Altering port timing/effect on power question
01-18-2011 | 06:31 PM
#26
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From: Tiffin,
OH
RE: Altering port timing/effect on power question
that is completely false, if that was true, then why do ball bearing turbo's use ceramic bearings and not steel? ceramic is harder and truer and outlasts steel.
01-18-2011 | 06:38 PM
#27
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RE: Altering port timing/effect on power question
ORIGINAL: joeshmoe_44883
another way to gain power is getting rid of as much parasitic drag as possible. for instance, see if you can find ceramic bearings to replace the cheap crappy steel ones. the difference is like going from a bushing'd engine to a ball bearing'd one. polish the crankpin and wrist pin, put a ceramic coat on top of piston and inside the head. the less energy that is soaked up by the head is more energy pushing down on the piston. its a bit of work, but like everything else its all in the details.
another way to gain power is getting rid of as much parasitic drag as possible. for instance, see if you can find ceramic bearings to replace the cheap crappy steel ones. the difference is like going from a bushing'd engine to a ball bearing'd one. polish the crankpin and wrist pin, put a ceramic coat on top of piston and inside the head. the less energy that is soaked up by the head is more energy pushing down on the piston. its a bit of work, but like everything else its all in the details.
01-18-2011 | 07:08 PM
#28
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RE: Altering port timing/effect on power question
Turbochargers operate in a different realm when discussing RPM. One advantage for high speed is ceramic balls are much lighter than steel. This results in much less centrifugal forces on the balls and increased RPM limits. I've been researching machine tool spindle bearings and the there is an advantage in high RPM applications to ceramic hybrid bearings. An engine is a low RPM (relative to bearing size) application. Bearing suppliers say that ceramics are not applicable to high loads and low speed. All of this information is available in engineering guides of bearing suppliers.
To the OP what base or reference engine is being described? Porting an engine to get the desired output is tricky.
To the OP what base or reference engine is being described? Porting an engine to get the desired output is tricky.
01-18-2011 | 07:21 PM
#29
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RE: Altering port timing/effect on power question
ORIGINAL: MrGreenSpeed
If You use a mac header and a tuned pipe on lets say an OS 91VR DF engine with a mac 15cc pipe and the header cut to the max RPMs for an 10x9 or 9X9 or 9x10 APC prop
If You use a mac header and a tuned pipe on lets say an OS 91VR DF engine with a mac 15cc pipe and the header cut to the max RPMs for an 10x9 or 9X9 or 9x10 APC prop
ORIGINAL: MrGreenSpeed
You'll turn 20,000 + rpms in the air, however there is no midrange throttle response.
You run the engine at idle or (on the pipe) 3/4 to full throttle only.
You'll turn 20,000 + rpms in the air, however there is no midrange throttle response.
You run the engine at idle or (on the pipe) 3/4 to full throttle only.
01-19-2011 | 07:10 AM
#30
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From: Tiffin,
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RE: Altering port timing/effect on power question
I' ve got plans and am getting supplies to build a plane called the vertigo. it uses an os 46 vxdf spinning a 9x6 prop in a shroud. the desinger of the plane is in here somewhere, i've never heard of anyone breaking props with it so who knows...
01-19-2011 | 08:41 AM
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From: Waseca,
MN
RE: Altering port timing/effect on power question
I tested ceramic bearings several times in high performance Nelson Racing motors turning in excess of 25,000 rpms.
I could detect absolutely no performance difference (on the ground, and in the air) between them and high quality Swiss bearings.
It is said they should last longer, but I'm not even convinced by that.
I could detect absolutely no performance difference (on the ground, and in the air) between them and high quality Swiss bearings.
It is said they should last longer, but I'm not even convinced by that.
01-19-2011 | 10:58 AM
#32
RE: Altering port timing/effect on power question
One thing to watch out for is with hybrid ceramic bearings (steel races, ceramic balls) the steel races can wear, score and pit faster due to the extra hard ceramic balls. This seems to be more in tune with maintenance where the bearings are exposed to things that lead to corrosion occurring.
So if you are using a ceramic hybrid bearing set, the bearings aren't going to last longer than a all steel bearing set. the steel races will be the weak point for corrosion and wear. The bicycle people have run into problems where the bearing races are wearing out faster with ceramic hybrid bearings, but this appears to be due to maintenance and not keep the bearings free from moisture and keeping them clean as much as possible.
