reasonable now that I think about it. Saves me the work, too. I'll wait to hear from you on details.
Ken
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Re: Immediate request on Maney sleeve alloy?
Ugh 00.00 brain static in posting haste. If not for exotic JSM short skirt forged pistons I'd feel better with .0065" for the extreme proving intervals. The plating similar to brass hobby sheet sissors can cut but stiff enough to resist deflection. Their video shows a hand size piece that came out a blown up engine. ugh. Cleaning-etching bath will remove any prior coat. One feature is better thermal conduction. Wish Peel well that long stroke friction limits too much fuel burn forcing. Turn around time ~2weeks. Opps there goes another new feature imaged-in dream machine.
Jeff was the tech that filled me in and confused on make and model question till I showed him Peels parts which got him off nice and into his own cycling love, which took us to the risky life style, like traffic and deer, which he said his best bud survived deer strikes, up to the fatal 8th a few year ago. Thanx for helping work Commando magic of our time left.
Ugh 00.00 brain static in posting haste. If not for exotic JSM short skirt forged pistons I'd feel better with .0065" for the extreme proving intervals. The plating similar to brass hobby sheet sissors can cut but stiff enough to resist deflection. Their video shows a hand size piece that came out a blown up engine. ugh. Cleaning-etching bath will remove any prior coat. One feature is better thermal conduction. Wish Peel well that long stroke friction limits too much fuel burn forcing. Turn around time ~2weeks. Opps there goes another new feature imaged-in dream machine.
Jeff was the tech that filled me in and confused on make and model question till I showed him Peels parts which got him off nice and into his own cycling love, which took us to the risky life style, like traffic and deer, which he said his best bud survived deer strikes, up to the fatal 8th a few year ago. Thanx for helping work Commando magic of our time left.
lcrken
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Re: Immediate request on Maney sleeve alloy?
Steve,
have you talked to these people? They've been around for a while, and even have some experience with supercharged motorcycles.
http://bore-tech.com/Carbide%20Bore%20Process
Ken
Steve,
have you talked to these people? They've been around for a while, and even have some experience with supercharged motorcycles.
http://bore-tech.com/Carbide%20Bore%20Process
Ken
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Re: Immediate request on Maney sleeve alloy?
OHhhh, good find Ken. I just talked to Bill that had a hand in the boosted air cooled cast iron sleeved Honda and said they ran its bore clearance at 0.0025". !!! Wow. Bore Tech's impregnating process does not add thickness like the Millienum Tech plating does so don't need to thin the sleeves as would be required by the Ni-Si-Carbide "thick" plating, which could be used to recover some bore wear. Bore Tech does a dry process so will not remove Swains exterior finish and costs about $100 less to boot. Bore Tech said the closer piston space is better on the bores and pistons d/t the extra side thrust of tippy short skirts. I asked about catching piston wear in time to just replace pistons before bore is bothered and told yep that's what their races are doing to save costs effectively. i asked if any oil cool jets use and told Nope. Bill said they are very busy so expect 5-6 weeks turn around time. So if an over heated salt lake air cooled supercharged land speeder on gasoline record taker can get away with half Norton standard clearance, I'd guess lets stick with more normal .005" or what it is right now and see what happens. i will be spraying water or water methanol so may not get too hot with the steam cleaning. Bill said just pack up cylinder and pistons with instructions and they'll process and send me a bill with shipping included. Can't wait to feel what its like to hang on to WOT down a mile long air strip.
OHhhh, good find Ken. I just talked to Bill that had a hand in the boosted air cooled cast iron sleeved Honda and said they ran its bore clearance at 0.0025". !!! Wow. Bore Tech's impregnating process does not add thickness like the Millienum Tech plating does so don't need to thin the sleeves as would be required by the Ni-Si-Carbide "thick" plating, which could be used to recover some bore wear. Bore Tech does a dry process so will not remove Swains exterior finish and costs about $100 less to boot. Bore Tech said the closer piston space is better on the bores and pistons d/t the extra side thrust of tippy short skirts. I asked about catching piston wear in time to just replace pistons before bore is bothered and told yep that's what their races are doing to save costs effectively. i asked if any oil cool jets use and told Nope. Bill said they are very busy so expect 5-6 weeks turn around time. So if an over heated salt lake air cooled supercharged land speeder on gasoline record taker can get away with half Norton standard clearance, I'd guess lets stick with more normal .005" or what it is right now and see what happens. i will be spraying water or water methanol so may not get too hot with the steam cleaning. Bill said just pack up cylinder and pistons with instructions and they'll process and send me a bill with shipping included. Can't wait to feel what its like to hang on to WOT down a mile long air strip.
