R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro On-Road

Reply
 
Thread Tools Search this Thread
Old 06-22-2004, 11:03 PM   #46
Tech Adept
 
sikgraffx's Avatar
 
Join Date: May 2004
Location: Glendora, Ca
Posts: 156
Default

sikgraffx is offline   Reply With Quote
Old 06-23-2004, 10:23 AM   #47
Tech Master
 
mop_iko's Avatar
 
Join Date: Sep 2003
Location: JOHOR BAHRU, MALAYSIA but now working in SHANGHAI
Posts: 1,797
Default pleaseeeee

Quote:
Originally posted by revzalot
This is a really cool thread. Can some of the master motor gurus post some tips, guidelines, or how-to to get started in engine modification? The article was informative but I'd like more info. Thanks in advance.
YEAH... WE NOOBies REALLY REALLY NEED YOUR INPUTS dear MASTERs.....

pleaseeeee....

where is MURNAN... can he share some tips?

mop
mop_iko is offline   Reply With Quote
Old 06-23-2004, 03:46 PM   #48
Tech Master
 
Grinder's Avatar
R/C Tech Elite Subscriber
 
Join Date: Feb 2003
Posts: 1,857
Trader Rating: 2 (100%+)
Default

I can't share exact numbers or designs, but I can answer some general questions if you like. One tip I will share is that most of the extra power in a modified motor is in the crankshaft. Like some other people have said on this thread, experiment a little at a time until you get something you like, if you go too far then you know what not to do on the next one. There are some pictures on my website of a modified Sirio crankshaft and sleeve, also a Novarossi sleeve. Some things you can't see from the pictures are timing figures and how light the crank is without losing balance.
__________________
www.murnanmodified.com
Grinder is offline   Reply With Quote
Old 06-23-2004, 04:51 PM   #49
Tech Fanatic
 
revzalot's Avatar
 
Join Date: Apr 2004
Location: Nor * Cal
Posts: 958
Trader Rating: 4 (100%+)
Default Anyone modify an OS 12TR

This engine has good low end but would like to improve its high end punch. What modifications needs to be done to hang with a NS12 or JP?
__________________
www.revzalotmotorsports.com
revzalot is offline   Reply With Quote
Old 06-23-2004, 05:21 PM   #50
Tech Adept
 
Bandeira's Avatar
 
Join Date: Apr 2004
Location: Oxford, UK
Posts: 167
Send a message via ICQ to Bandeira
Default

Hello guys...

I've already modded and old SX12SE Mega engine but only the Sleeve... This time I was planning to Mod the Crankshaft... But I don't know how can I get the balance between the weight I take from the weight part and how much I take from the pin part...
Isn't there any easier way of doing this apart from having a Dynamic balancing system?

thanks in advance....
Bandeira is offline   Reply With Quote
Old 06-23-2004, 05:43 PM   #51
Tech Master
 
Motorman's Avatar
 
Join Date: Nov 2001
Location: Michigan
Posts: 1,911
Trader Rating: 1 (100%+)
Default

banderia
heres a tip, on the current 12 engines you cannot get enough counterweight on them so that should give you a hint. you want to retain as much counterweight below the mid point of the crank centerline as possible. also the actual optimum weight offset is not directly below the crankpin it is offset to one side. look at a novarossi 21 crank that should give you another clue. dynamic balancing is only an issue when the engine gets bigger than a 21 and then it is not an exact science as the engine goes in and out of phase. However if the counterweight was to large or small an imbalance of such magnitude could occur that it will literally upset the fuel transfer through the engine limiting its ability. If a phased harmonic lines up with the port openings at high rpm it can literally stop the flow through the ports or change which ports are fed.

consider that the piston stops and starts at max rpm somwhere in the 1000 to 1500 times per second range (depending on the peak)and the port width is somewhere in the window of 20% of the piston stroke you can see it is open a very very small time. (microseconds)the fuel and air must also attempt to stop and start within that time window and it has physical mass. combine that with a shaking force of 20G's albiet at a very small magnitude can have a significant effect on its ability to flow. this physical displacement due to imbalance can short circuit the flow I've seen it and cured it by making a balance change.

Resist the urge to hog any more metal off the counterweight than absolutly necessary unless it actually aids flow.
__________________
Just here to give the world grief.

