Bore vs Stroke vs Displacement
09-27-2006, 03:20 PM
#106
Originally Posted by afm
Rainer
From my experience it's a question of tuning and setting.
If you really know how to properly tune your engine, match the right pipe, set your clutch accordingly and choose the proper gearing, you can take advantage of the power and torque of any engine.
Then there's the issue of beeing able to put the power on the track...if you have traction problems, you are better off with a milder wide power band engine, than a peaky high revving engine or a super torquier engine.
When you have lots of traction you can get away with lots of power and torque. With low traction, you're spinning tires all the time (which wears them fast) and getting low run time, and not able to put all the power on the track (I.E: ORION CRF)
With respect to track layout and size, you are allways going to be faster on a small tight track with a torquier engine with wide power band, because you are on the brakes a lot and have to pull up from very low rpm's on every turn....on the other hand, on a large open flowing track, in which you are on the gas all the time, you'll be best on a high revving engine with narrow powerband and lots of hp.
Now there are engines which have a well balanced power band, that when properly geared and tuned, as I said before, will perform well on any track.
So yes it is possibble on paper to more or less predict what an engine is capable of doing or not....then it's each one's abilities to tune it and set it properly.
90% of the time I've found that people don't know how to properly set their cars, more than a question of who has the most power out there, except for the pro's of course, because when you see them at a race they are so close on performace (we are talking 10th's of a second), and are using differnt cars, engines etc. etc....that one concludes that most of the top brand engines are quite even in performance.
Just my 2 cents
AFM
From my experience it's a question of tuning and setting.
If you really know how to properly tune your engine, match the right pipe, set your clutch accordingly and choose the proper gearing, you can take advantage of the power and torque of any engine.
Then there's the issue of beeing able to put the power on the track...if you have traction problems, you are better off with a milder wide power band engine, than a peaky high revving engine or a super torquier engine.
When you have lots of traction you can get away with lots of power and torque. With low traction, you're spinning tires all the time (which wears them fast) and getting low run time, and not able to put all the power on the track (I.E: ORION CRF)
With respect to track layout and size, you are allways going to be faster on a small tight track with a torquier engine with wide power band, because you are on the brakes a lot and have to pull up from very low rpm's on every turn....on the other hand, on a large open flowing track, in which you are on the gas all the time, you'll be best on a high revving engine with narrow powerband and lots of hp.
Now there are engines which have a well balanced power band, that when properly geared and tuned, as I said before, will perform well on any track.
So yes it is possibble on paper to more or less predict what an engine is capable of doing or not....then it's each one's abilities to tune it and set it properly.
90% of the time I've found that people don't know how to properly set their cars, more than a question of who has the most power out there, except for the pro's of course, because when you see them at a race they are so close on performace (we are talking 10th's of a second), and are using differnt cars, engines etc. etc....that one concludes that most of the top brand engines are quite even in performance.
Just my 2 cents
AFM
09-27-2006, 03:21 PM
#107
Originally Posted by EdwardN
Hi Reiner.
Can I add something to your chart?
I would suggest for total induction timing add when it is open and when it is close.
Can I add something to your chart?
I would suggest for total induction timing add when it is open and when it is close.
I'm helping Rainer with the chart, and I suggested the inclusion of timing numbers on it, but we don't have all the engines so it would be helpfull if you gave us a hand with any numbers you might have, of course i'm sure you do have them for the Axial engine...I also took the power numbers for the Profi .12 engine and asumed them to be the same for the Axial..am I right or wrong??
Please feel free to correct any number you know might be wrong on the chart.
I will send you an editable copy to your mail.
Regards
AFM
09-27-2006, 03:21 PM
#108
Originally Posted by EdwardN
Hi Reiner.
Can I add something to your chart?
I would suggest for total induction timing add when it is open and when it is close.
Can I add something to your chart?
I would suggest for total induction timing add when it is open and when it is close.
09-27-2006, 04:03 PM
#109
Originally Posted by afm
Hi Edward
I'm helping Rainer with the chart, and I suggested the inclusion of timing numbers on it, but we don't have all the engines so it would be helpfull if you gave us a hand with any numbers you might have, of course i'm sure you do have them for the Axial engine...I also took the power numbers for the Profi .12 engine and asumed them to be the same for the Axial..am I right or wrong??
