Building an engine, pile of parts. Looking for mod ideas
08-12-2014, 06:27 PM
#16
The Crank
So the pile of parts came in. Here is the crank. I am thinking of trimming the sides of the carb port down so they are a little thinner, but not knife edges. I am also thinking about trimming down the turbo cut on the counterweight so it has a knife edge instead of the blunt edge. The center channel and little whoop di do cut at the back of the center will just get polished along with all the other internal parts of the crank.
Last edited by Tug Driver; 08-20-2014 at 01:16 AM. Reason: added more pics
08-13-2014, 03:13 AM
#17
5 whp is enough eveidence for me. Measured on a dyno. Printed on paper with a graph and everything, id say thats more than placebo.
Gotta love armchair tuners.
Have a look at any new sleeve, pick your favourite motor, that sleeve is polished so shiny you could use it to put on your makeup in the morning. Think thats a coincedence?
You polish the hell out of the sleeve, do a 400g p&p on the block and add the fangs to the sleeve. More power. Its a done deal. There is no argument. The 400g on the block is mainly to smooth out casting blemishes. You dont polish the block, mirror finish would cause the fuel to bead rather than atomize properly. The sleeve being mirror polished isnt affecting atomization its allowing smooth flow to the intake ports. Again i have limited knowledge of nitro motors but a wealth of experience on 1:1 scale engines. A full p&p on a 1:1 scale engine, done properly, gasket matched and casting blemishes ground out can be worth 30+ whp, or bhp for those of you in europe, without any other mods(aside from ecu tuning). P&P should never just be shrugged off as unimportant they way it is in this thread. Smooth, unrestricted airflow is key to making power in any engine. Its common sense, its science for crying out loud. You think automotive/mechanical based schools offer p&p courses because it doesnt make a difference?!
Timing changes and head work make the biggest hp gains in large scale, as well as compression changes, so apply what you know to small scale. You dont have heads on these motors, not in the large scale sense anyway, your crank acts as your head. The intake opening acts as your intake manifold as well as your intake valves. If you make the opening bigger its like adding duration and lift the way you would normally do it with a cam in large scale. Making the intake ports taller is affecting timing. Correct me if im wrong but when doing this you need to add head shims otherwise you change compression ratio? I dont think theres much to change inside the motor regarding exhaust. Your biggest gains/losses come from the length of the manifold pipe and what pipe you choose. Eventually you will become limited to what you can do because of fuel delivery issues. I dont know enough to recommend anything here. Large scale would require bigger pump/ larger injectors and larger volume fuel rails or a re-jet or simply a larger carb in some cases
Gotta love armchair tuners.
Have a look at any new sleeve, pick your favourite motor, that sleeve is polished so shiny you could use it to put on your makeup in the morning. Think thats a coincedence?
You polish the hell out of the sleeve, do a 400g p&p on the block and add the fangs to the sleeve. More power. Its a done deal. There is no argument. The 400g on the block is mainly to smooth out casting blemishes. You dont polish the block, mirror finish would cause the fuel to bead rather than atomize properly. The sleeve being mirror polished isnt affecting atomization its allowing smooth flow to the intake ports. Again i have limited knowledge of nitro motors but a wealth of experience on 1:1 scale engines. A full p&p on a 1:1 scale engine, done properly, gasket matched and casting blemishes ground out can be worth 30+ whp, or bhp for those of you in europe, without any other mods(aside from ecu tuning). P&P should never just be shrugged off as unimportant they way it is in this thread. Smooth, unrestricted airflow is key to making power in any engine. Its common sense, its science for crying out loud. You think automotive/mechanical based schools offer p&p courses because it doesnt make a difference?!
Timing changes and head work make the biggest hp gains in large scale, as well as compression changes, so apply what you know to small scale. You dont have heads on these motors, not in the large scale sense anyway, your crank acts as your head. The intake opening acts as your intake manifold as well as your intake valves. If you make the opening bigger its like adding duration and lift the way you would normally do it with a cam in large scale. Making the intake ports taller is affecting timing. Correct me if im wrong but when doing this you need to add head shims otherwise you change compression ratio? I dont think theres much to change inside the motor regarding exhaust. Your biggest gains/losses come from the length of the manifold pipe and what pipe you choose. Eventually you will become limited to what you can do because of fuel delivery issues. I dont know enough to recommend anything here. Large scale would require bigger pump/ larger injectors and larger volume fuel rails or a re-jet or simply a larger carb in some cases
I own a dyno and have tens of thousands of hours under my belt modifying nitro engines...No engine makes 5 HP...and fangs and polishing dont add any power whatsoever to these engines......... end of story !
08-13-2014, 08:33 AM
#18
Tech Adept
I think you better re-read my posts. I said 5whp. I dont recall seeing any chassis dynos for rcs so youve clearly mistaken my comments as in reference to rcs. I was talking about 1:1 scale. Cars. Big ones. The kind you sit in and drive that have a steering wheel INSIDE the car rather than mounted to a remote control lol. No offense meant.