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Re: Immediate request on Maney sleeve alloy?
Bore Tech said they know about tappered bores from early air craft days and some old motorcycles but no longer done for many decades, as no benefit at least in the shorter stroke 'newer' air coolled engines. They put on the coating by aburnishing tool which does not change bore dimensions. This bottom bore lack of heat expansion may be a big factor that comnoz pointed out of too much friction on our long strokes to make more power above some rpm threshold. I really like the idea of .0045 at top and .006" at bottom of ring travel. Now how do I attain that?
Bore Tech said they know about tappered bores from early air craft days and some old motorcycles but no longer done for many decades, as no benefit at least in the shorter stroke 'newer' air coolled engines. They put on the coating by aburnishing tool which does not change bore dimensions. This bottom bore lack of heat expansion may be a big factor that comnoz pointed out of too much friction on our long strokes to make more power above some rpm threshold. I really like the idea of .0045 at top and .006" at bottom of ring travel. Now how do I attain that?
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Re: Immediate request on Maney sleeve alloy?
BoreTech is the way to go. I solved some serious severe premature cylinder wall wear with BoreTech on the 750 and 500 cc Ultra Short Stroke builds. Do it hobot and you will not regret.
BoreTech is the way to go. I solved some serious severe premature cylinder wall wear with BoreTech on the 750 and 500 cc Ultra Short Stroke builds. Do it hobot and you will not regret.
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Re: Immediate request on Maney sleeve alloy?
Alrighty Dances, Ken filled me in on pleased Bore Tech users tonight and we've settled on .005" at top tapering out some towards cooler bottom. Ken said he began with 920 Maney cylinder with modern .002-.003" clearances as suggested by JE pistons then seized, then opened a 1000th or so then seized, ditto ditto til .005" ran fine. I ain't gonna hit boost w/o anti-detonation-cooling fluids so may not get as piston swollen as Ken's did. Ah to wear out pistons like tires and just flip in another set.
Alrighty Dances, Ken filled me in on pleased Bore Tech users tonight and we've settled on .005" at top tapering out some towards cooler bottom. Ken said he began with 920 Maney cylinder with modern .002-.003" clearances as suggested by JE pistons then seized, then opened a 1000th or so then seized, ditto ditto til .005" ran fine. I ain't gonna hit boost w/o anti-detonation-cooling fluids so may not get as piston swollen as Ken's did. Ah to wear out pistons like tires and just flip in another set.
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Re: Immediate request on Maney sleeve alloy?
You're taking a risk at .005" Especially with a blower etc. The feed back I've been getting says they are tight enough.
See a 750cc JE piston below that was run at .004" (this is not one of my lightweight pistons). Another thou ain't gonna do it. You are pushing the extremes with a blower and anything can (and usually does) happen.
Below - Lightweight 750cc piston run at .0055 for half a racing season (your larger piston needs more)
Don't underestimate how much a forged pistons needs to expand or how much a Norton overheats with its inadequate fins.
hobot said:
You're taking a risk at .005" Especially with a blower etc. The feed back I've been getting says they are tight enough.
See a 750cc JE piston below that was run at .004" (this is not one of my lightweight pistons). Another thou ain't gonna do it. You are pushing the extremes with a blower and anything can (and usually does) happen.
Below - Lightweight 750cc piston run at .0055 for half a racing season (your larger piston needs more)
Don't underestimate how much a forged pistons needs to expand or how much a Norton overheats with its inadequate fins.
lcrken
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Re: Immediate request on Maney sleeve alloy?
