converting a .21 nitro to spark ignition
10-18-2010 | 05:11 AM
#1
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
converting a .21 nitro to spark ignition
Hi everybody, this is my first time posting in this particular forum (I usually stick to the giant scale cars forum).
For a while now I have been thinking about converting a .21 engine out of a 1/8th scale buggy to spark ignition. I have done alot of searching and found lots of good info regarding the conversion of airplane engines, and am amazed at how well they run. I understand that the engines run hotter on gasoline, make a bit less power and require more oil in the fuel than your typical zenoah. None of this worries me, as this is really just an experiment...I just think it will be cool to have such a small engine running on pump gas
There are just a few things I am unsure about:
First of all, I see that the engines you guys are converting are much bigger than my engine. Would there be any major problems with converting a .21? Im guessing the higher revs might have something to do with this.
Secondly, why is it that there have been no car/buggy engines converted to spark ignition? If anyone has any info/pictures of converted car engines I would love to see them
Finally, these are the parts I am looking at using for my conversion:
cdi : http://www.unitedhobbies.com/UNITEDH...idProduct=6292
hall sensor: http://www.unitedhobbies.com/UNITEDH...idProduct=7868
spark plug: http://www.dlenginesaustralia.com/dl...&productId=127
magnet: http://www.dlenginesaustralia.com/dl...&productId=305
Should this combination of parts be ok? I realise I will have to make an adapter for the spark plug cap
Any help would be greatly appreciated.
Thanks,
Sam.
For a while now I have been thinking about converting a .21 engine out of a 1/8th scale buggy to spark ignition. I have done alot of searching and found lots of good info regarding the conversion of airplane engines, and am amazed at how well they run. I understand that the engines run hotter on gasoline, make a bit less power and require more oil in the fuel than your typical zenoah. None of this worries me, as this is really just an experiment...I just think it will be cool to have such a small engine running on pump gas
There are just a few things I am unsure about:
First of all, I see that the engines you guys are converting are much bigger than my engine. Would there be any major problems with converting a .21? Im guessing the higher revs might have something to do with this.
Secondly, why is it that there have been no car/buggy engines converted to spark ignition? If anyone has any info/pictures of converted car engines I would love to see them
Finally, these are the parts I am looking at using for my conversion:
cdi : http://www.unitedhobbies.com/UNITEDH...idProduct=6292
hall sensor: http://www.unitedhobbies.com/UNITEDH...idProduct=7868
spark plug: http://www.dlenginesaustralia.com/dl...&productId=127
magnet: http://www.dlenginesaustralia.com/dl...&productId=305
Should this combination of parts be ok? I realise I will have to make an adapter for the spark plug cap
Any help would be greatly appreciated.
Thanks,
Sam.
10-18-2010 | 07:15 PM
#2
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
RE: converting a .21 nitro to spark ignition
Uh...so it looks like Im on my own then [
]. I thought somebody could have helped...
Oh well, im gonna give it a shot anyway.
]. I thought somebody could have helped...Oh well, im gonna give it a shot anyway
.
10-18-2010 | 08:23 PM
#4
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
RE: converting a .21 nitro to spark ignition
What parts are you looking for? I think all the stuff you need is the cdi, hall sensor, magnet, 1/4"-32 spark plug and a 4-cell reciever pack. Links to the parts I plan on buying can be found in my first post. A walbro carb might be needed to, but I doubt we will find one small enough for our engines. Im not really of much use other than that sorry. Once I have got my parts and given this a shot I will let you know if I get it working or not.
Is your engine a for a car?
Is your engine a for a car?
10-19-2010 | 08:58 AM
#7
Senior Member
Joined: Dec 2008
Posts: 136
Likes: 0
Received 0 Likes
on
0 Posts
From: Athens, GREECE
RE: converting a .21 nitro to spark ignition
ORIGINAL: sam123
Hi everybody, this is my first time posting in this particular forum (I usually stick to the giant scale cars forum).
