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CVO Technical => Twin Cam => Topic started by: skreminegul07 on October 08, 2008, 07:58:33 AM
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Can someone help me understand why Donny says that the heat in the 110" is due to the Compression Ration of only 9.3:1, and should be at least 10:1.
This is the full quote from this month on page 44. He also says an oil cooler would help. Doesn't he know the RK and ULtra's have them?
The CVO 110"
HD IS CURRENTLY HAVING BIG pronlems keeping the cVO 110" from overheating. The rear head gasket is blowing out, away from the oil return hole located between the cylinder and head. This is occurring after as little as 2000 miles of use. It is my belief that Harley had issues during the development of the CVO 110because the engine's compression ratio is low: a paltry 9.3:1. The stock TC 96 Twin Cam has a respectable compression ratio of 9.2:1, which is okay for a stock model. The TC 96 increases it's ratio by .4 points, up from the TC 88's ratio of 8.8:1. In a perfect world, the 110" engine needs a minimum ratio of 10:1 and preferably 10.5:1. Reduced compression ratios lower cylinder head temperatures and the probability of detonation. The addition of an oil cooler would assist in lowering the cylinder head temperatures, as well as control the devastating effects of ongoing detonation."
Does he mean the design was to have higher ratios but there was even more heat so they lowered the ratio? From what I learned here, the 255 cam causes some of these issues.
Comments?
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Can't comment on why but..... my compression is 10:1 on my 07 Ultra & doesn't seem to get as hot but I also have 575 Headquarters cams in as well. It was running never any hotter than 230 in Myrtle Beach last week. THE MUFFMAN
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Can someone help me understand why Donny says that the heat in the 110" is due to the Compression Ration of only 9.3:1, and should be at least 10:1.
This is the full quote from this month on page 44. He also says an oil cooler would help. Doesn't he know the RK and ULtra's have them?
The CVO 110"
HD IS CURRENTLY HAVING BIG pronlems keeping the cVO 110" from overheating. The rear head gasket is blowing out, away from the oil return hole located between the cylinder and head. This is occurring after as little as 2000 miles of use. It is my belief that Harley had issues during the development of the CVO 110because the engine's compression ratio is low: a paltry 9.3:1. The stock TC 96 Twin Cam has a respectable compression ratio of 9.2:1, which is okay for a stock model. The TC 96 increases it's ratio by .4 points, up from the TC 88's ratio of 8.8:1. In a perfect world, the 110" engine needs a minimum ratio of 10:1 and preferably 10.5:1. Reduced compression ratios lower cylinder head temperatures and the probability of detonation. The addition of an oil cooler would assist in lowering the cylinder head temperatures, as well as control the devastating effects of ongoing detonation."
Does he mean the design was to have higher ratios but there was even more heat so they lowered the ratio? From what I learned here, the 255 cam causes some of these issues.
Comments?
What he is theorizing is the compression ratio 9.3:1 is a result of the hot running engine - not the cause of the hot running engine - that the MOCO lowered the compression to lower operating temperatures and reduce the probability of detonation. He is suggesting the engine would perform better with more compression - but the MOCO could not build more compression into the motor due to heat. The amount of heat produced is greatly influenced by the geometry of the cams and the geometry of the cams is influenced by the EPA regulations.
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What he means is he doesn't really know. Anytime you compress something you PRODUCE HEAT!!!!! More compression equals more heat. Plain and simple. To cool it down you throw more fuel and more air into the cylinder.
Yes the cams and the A/F ratio are a direct result of EPA regs. The only way around it is to richen it up and let it flow more air.
Be Safe
THE DAWG
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What he means is he doesn't really know. Anytime you compress something you PRODUCE HEAT!!!!! More compression equals more heat. Plain and simple. To cool it down you throw more fuel and more air into the cylinder.
Yes the cams and the A/F ratio are a direct result of EPA regs. The only way around it is to richen it up and let it flow more air.
Be Safe
THE DAWG
Yep, exactly right. And Donnie is suggesting (guessing) that the paltry 9.3:1 compression ratio is because the MOCO had to reduce compression to reduce heat....
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Curious what the Mo Co did to lower the compresion? Head Gaskets????
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Curious what the Mo Co did to lower the compresion? Head Gaskets????
Probably left a gap at the rear cylinder to let air(oil) escape. THE MUFFMAN
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Probably left a gap at the rear cylinder to let air(oil) escape. THE MUFFMAN
too funny.
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too funny.
:huepfenlol2: :2vrolijk_21: :soapbox:
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What he is theorizing is the compression ratio 9.3:1 is a result of the hot running engine - not the cause of the hot running engine - that the MOCO lowered the compression to lower operating temperatures and reduce the probability of detonation. He is suggesting the engine would perform better with more compression - but the MOCO could not build more compression into the motor due to heat. The amount of heat produced is greatly influenced by the geometry of the cams and the geometry of the cams is influenced by the EPA regulations.
I have not read the article but Skreminegul07's first post it said the heat was because of the lower compression ratio. He then went on to say it should be at least 10.0 to 1. Did I miss something? Maybe I need to go pick up the mag and read it.
Be Safe
THE DAWG
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I was just looking at the specs for the 09 SE Ultra and noted that the compression ratio is at 9.15:1. Appears they've lowered even more. Since having performed the 0905 program on my bike with the new heads, I'm wondering if that is why the Ultras are getting new heads...to lower the compression ratio thereby reducing heat???
DCC
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I was just looking at the specs for the 09 SE Ultra and noted that the compression ratio is at 9.15:1. Appears they've lowered even more. Since having performed the 0905 program on my bike with the new heads, I'm wondering if that is why the Ultras are getting new heads...to lower the compression ratio thereby reducing heat???
DCC
Prolly accounts for a new thicker head gasket leak control system, is my guess. Just a guess though. Are the new HG's thicker? :nixweiss:
Hoist! 8)
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I have not read the article but Skreminegul07's first post it said the heat was because of the lower compression ratio. He then went on to say it should be at least 10.0 to 1. Did I miss something? Maybe I need to go pick up the mag and read it.
Be Safe
THE DAWG
That is what I have been trying to say, Dawg... I think Skremikngegul07 may have misinterpreted what Donnie was saying. Donnie was agreeing with what you are saying, he just chose convaluted words in how he said it. Donnie's point was that compression causes heat, and he thinks the MOCO lowered the compression in the 110 because they encountered excessive heat in the development of the motor. And that even with the lowered compression, the motor still runs to hot and as a result spit out head gaskets. At least that is how I interpret what Donnie said. Of course, I could be full of chit myself...but that's another story...
Scott
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I guess I need to read the article. They could of lowered the CR all they want I don't think that is all of the problem!!! It's funny the 103's were only 8.7 to 8.9 to 1 and they ran hot and just fine.
I still think the Cylinders were made overseas.
Be Safe
THE DAWG
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donny's a smart guy...seen some feedback from his customers at heavy duty and they love him...his articles are kinda loopy though...he needs a good editor