Correction time again. The history I told Steve about with 920 kits and forged pistons was not with Maney cylinders. This was way before Steve started making cylinders, and I was using stock iron cylinders sleeved to 81 mm bore. And it wasn't with JE pistons, because they weren't making Norton pistons back then. When I started working with 920 conversions in the late '70s I used pistons from Forgedtrue, Arias, and Venolia. They sold them with clearance recommendations in the.002" - .003" range, and I had immediate seizures when I tried to use those clearances on race engines. I went through a process of honing to larger clearances until I settled on .005" as the tightest clearance I could use and still not have seizures. Even at that clearance, if I got stupid and tried to go out on the track and run hard with a cold engine, I probably would have had seizure issues. I later used cast 920 pistons from Fair Spares, and they also worked well at .005" clearance. I've run 920s in race bikes with up to .010" of clearance and still had them work well on the track, although with more crankcase blowby, and probably a bit less horsepower. I wouldn't recommend that, but sometimes you just do what you have to in order to make the next race. FWIW, after I found a minimum clearance that would work, I discovered that I had to use a bore plate for boring and honing if I wanted to have decent ring seal at the top of the cylinder for the 81 mm bores, but that's another story, and I've already posted pictures of that somewhere on the forum.
Ken
hobot said:
Correction time again. The history I told Steve about with 920 kits and forged pistons was not with Maney cylinders. This was way before Steve started making cylinders, and I was using stock iron cylinders sleeved to 81 mm bore. And it wasn't with JE pistons, because they weren't making Norton pistons back then. When I started working with 920 conversions in the late '70s I used pistons from Forgedtrue, Arias, and Venolia. They sold them with clearance recommendations in the.002" - .003" range, and I had immediate seizures when I tried to use those clearances on race engines. I went through a process of honing to larger clearances until I settled on .005" as the tightest clearance I could use and still not have seizures. Even at that clearance, if I got stupid and tried to go out on the track and run hard with a cold engine, I probably would have had seizure issues. I later used cast 920 pistons from Fair Spares, and they also worked well at .005" clearance. I've run 920s in race bikes with up to .010" of clearance and still had them work well on the track, although with more crankcase blowby, and probably a bit less horsepower. I wouldn't recommend that, but sometimes you just do what you have to in order to make the next race. FWIW, after I found a minimum clearance that would work, I discovered that I had to use a bore plate for boring and honing if I wanted to have decent ring seal at the top of the cylinder for the 81 mm bores, but that's another story, and I've already posted pictures of that somewhere on the forum.
Ken
lcrken
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Re: Immediate request on Maney sleeve alloy?
I wouldn't disagree with that, Jim. Bore-Tech seems to think that you can use a bit tighter clearance with their coating, so Steve has settled on .005" at top of cylinder, with taper to .006" at bottom. I guess we'll see how it works out.
Ken
jseng1 said:
I wouldn't disagree with that, Jim. Bore-Tech seems to think that you can use a bit tighter clearance with their coating, so Steve has settled on .005" at top of cylinder, with taper to .006" at bottom. I guess we'll see how it works out.
Ken
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Re: Immediate request on Maney sleeve alloy?
For another data point, I ran 10.25:1 compression ratio Omega pistons in my street 850 Commando, mild cam and cast iron barrel at 0.0045" clearance. The bike ran with 10 psig boost - no piston or scuffing problems. Your results may vary. I don't recall if the pistons were cast or forged; maybe someone else can chime in on that matter.
Heat was phenomenal and left me with the distinct impression that the Norton twin could handle lots of heat. Lubrication was Kendall racing (I recall it as straight 50) and a Lockhart oil cooler. I think Kendall used petroleum from the blood of organically raised dinosaurs. Pistons and plugs came out as clean as a whistle.
This bike never received a BoreTech treatment (circa 1976) but the treatment provides other qualities in addition to improved durability over liners.
For another data point, I ran 10.25:1 compression ratio Omega pistons in my street 850 Commando, mild cam and cast iron barrel at 0.0045" clearance. The bike ran with 10 psig boost - no piston or scuffing problems. Your results may vary. I don't recall if the pistons were cast or forged; maybe someone else can chime in on that matter.
Heat was phenomenal and left me with the distinct impression that the Norton twin could handle lots of heat. Lubrication was Kendall racing (I recall it as straight 50) and a Lockhart oil cooler. I think Kendall used petroleum from the blood of organically raised dinosaurs. Pistons and plugs came out as clean as a whistle.