Please feel free to correct any number you know might be wrong on the chart.
I will send you an editable copy to your mail.
Regards
AFM
I'm helping Rainer with the chart, and I suggested the inclusion of timing numbers on it, but we don't have all the engines so it would be helpfull if you gave us a hand with any numbers you might have, of course i'm sure you do have them for the Axial engine...I also took the power numbers for the Profi .12 engine and asumed them to be the same for the Axial..am I right or wrong??
Please feel free to correct any number you know might be wrong on the chart.
I will send you an editable copy to your mail.
Regards
AFM
I will be more then happy to help you.
Axial numbers are 35 to open and 65 to close, so total induction is 210.
Profi engine is slightly different, 37 X 60
09-27-2006, 04:03 PM
#110
this is like a hobby with in a hobby 
this is good stuff i like to see this stuff.
this is good stuff i like to see this stuff.
09-27-2006, 04:11 PM
#111
Originally Posted by wallyedmonds
this is like a hobby with in a hobby this is good stuff i like to see this stuff.
this is good stuff i like to see this stuff.AFM
09-27-2006, 04:14 PM
#112
Originally Posted by EdwardN
Hi Alfonso.
I will be more then happy to help you.
Axial numbers are 35 to open and 65 to close, so total induction is 210.
Profi engine is slightly different, 37 X 60
I will be more then happy to help you.
Axial numbers are 35 to open and 65 to close, so total induction is 210.
Profi engine is slightly different, 37 X 60
When you have the other numbers just mail me corrected chart
AFM
09-27-2006, 06:17 PM
#113
Latest chart:
09-27-2006, 07:59 PM
#114
Originally Posted by rmdhawaii
Latest chart:
Induction open @38 close @65, exhaust 162, trnsfer 110
Edward
09-27-2006, 08:22 PM
#115
Originally Posted by EdwardN
Hi Reiner please add to your chart Sirio EVO3
Induction open @38 close @65, exhaust 162, trnsfer 110
Edward
Induction open @38 close @65, exhaust 162, trnsfer 110
Edward
What about the transfer and exhaust degrees on the Axial Ed ??
AFM
09-27-2006, 10:49 PM
#116
Tech Apprentice
timing
Hi reiner,another info on two italian engines: 
Vega VGT v12 E
SIRIO)
bore:13,97
stroke 13,65
max rpm :38000
ex 162°
tr 113°
ind.211°
open 36°
close 67°
Picco evoII (close to zx12 dsII)
ex 171°
tr 118°
ind 208°
ciao
carletto
Vega VGT v12 E
SIRIO)bore:13,97
stroke 13,65
max rpm :38000
ex 162°
tr 113°
ind.211°
open 36°
close 67°
Picco evoII (close to zx12 dsII)
ex 171°
tr 118°
ind 208°
ciao
carletto
09-28-2006, 08:49 AM
#117
Hey Reiner and Alfonso. You guys collected enough info and it will roll to fill up your table, now it is time to move forward. You will need to collect data of crancase volume, induction hole on cranck ( diameter), carburator lenght, induction angle on inserts, induction ports cavities sizing and then it will be time to go to the http://www.control-line-team.de/moto.../index_en.html.
Now I know next question will be how to collect data for crancase volume. Here we go: first of all it is pretty primature way to do that and it will depend on your accuracy.
on fully assembled motor, take the head off, put piston on BDC positon and from the top start filling up carncase through the transfer ports with fuel or very light oil using surange with volume graduation. Fill up till you see it is leveled with top of the piston, this will be crancase "base line" volume.
Let's keep it rolling-on the end you will have really good info.
Edward
Now I know next question will be how to collect data for crancase volume. Here we go: first of all it is pretty primature way to do that and it will depend on your accuracy.
on fully assembled motor, take the head off, put piston on BDC positon and from the top start filling up carncase through the transfer ports with fuel or very light oil using surange with volume graduation. Fill up till you see it is leveled with top of the piston, this will be crancase "base line" volume.
