"Thump-8" 4 stroke 1/8th scale engine
08-20-2009 | 05:58 PM
#17
08-20-2009 | 07:15 PM
#18
Tech Initiate
Joined: Jun 2009
Posts: 22
From: Cleveand Ohio
Cool! I didn't do much last night - hopefully I'll be more motivated tonight.
I thought about the need to maintain port velocity too. I'll likely end up changing the shape of the ports depending on how it works. The good thing about the prototype design I have is I can easily change the port shape, size, overlap, and timing by swapping out the upper valve seat (which is basically just a flat piece of steel with holes in it).
I even had thoughts of a guillotine-style power valve arrangement to vary the size of the ports depending on RPM. It wouldn't actually be all that hard to do, BUT it probably won't happen since the motto of all good RC engines is KISS... I guess I'll file that one under the "Anything is possible" category for later on.
I thought about the need to maintain port velocity too. I'll likely end up changing the shape of the ports depending on how it works. The good thing about the prototype design I have is I can easily change the port shape, size, overlap, and timing by swapping out the upper valve seat (which is basically just a flat piece of steel with holes in it).
I even had thoughts of a guillotine-style power valve arrangement to vary the size of the ports depending on RPM. It wouldn't actually be all that hard to do, BUT it probably won't happen since the motto of all good RC engines is KISS... I guess I'll file that one under the "Anything is possible" category for later on.
08-21-2009 | 08:00 AM
#19
Tech Regular
Joined: Apr 2009
Posts: 380
When an all-out racing engine is what you have in mind a cam will give you more.
Just look at the angle that the air way has in that rotary valve and only that gives back a chance to the poppet valve, and at the end you see the gears moving the shafts that rotate the rotary valves, there's the linearity that will kill it when you put it again side by side with a poppet valve race engine.
They say +14,000rpm, ok, but a hot bike will also do that all day, and a racing 1.6L-2.0L Honda is pretty close too, not to mention F1! and our little 4 strokes!, and way more importantly a poppet valve engine will probably have more power up there because of the timming available with the design. Whats good to be able to spin 20,000rpms if your torque curve is scrapping the floor?
X
08-21-2009 | 11:07 AM
#20
Thats exactly what I'm talking about.
When an all-out racing engine is what you have in mind a cam will give you more.
Just look at the angle that the air way has in that rotary valve and only that gives back a chance to the poppet valve, and at the end you see the gears moving the shafts that rotate the rotary valves, there's the linearity that will kill it when you put it again side by side with a poppet valve race engine.
They say +14,000rpm, ok, but a hot bike will also do that all day, and a racing 1.6L-2.0L Honda is pretty close too, not to mention F1! and our little 4 strokes!, and way more importantly a poppet valve engine will probably have more power up there because of the timming available with the design. Whats good to be able to spin 20,000rpms if your torque curve is scrapping the floor?
X
When an all-out racing engine is what you have in mind a cam will give you more.
Just look at the angle that the air way has in that rotary valve and only that gives back a chance to the poppet valve, and at the end you see the gears moving the shafts that rotate the rotary valves, there's the linearity that will kill it when you put it again side by side with a poppet valve race engine.
They say +14,000rpm, ok, but a hot bike will also do that all day, and a racing 1.6L-2.0L Honda is pretty close too, not to mention F1! and our little 4 strokes!, and way more importantly a poppet valve engine will probably have more power up there because of the timming available with the design. Whats good to be able to spin 20,000rpms if your torque curve is scrapping the floor?
X
heres a test by popular hotrodding on a Coates conversion on a Ford 302
Where the CSRV really shines is in its airflow potential compared to a poppet valve Bench-marking a 5.0 L engine from a Lincoln, the stock Ford casting (when tested at 28 inches of H2O) flowed approximately 180 cfm on the intake port at static. The rotary valve for the engine in comparison flowed a whopping 319-cfm at the same test pressure. Equipped with the poppet valve head, the Lincoln engine dynoed at 260 hp and 249 lb.-ft of torque. When equipped with the CSRV head at the same 5,500 rpm test protocol, it made 475 hp and 454 lb.-ft of torque, with no changes to the block or rotating assembly: The higher power was a result of diminished frictional and pumping losses, but the inherent airflow benefit of the spherical valve was the major contributor. With a conventional poppet valve, it can take 34 degrees of crankshaft rotation or more to reach a fully open position, wasting energy and limiting volumetric efficiency. With the CSRV, a comparable port area is exposed in only 2 degrees of crank rotation. The CSRV allows for superior surface flow coefficients from its spherical shape. With the standard 4-inch Ford bore, the factory poppet valve covers only 15.8 percent of the total bore area, while the rotary valve is measured at 20.5 percent.
