Single cyl for head development use,,balance problems.
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Single cyl for head development use,,balance problems.
I keep revisiting this project but get dead ended because of the inherent balance problems with single cylinder engines and the complexity to make it work
I’ve thought about using an available single cylinder water cooled 4 stroke engine but the size and it not being able to handle high rpms wasn’t feasible
So it would need to be one hole of a V8 and only one crank throw with two mains of the crank.
The problem is the lateral and secondary balance forces...
Is there a way around this that isn’t complicated?
I’ve thought about using an available single cylinder water cooled 4 stroke engine but the size and it not being able to handle high rpms wasn’t feasible
So it would need to be one hole of a V8 and only one crank throw with two mains of the crank.
The problem is the lateral and secondary balance forces...
Is there a way around this that isn’t complicated?
Last edited by gmrocket on Sat Aug 22, 2020 4:48 pm, edited 1 time in total.
Re: Single cyl for head development... balance problems.
Oh ya, it will be a very lite rotating assembly to start with, aluminum rod, lite pin and piston. Need it to run at 8500 or more
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Re: Single cyl for head development use,,balance problems.
Will run fine with a 55-60% balance factor
Re: Single cyl for head development use,,balance problems.
Engler is on the money, I have used 60 and 65% on British single engines with good reports back from riders.
British aircraft engine manufactures in the 30s and 40s did a lot of single cylinder proof of concept and development engines.
Cheers.
British aircraft engine manufactures in the 30s and 40s did a lot of single cylinder proof of concept and development engines.
Cheers.
Re: Single cyl for head development use,,balance problems.
So 55 to 60, or 60 to 65?
That’s a big spread. What cc were the bikes and airplane engines and did they turn fairly high rpm?
It’s going to be 950cc minimum, but better if I can 1000 plus
Is there anyone who specializes in big singles that I can contact about balancing this idea?
That’s a big spread. What cc were the bikes and airplane engines and did they turn fairly high rpm?
It’s going to be 950cc minimum, but better if I can 1000 plus
Is there anyone who specializes in big singles that I can contact about balancing this idea?
Re: Single cyl for head development use,,balance problems.
Stock Harley's in the 70's forward were balanced at 50%, S&S a performance V twin parts manufacturer settled on 60% in the seventies, 60 is by far the better percentage for touring to the point Harley adopted 60% in the mid late ninety's, how do i know this? i balance a lot of V Twin crankshafts and found from the later nineties that i was removing very little material to achieve 60%. A 45°V twin behaves a lot like a big single and these have been manufactured with up to around 70 cuin/cyl,[ the 145 has 4.375"bore 4.812"stroke with 8.250" rods, for street 11:1comp], these big engines do stretch the comfort component though.
These engines use a 6200rpm quite commonly. A good top end will run higher, I have had a 100" Sportster [pictured]that ran to 8000rpm.
The 65% ? that comes from the British single manufacturers.
Cheers.
These engines use a 6200rpm quite commonly. A good top end will run higher, I have had a 100" Sportster [pictured]that ran to 8000rpm.
The 65% ? that comes from the British single manufacturers.
Cheers.
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Re: Single cyl for head development use,,balance problems.
I may have just what you are thinking of.
I built a special purpose dyno with a TFX system to measure pressures at speed for a single cylinder ROTAX 650, it has a balance shaft.
Stock red line was 8000 RPM with a carb, now it is fuel injected.
The whole thing is on wheels and can fit in a closet.
My plan is to complete a book on the consequences of various intake and exhaust design parameters.
Lengths, tapers bell mouths etc.
I am moving to a new house in about 3 weeks, I have my doubts about whether the neighbourhood will be dyno friendly.
I built a special purpose dyno with a TFX system to measure pressures at speed for a single cylinder ROTAX 650, it has a balance shaft.
Stock red line was 8000 RPM with a carb, now it is fuel injected.
The whole thing is on wheels and can fit in a closet.
My plan is to complete a book on the consequences of various intake and exhaust design parameters.
Lengths, tapers bell mouths etc.
I am moving to a new house in about 3 weeks, I have my doubts about whether the neighbourhood will be dyno friendly.
Helping to Deliver the Promise of Flying Cars
Re: Single cyl for head development use,,balance problems.
if you want to use a v8 block....maybe, a pair of pistons, the other would just be along for the ride to make it into a 90dgree v twin.