For a while now I have been thinking about converting a .21 engine out of a 1/8th scale buggy to spark ignition. I have done alot of searching and found lots of good info regarding the conversion of airplane engines, and am amazed at how well they run. I understand that the engines run hotter on gasoline, make a bit less power and require more oil in the fuel than your typical zenoah. None of this worries me, as this is really just an experiment...I just think it will be cool to have such a small engine running on pump gas
There are just a few things I am unsure about:
First of all, I see that the engines you guys are converting are much bigger than my engine. Would there be any major problems with converting a .21? Im guessing the higher revs might have something to do with this.
Secondly, why is it that there have been no car/buggy engines converted to spark ignition? If anyone has any info/pictures of converted car engines I would love to see them
Finally, these are the parts I am looking at using for my conversion:
cdi : http://www.unitedhobbies.com/UNITEDH...idProduct=6292
hall sensor: http://www.unitedhobbies.com/UNITEDH...idProduct=7868
spark plug: http://www.dlenginesaustralia.com/dl...&productId=127
magnet: http://www.dlenginesaustralia.com/dl...&productId=305
Should this combination of parts be ok? I realise I will have to make an adapter for the spark plug cap
Any help would be greatly appreciated.
Thanks,
Sam.
Hi everybody, this is my first time posting in this particular forum (I usually stick to the giant scale cars forum).
For a while now I have been thinking about converting a .21 engine out of a 1/8th scale buggy to spark ignition. I have done alot of searching and found lots of good info regarding the conversion of airplane engines, and am amazed at how well they run. I understand that the engines run hotter on gasoline, make a bit less power and require more oil in the fuel than your typical zenoah. None of this worries me, as this is really just an experiment...I just think it will be cool to have such a small engine running on pump gas
There are just a few things I am unsure about:
First of all, I see that the engines you guys are converting are much bigger than my engine. Would there be any major problems with converting a .21? Im guessing the higher revs might have something to do with this.
Secondly, why is it that there have been no car/buggy engines converted to spark ignition? If anyone has any info/pictures of converted car engines I would love to see them
Finally, these are the parts I am looking at using for my conversion:
cdi : http://www.unitedhobbies.com/UNITEDH...idProduct=6292
hall sensor: http://www.unitedhobbies.com/UNITEDH...idProduct=7868
spark plug: http://www.dlenginesaustralia.com/dl...&productId=127
magnet: http://www.dlenginesaustralia.com/dl...&productId=305
Should this combination of parts be ok? I realise I will have to make an adapter for the spark plug cap
Any help would be greatly appreciated.
Thanks,
Sam.
Sam,
You are driven by the same motivation that has driven me in converting an ASP .52FS into a gasser. Watch my videos in Youtube if you want. The engine runs extremely well and now I am willing to fly it also, however I have to find the time to install it in the airplane. Anyway, for your engine:
It is indeed a small engine to convert. My idea is that a .50 engine and up is most suitable, as in smaller engines the weight of batteries and ignition system becomes an issue. However, if you want to convert to a gasser, it can be done (imagine, in the '20s, '30s and '40s, before the glow plug invented, there were as small as 0.09 gassers and people were still flying-of course without radio control systems and with large span, slow, airplanes).
As I can see, most of the parts needed are there. However, you need to manufacture a spark plug boot, if you buy this ignition unit. You might also want to consider RCEXL ignition modules for 1/4-32 spark plugs, whose spark plug boot is already there!
Also, the greatest challenge you will face, during conversion according to my opinion, is placing the magnet on the small propellor hub of a .20 engine. It might even bee too big (the magnet) for being properly glued in place...But I do not know your engine exactly, so I cannot imagine your hub.
The timing of the ignition is straightforward, if you have a degree wheel, but another challenge would be placing the sensor holder on the engine. Again, I do not know how you are going to do it, but I used a hose clamp and glued the sensor holder on it. Thus, ignition timing is adjustable, which is a good idea if you make it adjustable as well. My engine needed to lag the ignition some degrees in order to start and work properly without backfires (I haven't reduce the compression).If I had fixed the sensor holder, I would not be able to do so.