This bike never received a BoreTech treatment (circa 1976) but the treatment provides other qualities in addition to improved durability over liners.
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Re: Immediate request on Maney sleeve alloy?
Ugh JSM, thanx for the expensive views of thrilling useage. I stand corrected Ken on the missing details you earned the hard way. I just want to be a pilot on just a need to know amount of engine issues. I want to believe most in John's/Dancers boosted report than the rest of ya'lls. Help me reason out what the data implies. I've got lawn mower twin bores to recover ahead of Peel's deal too that'll get Bore Tech after examine and conversation today with small engine builder that said they quit rehoning or reboring cast iron bores as just didn't last a season so best they'd try was new rings and hope for the best. He also reasoned the hardened surface was lost in the process. The garden tractor guys can get similar or more power per displacement than most Commandos. Ken reminded me its the speed of rings friction on bores that stifles hi rpm power in our long strokes. What would Kenny Dreer do?
http://www.homebuiltairplanes.com/forum ... nders.html
How does the head and cylinder fasteners tend to distort bores?
Does ring or piston bind happen more at TDC or BDC or inbetween?
Do Maney alloy spin cast iron bores expand more or less than the Norton barrels?
Does the forged JE piston expand more or less than the bores?
How much does upper bore expand in comparison to lower bore?
I think Peel will have enough of power even with some non-optimal clearance fudging and now is the time to nail down experimental spending. Peel will have adjustable amounts of water or windshield fluid so heat might not be as harsh as some racers but the pressure will be higher. Ain't looked up my mower boxer engine clearances nor what the insane pullers do but will soon.
Ugh JSM, thanx for the expensive views of thrilling useage. I stand corrected Ken on the missing details you earned the hard way. I just want to be a pilot on just a need to know amount of engine issues. I want to believe most in John's/Dancers boosted report than the rest of ya'lls. Help me reason out what the data implies. I've got lawn mower twin bores to recover ahead of Peel's deal too that'll get Bore Tech after examine and conversation today with small engine builder that said they quit rehoning or reboring cast iron bores as just didn't last a season so best they'd try was new rings and hope for the best. He also reasoned the hardened surface was lost in the process. The garden tractor guys can get similar or more power per displacement than most Commandos. Ken reminded me its the speed of rings friction on bores that stifles hi rpm power in our long strokes. What would Kenny Dreer do?
Bore "choke" leave aircraft builders mystified too.
http://www.homebuiltairplanes.com/forum ... nders.html
http://www.vansairforce.com/community/s ... hp?t=12521
How does the head and cylinder fasteners tend to distort bores?
Does ring or piston bind happen more at TDC or BDC or inbetween?
Do Maney alloy spin cast iron bores expand more or less than the Norton barrels?
Does the forged JE piston expand more or less than the bores?
How much does upper bore expand in comparison to lower bore?
I think Peel will have enough of power even with some non-optimal clearance fudging and now is the time to nail down experimental spending. Peel will have adjustable amounts of water or windshield fluid so heat might not be as harsh as some racers but the pressure will be higher. Ain't looked up my mower boxer engine clearances nor what the insane pullers do but will soon.
Re: Immediate request on Maney sleeve alloy?
Using boring plates top and bottom when sizing cylinder should circumvent any concern regarding fastener distortion.
Regarding the last 2 questions, perhaps incite can be gained by applying the coefficients of thermal expansion (CTE) to a model system (850 CDO with 77 mm bore) consisting of a forged aluminum piston from 2618 alloy (JE) and a grey cast iron cylinder, and simply looking at how the bore and piston dimensions change with temp. Assembling a small data table with these values, taken over a range of temperature, allows one to examine the piston fit at each temp. Likewise you can observe bore dimensions at each temp, estimate what sort of temperature gradient you are seeing in your mind's eye from cylinder top to bottom, and note differences in bore dia from the top to bottom of bore. The values used for CTE were 11.4 for 2618 alloy and 5.8 for cast iron (u inch/inch-F). The starting RT clearance was set at 0.005". All values in the table are in inches.