Balance the crank with one bobweight OR make collars to bolt on the other crank throws for balance and to block the oil holes also.
Balance the crank with one bobweight OR make collars to bolt on the other crank throws for balance and to block the oil holes also.
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Re: Single cyl for head development use,,balance problems.
What cylinder head do you want to develop?
If you use a motorcycle engine it may be a lot of work to adapt a head.
I considered adding a cam in block and adapting pushrod heads to my ROTAX 650 but after looking at the details it seems like putting a dinosaur head and a third arm on Scarlett Johansson.
If you use a motorcycle engine it may be a lot of work to adapt a head.
I considered adding a cam in block and adapting pushrod heads to my ROTAX 650 but after looking at the details it seems like putting a dinosaur head and a third arm on Scarlett Johansson.
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Re: Single cyl for head development use,,balance problems.
So I did a lot of reading and some experimentation on speedway motors 87mm stroke on some 3.45"
You CAN use 50% or 60%
Lower numbers have less counteraction of forces inline with the cylinder. Higher numbers counteract inline forces better but as the crank passes TDC/BDC it starts swinging the engine fore and aft perpendicular to the bore.
For operator comfort it is ideal to find the number where these two effects are "balanced" where the balance factor is high enough to counteract the parallel forces but not so high that the perpindicular forces begin to exceed the inline forces.
50 is a reasonable mechanically sound number and is a logical choice right? Well its actually not where the cross over occurs
If you play with tonys calculator here https://motochassis.com/freeware/
Click the box that says something about secondaries
Enter your bore and stroke
The effects of the connecting rod ratio alter that cross over point. If you scroll through the balance factors looking at the graph you can can see these effects.
0% pure inline
100% pure perpindicular
Some anecdotes
A rider can precieve verticle shaking in the handlebar easier than horizontal shaking.
Motorcycles with verticle engines may often be balanced with higher percentages like 65 or so
Motorcycles with horizontal engines may often be balanced with lower balance factors.
Infact in speedway bikes the same engine exist in verticle and horizontal variants.
The spec is 64 for verticle, 56 horizontal, on otherwise identical engines (aside from oil pump considerations)
For our verticle speedway engine tonys calculator spit out 59%
Smoothest running jawa we had ever experienced.
Conversely one of my brothers early motors had a heavy rod and piston (so a low unknown balance factor) it shook him so hard it blurred his vision.....
So to put you at ease
50% will easily work
55-65% redistributes some remaining inline forces into perpindicular forces.
You won't know the difference between 50 and 65 as your not going to be riding it.
You CAN use 50% or 60%
Lower numbers have less counteraction of forces inline with the cylinder. Higher numbers counteract inline forces better but as the crank passes TDC/BDC it starts swinging the engine fore and aft perpendicular to the bore.
For operator comfort it is ideal to find the number where these two effects are "balanced" where the balance factor is high enough to counteract the parallel forces but not so high that the perpindicular forces begin to exceed the inline forces.
50 is a reasonable mechanically sound number and is a logical choice right? Well its actually not where the cross over occurs
If you play with tonys calculator here https://motochassis.com/freeware/
Click the box that says something about secondaries
Enter your bore and stroke
The effects of the connecting rod ratio alter that cross over point. If you scroll through the balance factors looking at the graph you can can see these effects.
0% pure inline
100% pure perpindicular
Some anecdotes
A rider can precieve verticle shaking in the handlebar easier than horizontal shaking.
Motorcycles with verticle engines may often be balanced with higher percentages like 65 or so
Motorcycles with horizontal engines may often be balanced with lower balance factors.
Infact in speedway bikes the same engine exist in verticle and horizontal variants.
The spec is 64 for verticle, 56 horizontal, on otherwise identical engines (aside from oil pump considerations)
For our verticle speedway engine tonys calculator spit out 59%
Smoothest running jawa we had ever experienced.
Conversely one of my brothers early motors had a heavy rod and piston (so a low unknown balance factor) it shook him so hard it blurred his vision.....
So to put you at ease
50% will easily work
55-65% redistributes some remaining inline forces into perpindicular forces.
You won't know the difference between 50 and 65 as your not going to be riding it.
