bell valve

[Jim Allen]

Bell valve type inductions, those with a center shaft & those that are screwed to the crank pin should not be used in rods with bushed bottom ends; especially when rpm's exceed 24,000. Some examples of bushing materials tested include phosphor bronze alloys #534(B-1); #544(B-2) & full hard beryllium copper alloy #172. These materials were tested in both aluminum (2024-T351 & 7075-T651) & titanium (6AL4F) rods at clearances from .002 to .008 with little success. The reason is, the window location of a bell valve is on its circumference; therefore preventing any incomming lubrication from wetting the bottom end of the connecting rod. Only high quality steel caged roller rods should be used for rpm's of 30,000 to 35,000, when using a bell valve. Bell valves are tested in backend assemblies using compressed air to drive the valve & a strobe to measure rpm. Maximum achieved rpm was 38,000 for 2 minutes. Lubrication used through center oil hole was 5 wt. spindle oil.

 

[Ray Sametz]

Jim, If I remember correct we met in early 90's in Jersey. Bat Boat with scratch built motor. If I'm right maybe we can get Brian C. to join us on this forum. You two were the best engine guru's in the northeast. Ray

 

[F.Orlic]

Bell valve type inductions, those with a center shaft & those that are screwed to the crank pin should not be used in rods with bushed bottom ends; especially when rpm's exceed 24,000. Some examples of bushing materials tested include phosphor bronze alloys #534(B-1); #544(B-2) & full hard beryllium copper alloy #172. These materials were tested in both aluminum (2024-T351 & 7075-T651) & titanium (6AL4F) rods at clearances from .002 to .008 with little success. The reason is, the window location of a bell valve is on its circumference; therefore preventing any incomming lubrication from wetting the bottom end of the connecting rod. Only high quality steel caged roller rods should be used for rpm's of 30,000 to 35,000, when using a bell valve. Bell valves are tested in backend assemblies using compressed air to drive the valve & a strobe to measure rpm. Maximum achieved rpm was 38,000 for 2 minutes. Lubrication used through center oil hole was 5 wt. spindle oil.  

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Nice to see you on this board Jim

Bell valve is a very interesting concept with potential for big gains in bigger engines but it is not the easiest to build. It would be very hard to build bell intake for .21 engine or anything smaller than .90. I'm not sure why would there be any isues with connectin rod, most modern engines have drum induction with intake located on circumference, rods are either bushed or with crowded needles and most have only one oil hole. There is allways a lot of fuel sitting in a bottom of the case so rod lubrication should not be a problem.

It is always nice to hear from people who experimet a lot and share their findings.

 

[Jim Allen]

Jim, If I remember correct we met in early 90's in Jersey. Bat Boat with scratch built motor. If I'm right maybe we can get Brian C. to join us on this forum. You two were the best engine guru's in the northeast. Ray

103634[/snapback]

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Ray,

I think Brian & I will be running again next year. I have keep in contact with him. As soon as I have completed the new hull we'll be back at it again.

Jim

 

[Jim Allen]

Bell valve type inductions, those with a center shaft & those that are screwed to the crank pin should not be used in rods with bushed bottom ends; especially when rpm's exceed 24,000. Some examples of bushing materials tested include phosphor bronze alloys #534(B-1); #544(B-2) & full hard beryllium copper alloy #172. These materials were tested in both aluminum (2024-T351 & 7075-T651) & titanium (6AL4F) rods at clearances from .002 to .008 with little success. The reason is, the window location of a bell valve is on its circumference; therefore preventing any incomming lubrication from wetting the bottom end of the connecting rod. Only high quality steel caged roller rods should be used for rpm's of 30,000 to 35,000, when using a bell valve. Bell valves are tested in backend assemblies using compressed air to drive the valve & a strobe to measure rpm. Maximum achieved rpm was 38,000 for 2 minutes. Lubrication used through center oil hole was 5 wt. spindle oil.  

103615[/snapback]

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Nice to see you on this board Jim

Bell valve is a very interesting concept with potential for big gains in bigger engines but it is not the easiest to build. It would be very hard to build bell intake for .21 engine or anything smaller than .90. I'm not sure why would there be any isues with connectin rod, most modern engines have drum induction with intake located on circumference, rods are either bushed or with crowded needles and most have only one oil hole. There is allways a lot of fuel sitting in a bottom of the case so rod lubrication should not be a problem.