Note that the data suggest very little clearance exists at 350F, and at 400F piston/bore interference occurs. Regarding bore dimensions at cylinder top and bottom, if we assume a temperature gradient exists whereby the top were 400F and the bottom were 250F, the bottom would be ~ 0.003" smaller dia.
Hope this helps with your mental gymnastics on this front.
hobot said:
Using boring plates top and bottom when sizing cylinder should circumvent any concern regarding fastener distortion.
Regarding the last 2 questions, perhaps incite can be gained by applying the coefficients of thermal expansion (CTE) to a model system (850 CDO with 77 mm bore) consisting of a forged aluminum piston from 2618 alloy (JE) and a grey cast iron cylinder, and simply looking at how the bore and piston dimensions change with temp. Assembling a small data table with these values, taken over a range of temperature, allows one to examine the piston fit at each temp. Likewise you can observe bore dimensions at each temp, estimate what sort of temperature gradient you are seeing in your mind's eye from cylinder top to bottom, and note differences in bore dia from the top to bottom of bore. The values used for CTE were 11.4 for 2618 alloy and 5.8 for cast iron (u inch/inch-F). The starting RT clearance was set at 0.005". All values in the table are in inches.
Note that the data suggest very little clearance exists at 350F, and at 400F piston/bore interference occurs. Regarding bore dimensions at cylinder top and bottom, if we assume a temperature gradient exists whereby the top were 400F and the bottom were 250F, the bottom would be ~ 0.003" smaller dia.
Hope this helps with your mental gymnastics on this front.
Re: Immediate request on Maney sleeve alloy?
On a somewhat unrelated note I've recently seen some info on an abradable powder coat (APC) for pistons by Line2Line Coatings. Some info and videos are available here.
http://www.line2linecoatings.com/
There was also a short write-up on it in last month's Engine Builder mag, a link to which is attached below
http://www.enginebuildermag.com/2014/03 ... ng-longer/
As I understand their technology (this is my interpretation not necessarily the correct interpretation) I believe a low COF abradable powder coating is applied to the piston, slightly thicker than required to achieve proper piston/bore clearance, and in use, the coating is partially consumed (abraded away by bore friction) up to the point that proper clearance is established and thereafter, sufficient coating remains to protect the piston skirt and no/minimal wear occurs thereafter. It is recommended that this wear-in protocol occur over several thermal and load cycles so the abradable coating is removed incrementally (akin to an old fashioned break-in protocol) as break-in load and temperature increase.
Thereafter the coating remains stable (I believe it is textured, but am unaware of the scale of the texture), maintains proper clearance and imparts a low COF and proper oil film thickness to the piston skirt. In this situation the piston and bore are supposedly happy, piston fit and oil film thickness are optimum, which in turn makes the rings happy and keeps friction to a minimum.
To be clear, I'm by no means an advocate of this technology, just bringing it up for the edification of the forum and airing it out as a possibility for consideration in the hobot project. In fact I'm a firm advocate that the technology is not required in applications where materials and clearances are well understood and temperature is well controlled.
That said, if my description above is correct (and that's a big "if"), it seems like APC might provide a reasonable technical approach for the hobot application, and might afford a measure of latitude not offered by any other means.
Consider the following. We're presently debating proper piston fit for this project, and if the wrong clearance is chosen the results are catastrophic. I think it's well established that Norton's run on the warm end of the air-cooled engine spectrum and therefore piston clearance must also be on the generous end of the piston fit spectrum. Hobot is not making "your father's" Norton, he is making a fire-breathing dragon that might be 2-3X the HP of a stocker, and since power is heat and vice versa, he will be making heat unlike anything normally encountered. It would therefore follow that he may likely need piston/bore clearance unlike anything normally encountered.
Bringing this back around to the APC coating, what if …… the piston and bore were sized conventionally for a clearance of 0.007". Subsequently, the piston was APC coated to reduce the piston/bore clearance to 0.0045". The engine would then be assembled with a piston/bore fit of 0.0045", with the ability to grow, via abrasion of the APC coating, an additional 0.0025", all the way to 0.007" if necessary. Or viewed another way, if conventional piston fitting resulted in seizure occurring in the range of 0.0045 to 0.0055", this approach should afford an additional 0.0015" of bore clearance, which might be the difference between
and :cry: .
Hopefully some food for thought.