Last edited by Maximo; 08-21-2009 at 11:23 AM.
08-21-2009 | 02:23 PM
#21
Those Coates cylinder heads look so trick! I've always liked the way that design looks. They must have some VERY special materials to make the seal work properly. OK, so now I have the motivation to do some math to find out what kind of numbers my design allows.
08-21-2009 | 05:37 PM
#22
So, I ran some numbers and did some graphs. Compared to a .40 size engine with 9.5mm diameter poppet valves, my ports should flow better, just based on cross-sectional area. Not MUCH better though, which made me think of ways to revise my design to get even bigger ports. I'll have to draw my new idea so I can make sure it's physically possible, then run some more numbers and graph it to make sure it did what I wanted.
I'm still pretty sure my original idea would work well, since there's no obstruction in the path of the gas flow. It's like dumping water into an open hole vs. one with a valve face sitting in the middle of it.
I haven't even cut metal yet, and this is already FUN!
I'm still pretty sure my original idea would work well, since there's no obstruction in the path of the gas flow. It's like dumping water into an open hole vs. one with a valve face sitting in the middle of it.
I haven't even cut metal yet, and this is already FUN!
08-21-2009 | 06:49 PM
#23
It is very easy to make something that will improve a stock Ford's performance. When they bolt it on an F1 motor and start winning races, then I will believe. Yes, poppet valves are old tech and have some major drawbacks but they are still in use for very good reasons. No one has as yet figured out a way to make any sort of rotary valve with a non linear type motion. Until they do, poppet will rule.
I see the best bet for future 4 stroke innovation being electro-mechanical valves. Keep the poppets and their motions but ditch the cam shaft.
08-21-2009 | 07:26 PM
#24
Tech Adept
Joined: Jan 2004
Posts: 132
From: Hamilton,Ontario,Canada
08-21-2009 | 09:53 PM
#26
Tech Regular
Joined: Apr 2009
Posts: 380
I am quite sure they saw big gains because they are comparing it with a stock motor. Conventional valved Ford 5.0's have been built that make even more power then that.
It is very easy to make something that will improve a stock Ford's performance. When they bolt it on an F1 motor and start winning races, then I will believe. Yes, poppet valves are old tech and have some major drawbacks but they are still in use for very good reasons. No one has as yet figured out a way to make any sort of rotary valve with a non linear type motion. Until they do, poppet will rule.
I see the best bet for future 4 stroke innovation being electro-mechanical valves. Keep the poppets and their motions but ditch the cam shaft.
It is very easy to make something that will improve a stock Ford's performance. When they bolt it on an F1 motor and start winning races, then I will believe. Yes, poppet valves are old tech and have some major drawbacks but they are still in use for very good reasons. No one has as yet figured out a way to make any sort of rotary valve with a non linear type motion. Until they do, poppet will rule.
I see the best bet for future 4 stroke innovation being electro-mechanical valves. Keep the poppets and their motions but ditch the cam shaft.
Common maximus
aples to aples dude! reading...
? a stock Ford 5.0 flows nothing, but there are enough aftermaket heads for that engine that flow close to 400 cfm. A ported modern Hemi head flows around that too. And max flow is just one part of the equation! the speed that the poppet valve design allows the valve to open, and after it stays fully opened for a while, close, will never be attained with - at least - that design, it's just phisically imposible. It's area under the curve what gives you power. That head flows 319cfm for a degree or two, and is the other 90 deg or whatever following a linear curve from 0cfm to 319 and back to 0, not the case at all for apoppet valve, you can use the first 10~15 deg to raise it to the max for full flow, be there for ~60 deg and bring it down to 0 in the last 15 again and sudenlly the head flowed an average that is huge compared to the rotax head.LOL, almost all modern stock heads do about 315cfm with good porting.
that type of head can ONLY do maximun flow at precisely the cam position that the valve is fully opened, lets give it 5 degrees for example if you make the hole bigger than the port, a poppet valve can be opened at maximum for whatever degrees you want - it not linear!!! And you cant do the holetoo big because it takes degrees to do it because of its linearity, not the casewith poppet valves.
