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Lycoming Cylinder question

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drogers(at)maf.org
Guest

Posted: Sun Mar 18, 2007 9:59 am Post subject: Lycoming Cylinder question

I have some questions about Lycoming Cylinders.  I understand that all 

their 360 and 540 engines use the same size cylinders.  Also that there 

are 2 types of cylinders: Straight valve and Angle valve.  I know what 

the cylinders look like and can easily tell the difference but what are 

the differences in engine application?  How can you know whether a IO540 

L (for example, if there is such a thing) has one or the other type of 

cyl?  Do the high HP engines have one type and the Lower hp the other 

type?  Is one type of cylinder newer than the other?



Thanks,



Dan

wbecker(at)centurytel.net
Guest

Posted: Sun Mar 18, 2007 3:40 pm Post subject: Lycoming Cylinder question

I'm no expert but, The angle valve engines make more HP due to better 

flow. They are both manufactured currently. Bill B

---

glcasey(at)adelphia.net
Guest

Posted: Mon Mar 19, 2007 5:00 am Post subject: Lycoming Cylinder question

I'm not "the" Lycoming expert, but as far as I can tell everything  

with a power rating of 300 or more has the angle-valve cylinders.  A  

sure-fire way to tell is to look at the Lycoming spec sheet on their  

website and the parallel-valve engines are narrower.  Other than that  

the model numbers don't give much of a clue unless you just know  

which is which.  As Bill said, the angle-valve heads flow better.   

The naturally-aspirated versions have a 8.7 compression ratio vs. the  

8.5 of the parallel-valve engine, and that also helps to produce  

slightly more power.  With more space between the valves the angle- 

valve engine requires less pressure drop for cooling, theoretically  

reducing cooling drag.  But they are heavier, to the tune of 4 or 5  

pounds per cylinder and the angle-valve engines don't have the same  

reputation for longevity as the parallel-valve engines.  An expert  

told me that there is nothing to be gained by porting and polishing  

the angle-valve cylinder, while the parallel-valve version can be  

ported to achieve almost the same airflow as the angle-valve cylinder.

Gary Casey

Parallel-valve IO-540 with 10:1 compression dyno tested at 305 hp



 	  Quote: 	
		   From: Dan Rogers <drogers(at)maf.org>

 Subject: Lycoming Cylinder question

 I have some questions about Lycoming Cylinders.  I understand that all

 their 360 and 540 engines use the same size cylinders.  Also that  

 there

 are 2 types of cylinders: Straight valve and Angle valve.  I know what

 the cylinders look like and can easily tell the difference but what  

 are

 the differences in engine application?  How can you know whether a  

 IO540

 L (for example, if there is such a thing) has one or the other type of

 cyl?  Do the high HP engines have one type and the Lower hp the other

 type?  Is one type of cylinder newer than the other?



 Thanks,



 Dan

drogers(at)maf.org
Guest

Posted: Tue Mar 20, 2007 1:03 pm Post subject: Lycoming Cylinder question

Thank you, Gary and Bill,



I have now studied the Lycoming website engine lists and can see a clear 

relationship between comp ratio, engine width and weight.  There is also 

power corelation, but because of turbo and various RPM combinations, it 

is not as clear cut.



Thanks again,



Dan



Gary Casey wrote:

 	  Quote: 	
		   

 

 I'm not "the" Lycoming expert, but as far as I can tell everything with 

 a power rating of 300 or more has the angle-valve cylinders.  A 

 sure-fire way to tell is to look at the Lycoming spec sheet on their 

 website and the parallel-valve engines are narrower.  Other than that 

 the model numbers don't give much of a clue unless you just know which 

 is which.  As Bill said, the angle-valve heads flow better.  The 

 naturally-aspirated versions have a 8.7 compression ratio vs. the 8.5 of 

 the parallel-valve engine, and that also helps to produce slightly more 

 power.  With more space between the valves the angle-valve engine 

 requires less pressure drop for cooling, theoretically reducing cooling 

 drag.  But they are heavier, to the tune of 4 or 5 pounds per cylinder 

 and the angle-valve engines don't have the same reputation for longevity 

 as the parallel-valve engines.  An expert told me that there is nothing 

 to be gained by porting and polishing the angle-valve cylinder, while 

 the parallel-valve version can be ported to achieve almost the same 

 airflow as the angle-valve cylinder.

 Gary Casey

 Parallel-valve IO-540 with 10:1 compression dyno tested at 305 hp

apilot2(at)gmail.com
Guest

Posted: Tue Mar 20, 2007 1:57 pm Post subject: Lycoming Cylinder question

Probably just as important, the angle valve engines are designed for

more cooling, both in the cylinder head design, and with oil squirt

nozzles spraying oil on the bottom side of the pistons. The weight

increase is unfortunate, as it somewhat degrades the performance

increase. I would think that the angle valve cylinders would be more

desirable for turbocharging, with the better heat dissipation

capability. The one factory TIO540 with parallel valve cylinders that

I am familiar with, had to be retrofitted with oil cooled valve guides

to make the valve stems and guides last.



On 3/20/07, Dan Rogers <drogers(at)maf.org> wrote:

 	  Quote: 	
		   



 Thank you, Gary and Bill,



 I have now studied the Lycoming website engine lists and can see a clear

 relationship between comp ratio, engine width and weight.  There is also

 power corelation, but because of turbo and various RPM combinations, it

 is not as clear cut.