If you have more specific answers, do not hesitate to ask.
10-19-2010 | 01:25 PM
#8
My Feedback: (9)
Joined: Jan 2002
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
From: Copperas Cove, Tx.
RE: converting a .21 nitro to spark ignition
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
Mike
10-20-2010 | 04:02 AM
#9
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
RE: converting a .21 nitro to spark ignition
ORIGINAL: Nikolas K
Sam,
You are driven by the same motivation that has driven me in converting an ASP .52FS into a gasser. Watch my videos in Youtube if you want. The engine runs extremely well and now I am willing to fly it also, however I have to find the time to install it in the airplane. Anyway, for your engine:
It is indeed a small engine to convert. My idea is that a .50 engine and up is most suitable, as in smaller engines the weight of batteries and ignition system becomes an issue. However, if you want to convert to a gasser, it can be done (imagine, in the '20s, '30s and '40s, before the glow plug invented, there were as small as 0.09 gassers and people were still flying-of course without radio control systems and with large span, slow, airplanes).
As I can see, most of the parts needed are there. However, you need to manufacture a spark plug boot, if you buy this ignition unit. You might also want to consider RCEXL ignition modules for 1/4-32 spark plugs, whose spark plug boot is already there!
Also, the greatest challenge you will face, during conversion according to my opinion, is placing the magnet on the small propellor hub of a .20 engine. It might even bee too big (the magnet) for being properly glued in place...But I do not know your engine exactly, so I cannot imagine your hub.
The timing of the ignition is straightforward, if you have a degree wheel, but another challenge would be placing the sensor holder on the engine. Again, I do not know how you are going to do it, but I used a hose clamp and glued the sensor holder on it. Thus, ignition timing is adjustable, which is a good idea if you make it adjustable as well. My engine needed to lag the ignition some degrees in order to start and work properly without backfires (I haven't reduce the compression).If I had fixed the sensor holder, I would not be able to do so.
If you have more specific answers, do not hesitate to ask.
Sam,
You are driven by the same motivation that has driven me in converting an ASP .52FS into a gasser. Watch my videos in Youtube if you want. The engine runs extremely well and now I am willing to fly it also, however I have to find the time to install it in the airplane. Anyway, for your engine:
It is indeed a small engine to convert. My idea is that a .50 engine and up is most suitable, as in smaller engines the weight of batteries and ignition system becomes an issue. However, if you want to convert to a gasser, it can be done (imagine, in the '20s, '30s and '40s, before the glow plug invented, there were as small as 0.09 gassers and people were still flying-of course without radio control systems and with large span, slow, airplanes).
As I can see, most of the parts needed are there. However, you need to manufacture a spark plug boot, if you buy this ignition unit. You might also want to consider RCEXL ignition modules for 1/4-32 spark plugs, whose spark plug boot is already there!
Also, the greatest challenge you will face, during conversion according to my opinion, is placing the magnet on the small propellor hub of a .20 engine. It might even bee too big (the magnet) for being properly glued in place...But I do not know your engine exactly, so I cannot imagine your hub.
The timing of the ignition is straightforward, if you have a degree wheel, but another challenge would be placing the sensor holder on the engine. Again, I do not know how you are going to do it, but I used a hose clamp and glued the sensor holder on it. Thus, ignition timing is adjustable, which is a good idea if you make it adjustable as well. My engine needed to lag the ignition some degrees in order to start and work properly without backfires (I haven't reduce the compression).If I had fixed the sensor holder, I would not be able to do so.
If you have more specific answers, do not hesitate to ask.
Thats a good point you make about the old engines running spark ignition. I always just assumed they were nitro.
The weight of the system dosen't really bother me, as this is just an experiment i've wanted to do for a while. Later on I might end up buying a bigger, ringed heli or plane engine and modifying it to use on an rc car.