AND again, I'm not saying is imposible, I'm just saying that as long as the valve opens with a linear relation to the crankshaft/camshaft position, the poppet valve will have a chance to shine if done correctly.
But as the wingman said, the big dogs would be using it if it where that good, at least when full blown racing is what you want.
X
Last edited by maxflo777; 08-21-2009 at 10:00 PM. Reason: gram
08-22-2009 | 12:40 AM
#27
I haven't made metal chips fly yet, but I have discovered Google SketchUp, which allows me to model my engine in 3 dimensions. It's pretty easy to use, and I've already modeled a good portion of the valve system. As I continue to learn how to use the program, I can see it's going to benefit the design and engineering process in a big way. Much better than drawing in 2 dimensions and just trying to imagine how it would work in 3-D. 
Tonight, I get to pick up my prototype piston, ring, wristpin, and sleeve. Once that stuff gets digitized, I'll have something concrete to base some dimensions off of.
Tonight, I get to pick up my prototype piston, ring, wristpin, and sleeve. Once that stuff gets digitized, I'll have something concrete to base some dimensions off of.
Anyway-good luck on your project.
I suggest you to contact to MXwrench here in forum, he is moderator for this section-he knows 4 strock RC engines as anybody else and I know he preformed a lot of development on them
08-22-2009 | 09:39 AM
#28
EXACTLLY!!!
Common maximus aples to aples dude! reading...? a stock Ford 5.0 flows nothing, but there are enough aftermaket heads for that engine that flow close to 400 cfm. A ported modern Hemi head flows around that too. And max flow is just one part of the equation! the speed that the poppet valve design allows the valve to open, and after it stays fully opened for a while, close, will never be attained with - at least - that design, it's just phisically imposible. It's area under the curve what gives you power. That head flows 319cfm for a degree or two, and is the other 90 deg or whatever following a linear curve from 0cfm to 319 and back to 0, not the case at all for apoppet valve, you can use the first 10~15 deg to raise it to the max for full flow, be there for ~60 deg and bring it down to 0 in the last 15 again and sudenlly the head flowed an average that is huge compared to the rotax head.
LOL, almost all modern stock heads do about 315cfm with good porting.
that type of head can ONLY do maximun flow at precisely the cam position that the valve is fully opened, lets give it 5 degrees for example if you make the hole bigger than the port, a poppet valve can be opened at maximum for whatever degrees you want - it not linear!!! And you cant do the holetoo big because it takes degrees to do it because of its linearity, not the casewith poppet valves.
AND again, I'm not saying is imposible, I'm just saying that as long as the valve opens with a linear relation to the crankshaft/camshaft position, the poppet valve will have a chance to shine if done correctly.
But as the wingman said, the big dogs would be using it if it where that good, at least when full blown racing is what you want.
X
Common maximus
aples to aples dude! reading...? a stock Ford 5.0 flows nothing, but there are enough aftermaket heads for that engine that flow close to 400 cfm. A ported modern Hemi head flows around that too. And max flow is just one part of the equation! the speed that the poppet valve design allows the valve to open, and after it stays fully opened for a while, close, will never be attained with - at least - that design, it's just phisically imposible. It's area under the curve what gives you power. That head flows 319cfm for a degree or two, and is the other 90 deg or whatever following a linear curve from 0cfm to 319 and back to 0, not the case at all for apoppet valve, you can use the first 10~15 deg to raise it to the max for full flow, be there for ~60 deg and bring it down to 0 in the last 15 again and sudenlly the head flowed an average that is huge compared to the rotax head.LOL, almost all modern stock heads do about 315cfm with good porting.
that type of head can ONLY do maximun flow at precisely the cam position that the valve is fully opened, lets give it 5 degrees for example if you make the hole bigger than the port, a poppet valve can be opened at maximum for whatever degrees you want - it not linear!!! And you cant do the holetoo big because it takes degrees to do it because of its linearity, not the casewith poppet valves.