Let's keep it rolling-on the end you will have really good info.
Edward
09-28-2006, 01:46 PM
#118
But Edward …
Unless you’ve found a 2-stroke engine simulator program that takes these parameters and accurately predict the HP and torque curve of nitro R/C engines, what’s the point?
So I did some Googling and found this: http://rc-engine-analysis-software.com If anything, the technical articles are interesting to read.
It's too bad we don't all live in the same area, then we could get together to conduct this little science project. In order to do this correctly, we really need a prescribed methodology for measuring these things. Otherwise the measurements will be totally off. I'm starting to feel like I need research grant money.
This is getting a bit deep for me guys.
Before you know it, I'll have to learn how to use software from The MathWorks
Unless you’ve found a 2-stroke engine simulator program that takes these parameters and accurately predict the HP and torque curve of nitro R/C engines, what’s the point?
So I did some Googling and found this: http://rc-engine-analysis-software.com If anything, the technical articles are interesting to read.
It's too bad we don't all live in the same area, then we could get together to conduct this little science project. In order to do this correctly, we really need a prescribed methodology for measuring these things. Otherwise the measurements will be totally off. I'm starting to feel like I need research grant money.
This is getting a bit deep for me guys.
Before you know it, I'll have to learn how to use software from The MathWorks
09-28-2006, 04:33 PM
#119
Originally Posted by rmdhawaii
But Edward …
Unless you’ve found a 2-stroke engine simulator program that takes these parameters and accurately predict the HP and torque curve of nitro R/C engines, what’s the point?
So I did some Googling and found this: http://rc-engine-analysis-software.com If anything, the technical articles are interesting to read.
It's too bad we don't all live in the same area, then we could get together to conduct this little science project. In order to do this correctly, we really need a prescribed methodology for measuring these things. Otherwise the measurements will be totally off. I'm starting to feel like I need research grant money.
This is getting a bit deep for me guys. Before you know it, I'll have to learn how to use software from The MathWorks
Unless you’ve found a 2-stroke engine simulator program that takes these parameters and accurately predict the HP and torque curve of nitro R/C engines, what’s the point?
So I did some Googling and found this: http://rc-engine-analysis-software.com If anything, the technical articles are interesting to read.
It's too bad we don't all live in the same area, then we could get together to conduct this little science project. In order to do this correctly, we really need a prescribed methodology for measuring these things. Otherwise the measurements will be totally off. I'm starting to feel like I need research grant money.
This is getting a bit deep for me guys.
Before you know it, I'll have to learn how to use software from The MathWorks I found very instructing the articles in the link you posted, and everyday I know more of what to look for in an engine...i'ts a balancing act between usable HP, torque and fuel consumption...
Keep on reading and you'll find the answers sooner or later...but before, you need to know all the theory behind the design and application of 2 stroke engines, than the chart we've been working on finaly makes sense and choosing an engine a breeze...
Yes it is a pity we don't live within drivable distance to sit down and talk oversome beers about this facinating hobby.
AFM
09-28-2006, 05:49 PM
#120
Agree with afm, keep it up knowledge is a good thing. I dont think there ever is a predictor of how a motor will work with certainty, but the more people know the better.
You would be surprised how many people I talk to at the track insist to me that the manufacturers horsepower figures are precice and are worth relying on as a performance measure between motors. I have been unable to convince them otherwise even though many of use know that a N12 does not in fact turn 1.6hp SAE.
I think your spreadsheet can be a useful reference even without port timings and crankcase volumes as an exercise to show how the internal geometry of a motor can have an effect on the powerband and engine output, without it becoming an absolute predictor of engine power.
You would be surprised how many people I talk to at the track insist to me that the manufacturers horsepower figures are precice and are worth relying on as a performance measure between motors. I have been unable to convince them otherwise even though many of use know that a N12 does not in fact turn 1.6hp SAE.
I think your spreadsheet can be a useful reference even without port timings and crankcase volumes as an exercise to show how the internal geometry of a motor can have an effect on the powerband and engine output, without it becoming an absolute predictor of engine power.