Re: Single cyl for head development use,,balance problems.
I was thinking the exact same thing.. but wouldn’t that defeat the purpose as the data would be screwed as it’s doing work to move that opposing piston?modok wrote: ↑Sun Aug 23, 2020 2:52 am if you want to use a v8 block....maybe, a pair of pistons, the other would just be along for the ride to make it into a 90dgree v twin.
Balance the crank with one bobweight OR make collars to bolt on the other crank throws for balance and to block the oil holes also.
The weight on the same journal to replicate some of the missing other piston and rod is the easiest.. which would also keep the working rod where it should be
Re: Single cyl for head development use,,balance problems.
If the engine and it's mountings are heavy and strong (rigid) enough then the vibration is not really important.
90 degree twin should be a lot smoother than a single. A twisted crank v8 is basically 4 v-twins connected for even firing.... as far as balance is concerned.
90 degree twin should be a lot smoother than a single. A twisted crank v8 is basically 4 v-twins connected for even firing.... as far as balance is concerned.
Re: Single cyl for head development use,,balance problems.
Interesting stuff but I can’t open that article on balancingenglertracing wrote: ↑Sun Aug 23, 2020 2:33 pm So I did a lot of reading and some experimentation on speedway motors 87mm stroke on some 3.45"
You CAN use 50% or 60%
Lower numbers have less counteraction of forces inline with the cylinder. Higher numbers counteract inline forces better but as the crank passes TDC/BDC it starts swinging the engine fore and aft perpendicular to the bore.
For operator comfort it is ideal to find the number where these two effects are "balanced" where the balance factor is high enough to counteract the parallel forces but not so high that the perpindicular forces begin to exceed the inline forces.
50 is a reasonable mechanically sound number and is a logical choice right? Well its actually not where the cross over occurs
If you play with tonys calculator here https://motochassis.com/freeware/
Click the box that says something about secondaries
Enter your bore and stroke
The effects of the connecting rod ratio alter that cross over point. If you scroll through the balance factors looking at the graph you can can see these effects.
0% pure inline
100% pure perpindicular
Some anecdotes
A rider can precieve verticle shaking in the handlebar easier than horizontal shaking.
Motorcycles with verticle engines may often be balanced with higher percentages like 65 or so
Motorcycles with horizontal engines may often be balanced with lower balance factors.
Infact in speedway bikes the same engine exist in verticle and horizontal variants.
The spec is 64 for verticle, 56 horizontal, on otherwise identical engines (aside from oil pump considerations)
For our verticle speedway engine tonys calculator spit out 59%
Smoothest running jawa we had ever experienced.
Conversely one of my brothers early motors had a heavy rod and piston (so a low unknown balance factor) it shook him so hard it blurred his vision.....
So to put you at ease
50% will easily work
55-65% redistributes some remaining inline forces into perpindicular forces.
You won't know the difference between 50 and 65 as your not going to be riding it.
Re: Single cyl for head development use,,balance problems.
Yup, it will be a full engine block to help soak up any vibrations...modok wrote: ↑Sun Aug 23, 2020 6:28 pm If the engine and it's mountings are heavy and strong (rigid) enough then the vibration is not really important.
90 degree twin should be a lot smoother than a single. A twisted crank v8 is basically 4 v-twins connected for even firing.... as far as balance is concerned.
Re: Single cyl for head development use,,balance problems.
It won’t be a motorcycle engine, just too complicatedSchmidtMotorWorks wrote: ↑Sun Aug 23, 2020 2:04 pm What cylinder head do you want to develop?
If you use a motorcycle engine it may be a lot of work to adapt a head.
I considered adding a cam in block and adapting pushrod heads to my ROTAX 650 but after looking at the details it seems like putting a dinosaur head and a third arm on Scarlett Johansson.
One hole of a V8 will probably be it ..one back cylinder so I can easily run a heavy flywheel and starter. The last throw and two mains of the crank...run a mini drive rod forward to a gear that will drive the timing chain and cam as normal
Regular cam, oil pan, oiling system , distributor, electric water pump circulating water through one bank, single throat carb, blank plate on opposite bank.
It will oil the rockers through the pushrod like normal and a valley pan.
Maybe a big throat mikuni for simplicity and easy jetting