Now what i find disturbing is that you would say something like fangs and polishing do nothing. They do SOMETHING. Scale has nothing to do with how you mod an engine to make more power. Its an internal combustion engine. You can take a 454 chevy for example and sit it next to your favourite Rossi/Picco nitro engine and youre going to use the same theories to add power in both examples. You MUST add more fuel and air. In order to add more air you need to make intake openings bigger. ANY time you port/polish you are removing material from whatever you are porting effectively making the hole/opening bigger.
Now what i find disturbing is that you would say something like fangs and polishing do nothing. They do SOMETHING. Scale has nothing to do with how you mod an engine to make more power. Its an internal combustion engine. You can take a 454 chevy for example and sit it next to your favourite Rossi/Picco nitro engine and youre going to use the same theories to add power in both examples. You MUST add more fuel and air. In order to add more air you need to make intake openings bigger. ANY time you port/polish you are removing material from whatever you are porting effectively making the hole/opening bigger.
08-13-2014, 08:44 AM
#19
Tech Adept
Polishing makes the path the air/fuel takes have less resistance making the engine more efficient. Any restriction in the intake path is robbing you of power. It may be measurable it may not. The small scale and relatively small power being made leads me to believe that some small changes that would normally equate to small but measurable gains on a large scale car engine may not be measured with a small scale engine dyno.
How accurrate are these nitro engine dynos realistically?
How accurrate are these nitro engine dynos realistically?
08-13-2014, 10:25 AM
#20
Polishing makes the path the air/fuel takes have less resistance making the engine more efficient. Any restriction in the intake path is robbing you of power. It may be measurable it may not. The small scale and relatively small power being made leads me to believe that some small changes that would normally equate to small but measurable gains on a large scale car engine may not be measured with a small scale engine dyno.
How accurrate are these nitro engine dynos realistically?
How accurrate are these nitro engine dynos realistically?
Now your are assuming fangs and polishing the sleeve actually make the fuel path better,,, which they do not... fangs are at the bottom of the port, nearly all the flow happens at the top of the port and untill the piston reaches BDC the bottom of the port is blocked by the piston... then when the piston hits BDC there is no longer any flow or pressure differential driving the flow....So you can dress up the bottom of the port all you want it will have almost zero effect on the mixture flow.....Some blending to remove any sharp angles is smart, but anything more can effect engine by altering the crankcase volume..tho usually effects can't be felt one way or the other..... Want to really make these engines work well start looking at the top of the ports where most of the mixture transfer actually happens....As for most of the transfer process the piston is blocking the ports.......
08-13-2014, 11:28 AM
#21
Polishing makes the path the air/fuel takes have less resistance making the engine more efficient. Any restriction in the intake path is robbing you of power. It may be measurable it may not. The small scale and relatively small power being made leads me to believe that some small changes that would normally equate to small but measurable gains on a large scale car engine may not be measured with a small scale engine dyno.
How accurrate are these nitro engine dynos realistically?
How accurrate are these nitro engine dynos realistically?
Porting is a balancing act because one usually needs to gain power without loss of torque which is a challenge in itself never mind adding say a rev limit and fuel consumption into the equation .
Who gives a shit how accurate Neils dyno is, as long as he is measuring comparatively that’s all that matters.
If you interested in 4 stroke porting I have a couple of links I could send you and if you interested in two stroke porting the best person will be someone who does loads of experimental work to dial in the sweet spot .
08-13-2014, 10:04 PM
#22
Tech Adept
Lol thats cute. 220 to finish a head. Ive got dull carbide burrs ive used that wouldnt leave that coarse of a finish. I leave a 400g finish whenever i do heads. Thats enough "bite" for good atomization while still being smooth as hell.
Ive done lots of porting on superchargers as well. Mainly M90 and M112s. With this situation youre free to go nuts as there is no fuel introduced untill further down the line. In fact on many newer cars that have a factory supercharger you are free to p&p till youre blue in the face as many of those engines fire the injectors either directly into the combustion chamber (called direct injection) or into an intake runner in the head. This means you can put as fine a finish as you want on the s/c and the lower intake.
Its a bad idea to play with size/shape of exhaust ports. But its no issue to mirror finish if desired as there is no fuel here and there is no such thing as too smooth of an exhaust flow. Although id recommend not wasting your time as its not nessicary.
You will not loose any torque by doing p&p unless you really f-ed up. You would have to take a serious ammount of material away to accomplish this. As i said before, a proper port job is to smooth factory casting marks, smooth intake runners and match heads to intakes (gasket matching) it is not a good idea to attempt to reshape any surface. If you dont have a flow bench for such operations you might as well piss in the wind. P&p isnt as delicate an operation as you might think, but things can go wrong quick. I use carbide burrs and they cut very fast compared to a stone. On aluminum you can do most jobs with a sanding drum. I still use carbides because they leave a finish that generally doesnt require further sanding. On harder steel the carbides are the only way to go. Stones wear out before you accomplish anything and a sanding drum might as well be a q-tip.