Last edited by Motorman; 06-23-2004 at 05:56 PM.
Motorman is offline   Reply With Quote
Old 06-23-2004, 06:03 PM   #52
Tech Adept
 
Bandeira's Avatar
 
Join Date: Apr 2004
Location: Oxford, UK
Posts: 167
Send a message via ICQ to Bandeira
Default

Quote:
Originally posted by Motorman
banderia
heres a tip, on the current 12 engines you cannot get enough counterweight on them so that should give you a hint. you want to retain as much counterweight below the mid point of the crank centerline as possible. also the actual optimum weight offset is not directly below the crankpin it is offset to one side. look at a novarossi 21 crank that should give you another clue. dynamic balancing is only an issue when the engine gets bigger than a 21 and then it is not an exact science as the engine goes in and out of phase. However if the counterweight was to large or small an imbalance of such magnitude could occur that it will literally upset the fuel transfer through the engine limiting its ability. If a phased harmonic lines up with the port openings at high rpm it can literally stop the flow through the ports or change which ports are fed.

consider that the piston stops and starts at max rpm somwhere in the 1000 to 1500 times per second range (depending on the peak)and the port width is somewhere in the window of 20% of the piston stroke you can see it is open a very very small time. (microseconds)the fuel and air must also attempt to stop and start within that time window and it has physical mass. combine that with a shaking force of 20G's albiet at a very small magnitude can have a significant effect on its ability to flow. this physical displacement due to imbalance can short circuit the flow I've seen it and cured it by making a balance change.

Resist the urge to hog any more metal off the counterweight than absolutly necessary unless it actually aids flow.
Thanks for the feedback...

I was thinking of practising in my old Mega SX12RE which haven't got turbo crankshafts... It is the older one, which viewed from the front are round... Not as our new engines, round at the bottom and kind of triangular shaped on the upper most part... I wanted to know how can I judge the amount of metal i should take from the counterweight(to make a turbo scoop) and also for making the uppermost part more a triangular part to keep the shaft balanced....

I hope I've made myself understood...
Bandeira is offline   Reply With Quote
Old 06-24-2004, 09:48 AM   #53
Tech Master
 
mop_iko's Avatar
 
Join Date: Sep 2003
Location: JOHOR BAHRU, MALAYSIA but now working in SHANGHAI
Posts: 1,797
Default balance crankshaft

after reading above posts, i conclude the first thing to do MOD is your PISTON SLEEVE. (am i correct so far?) and do the MOD a bit and a bit. and test your engine performance and feel the difference.

if you feel the power after the PISTON SLEEVE MOD is giving enough power.... you should stop the MOD process.

if you feel you need more power, proceed to do the CRANKSHAFT. Do it in such a way keeping the crankshaft to be BALANCED all the time. (am i correct so far?)

my question:
how to know your CRANKSHAFT is still in balanced state?

and

what will happen to your engine IF your CRANKSHAFT is not balance?


mop
mop_iko is offline   Reply With Quote
Old 06-24-2004, 10:04 AM   #54
Tech Elite
 
EdwardN's Avatar
 
Join Date: May 2003
Location: SoCal
Posts: 2,144
Trader Rating: 1 (100%+)
Default Re: balance crankshaft

Quote:
Originally posted by mop_iko
after reading above posts, i conclude the first thing to do MOD is your PISTON SLEEVE. (am i correct so far?) and do the MOD a bit and a bit. and test your engine performance and feel the difference.

if you feel the power after the PISTON SLEEVE MOD is giving enough power.... you should stop the MOD process.

if you feel you need more power, proceed to do the CRANKSHAFT. Do it in such a way keeping the crankshaft to be BALANCED all the time. (am i correct so far?)
I would sugest to say that modding is complex of action and there is no first or second- all of them has to be done to ge the best possible performance.
Yes for the beginner it is better to curving little by little, but to do the modding still needs to know what do you want to achive. I think the best way to start with is just copy existing designs.
Cranckshaft is one of the most important part of engine and it is defenetly required one of the first attention.
About balancing-there is no perfect balancing on our engines, the best way is to intentionaly create right amount of disbalance (underbalance or overbalance). Every each of them does certain positive and negative impact on engine performance.
There are couple different theories where crankshaft has to be-over balance or uderbalance.
I am sure every engine modifyer has its own theory and it will be very interesting to hear from them!!!!!!!!!
My theory can be easy see on my cranck pics in Palmaris engine tread.