It is always nice to hear from people who experimet a lot and share their findings.

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Frank,

Bell valves were first used by Paul Bugal in his .15 team race diesel's. Large increases in hp and rpm's were gained because these valves were screwed to the crank pin. These valves were made of aluminum & rotated without any part touching or rubbing other motor parts. No balancing was necessary on aluminum valves. An alignment fixture which centered the valve in the crankcase is required for assembly. Once the left hand threaded screw was locked in the crank pin; the valve rotated without any frictional loses. These engines also had hanger pistons with windows which reduced reciprocating weight to a minimum. Hanger pistons give the longest rod center to center distance. This reduces rod angularity to a minimum; a requirement for high rpm's. Most drum induction motors have the driving slot for the valve machined through (as per Rossi drum valve) thus allowing lubrication to the bottom end. You are correct about fuel in the bottom of a crankcase; especially if the case is grooved for rod clearance. Even with this groove, I use two staggared oil slots in the bottom of a grooved rod. This has allowed me to run oil contents as low as 5% at 30,000+ rpm's with no problems. Paul Bugal is said to have tested these valves at rpm's above 40,000.

Jim

 

[HendricX]

Just to enlighten the ignorent ... what is a bell-type induction ?

Can someone please explain ?

Thanks ; Hendrick

Someone gave me the >link to a picture< ..... Thanks Tom .

 

[Tim_Duggan]

Hi Jim,

I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is B)

Thanks again for sharing the cool pic's and info.

Tim.

 

[Jim Allen]

Hi Jim,I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is  B)

Thanks again for sharing the cool pic's and info.

Tim.

103923[/snapback]

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Tim,

I have been taught that drum valves which have the carburetor mounted similar to a front intake motor are called standard drum valves & those with the carburetor mounted in the center of the back end are called inverted drum valves. I have tested inverted drums (Rossi type); standard drums ( Kalistratovs & MAC types); rotary valves (Hoffman & disc types) & bell valves (Bugl type). All of these valves, except the fastened bell valve have inherent drag & friction resulting from the crankcase pumping as the engine runs. All induction valves tested had comparable window areas & timings; with the exception of the rotary valves. Rotary valve window areas were restricted by the center pin & the crankcase id. All valves used the same bore carburetors; .475, .525, & .625 bores with velocity stacks. All drum valves had .625 bores; were partially balanced; & ran in bushed back ends. None of these valves achieved the performance figures (hp & rpm's) of the bell valve. The bell valve has the best time area numbers & 45 to 55 deg's of wide open area with no window restriction. The bell valve has no fricitional loses & effectively packs the crankcase.

Pistons are fitted to stop in the cylinder bore .125 to .187 from TDC. This fitting is done with both pieces clean & dry. Liners are ground (not honed) to give a true taper in the critical upper sealing area of the liner; rather than the bell mouth created from back honing. Industrial grade chrome (1100 vickers) is typically ground to a 6 to 8 micro inch finish. Pistons are machined with diamond tooling only. Tapers on both the liner & piston are held to very precise numbers by setting up machines with a taper master. Many different tapers & fits were tested to achieve a very long piston life with no piston scuffing when running with small amounts of oil. You can ask Brian Charney how long a correct setup can last. I hope this answers your questions.

Jim

 

[Tim_Duggan]

Thank you Jim,

Very informative post.

Have you seen any evidence of scuffing etc with the bell valve when using high nitro contents, and what is the maintenace aspect of the bell valve (if any)

Would you have any CAD drawings etc of the bell valve design by any chance? You have me very interested in this induction method.

Tim.

 

[Ray Sametz]

Jim, Didn't understand a word you said. Thats why Charney builds my motors. Great to have you here on this forum. Ray h34r: h34r: h34r: h34r:

 

[Jim Allen]

Thank you Jim,Very informative post.

Have you seen any evidence of scuffing etc with the bell valve when using high nitro contents, and what is the maintenace aspect of the bell valve (if any)

Would you have any CAD drawings etc of the bell valve design by any chance? You have me very interested in this induction method.

Tim.

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Tim,

My fuel of choice was 80% nitro; 12 to 15% ethylene oxide; 8 to 5% oil. Very easy to needle in changing weather conditions; & no scuffing. From my testing, I believe piston scuffing is the result of incorrect tapers on the piston & liner. I have tested different silicone content pistons with the same results.