I might give the ceramic bearings a try one day. but heck, they cost as much or more than the engine I would want to put them in. so i still do not find it all that worthwhile yet. But if I got back into pylon racing or something where every RPM counts, it might be worth it. But like Daven stated, I don't think you can measure the improvement in performance with a engine.
10quicksport, consideirng how many parts one can trash in changing the port timing and making other mods along the way, I would just get a Nelson engine to start with. Then you don't have to destroy a bunch of parts trying to get that extra bit of performance of the engine.
The typical method is to take a part and machine a little off of it, then assemble the engine and test, then disassemble the engine, machine a little more off the part and repeat until you go too far, then chunk the bad part and machine a new part to the point where you got your best performance.
Then with ABC cylinder sleeves, you can't machine anything off the ports without risking the chrome being damaged, about all one can do is maybe using a shim to raise the cylinder a teensy bit and see what happens. although some guys have been known to machine their own sleeves and somehow get them chromed to testing with.
So if you are using a ceramic hybrid bearing set, the bearings aren't going to last longer than a all steel bearing set. the steel races will be the weak point for corrosion and wear. The bicycle people have run into problems where the bearing races are wearing out faster with ceramic hybrid bearings, but this appears to be due to maintenance and not keep the bearings free from moisture and keeping them clean as much as possible.
I might give the ceramic bearings a try one day. but heck, they cost as much or more than the engine I would want to put them in. so i still do not find it all that worthwhile yet. But if I got back into pylon racing or something where every RPM counts, it might be worth it. But like Daven stated, I don't think you can measure the improvement in performance with a engine.
10quicksport, consideirng how many parts one can trash in changing the port timing and making other mods along the way, I would just get a Nelson engine to start with. Then you don't have to destroy a bunch of parts trying to get that extra bit of performance of the engine.
The typical method is to take a part and machine a little off of it, then assemble the engine and test, then disassemble the engine, machine a little more off the part and repeat until you go too far, then chunk the bad part and machine a new part to the point where you got your best performance.
Then with ABC cylinder sleeves, you can't machine anything off the ports without risking the chrome being damaged, about all one can do is maybe using a shim to raise the cylinder a teensy bit and see what happens. although some guys have been known to machine their own sleeves and somehow get them chromed to testing with.
01-19-2011 | 11:54 AM
#33
RE: Altering port timing/effect on power question
Ceramic bearings have an advatage of high hardness at high temps. Thus it is ideal for jets and turbochargers. For our models high quality (much higher than those that come with sport engines) steel bearings would work about a well as a ceramic bearings.</p>
01-19-2011 | 01:24 PM
#34
Thread Starter
RE: Altering port timing/effect on power question
ORIGINAL: earlwb
One thing to watch out for is with hybrid ceramic bearings (steel races, ceramic balls) the steel races can wear, score and pit faster due to the extra hard ceramic balls. This seems to be more in tune with maintenance where the bearings are exposed to things that lead to corrosion occurring.
So if you are using a ceramic hybrid bearing set, the bearings aren't going to last longer than a all steel bearing set. the steel races will be the weak point for corrosion and wear. The bicycle people have run into problems where the bearing races are wearing out faster with ceramic hybrid bearings, but this appears to be due to maintenance and not keep the bearings free from moisture and keeping them clean as much as possible.
I might give the ceramic bearings a try one day. but heck, they cost as much or more than the engine I would want to put them in. so i still do not find it all that worthwhile yet. But if I got back into pylon racing or something where every RPM counts, it might be worth it. But like Daven stated, I don't think you can measure the improvement in performance with a engine.
10quicksport, consideirng how many parts one can trash in changing the port timing and making other mods along the way, I would just get a Nelson engine to start with. Then you don't have to destroy a bunch of parts trying to get that extra bit of performance of the engine.
The typical method is to take a part and machine a little off of it, then assemble the engine and test, then disassemble the engine, machine a little more off the part and repeat until you go too far, then chunk the bad part and machine a new part to the point where you got your best performance.