my question:
how to know your CRANKSHAFT is still in balanced state?

and

what will happen to your engine IF your CRANKSHAFT is not balance?


mop
__________________
DISCLAIMER: Since 90% of my posts may be BS, and since my posts may be either insanely idiotic, incoherent, and/or not even close to a rational thought, please accord my posts no more than 10% of credibility.
EdwardN is offline   Reply With Quote
Old 06-25-2004, 05:42 AM   #55
Tech Master
 
mop_iko's Avatar
 
Join Date: Sep 2003
Location: JOHOR BAHRU, MALAYSIA but now working in SHANGHAI
Posts: 1,797
Default Re: Re: balance crankshaft

Quote:
Originally posted by Top Gun 777
u delete your reply?
...

emmmmmmm.....

mop
mop_iko is offline   Reply With Quote
Old 06-25-2004, 07:14 AM   #56
Tech Fanatic
 
teammpp's Avatar
 
Join Date: Mar 2004
Location: Northern Ireland
Posts: 894
Default Re: Re: Re: balance crankshaft

Quote:
Originally posted by mop_iko
u delete your reply?
...

emmmmmmm.....

mop
The reply is inside the quote. TG must have typed it in the wrong place. Here it is cut out:
Quote:
Originally posted by Top Gun 777

I would sugest to say that modding is complex of action and there is no first or second- all of them has to be done to ge the best possible performance.
Yes for the beginner it is better to curving little by little, but to do the modding still needs to know what do you want to achive. I think the best way to start with is just copy existing designs.
Cranckshaft is one of the most important part of engine and it is defenetly required one of the first attention.
About balancing-there is no perfect balancing on our engines, the best way is to intentionaly create right amount of disbalance (underbalance or overbalance). Every each of them does certain positive and negative impact on engine performance.
There are couple different theories where crankshaft has to be-over balance or uderbalance.
I am sure every engine modifyer has its own theory and it will be very interesting to hear from them!!!!!!!!!
My theory can be easy see on my cranck pics in Palmaris engine tread.
teammpp is offline   Reply With Quote
Old 06-25-2004, 09:46 AM   #57
Tech Master
 
mop_iko's Avatar
 
Join Date: Sep 2003
Location: JOHOR BAHRU, MALAYSIA but now working in SHANGHAI
Posts: 1,797
Default Re: Re: Re: Re: balance crankshaft

Quote:
Originally posted by Palmaris Europe
The reply is inside the quote. TG must have typed it in the wrong place. Here it is cut out:
Thank you Mr. PALMARIS.

I will refer to your thread from now on!


mop
mop_iko is offline   Reply With Quote
Old 06-26-2004, 01:42 AM   #58
Tech Fanatic
 
HELLION's Avatar
 
Join Date: Aug 2003
Location: Colorado
Posts: 802
Default good ideas but!

Guys: I just wanted to point out a few things about go fast engines. First of all there are many factors involved that are over looked I.E. altitude,% of nitro,%oil ,glowplug heat range,gearing,exhaust pipes and much more.Also you need to check your engine for wear I.E. if it has a streched rod,bad bearings worn crank,piston tolerances, squash band .Also hot engines demand a lot more maintenance And you should have some type of dyno to tell you if you are going in the right direction! ( I'll post one later that you can build for under 30 bones US) And one of the most overlooked things is the car itself! Go fast engines will run at a higher temp so if your car has wornout wheel bearings then you are just going to flame out faster! By hand turn the gear on your car that drives the tiers. (this is what your little engine has to do!) So the easier you can spin it by hand the more power can be deliverd by your engine thus it will be faster!!!!
HELLION is offline   Reply With Quote
Old 06-26-2004, 04:12 AM   #59
Tech Master
 
mop_iko's Avatar
 
Join Date: Sep 2003
Location: JOHOR BAHRU, MALAYSIA but now working in SHANGHAI
Posts: 1,797
Default Re: good ideas but!