The bell valve is maintenance free even though the initial setup has very close tolerances (.0001 on valve circumfrence; .001 end play). The entire thrust

load is applied to the .125X.375 ball bearing. This is the only part to be replaced after many hours of running. The bushing in the front end of the back end shows no sign of wear (.0001 clearance). Also helping this situation, I have the connecting rod guided in the upper end between the piston bosses.

I only have sketches for the many assemblies used in motors & they are very hard to read. Sample valves can be seen in HP .60 motors produced in 1977 & team race diesel's of the same year.

Jim Allen

 

[Jim Allen]

Jim, Didn't understand a word you said. Thats why Charney builds my motors. Great to have you here on this forum. Ray  h34r:   h34r:   h34r:   h34r:

104335[/snapback]

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Ray,

I will let you know about Brian's phone number. E-mail me at [email protected].

Jim

 

[F.Orlic]

Hi Jim,I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is  B)

Thanks again for sharing the cool pic's and info.

Tim.

103923[/snapback]

​

Tim,

I have been taught that drum valves which have the carburetor mounted similar to a front intake motor are called standard drum valves & those with the carburetor mounted in the center of the back end are called inverted drum valves. I have tested inverted drums (Rossi type); standard drums ( Kalistratovs & MAC types); rotary valves (Hoffman & disc types) & bell valves (Bugl type). All of these valves, except the fastened bell valve have inherent drag & friction resulting from the crankcase pumping as the engine runs. All induction valves tested had comparable window areas & timings; with the exception of the rotary valves. Rotary valve window areas were restricted by the center pin & the crankcase id. All valves used the same bore carburetors; .475, .525, & .625 bores with velocity stacks. All drum valves had .625 bores; were partially balanced; & ran in bushed back ends. None of these valves achieved the performance figures (hp & rpm's) of the bell valve. The bell valve has the best time area numbers & 45 to 55 deg's of wide open area with no window restriction. The bell valve has no fricitional loses & effectively packs the crankcase.

Pistons are fitted to stop in the cylinder bore .125 to .187 from TDC. This fitting is done with both pieces clean & dry. Liners are ground (not honed) to give a true taper in the critical upper sealing area of the liner; rather than the bell mouth created from back honing. Industrial grade chrome (1100 vickers) is typically ground to a 6 to 8 micro inch finish. Pistons are machined with diamond tooling only. Tapers on both the liner & piston are held to very precise numbers by setting up machines with a taper master. Many different tapers & fits were tested to achieve a very long piston life with no piston scuffing when running with small amounts of oil. You can ask Brian Charney how long a correct setup can last. I hope this answers your questions.

Jim

104245[/snapback]

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From doing my own testing I must say that disc valve has very little drag compared to drum or Zimmerman but as you pointed out the port area is restricted. One way around it is fitting bigger dia valves if possible. Few advantages disc valve have are weight and small contact area. Drag is not only caused by rotating valve rubbing against the housing but the fuel itself. more oil more drag, so every rotating valve has a drag ; disc, Zimmerman , drum or Bugl. With Bugl valve drag is not apearent without fuel as the valve is suspended by bearings. Only reed valve is drag free that I know. By the way what timing nubers give you best results with Bugl valve?

 

[Jim Allen]

Hi Jim,I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is  B)

Thanks again for sharing the cool pic's and info.

Tim.

103923[/snapback]

​

Tim,

I have been taught that drum valves which have the carburetor mounted similar to a front intake motor are called standard drum valves & those with the carburetor mounted in the center of the back end are called inverted drum valves. I have tested inverted drums (Rossi type); standard drums ( Kalistratovs & MAC types); rotary valves (Hoffman & disc types) & bell valves (Bugl type). All of these valves, except the fastened bell valve have inherent drag & friction resulting from the crankcase pumping as the engine runs. All induction valves tested had comparable window areas & timings; with the exception of the rotary valves. Rotary valve window areas were restricted by the center pin & the crankcase id. All valves used the same bore carburetors; .475, .525, & .625 bores with velocity stacks. All drum valves had .625 bores; were partially balanced; & ran in bushed back ends. None of these valves achieved the performance figures (hp & rpm's) of the bell valve. The bell valve has the best time area numbers & 45 to 55 deg's of wide open area with no window restriction. The bell valve has no fricitional loses & effectively packs the crankcase.