On a somewhat unrelated note I've recently seen some info on an abradable powder coat (APC) for pistons by Line2Line Coatings. Some info and videos are available here.
http://www.line2linecoatings.com/
There was also a short write-up on it in last month's Engine Builder mag, a link to which is attached below
http://www.enginebuildermag.com/2014/03 ... ng-longer/
As I understand their technology (this is my interpretation not necessarily the correct interpretation) I believe a low COF abradable powder coating is applied to the piston, slightly thicker than required to achieve proper piston/bore clearance, and in use, the coating is partially consumed (abraded away by bore friction) up to the point that proper clearance is established and thereafter, sufficient coating remains to protect the piston skirt and no/minimal wear occurs thereafter. It is recommended that this wear-in protocol occur over several thermal and load cycles so the abradable coating is removed incrementally (akin to an old fashioned break-in protocol) as break-in load and temperature increase.
Thereafter the coating remains stable (I believe it is textured, but am unaware of the scale of the texture), maintains proper clearance and imparts a low COF and proper oil film thickness to the piston skirt. In this situation the piston and bore are supposedly happy, piston fit and oil film thickness are optimum, which in turn makes the rings happy and keeps friction to a minimum.
To be clear, I'm by no means an advocate of this technology, just bringing it up for the edification of the forum and airing it out as a possibility for consideration in the hobot project. In fact I'm a firm advocate that the technology is not required in applications where materials and clearances are well understood and temperature is well controlled.
That said, if my description above is correct (and that's a big "if"), it seems like APC might provide a reasonable technical approach for the hobot application, and might afford a measure of latitude not offered by any other means.
Consider the following. We're presently debating proper piston fit for this project, and if the wrong clearance is chosen the results are catastrophic. I think it's well established that Norton's run on the warm end of the air-cooled engine spectrum and therefore piston clearance must also be on the generous end of the piston fit spectrum. Hobot is not making "your father's" Norton, he is making a fire-breathing dragon that might be 2-3X the HP of a stocker, and since power is heat and vice versa, he will be making heat unlike anything normally encountered. It would therefore follow that he may likely need piston/bore clearance unlike anything normally encountered.
Bringing this back around to the APC coating, what if …… the piston and bore were sized conventionally for a clearance of 0.007". Subsequently, the piston was APC coated to reduce the piston/bore clearance to 0.0045". The engine would then be assembled with a piston/bore fit of 0.0045", with the ability to grow, via abrasion of the APC coating, an additional 0.0025", all the way to 0.007" if necessary. Or viewed another way, if conventional piston fitting resulted in seizure occurring in the range of 0.0045 to 0.0055", this approach should afford an additional 0.0015" of bore clearance, which might be the difference between
and :cry: .Hopefully some food for thought.
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Re: Immediate request on Maney sleeve alloy?
Whoa WZ that some brain swelling stuff to take in. Peel's bore's could get into 600'F+ for a time. Your data implies over 6000th's possible, ugh. I've not time enough to post the rules of thumb on bossted applications and special fuel but adding a couple to 3+ 1000th's is usually recommend, more so on bigger bores. On the other hand Peel has piston, chamber, valves and ports ceramic insulated coated which they claim to reduce clearance needs not to mention the carbide Bore Tech.
Going by educated judgement
Or by the calculated numbers
Time to change subject line to Bore Tech compromises.
Whoa WZ that some brain swelling stuff to take in. Peel's bore's could get into 600'F+ for a time. Your data implies over 6000th's possible, ugh. I've not time enough to post the rules of thumb on bossted applications and special fuel but adding a couple to 3+ 1000th's is usually recommend, more so on bigger bores. On the other hand Peel has piston, chamber, valves and ports ceramic insulated coated which they claim to reduce clearance needs not to mention the carbide Bore Tech.
Going by educated judgement
Or by the calculated numbers
Time to change subject line to Bore Tech compromises.
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Re: Immediate request on Maney sleeve alloy?
Not trying to suggest you go out and do what I have done in this instance, just stating the facts of my experience but this brings up some interesting aspects to the discussion.
The engine/blower combination I described earlier was something I would not try as a combination today and back then I even knew I really should have been starting with lower compression pistons and different cam but the question is "why didn't I have problems with it?"