 Thanks again,



 Dan



 Gary Casey wrote:

 > 

 >

 > I'm not "the" Lycoming expert, but as far as I can tell everything with

 > a power rating of 300 or more has the angle-valve cylinders.  A

 > sure-fire way to tell is to look at the Lycoming spec sheet on their

 > website and the parallel-valve engines are narrower.  Other than that

 > the model numbers don't give much of a clue unless you just know which

 > is which.  As Bill said, the angle-valve heads flow better.  The

 > naturally-aspirated versions have a 8.7 compression ratio vs. the 8.5 of

 > the parallel-valve engine, and that also helps to produce slightly more

 > power.  With more space between the valves the angle-valve engine

 > requires less pressure drop for cooling, theoretically reducing cooling

 > drag.  But they are heavier, to the tune of 4 or 5 pounds per cylinder

 > and the angle-valve engines don't have the same reputation for longevity

 > as the parallel-valve engines.  An expert told me that there is nothing

 > to be gained by porting and polishing the angle-valve cylinder, while

 > the parallel-valve version can be ported to achieve almost the same

 > airflow as the angle-valve cylinder.

 > Gary Casey

 > Parallel-valve IO-540 with 10:1 compression dyno tested at 305 hp

 >

 >

Jon A. Delamarter

Joined: 20 Jul 2006
Posts: 14
Location: Williamsport, PA

Posted: Wed Mar 21, 2007 5:46 am Post subject: Re: Lycoming Cylinder question

Dan:



Here's a brief overview I wrote for the new Lycoming website.  Let me know if I can help with more details.



Parallel Valve Cylinder – The intake and exhaust valves of a parallel valve cylinder are mounted in parallel to one another in the cylinder head and share a common rocker shaft which is retained by the rocker cover.  This arrangement gives the parallel valve cylinder’s rocker cover its distinctive “parallel” or square shape; parallel valve rocker covers are also distinguished from angle valve rocker covers by their greater thickness.  Parallel valve cylinders are utilized on carbureted and some lower output, lightweight fuel injected engines.  Most parallel valve 4 cylinder engines do not incorporate a counterweighted crankshaft which further contributes to their relative lightweight.  



Angle Valve Cylinder – The intake and exhaust valves of an angle valve cylinder are mounted at angles to one another in the cylinder head.  Angle valve cylinders utilize separate rocker shafts for intake and exhaust rockers; the rocker shafts are held in the cylinder head by separate retaining plates.  This arrangement gives the angle valve cylinder’s rocker cover its distinctive “angle” shape; angle valve rocker covers are also distinguished from parallel valve rocker covers by their lesser thickness.  Utilized on high output engines.  Angle valve engines are heavier and slightly wider than their parallel valve counterparts but are capable of safely and efficiently producing more horsepower due to increased head density and improved head design.  Angle valve engines incorporate counterweighted crankshafts which reduce torsional vibration.

_________________
Jon A. Delamarter
Thunderbolt Manager
Lycoming Engines

apilot2(at)gmail.com
Guest

Posted: Wed Mar 21, 2007 6:13 am Post subject: Lycoming Cylinder question

That last sentence needs a bit of qualification. A large number of

angle valve engines do NOT have counterweighted crankshafts. In

particular, the IO-360-A1A, used extensively from 1964-1976.



On 3/21/07, Jon A. Delamarter <jdelamarter(at)lycoming.textron.com> wrote:

  Angle valve engines incorporate counterweighted crankshafts which

reduce torsional vibration.

 	  Quote:

Jon A. Delamarter

Joined: 20 Jul 2006
Posts: 14
Location: Williamsport, PA

Posted: Wed Mar 21, 2007 6:50 am Post subject: Re: Lycoming Cylinder question

Touche'!



  You are absolutely correct.  See what over-generalization gets me?  I should have said "most" angle valve engines incorporate counter-weighted crankshafts.  Hmm, I see I already have to edit my new website.  



Thanks for keeping me straight!



 	  Quote: 	
		   	  apilot2(at)gmail.com wrote: 	
		  That last sentence needs a bit of qualification. A large number of

angle valve engines do NOT have counterweighted crankshafts. In

particular, the IO-360-A1A, used extensively from 1964-1976.



On 3/21/07, Jon A. Delamarter <jdelamarter> wrote:

  Angle valve engines incorporate counterweighted crankshafts which

reduce torsional vibration.

 	  Quote:

_________________
Jon A. Delamarter
Thunderbolt Manager
Lycoming Engines

drogers(at)maf.org
Guest

Posted: Wed Mar 21, 2007 11:18 am Post subject: Lycoming Cylinder question

Is this already on the Lycoming website??  If so I didn't find it when I 

went looking for this info!



Dan R



Jon A. Delamarter wrote:

 	  Quote: 	
		   

 

 Dan:

 

 Here's a brief overview I wrote for the new Lycoming website.  Let me know if I can help with more details.

Jon A. Delamarter

Joined: 20 Jul 2006
Posts: 14
Location: Williamsport, PA

Posted: Wed Mar 21, 2007 12:29 pm Post subject: Re: Lycoming Cylinder question

Dan:



Yes it is, but you're not going to see it unless you go through the engine configurator on the Thunderbolt microsite.  Go to www.lycoming.com/thunderbolt or direct link at http://www.lycoming.com/thunderbolt_configurator/initializePowerplantConfiguratorFlow.do?methodToCall=initializePowerPlantConfigurationPageFlow



 If you go through and configure a Thunderbolt engine, there is an option on the final page to view a printable version of the estimate.  The bottom of the estimate has a ton of data.  The info I posted is only a small portion.  



You always have the option of emailing me directly at jdelamarter(at)lycoming.textron.com.  I don't have all the answers, but I work with the folks that have most of them!



Kind regards,



 	  Quote: 	
		  [quote="drogers(at)maf.org"]Is this already on the Lycoming website??  If so I didn't find it when I 

went looking for this info!

_________________
Jon A. Delamarter
Thunderbolt Manager
Lycoming Engines

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