Pistons are fitted to stop in the cylinder bore .125 to .187 from TDC. This fitting is done with both pieces clean & dry. Liners are ground (not honed) to give a true taper in the critical upper sealing area of the liner; rather than the bell mouth created from back honing. Industrial grade chrome (1100 vickers) is typically ground to a 6 to 8 micro inch finish. Pistons are machined with diamond tooling only. Tapers on both the liner & piston are held to very precise numbers by setting up machines with a taper master. Many different tapers & fits were tested to achieve a very long piston life with no piston scuffing when running with small amounts of oil. You can ask Brian Charney how long a correct setup can last. I hope this answers your questions.

Jim

104245[/snapback]

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From doing my own testing I must say that disc valve has very little drag compared to drum or Zimmerman but as you pointed out the port area is restricted. One way around it is fitting bigger dia valves if possible. Few advantages disc valve have are weight and small contact area. Drag is not only caused by rotating valve rubbing against the housing but the fuel itself. more oil more drag, so every rotating valve has a drag ; disc, Zimmerman , drum or Bugl. With Bugl valve drag is not apearent without fuel as the valve is suspended by bearings. Only reed valve is drag free that I know. By the way what timing nubers give you best results with Bugl valve?

104945[/snapback]

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Frank,

Yes, rotary disc valves are light in weight and have small contact areas & yes all valves have fuel drag necessary for lubrication. Testing shows that rotary valves when running againts aluminum back ends show wear after little use. Is this wear the results of hard rubbing as the crankcase is pumping? Certainly in this well lubricated area you would think wear would not be a problem. Drum valves do not show any wear from drag and rubbing friction, except when mounted in poor quality aluminum back ends. The drag & friction I'm refering to is caused by the pumping action of the crankcase as the motor runs. Take a motor with a properly fitted drum or rotary valve & flip it back & forth , but not through TDC. That distinct clicking sound is the valve going in & out as the piston pumps the crankcase. At 30,000 rmp's this happens 500 times a second. Positive proof of this rubbing friction can be seen when running a hardened steel connecting rod. Both the rotary valve & drum valve have distinct wear patterns where the bottom end of the connecting rod (very high velocity) is being rubbed hard. This wear mark on the face of the drum valve can be seen in the photo's I posted. I tested drum valves with bottom end clearances as high as .020 & with rods that were guided in the upper end, & still had a problem. Ed Kalfus, in his .90 motor used a rotary valve that was fastened to two ball bearings. The valve (.025 thick with angle on the leading edge of the window) was made of linen based phenolic, & was fully balanced with brass counter weights; & had .0005 clearance from the back end. This valve should no signs of wear after many hours of testing. This motor also used a steel roller rod.

As I said in my post the bell valve was tested in my motor back ends by pumping oil through the oil hole that can be seen in the posted photo's. The ball bearing for this valve sets behind the visible bushing & is lubricated from the incoming charge in the intake track, as well as the oil hole. Also notice the small sealing area possible around the window in the case, with the remainding area relieved to reduce oil drag. This is possible only because the valve rotates without touching anything.

I tested timmings that opened as early as 15 deg. ABDC & closed as late as 69 deg. ATDC. This was done by changing the window in the crankcase from 82 deg. to 105 deg. Bell valve windows remained at 127 deg. In general, higher timings would increase rpm's but not hp. I found that the best hp, rpm numbers for my motor to be; open 34 ABDC; close 63 ATDC, for a total duration of 209 deg's. The window in the case was 82 deg. & symmetrically located on the case center line. The window in the valve was 127 deg., giving 45 deg. of rotation where the window is wide open. Earlest opening & latest closing gave 22 deg of wide open area. There are many possible combinations which could be tested in many different motors. I changed valve openings in 5 deg. steps & valve closings in 1 deg. steps. I'm sure there other numbers which would work better for high rpm applications. To find them can only be done by cutting & testing.

Hope this answers all questions.

Regards,

Jim Allen

 

[F.Orlic]

Hi Jim,I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is  B)

Thanks again for sharing the cool pic's and info.

Tim.