I think I should be ok with placing the magnet in the flywheel, as I was going to make a new flywheel for it anyway on my mini lathe. I also plan to cut a groove into the circumference of the flywheel and use it as a drive pulley for a cooling fan....but that can wait I guess. And I will definately be making the mount for sensor adjustable, thanks for the tip!
10-20-2010 | 04:14 AM
#10
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
RE: converting a .21 nitro to spark ignition
ORIGINAL: optech
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
10-20-2010 | 01:34 PM
#13
Senior Member
Joined: Dec 2008
Posts: 136
Likes: 0
Received 0 Likes
on
0 Posts
From: Athens, GREECE
RE: converting a .21 nitro to spark ignition
ORIGINAL: sam123
Hmm, the engine I have is of ABC construction, like you mentioned. I guess this could cause some problems [:@]. Do you think I could avoid this by keeping it as cool as possible (using a cooling fan and avoiding full throttle), and use a higher oil content? If the engine does end up dieing, I will definately upgrade to a bigger, ringed engine.
ORIGINAL: optech
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
Optech, is right. This is a point I 've forgotten to mention to you. Conversions work better for ringed engines. But then again, in the years before glow plug, the small engines at least were not ringed. And I have seen many plans and patents of old engines (like the Atom and 0.099 of Arden design) and I haven't noticed a ringed piston. Neither a ball bearing in the con-rod... And considering the materials available back then, I assume all these made it worst.
I think that by going conservative (i.e at least 14:1-15:1 gasoline-oil mix, rich settings, sufficient cooling) you will not have a problem.
After all, the worst that can happen for an ABC engine is to increase the clearance between piston and sleeve and lose power, or stall the engine. It has the characteristic that it cannot "stick together", because Brass sleeve expands more than the aluminium piston and so you are protected from sudden destruction. The best of course is to have the metals already stabilised, i.e. have the engine run-in with glow fuel and glow plug.
As for longevity of the engine is considered however, keep in mind that increased temperatures and less lubrication may cause the converted engine to wear before the glow version. How fast, I do not know. My experiment is still ongoing for the four stroke...
Try to convert a cheap engine as this is an experiment. You didn't tell us which engine you are thinking of converting.
10-20-2010 | 03:38 PM
#15
RE: converting a .21 nitro to spark ignition
The "real old" spark ignition engines had a different metallurgy than todays modern ABC/ABN screamers. Typically the cylinders were steel and the pistons were cast iron but fear not the little .21 will run for a while. Eventually the piston to cylinder seal will deteriorate enough that it will become hard to start but that will take a while especially if you keep the fuel/oil ratio rich. I'm running my ringed SuperTigre's at 16:1 but I'd go for something more in the 10 to 12:1 range on the ABC stuff. Set the timing up around 28 degs BTDC, + or - a deg or two and she'll run good. Also, remember the carb is going to need to be significantly leaner than with glow fuel. (it takes 2.3 times more methanol than gasoline to have a stoichiometric mixture) The needles will be quite sensitive with only a click or two being the difference between very rich and very lean on the high needle, the low needle being equally sensitive. Good luck and remember to have fun, after all, that's what it's all about.
P.S. Be safe and remember the voltage discharge from the CDI is quite high and can hurt you.
P.S. Be safe and remember the voltage discharge from the CDI is quite high and can hurt you.
10-20-2010 | 05:24 PM
#16
Junior Member
Joined: Oct 2010
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
From: Mississauga, ON, CANADA
RE: converting a .21 nitro to spark ignition
but can i put a walbro carb on traxxas 3.3 engine. do i need a walbro carb on a traxxas 3.3engine for a glow to gas converstion
10-20-2010 | 10:11 PM
#19
RE: converting a .21 nitro to spark ignition
For the magnet install...machine a ring that slips on the flywheel or hub. Install magnet in ring and a small setscrew on the opisite side of the ring. To get the right timing...just loosen set screw...and turn ring a tad.