Then with ABC cylinder sleeves, you can't machine anything off the ports without risking the chrome being damaged, about all one can do is maybe using a shim to raise the cylinder a teensy bit and see what happens. although some guys have been known to machine their own sleeves and somehow get them chromed to testing with.
One thing to watch out for is with hybrid ceramic bearings (steel races, ceramic balls) the steel races can wear, score and pit faster due to the extra hard ceramic balls. This seems to be more in tune with maintenance where the bearings are exposed to things that lead to corrosion occurring.
So if you are using a ceramic hybrid bearing set, the bearings aren't going to last longer than a all steel bearing set. the steel races will be the weak point for corrosion and wear. The bicycle people have run into problems where the bearing races are wearing out faster with ceramic hybrid bearings, but this appears to be due to maintenance and not keep the bearings free from moisture and keeping them clean as much as possible.
I might give the ceramic bearings a try one day. but heck, they cost as much or more than the engine I would want to put them in. so i still do not find it all that worthwhile yet. But if I got back into pylon racing or something where every RPM counts, it might be worth it. But like Daven stated, I don't think you can measure the improvement in performance with a engine.
10quicksport, consideirng how many parts one can trash in changing the port timing and making other mods along the way, I would just get a Nelson engine to start with. Then you don't have to destroy a bunch of parts trying to get that extra bit of performance of the engine.
The typical method is to take a part and machine a little off of it, then assemble the engine and test, then disassemble the engine, machine a little more off the part and repeat until you go too far, then chunk the bad part and machine a new part to the point where you got your best performance.
Then with ABC cylinder sleeves, you can't machine anything off the ports without risking the chrome being damaged, about all one can do is maybe using a shim to raise the cylinder a teensy bit and see what happens. although some guys have been known to machine their own sleeves and somehow get them chromed to testing with.
I've heard of some people shimming the sleeve higher - if this is something to try, where do you get shims to fit the outside of the sleeve?
01-19-2011 | 01:28 PM
#35
Thread Starter
RE: Altering port timing/effect on power question
ORIGINAL: gkamysz
Turbochargers operate in a different realm when discussing RPM. One advantage for high speed is ceramic balls are much lighter than steel. This results in much less centrifugal forces on the balls and increased RPM limits. I've been researching machine tool spindle bearings and the there is an advantage in high RPM applications to ceramic hybrid bearings. An engine is a low RPM (relative to bearing size) application. Bearing suppliers say that ceramics are not applicable to high loads and low speed. All of this information is available in engineering guides of bearing suppliers.
To the OP what base or reference engine is being described? Porting an engine to get the desired output is tricky.
Turbochargers operate in a different realm when discussing RPM. One advantage for high speed is ceramic balls are much lighter than steel. This results in much less centrifugal forces on the balls and increased RPM limits. I've been researching machine tool spindle bearings and the there is an advantage in high RPM applications to ceramic hybrid bearings. An engine is a low RPM (relative to bearing size) application. Bearing suppliers say that ceramics are not applicable to high loads and low speed. All of this information is available in engineering guides of bearing suppliers.
To the OP what base or reference engine is being described? Porting an engine to get the desired output is tricky.
01-19-2011 | 02:00 PM
#37
RE: Altering port timing/effect on power question
many many years ago, circa 1972-1973 I used to file notches in the top of the piston on my Yamaha 350 twin cylinder motorcycles to advance the port timing. This allowed me to advance the port timing a little. i filed each notch to be the width of the port and angled it gently. it worked great at the time, as a couple of guys with hopped up Honda CB750 fours couldn't outrun it. I could stay with them at WOT no problem. it did require checking the ignition points quite often and making sure the timing was just right too. it used to urk those two fellows to no end. One of them figured out a way to bore out his engine more, but even then he couldn't pull away from the little Yamaha 350.
so anyway to avoid trying to cut the ports higher on a ABC cylinder (which will result in the chrome peeling off at the ports), I would consider notching the piston to advance the port timing. But you need to check the piston crown and side thickness there on the piston though to ensure you have enough material to be able to notch it a little. You could also put a shim under the cylinder sleeve to raise it slightly too. with a glow engine you don't have to deal with igniton points et cetera. I guess they don't sell the pistons separate from the cylinder sleeve, so one could machine the ports if they really want to and see what happens. it isn't like you are flying inside the airplane yourself.