103923[/snapback]

​

Tim,

I have been taught that drum valves which have the carburetor mounted similar to a front intake motor are called standard drum valves & those with the carburetor mounted in the center of the back end are called inverted drum valves. I have tested inverted drums (Rossi type); standard drums ( Kalistratovs & MAC types); rotary valves (Hoffman & disc types) & bell valves (Bugl type). All of these valves, except the fastened bell valve have inherent drag & friction resulting from the crankcase pumping as the engine runs. All induction valves tested had comparable window areas & timings; with the exception of the rotary valves. Rotary valve window areas were restricted by the center pin & the crankcase id. All valves used the same bore carburetors; .475, .525, & .625 bores with velocity stacks. All drum valves had .625 bores; were partially balanced; & ran in bushed back ends. None of these valves achieved the performance figures (hp & rpm's) of the bell valve. The bell valve has the best time area numbers & 45 to 55 deg's of wide open area with no window restriction. The bell valve has no fricitional loses & effectively packs the crankcase.

Pistons are fitted to stop in the cylinder bore .125 to .187 from TDC. This fitting is done with both pieces clean & dry. Liners are ground (not honed) to give a true taper in the critical upper sealing area of the liner; rather than the bell mouth created from back honing. Industrial grade chrome (1100 vickers) is typically ground to a 6 to 8 micro inch finish. Pistons are machined with diamond tooling only. Tapers on both the liner & piston are held to very precise numbers by setting up machines with a taper master. Many different tapers & fits were tested to achieve a very long piston life with no piston scuffing when running with small amounts of oil. You can ask Brian Charney how long a correct setup can last. I hope this answers your questions.

Jim

104245[/snapback]

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From doing my own testing I must say that disc valve has very little drag compared to drum or Zimmerman but as you pointed out the port area is restricted. One way around it is fitting bigger dia valves if possible. Few advantages disc valve have are weight and small contact area. Drag is not only caused by rotating valve rubbing against the housing but the fuel itself. more oil more drag, so every rotating valve has a drag ; disc, Zimmerman , drum or Bugl. With Bugl valve drag is not apearent without fuel as the valve is suspended by bearings. Only reed valve is drag free that I know. By the way what timing nubers give you best results with Bugl valve?

104945[/snapback]

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Frank,

Yes, rotary disc valves are light in weight and have small contact areas & yes all valves have fuel drag necessary for lubrication. Testing shows that rotary valves when running againts aluminum back ends show wear after little use. Is this wear the results of hard rubbing as the crankcase is pumping? Certainly in this well lubricated area you would think wear would not be a problem. Drum valves do not show any wear from drag and rubbing friction, except when mounted in poor quality aluminum back ends. The drag & friction I'm refering to is caused by the pumping action of the crankcase as the motor runs. Take a motor with a properly fitted drum or rotary valve & flip it back & forth , but not through TDC. That distinct clicking sound is the valve going in & out as the piston pumps the crankcase. At 30,000 rmp's this happens 500 times a second. Positive proof of this rubbing friction can be seen when running a hardened steel connecting rod. Both the rotary valve & drum valve have distinct wear patterns where the bottom end of the connecting rod (very high velocity) is being rubbed hard. This wear mark on the face of the drum valve can be seen in the photo's I posted. I tested drum valves with bottom end clearances as high as .020 & with rods that were guided in the upper end, & still had a problem. Ed Kalfus, in his .90 motor used a rotary valve that was fastened to two ball bearings. The valve (.025 thick with angle on the leading edge of the window) was made of linen based phenolic, & was fully balanced with brass counter weights; & had .0005 clearance from the back end. This valve should no signs of wear after many hours of testing. This motor also used a steel roller rod.

As I said in my post the bell valve was tested in my motor back ends by pumping oil through the oil hole that can be seen in the posted photo's. The ball bearing for this valve sets behind the visible bushing & is lubricated from the incoming charge in the intake track, as well as the oil hole. Also notice the small sealing area possible around the window in the case, with the remainding area relieved to reduce oil drag. This is possible only because the valve rotates without touching anything.

I tested timmings that opened as early as 15 deg. ABDC & closed as late as 69 deg. ATDC. This was done by changing the window in the crankcase from 82 deg. to 105 deg. Bell valve windows remained at 127 deg. In general, higher timings would increase rpm's but not hp. I found that the best hp, rpm numbers for my motor to be; open 34 ABDC; close 63 ATDC, for a total duration of 209 deg's. The window in the case was 82 deg. & symmetrically located on the case center line. The window in the valve was 127 deg., giving 45 deg. of rotation where the window is wide open. Earlest opening & latest closing gave 22 deg of wide open area. There are many possible combinations which could be tested in many different motors. I changed valve openings in 5 deg. steps & valve closings in 1 deg. steps. I'm sure there other numbers which would work better for high rpm applications. To find them can only be done by cutting & testing.