Ive done lots of porting on superchargers as well. Mainly M90 and M112s. With this situation youre free to go nuts as there is no fuel introduced untill further down the line. In fact on many newer cars that have a factory supercharger you are free to p&p till youre blue in the face as many of those engines fire the injectors either directly into the combustion chamber (called direct injection) or into an intake runner in the head. This means you can put as fine a finish as you want on the s/c and the lower intake.
Its a bad idea to play with size/shape of exhaust ports. But its no issue to mirror finish if desired as there is no fuel here and there is no such thing as too smooth of an exhaust flow. Although id recommend not wasting your time as its not nessicary.
You will not loose any torque by doing p&p unless you really f-ed up. You would have to take a serious ammount of material away to accomplish this. As i said before, a proper port job is to smooth factory casting marks, smooth intake runners and match heads to intakes (gasket matching) it is not a good idea to attempt to reshape any surface. If you dont have a flow bench for such operations you might as well piss in the wind. P&p isnt as delicate an operation as you might think, but things can go wrong quick. I use carbide burrs and they cut very fast compared to a stone. On aluminum you can do most jobs with a sanding drum. I still use carbides because they leave a finish that generally doesnt require further sanding. On harder steel the carbides are the only way to go. Stones wear out before you accomplish anything and a sanding drum might as well be a q-tip.
08-13-2014, 10:07 PM
#23
Tech Adept
Also i never asked how accurate his particular dyno is, i asked if the dynos in general are accurate. And it most certainly matters. If they cant be consistant then they should not be trusted.
08-14-2014, 12:34 AM
#24
Tech Adept
These .21 engine are different in a way than 1:1 scale Cars engines, there is a balance/sweet spot to modding this engines like crank timming,port timming,exhaust timming,case volume, button shape,compression ratio, not just ''more air more fuel more power'' we use from a 5.4,6.0,6.5mm venturis on the carbs. If that is the only case every one would use a 9mm venturi.We used this engines for nascar style racing were we need to pit, so fuel consumption is critical.About polishing the sleeve to a mirror finish, Methanol is corrossive so that mirror finish is gone in about one gallon.
Last edited by kyosho28; 08-14-2014 at 03:14 AM.
08-14-2014, 06:46 AM
#25
Tech Adept
Whats it coroding(sp?) The polishing doesnt leave anything residual. I always wipe (the engine parts) with rubbing alcohol when im done. Gets rid of any left over polishing compound and youd be surprised the places you find little pieces of the cotton wheel, so it gets rid of that too.
Anyway, im no expert in nitro engines. I wouldnt claim that, im just starting to learn them. I also will not claim to be an expert in porting. Ive probably done 30+ sets of heads, more intakes than i care to count as well as 15-20 superchargers. Lots of gasket matching. I DO NOT reshape combustion chambers tho. Not brave enough for that lol
Anyway, im no expert in nitro engines. I wouldnt claim that, im just starting to learn them. I also will not claim to be an expert in porting. Ive probably done 30+ sets of heads, more intakes than i care to count as well as 15-20 superchargers. Lots of gasket matching. I DO NOT reshape combustion chambers tho. Not brave enough for that lol
08-14-2014, 07:03 AM
#26
Tech Adept
Now, Neil, when you say play with the top of the port, changing the length will change the timing correct? Will it also not lower compression?
08-14-2014, 11:13 AM
#27
The build up of the compression starts above the ports due the taper in the sleeve.
Making the exhaust port higher will loose some torque due the less combustion stroke but the overal gain will be more. I always make the exhaust wider, it does change the timing as well but without affecting the torque.
Making the exhaust port higher will loose some torque due the less combustion stroke but the overal gain will be more. I always make the exhaust wider, it does change the timing as well but without affecting the torque.
08-15-2014, 03:14 PM
#28
Tech Adept
Taller or wider? What happens to things when you go wider with the intake ports?
08-16-2014, 02:02 AM
#29
The sleeve will snap in 2.....
On the old Novarossi R1 JP modified (purple head) the intakes were made wider and they always broke the sleeve in 2 pieces, you take out the strength.
Making the upper edges of the exhaust port wider is easy because that is above the intakes.
http://www.debaanbrekers.com/ftp/DSCF1642.JPG
On the old Novarossi R1 JP modified (purple head) the intakes were made wider and they always broke the sleeve in 2 pieces, you take out the strength.
Making the upper edges of the exhaust port wider is easy because that is above the intakes.
http://www.debaanbrekers.com/ftp/DSCF1642.JPG
08-20-2014, 01:20 AM
#30
The piston/sleeve
Here is the piston sleeve. What do you guys think? there are a few rough edges in the side ports I'm thinking about dressing up a little bit. As far as the design, it's odd that it's a 4+2 engine. It seems like instead of a wide front port they just used 2 ports of roughly the same size.