I had notched the intake and exhaust ports on the piston to advance both the intake and exhaust port timing.
ref http://www.scribd.com/doc/9726341/Tw...ormance-Tuning
so anyway to avoid trying to cut the ports higher on a ABC cylinder (which will result in the chrome peeling off at the ports), I would consider notching the piston to advance the port timing. But you need to check the piston crown and side thickness there on the piston though to ensure you have enough material to be able to notch it a little. You could also put a shim under the cylinder sleeve to raise it slightly too. with a glow engine you don't have to deal with igniton points et cetera. I guess they don't sell the pistons separate from the cylinder sleeve, so one could machine the ports if they really want to and see what happens. it isn't like you are flying inside the airplane yourself.
I had notched the intake and exhaust ports on the piston to advance both the intake and exhaust port timing.
ref http://www.scribd.com/doc/9726341/Tw...ormance-Tuning
01-19-2011 | 03:21 PM
#38
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RE: Altering port timing/effect on power question
ORIGINAL: earlwb
many many years ago, circa 1972-1973 I used to file notches in the top of the piston on my Yamaha 350 twin cylinder motorcycles to advance the port timing.
many many years ago, circa 1972-1973 I used to file notches in the top of the piston on my Yamaha 350 twin cylinder motorcycles to advance the port timing.
01-19-2011 | 03:33 PM
#39
RE: Altering port timing/effect on power question
Yeah I had three 350's over a period of years back then starting in 1967. In between was a Suzuki 500 Titan two stroke motorcycle also. The last two stroke street bike I owned was a Kawasaki 750 triple. After that it was assorted 4 stroke engine powered motorcycles.
I had a scary powerful Maico 500 dirt bike for a while too.
When I was stationed at TwentyNine Palms California way back then, we used to do some fast rides to Arizona on the long sparsely traveled roads back then. You had something like a ninety mile long straight road to the Colorado river.
I had a scary powerful Maico 500 dirt bike for a while too.
When I was stationed at TwentyNine Palms California way back then, we used to do some fast rides to Arizona on the long sparsely traveled roads back then. You had something like a ninety mile long straight road to the Colorado river.
01-19-2011 | 08:00 PM
#40
Senior Member
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RE: Altering port timing/effect on power question
ORIGINAL: joeshmoe_44883
I' ve got plans and am getting supplies to build a plane called the vertigo. it uses an os 46 vxdf spinning a 9x6 prop in a shroud. the desinger of the plane is in here somewhere, i've never heard of anyone breaking props with it so who knows...
I' ve got plans and am getting supplies to build a plane called the vertigo. it uses an os 46 vxdf spinning a 9x6 prop in a shroud. the desinger of the plane is in here somewhere, i've never heard of anyone breaking props with it so who knows...
After you have drilled that large hole in that small hub, it doesn't leave enough meat to keep it together. Could be deadly.
Pylon prop hubs are bigger and will hold up, but the tip are thin and tend to fly off at high speed especially after a hard turn. Only the most aggressive pylon prop will hold the engine back, something like a 8.8X 9.5 or 8.8 X9.25. A carbon prop like the 7.4x8.1C is a better choice turning it over 25,000 rpm, APC discontinued a better carbon prop a year ago so this is what's left.
Could a 9X6 sport prop hold up? Sure but not at this engine's full potential.
01-20-2011 | 07:16 AM
#41
Senior Member
RE: Altering port timing/effect on power question
I have done this as well with very good results. 0.5mm on the transfer port is a lot in some applications.
Or lowering the cylinder for less transfer timing and cutting the piston for the required exhaust duration also is a good idea. The head needs to be shimmed back to squish requirements.
BTW, the link will only load the first page. Better go to my www.prme.nl/forum (questions and answers). (engine-2) The picture is on page 37.
Or lowering the cylinder for less transfer timing and cutting the piston for the required exhaust duration also is a good idea. The head needs to be shimmed back to squish requirements.
BTW, the link will only load the first page. Better go to my www.prme.nl/forum (questions and answers). (engine-2) The picture is on page 37.