Hope this answers all questions.

Regards,

Jim Allen

104986[/snapback]

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You are absolutely right about rotay rubbing against the housing, I don't think is the pumping action but rather because of poor design. All engines available with rotay valve have a valve hanging on a pin with little or no guide to keep them straight, hosings are made of very soft cast aluminum and many housings have a pin hole drilled out of square causing rotor to rub. When a valve reaches high RPM it starts to fluter and bigger the valve worst it gets. Having said all that properly designed valve does work Kalfus design) Bell vlve had advantage of staying open for very long time alowing to run modest intake timing numbers and still getting excelent induction but since my interest is primerely in .21 engines I don't think bell would work for me. It would be very hard to build it as small as needed to fit .21.It is worth to note that two best .40 enignes in pylon racing are MB 40 crank induction and RPM disc induction. For time being crank induction is probably best for .21.

 

[Tim_Duggan]

It is worth to note that two best .40 enignes in pylon racing are MB 40 crank induction and RPM disc induction.

105239[/snapback]

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It's funny that you should mention that Frank - I had a discussion with Ranjit (RPM) about this very subject about 6 months ago.

He prefer's a disc for FAI control fuel, but for nitro based fuel he prefers a ballraced drum valve of similar design principle (but not the same) as the Kalistratov.

He mentioned that the same engine disc tested on control fuel gave no evidence of disc scuffing, where the engine running on 50% would scuff the disc.

Needless to say his 45 marine engine that will be available soon has a ballraced drum valve.

 

[Jim Allen]

Hi Jim,I was admiring your pic's on the gallery - just awesome!

I'm curious to know if you tried the inverted drum style as used on the Kalistratovs and MAC's as a part of your testing, and if so what sort of results did you see in comparison to the more conventional drum housing and the Bell-type arrangement.

It would be interesting to me to see if the volume within the induction system has any considerable effect on performance, or if it is a case of a Myth being busted.

I'd also love to know what the piston and sleeve fit "life" was like running 30krpm @ 5% oil content, if you would care to divulge some more info that is  B)

Thanks again for sharing the cool pic's and info.

Tim.

103923[/snapback]

​

Tim,

I have been taught that drum valves which have the carburetor mounted similar to a front intake motor are called standard drum valves & those with the carburetor mounted in the center of the back end are called inverted drum valves. I have tested inverted drums (Rossi type); standard drums ( Kalistratovs & MAC types); rotary valves (Hoffman & disc types) & bell valves (Bugl type). All of these valves, except the fastened bell valve have inherent drag & friction resulting from the crankcase pumping as the engine runs. All induction valves tested had comparable window areas & timings; with the exception of the rotary valves. Rotary valve window areas were restricted by the center pin & the crankcase id. All valves used the same bore carburetors; .475, .525, & .625 bores with velocity stacks. All drum valves had .625 bores; were partially balanced; & ran in bushed back ends. None of these valves achieved the performance figures (hp & rpm's) of the bell valve. The bell valve has the best time area numbers & 45 to 55 deg's of wide open area with no window restriction. The bell valve has no fricitional loses & effectively packs the crankcase.

Pistons are fitted to stop in the cylinder bore .125 to .187 from TDC. This fitting is done with both pieces clean & dry. Liners are ground (not honed) to give a true taper in the critical upper sealing area of the liner; rather than the bell mouth created from back honing. Industrial grade chrome (1100 vickers) is typically ground to a 6 to 8 micro inch finish. Pistons are machined with diamond tooling only. Tapers on both the liner & piston are held to very precise numbers by setting up machines with a taper master. Many different tapers & fits were tested to achieve a very long piston life with no piston scuffing when running with small amounts of oil. You can ask Brian Charney how long a correct setup can last. I hope this answers your questions.

Jim

104245[/snapback]

​

From doing my own testing I must say that disc valve has very little drag compared to drum or Zimmerman but as you pointed out the port area is restricted. One way around it is fitting bigger dia valves if possible. Few advantages disc valve have are weight and small contact area. Drag is not only caused by rotating valve rubbing against the housing but the fuel itself. more oil more drag, so every rotating valve has a drag ; disc, Zimmerman , drum or Bugl. With Bugl valve drag is not apearent without fuel as the valve is suspended by bearings. Only reed valve is drag free that I know. By the way what timing nubers give you best results with Bugl valve?