Today I can only speculate that the engine survived the combination of pistons, compression ratio and boost by way of a more aggressive cam overlap which allowed more blow through at lower rpms. I seem to recall Tom Drouin recommending a stock cam whereas I was using something a little more "racier" than stock. This in conjunction with the blower delivery curve (ie higher boost at higher rpm) probably kept the real high volumetric efficiencies limited to higher rpm WOT situations. Call it dumb luck? The facts are no scuffing and incredible heat. I attributed most of the heat due to the parasitic (I think that is the appropriate term) losses associated with driving the blower. I'll see if I can come up with a power versus rpm for 10 psig curve or table assuming some volumetric efficiency as it would be intersting to see how much crankshaft power goes into driving the blower.
As for the BoreTech, it has saved my hide on two builds but this was in the context of alloy barrels with sleeves. I read that the BoreTech process also provides enhanced lubrication retention properties which I assume translates to lower friction thus less heat. I don't think I would use BoreTech on stock or bored Commando cast iron barrels as they seem to perform very well as is.
As I understand your situation Steve, you are using Alloy barrels with sleeves so read the various experiences and you decide. I would also recommend the piston skirt treatments to reduce skirt scuffing. I had used a product similar to GunKote; look for the Molybedenum type and not the PTFE type. Mr. Canaga knows his stuff and I would follow his guidance for clearance. I think an awful lot has to do with throttle time (duty cycle) so with Ken's and other's scuffing experience ask what the application was. As an example, a land speed record or road race machine will have different WOT durations than a street application. There's a lot of balancing and weighing of information to be done but err on the side of caution.
Look at it this way, go liberal with clearance as you will probably loose little max power and will likely increase blow-by by some amount and if you don't like it and want to push the envelope you can simply buy and install new sleeves and bore to a slightly tighter fit but if you go too tight at first you may be into new pistons and sleeves and maybe a new motor. Manage your risks accordingly and have fun.
hobot said:
Not trying to suggest you go out and do what I have done in this instance, just stating the facts of my experience but this brings up some interesting aspects to the discussion.
The engine/blower combination I described earlier was something I would not try as a combination today and back then I even knew I really should have been starting with lower compression pistons and different cam but the question is "why didn't I have problems with it?"
Today I can only speculate that the engine survived the combination of pistons, compression ratio and boost by way of a more aggressive cam overlap which allowed more blow through at lower rpms. I seem to recall Tom Drouin recommending a stock cam whereas I was using something a little more "racier" than stock. This in conjunction with the blower delivery curve (ie higher boost at higher rpm) probably kept the real high volumetric efficiencies limited to higher rpm WOT situations. Call it dumb luck? The facts are no scuffing and incredible heat. I attributed most of the heat due to the parasitic (I think that is the appropriate term) losses associated with driving the blower. I'll see if I can come up with a power versus rpm for 10 psig curve or table assuming some volumetric efficiency as it would be intersting to see how much crankshaft power goes into driving the blower.
As for the BoreTech, it has saved my hide on two builds but this was in the context of alloy barrels with sleeves. I read that the BoreTech process also provides enhanced lubrication retention properties which I assume translates to lower friction thus less heat. I don't think I would use BoreTech on stock or bored Commando cast iron barrels as they seem to perform very well as is.
As I understand your situation Steve, you are using Alloy barrels with sleeves so read the various experiences and you decide. I would also recommend the piston skirt treatments to reduce skirt scuffing. I had used a product similar to GunKote; look for the Molybedenum type and not the PTFE type. Mr. Canaga knows his stuff and I would follow his guidance for clearance. I think an awful lot has to do with throttle time (duty cycle) so with Ken's and other's scuffing experience ask what the application was. As an example, a land speed record or road race machine will have different WOT durations than a street application. There's a lot of balancing and weighing of information to be done but err on the side of caution.
Look at it this way, go liberal with clearance as you will probably loose little max power and will likely increase blow-by by some amount and if you don't like it and want to push the envelope you can simply buy and install new sleeves and bore to a slightly tighter fit but if you go too tight at first you may be into new pistons and sleeves and maybe a new motor. Manage your risks accordingly and have fun.
- Status