ORIGINAL: earlwb
many many years ago, circa 1972-1973 I used to file notches in the top of the piston on my Yamaha 350 twin cylinder motorcycles to advance the port timing. This allowed me to advance the port timing a little. i filed each notch to be the width of the port and angled it gently. it worked great at the time, as a couple of guys with hopped up Honda CB750 fours couldn't outrun it. I could stay with them at WOT no problem. it did require checking the ignition points quite often and making sure the timing was just right too. it used to urk those two fellows to no end. One of them figured out a way to bore out his engine more, but even then he couldn't pull away from the little Yamaha 350.
so anyway to avoid trying to cut the ports higher on a ABC cylinder (which will result in the chrome peeling off at the ports), I would consider notching the piston to advance the port timing. But you need to check the piston crown and side thickness there on the piston though to ensure you have enough material to be able to notch it a little. You could also put a shim under the cylinder sleeve to raise it slightly too. with a glow engine you don't have to deal with igniton points et cetera. I guess they don't sell the pistons separate from the cylinder sleeve, so one could machine the ports if they really want to and see what happens. it isn't like you are flying inside the airplane yourself.
I had notched the intake and exhaust ports on the piston to advance both the intake and exhaust port timing.
ref http://www.scribd.com/doc/9726341/Tw...ormance-Tuning
many many years ago, circa 1972-1973 I used to file notches in the top of the piston on my Yamaha 350 twin cylinder motorcycles to advance the port timing. This allowed me to advance the port timing a little. i filed each notch to be the width of the port and angled it gently. it worked great at the time, as a couple of guys with hopped up Honda CB750 fours couldn't outrun it. I could stay with them at WOT no problem. it did require checking the ignition points quite often and making sure the timing was just right too. it used to urk those two fellows to no end. One of them figured out a way to bore out his engine more, but even then he couldn't pull away from the little Yamaha 350.
so anyway to avoid trying to cut the ports higher on a ABC cylinder (which will result in the chrome peeling off at the ports), I would consider notching the piston to advance the port timing. But you need to check the piston crown and side thickness there on the piston though to ensure you have enough material to be able to notch it a little. You could also put a shim under the cylinder sleeve to raise it slightly too. with a glow engine you don't have to deal with igniton points et cetera. I guess they don't sell the pistons separate from the cylinder sleeve, so one could machine the ports if they really want to and see what happens. it isn't like you are flying inside the airplane yourself.
I had notched the intake and exhaust ports on the piston to advance both the intake and exhaust port timing.
ref http://www.scribd.com/doc/9726341/Tw...ormance-Tuning
01-20-2011 | 12:44 PM
#42
My Feedback: (1)
RE: Altering port timing/effect on power question
ORIGINAL: blw
The RD-350? I had one of those from about the same year. I can't remember and I didn't buy it new.
The RD-350? I had one of those from about the same year. I can't remember and I didn't buy it new.
Ring ding ding ding ding ring ding ding ding... wheeeeeelie!!
01-20-2011 | 01:45 PM
#43
My Feedback: (3)
RE: Altering port timing/effect on power question
ORIGINAL: earlwb
Yeah I had three 350's over a period of years back then starting in 1967. In between was a Suzuki 500 Titan two stroke motorcycle also. The last two stroke street bike I owned was a Kawasaki 750 triple.
Yeah I had three 350's over a period of years back then starting in 1967. In between was a Suzuki 500 Titan two stroke motorcycle also. The last two stroke street bike I owned was a Kawasaki 750 triple.
01-20-2011 | 04:07 PM
#44
Senior Member
RE: Altering port timing/effect on power question
I rode a 500x3 suzy at one time. Lightning fast, and it would beat my friend's 750 triumph every time, except on straights over a mile long. I then had to roll back throttle to prevent seisure, and the 750 would catch up quickly.
01-20-2011 | 04:29 PM
#45
My Feedback: (1)
RE: Altering port timing/effect on power question
ORIGINAL: blw
I liked the RD-350, but mine had a lot of major problems. I rode another one sometime like 1979 and I probably had that far away look MJD mentioned. The last bikes my dad had were two 500 triples. One had the expansion pipes and wheelie bars.
I liked the RD-350, but mine had a lot of major problems. I rode another one sometime like 1979 and I probably had that far away look MJD mentioned. The last bikes my dad had were two 500 triples. One had the expansion pipes and wheelie bars.
