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RC Car Actions "How to port a Nitro Engine"

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RC Car Actions "How to port a Nitro Engine"

Old 02-09-2007, 12:00 AM
  #51  
SManMTB
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Default RE: RC Car Actions "How to port a Nitro Engine"


ORIGINAL: SAVAGEJIM

Does anyone know what grade of alum they use in most engines? Particularly, I'm looking for the alum alloy that the K4.6 uses; I want to calculate the new failing stresses for the conrod I modified. If anyone knows this, please post.

Also, I attempted to port a sleeve just last night, the attempt was an aberration. Looks like I need more practice; good thing the sleeve was junk to begin with.
For the conrod I would guess 7075 probably tempered T5 or something. The piston in all engines are high in silicone.
Old 02-09-2007, 01:25 AM
  #52  
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Default RE: RC Car Actions "How to port a Nitro Engine"


ORIGINAL: Pro Twister Mods

what kind of bit are you using?
I used several. The primary bit I used was a carbide-metal bit to cut and reshape the ports. I want to drop the rear portion of the rear later port dramatically to have a ong vericla (actually diagnal) port shape like the STS D30M has. I then switched to a grinding stone o touch up the port and to ut flow channels like the 1st post instructions showed.

Overall, I think with good skill and steady hands, a very nice and cleen job can be done. I still lack those sklls so I will continue to practice on these sleeves; I have 3 useless sleeves (worn out form about 10gal of running each).
Old 02-09-2007, 01:29 AM
  #53  
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Default RE: RC Car Actions "How to port a Nitro Engine"


ORIGINAL: SManMTB

For the conrod I would guess 7075 probably tempered T5 or something. The piston in all engines are high in silicone.
Thanks for this informaton, I'm going to look up T5 and 7075 in my alloys reference guide and hunt down their moduli of elasticity. If my refernec book doe not show this, then I guess I can try to find the information on-line.

As for the piston, I do not intend to do any modifications at all so knowing what stresses they can take is moot for me at the moment, but thanks anyway for the information.
Old 02-09-2007, 11:18 AM
  #54  
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Default RE: RC Car Actions "How to port a Nitro Engine"










Still have to do the epoxy filling and ramping, just didn't have time before the pics...
Old 02-10-2007, 04:30 AM
  #55  
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Default RE: RC Car Actions "How to port a Nitro Engine"

I finally got a hold of my brother's camer and took some quick pics of my modded K4.6 crank. I put it next to a stock K4.6 crank for comparison. Check out these pics and let me know what you guys think. I want to know in particular if I cut too much material off.
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Old 02-10-2007, 04:42 AM
  #56  
SAVAGEJIM
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Default RE: RC Car Actions "How to port a Nitro Engine"

Here are more pics, this time of the K4.6 conrod I modified. I dont have a stock one to put next to it readily available, but the work I did was to lighten the bottom end of the conrod and also lighten the shaft as well. I sanded and polished the work as best I could; the shaft work I think was more easy to sand, polish, and clean up. I feel that the work is so seamles that it will be hard to point out that I even touched it there.
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Old 02-10-2007, 04:47 AM
  #57  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Here is a pic of the K4.6 block looking down the hole into which the carb goes into. In my effort to accurately calculate the induction timing, I need to know what the width of the port in this block is. This is the width of the port that is adjacent to the crankshaft. I cannot put my dial calipers far enough down in there to measure the width of this port. Anyone have a clue on ow to measure this port in the block?
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Old 02-10-2007, 08:52 AM
  #58  
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Default RE: RC Car Actions "How to port a Nitro Engine"

ORIGINAL: SAVAGEJIM

Here is a pic of the K4.6 block looking down the hole into which the carb goes into. In my effort to accurately calculate the induction timing, I need to know what the width of the port in this block is. This is the width of the port that is adjacent to the crankshaft. I cannot put my dial calipers far enough down in there to measure the width of this port. Anyone have a clue on ow to measure this port in the block?
jim use a degree wheel and a small flashlight !
Old 02-10-2007, 10:28 AM
  #59  
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Default RE: RC Car Actions "How to port a Nitro Engine"

I have a degree wheel...well, my attempt at making one. That round "dish" thing that the parts are sitting in when I took the pics is a lid to a tuna can in which I glued a circle with degrees marked to 5degree increments. It's horribly inaccurate, I attempted to take the K4.6's measurements with it and these are the following results I measured (stock timings):

Crankshaft induction: 193degrees
Boost port: 106degrees
Lateral (Schneurle) ports: 114 degrees
Exhaust port: 154degrees
Degrees ATDC before crank induction port opens: 223degrees.