The carb may be tricky.But a regular glow carb may work if it will draw fuel & if the needle is not to touchy to adjust. Look up a small RC car that was made in Italy. It was about the same cc & was gas with CD ignition. Capt,n
http://www.classic.rc-junkies.net/?page_id=637
The carb may be tricky.But a regular glow carb may work if it will draw fuel & if the needle is not to touchy to adjust. Look up a small RC car that was made in Italy. It was about the same cc & was gas with CD ignition. Capt,n
http://www.classic.rc-junkies.net/?page_id=637
10-21-2010 | 05:34 AM
#20
Thread Starter
Senior Member
My Feedback: (1)
Joined: Feb 2005
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
From: Melbourne, AUSTRALIA
RE: converting a .21 nitro to spark ignition
Thanks for all the help guys .
So I guess the piston and liner should be ok as long as I use more oil than usual. Maybe once I get it going I could experiment with different fuel-oil ratios and oil types.
Nikolas, the engine I plan on converting is a Thunder Tiger .21 Pro. Apparently it is a re-badged OS engine. So, the quality is not too bad. It has not been used much, but has already been broken in on 5% nitro.
Jezmo and captinjohn, I am fairly confident that the carb will be ok. It dosen't use the same 'click' system as the plane engines, but fully adjustable screws like on the weed eater engines. I do have a few spare walbro carbs, but the smallest I have is from an 18cc weed eater, so it would probably be too big.
And yes I know what you mean about being careful with the cdi. Ive been shocked a few times by my weed eater engines and wow did it hurt.
Also, captinjohn, I will have to take a look at that engine you speak of! Sounds very interesting . And thanks for the link.
I have another question for you guys: How much does the entire cdi system weigh, including the battery (approximately)? Could the cdi be run off the reciever battery if I use higher capacity cells?
. So I guess the piston and liner should be ok as long as I use more oil than usual. Maybe once I get it going I could experiment with different fuel-oil ratios and oil types.
Nikolas, the engine I plan on converting is a Thunder Tiger .21 Pro. Apparently it is a re-badged OS engine. So, the quality is not too bad. It has not been used much, but has already been broken in on 5% nitro.
Jezmo and captinjohn, I am fairly confident that the carb will be ok. It dosen't use the same 'click' system as the plane engines, but fully adjustable screws like on the weed eater engines. I do have a few spare walbro carbs, but the smallest I have is from an 18cc weed eater, so it would probably be too big.
And yes I know what you mean about being careful with the cdi
. Ive been shocked a few times by my weed eater engines and wow did it hurt.Also, captinjohn, I will have to take a look at that engine you speak of! Sounds very interesting . And thanks for the link.
I have another question for you guys: How much does the entire cdi system weigh, including the battery (approximately)? Could the cdi be run off the reciever battery if I use higher capacity cells?
10-21-2010 | 02:11 PM
#24
My Feedback: (9)
Joined: Jan 2002
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
From: Copperas Cove, Tx.
RE: converting a .21 nitro to spark ignition
ORIGINAL: captinjohn
The carb may be tricky. But a regular glow carb may work if it will draw fuel & if the needle is not to touchy to adjust. Look up a small RC car that was made in Italy. It was about the same cc & was gas with CD ignition. Capt,n
http://www.classic.rc-junkies.net/?page_id=637
The carb may be tricky. But a regular glow carb may work if it will draw fuel & if the needle is not to touchy to adjust. Look up a small RC car that was made in Italy. It was about the same cc & was gas with CD ignition. Capt,n
http://www.classic.rc-junkies.net/?page_id=637
10-21-2010 | 02:43 PM
#25
Junior Member
Joined: Oct 2010
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
From: Mississauga, ON, CANADA
RE: converting a .21 nitro to spark ignition
Ok i got the spark plug and the cdi also the 4 cell battery and the hall censor for my traxxas 3.3. by the way whats the hall censory for. Also wats the ratio gonna be for gas to 2 cycle oil. And how will i ignite the engine.