AND again, I'm not saying is imposible, I'm just saying that as long as the valve opens with a linear relation to the crankshaft/camshaft position, the poppet valve will have a chance to shine if done correctly.
But as the wingman said, the big dogs would be using it if it where that good, at least when full blown racing is what you want.
X
With a conventional poppet valve, it can take 34 degrees of crankshaft rotation or more to reach a fully open position, wasting energy and limiting volumetric efficiency. With the CSRV, a comparable port area is exposed in only 2 degrees of crank rotation. The CSRV allows for superior surface flow coefficients from its spherical shape
remeber they made that HP on a bone stock Ford 5.0 from a lincoln.. this is not a race built engine at all, no headers, no high compresion pistons, just a stock motor with this intake technology....Good luck reaching that level of power bolting on just a set of aftermarket heads onto a stock 5.0..
I am unsure where this technology is headed, Coates holds all the patents on it and likely wants some huge money to allow any of the big guns to use it..... I myself wouldn't so quick to write it off, as you have to remeber the testing was done with first prototype heads, not with heads that were developed for racing.... being able to almost double the engines power output and nearly triple its RPM range is nothing to sneeze at..especially considering they are a first generation test head...with proper development this system would by far exceed what they currently are doing...You shouldn't be so quick to write off new technology, as you really don't know anything about it, its limitations or its advantages..... As i say your not going to bolt on a set of aftermerket heads on a bone stock Ford 5.0 from a Lincoln and hit that kind of power, sorry but its not going to happen......I know you can build an engine to hit that power, but this was done on a fully stock Lincoln engine, full emissions, stock pistons, stock exhaust, everything the way it comes from Ford....that is nearly a 100% increase in power and nearly triple the effective RPM ranage.... find me a set of aftermerket heads that can do that please..... then keep in mind this was done on a first generation head LOL you guys seriously crack me up !
08-22-2009 | 11:08 AM
#29
With a conventional poppet valve, it can take 34 degrees of crankshaft rotation or more to reach a fully open position, wasting energy and limiting volumetric efficiency. With the CSRV, a comparable port area is exposed in only 2 degrees of crank rotation. The CSRV allows for superior surface flow coefficients from its spherical shape
remeber they made that HP on a bone stock Ford 5.0 from a lincoln.. this is not a race built engine at all, no headers, no high compresion pistons, just a stock motor with this intake technology....Good luck reaching that level of power bolting on just a set of aftermarket heads onto a stock 5.0..
I am unsure where this technology is headed, Coates holds all the patents on it and likely wants some huge money to allow any of the big guns to use it..... I myself wouldn't so quick to write it off, as you have to remeber the testing was done with first prototype heads, not with heads that were developed for racing.... being able to almost double the engines power output and nearly triple its RPM range is nothing to sneeze at..especially considering they are a first generation test head...with proper development this system would by far exceed what they currently are doing...You shouldn't be so quick to write off new technology, as you really don't know anything about it, its limitations or its advantages..... As i say your not going to bolt on a set of aftermerket heads on a bone stock Ford 5.0 from a Lincoln and hit that kind of power, sorry but its not going to happen......I know you can build an engine to hit that power, but this was done on a fully stock Lincoln engine, full emissions, stock pistons, stock exhaust, everything the way it comes from Ford....that is nearly a 100% increase in power and nearly triple the effective RPM ranage.... find me a set of aftermerket heads that can do that please..... then keep in mind this was done on a first generation head LOL you guys seriously crack me up !
remeber they made that HP on a bone stock Ford 5.0 from a lincoln.. this is not a race built engine at all, no headers, no high compresion pistons, just a stock motor with this intake technology....Good luck reaching that level of power bolting on just a set of aftermarket heads onto a stock 5.0..
I am unsure where this technology is headed, Coates holds all the patents on it and likely wants some huge money to allow any of the big guns to use it..... I myself wouldn't so quick to write it off, as you have to remeber the testing was done with first prototype heads, not with heads that were developed for racing.... being able to almost double the engines power output and nearly triple its RPM range is nothing to sneeze at..especially considering they are a first generation test head...with proper development this system would by far exceed what they currently are doing...You shouldn't be so quick to write off new technology, as you really don't know anything about it, its limitations or its advantages..... As i say your not going to bolt on a set of aftermerket heads on a bone stock Ford 5.0 from a Lincoln and hit that kind of power, sorry but its not going to happen......I know you can build an engine to hit that power, but this was done on a fully stock Lincoln engine, full emissions, stock pistons, stock exhaust, everything the way it comes from Ford....that is nearly a 100% increase in power and nearly triple the effective RPM ranage.... find me a set of aftermerket heads that can do that please..... then keep in mind this was done on a first generation head LOL you guys seriously crack me up !