104945[/snapback]

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Frank,

Yes, rotary disc valves are light in weight and have small contact areas & yes all valves have fuel drag necessary for lubrication. Testing shows that rotary valves when running againts aluminum back ends show wear after little use. Is this wear the results of hard rubbing as the crankcase is pumping? Certainly in this well lubricated area you would think wear would not be a problem. Drum valves do not show any wear from drag and rubbing friction, except when mounted in poor quality aluminum back ends. The drag & friction I'm refering to is caused by the pumping action of the crankcase as the motor runs. Take a motor with a properly fitted drum or rotary valve & flip it back & forth , but not through TDC. That distinct clicking sound is the valve going in & out as the piston pumps the crankcase. At 30,000 rmp's this happens 500 times a second. Positive proof of this rubbing friction can be seen when running a hardened steel connecting rod. Both the rotary valve & drum valve have distinct wear patterns where the bottom end of the connecting rod (very high velocity) is being rubbed hard. This wear mark on the face of the drum valve can be seen in the photo's I posted. I tested drum valves with bottom end clearances as high as .020 & with rods that were guided in the upper end, & still had a problem. Ed Kalfus, in his .90 motor used a rotary valve that was fastened to two ball bearings. The valve (.025 thick with angle on the leading edge of the window) was made of linen based phenolic, & was fully balanced with brass counter weights; & had .0005 clearance from the back end. This valve should no signs of wear after many hours of testing. This motor also used a steel roller rod.

As I said in my post the bell valve was tested in my motor back ends by pumping oil through the oil hole that can be seen in the posted photo's. The ball bearing for this valve sets behind the visible bushing & is lubricated from the incoming charge in the intake track, as well as the oil hole. Also notice the small sealing area possible around the window in the case, with the remainding area relieved to reduce oil drag. This is possible only because the valve rotates without touching anything.

I tested timmings that opened as early as 15 deg. ABDC & closed as late as 69 deg. ATDC. This was done by changing the window in the crankcase from 82 deg. to 105 deg. Bell valve windows remained at 127 deg. In general, higher timings would increase rpm's but not hp. I found that the best hp, rpm numbers for my motor to be; open 34 ABDC; close 63 ATDC, for a total duration of 209 deg's. The window in the case was 82 deg. & symmetrically located on the case center line. The window in the valve was 127 deg., giving 45 deg. of rotation where the window is wide open. Earlest opening & latest closing gave 22 deg of wide open area. There are many possible combinations which could be tested in many different motors. I changed valve openings in 5 deg. steps & valve closings in 1 deg. steps. I'm sure there other numbers which would work better for high rpm applications. To find them can only be done by cutting & testing.

Hope this answers all questions.

Regards,

Jim Allen

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You are absolutely right about rotay rubbing against the housing, I don't think is the pumping action but rather because of poor design. All engines available with rotay valve have a valve hanging on a pin with little or no guide to keep them straight, hosings are made of very soft cast aluminum and many housings have a pin hole drilled out of square causing rotor to rub. When a valve reaches high RPM it starts to fluter and bigger the valve worst it gets. Having said all that properly designed valve does work Kalfus design) Bell vlve had advantage of staying open for very long time alowing to run modest intake timing numbers and still getting excelent induction but since my interest is primerely in .21 engines I don't think bell would work for me. It would be very hard to build it as small as needed to fit .21.It is worth to note that two best .40 enignes in pylon racing are MB 40 crank induction and RPM disc induction. For time being crank induction is probably best for .21.

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Frank,

I will post pictures of the bell valve used in Bugl's .15 motor. This assembly is very easy to make, since it is machined from 2024-T351 aluminum & has no center pin. The valve is fastened to the crank pin with an allen screw; the crank pin is drilled through & tapped. The valve has a very large window, giving maxium open area without any restriction. Also, no balancing was done to valves made of aluminum. The only part required for assembly is a alignment fixture. I have been told by Henry Nelson that he has been able to make front induction .40 motors run faster & produce more hp than those with various induction systems; not including the bell valve. Is this because of the elimination of the drag in this area?

Jim