Quote:
Originally posted by HELLION
Guys: I just wanted to point out a few things about go fast engines. First of all there are many factors involved that are over looked I.E. altitude,% of nitro,%oil ,glowplug heat range,gearing,exhaust pipes and much more.Also you need to check your engine for wear I.E. if it has a streched rod,bad bearings worn crank,piston tolerances, squash band .
waahhh... a lot of things to consider.

how can you know your CONROD has ben stretched?
how can you know your bearing goes bad?
how can you know your crankshaft has worn out?
what is PISTON tolerance?
what is SQUASH tolerance? yikes!

am i correct that, immidiately after you buy your new engine, you need to take apart your engine to:
1) check whether the engine is clean from metal chips.
2) check all the ORIGINAL dimensions of the elements like the conrod etc etc and keep record for future checking.
3) reinstall the engine and check for any air tightness.


Quote:
Also hot engines demand a lot more maintenance And you should have some type of dyno to tell you if you are going in the right direction! ( I'll post one later that you can build for under 30 bones US)
how about you build the DYNO and sell them? and i do hope that you can teach us here.... how to build our own DYNO tester. I think that one is a vital machine so that you know your engine is giving you the power that you need after a MOD.


Quote:
And one of the most overlooked things is the car itself! Go fast engines will run at a higher temp so if your car has wornout wheel bearings then you are just going to flame out faster! By hand turn the gear on your car that drives the tiers. (this is what your little engine has to do!) So the easier you can spin it by hand the more power can be deliverd by your engine thus it will be faster!!!!
yeah i remember one of your post saying about the graphite bearings. it really smoothen your tyres spinning but later on giving you trouble due to OVERHEATED bearing and slows/drag the car and give more load to the engine and OVER HEAT the engine. Now i know how important to keep the smoothness of you car's DRIVETRAIN. check everything from your spurs, gears, diff, belts or shafts, drive cups, dog bones until your tyres. no binding what so ever.

mop

by the way... talking about changing your CONROD and BEARING in yoru crankcase... i found a link in chinese forum... but hey i dont know how to read chinese... but PICTURES tells a thousand words... here is the link ... thanks to my malaysian friends, they told me the content of the thread is about HOW-TO-CHANGE conrod and bearings. and this procedure will cost you HALF THE ENGINE PRICE usually! is this true?
mop_iko is offline   Reply With Quote
Old 06-27-2004, 07:59 PM   #60
Tech Regular
 
gonzoY5's Avatar
 
Join Date: Mar 2004
Location: Miami, FL
Posts: 392
Default

OK guru's let me ask you this. I did the mods that were posted earlier from the RC Car magazine on an MT12. I only wound up doing the modification of the transfer ports because the other mods in the article, were already done to the sleeve from factory. I just "ramped" the lower outside edge of the transfer ports and gave them grooves that runs down along the sleeve. Since this wasn't a new engine, it had stains along the sides of the where the fuel flows, so i just followed them to make the grooves along the flow lines. I didn't get close to the inside edge of the ports with all my grinding, so no timing was changed. Now here's my situation. I've found the engine today to be running hotter, BUT, it ran fine hot. At the end of my 20 min main the engine was at 307*F ( yes i know that's REALLY hot) but the whole race, there was plenty of smoke coming from the pipe, and I never lost any power, nor did I flame out during a pit after the race I looked at my plug and it was a nice grey, not distorted.
I live in Miami, FL the temp was 92*F and the humidity was at about 70% (yes, we were sweating just sitting down in the shade) The track temp was in the 130's So it was blistering all day.
The thing is, before the mods, if my engine ever hit the 290's it would start losing power and often flame out. Now today it didn't. Do you think my mod could have something to do with the high temps? Or do you think it was the hot/humid day? There were a few other guys running hot at the track, but just from what I heard, i don't know any details. I dont know. Just curious if what I did to my sleeve actually made a difference or not. Any thoughts?
gonzoY5 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
modifying motors compcast Rookie Zone 3 07-08-2006 08:25 AM
Modifying a 19 turn? 4ou Electric On-Road 2 06-19-2005 11:24 PM
Modifying Thread mafiaracers Electric On-Road 9 08-21-2004 04:10 PM
Engine Modifying Services eddiethefish Nitro On-Road 49 09-01-2003 11:28 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 01:59 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net