08-23-2009 | 12:53 AM
#30
Tech Regular
Joined: Apr 2009
Posts: 380
maximo, I really dont know like you said, I dont have THAT system in front of me, but really, how is it possible that the rotary valve in this design opens completely or enogh for any substantial flow with 2 deg of crank rotaion? look at the picture! just rotate it in your mind with out david blaine in the room and you will see, who cares what they say, its simple mechanics that can be seen from the picture, its almost exactly like opening our 2stroke crankshafts(?), but worst, divided by 2, how can 1 degree of camshaft rotation open up a rotary valve that is about 90 degrees of its circumference? I dont see it man. It will probably take about 90 deg of rotation to open the valve to full flow,then the valve will be there for an instant (ok, unless the valve is expossed completely in the chamber like it is in the upper section of the picture for, I dont know, about 90 deg? - but then compression goes to the trash and piston weight tothe roof trying to get the compression back) and then it will be the other 90 deg closing it.
Only with that disadvantage the system probably can be easely bettered by a good poppet cam, a good roller cam can open a valve at least ~90% of full flow in ~10 -15 deg not 34 like an engine designed for swirl and low end torque. One of us really does not understand something here because to me this is more than simple when applyed, dont get me wrong, it can be me
its just that I gave a lot of thought to that type of design years ago with big-name people that really know their stuff and at the end of the day there where two things that the system did not do with any effyciency - opening/closing the valves (extremely slow and again linear and cooling /lubricating the exhaust valve, look at the struggles that the wankle engine has had through its life span to keep its act clean and fuel efficient.
In our earlyer designs our rotary valves even had that same exact round shape in the opening and closing faces and then we noticed that the port opens "quicker" only because it robs it from the area under the curve, the thing that gives you all the power.
Im telling you Ive been there.
Im telling you, if it where good the big dogs would be using it, a lot of people do a lot of mind burnouts over that design and end up with the classic power maker. I'm a proud one, dont worry, theres space for you 
And just for the record, that head probably requires a different ehaust manifold/header, and different intake manifold, and it obviouslly has a diferent cam, if you put a good head/cam/intake/hearder combination to a 5L ford you can obtain 500 to 550hp, and thats done every day just take alook at any mustang mag. if you do the really trick stuff you can get 750 from 302 cubic inches, again, its been done every day, no turbos or alcohol or nitro, just high octain gasoline, compression and flow.
X
Only with that disadvantage the system probably can be easely bettered by a good poppet cam, a good roller cam can open a valve at least ~90% of full flow in ~10 -15 deg not 34 like an engine designed for swirl and low end torque. One of us really does not understand something here because to me this is more than simple when applyed, dont get me wrong, it can be me
its just that I gave a lot of thought to that type of design years ago with big-name people that really know their stuff and at the end of the day there where two things that the system did not do with any effyciency - opening/closing the valves (extremely slow and again linear and cooling /lubricating the exhaust valve, look at the struggles that the wankle engine has had through its life span to keep its act clean and fuel efficient.In our earlyer designs our rotary valves even had that same exact round shape in the opening and closing faces and then we noticed that the port opens "quicker" only because it robs it from the area under the curve, the thing that gives you all the power.
Im telling you Ive been there. Im telling you, if it where good the big dogs would be using it, a lot of people do a lot of mind burnouts over that design and end up with the classic power maker. I'm a proud one
, dont worry, theres space for you And just for the record, that head probably requires a different ehaust manifold/header, and different intake manifold, and it obviouslly has a diferent cam, if you put a good head/cam/intake/hearder combination to a 5L ford you can obtain 500 to 550hp, and thats done every day just take alook at any mustang mag. if you do the really trick stuff you can get 750 from 302 cubic inches, again, its been done every day, no turbos or alcohol or nitro, just high octain gasoline, compression and flow.
X