My error factors are at least plus or minus 5 degrees since I could not draw the wheel to any high accuracy. Also, I estimate another plus of minus 2degrees for my manual drawing inaccuracies and how I placed the ruler on the paper when I was drawing the wheel.
This is a horrid plus or minus 7degree error margin.

Pro Twister Mods in the other porting thread posted some tools I could use to make a more accurate degree wheel; I have one on order, but in the mean time, I am going to try to hit the local hardware store and see if they have someting just as suitable. I might also hit the local print shop; they carry all sorts of stencils, slide rules, and just might have an accurate degree disc.

Once I have the degree wheel, my next odstacle would be to make a reliable jig so I can mount a needle to point at the degree graduations with accuracy.
Old 02-10-2007, 11:45 AM
  #60  
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Default RE: RC Car Actions "How to port a Nitro Engine"

okay here ya go..... print this wheel as large as you can make it, then use a peice of thin plastic/aluminum, wallboard and make a wheel and adhere this printout to it..

http://machinerycleanery.com/DWCounterClockwise.htm

the STS 30's timing

238 crank
112 transfer and boost
176 exhaust.

and she's a screamer of a mill big time
Old 02-10-2007, 04:40 PM
  #61  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Nice! Thaks for the link! That is just what I am looking for!
Old 02-10-2007, 09:43 PM
  #62  
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Default RE: RC Car Actions "How to port a Nitro Engine"

This is the timing wheel I use. It's just a 360 degree protractor as used in schools or whatever with a hole drilled through the exact centre to mount it to the crankshaft. The pointer is just a bit of soft wire bolted to one of the engine mounts or any other suitable screw holes. Soft wire allows a bit of bending to fine tune the pointer to exact TDC.

If you just want to find duration of any ports then it's not necessary to have the pointer at exact TDC but with the crankshaft port you really need to know its opening and closing times which means finding TDC.

There's a couple of ways to do this quite accurately. One is to slip a bit of paper into the exhaust port and get the same reading either side of the 180 mark when the piston just nips the paper on the way up. This works for 99.9% of all engines, the rest have what's called Desaxe crankshafts which gives non-symmetrical timing.

The most accurate way is to use a piston stop tool (and this is the only time one of these things should be used, they should never be used to help tighten a flywheel). Set the stop tool so it contacts the piston just before the piston gets into the pinch but around 20 degrees total movement either side of TDC is good. The aim is to get the same reading either side of TDC by turning the crankshaft in one direction then back around in the other direction. This is where the bendy pointer helps. When it reads exactly the same either side then the pointer will be right on the 0 mark at TDC.

With the head off the engine, use a head screw or backplate screw (they're a bit shorter) to lightly clamp the liner so it won't lift if there's a good pinch. I check the exhaust timing by looking through the exhaust with a bright light shining down the bore and turn the crank until there's just the slightest glimmer of light showing. Doing this in both directions should give the same reading but always do it with the piston going up the bore to load the rod bushes and take out any clearances. I like to use a magnifying glass to check the other ports because they can be a bit hard to see properly. Usually I'll check them 3 or 4 times to make sure I'm getting a consistent reading.

For the opening point of the crankshaft, I prefer to turn it backwards because it's much easier to pick when the crankshaft port just closes rather than just opens. Once again, I use a magnifying glass for that.

How you record the timings is a matter of personal preference. I prefer giving the exhaust and transfer timings just as their opening time which is exactly half the total duration. Either way it means the same thing. In supertib's engine I'd have written the exhaust as 88 and the transfer as 56 so I'd know immediately there was 32 degrees of blowdown.
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Old 02-11-2007, 03:51 AM
  #63  
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Default RE: RC Car Actions "How to port a Nitro Engine"

hey i ported a stock torque 16, tell me how i did and isn't the crank all balanced, so if u mod it wont it be un-balanced or is it not balanced at all?
it was a tired engine and now its a beast i would assume it gained about 3000RPMs but im not sure that just what it sounds like lol
the none modified one is a stock sleeve for comparison
and is there any other do it ur self mods that can gain u power and aren't to professional?






Old 02-23-2007, 10:51 PM
  #64  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Hey Jim, how did you pull out the piston from the bluck of the K4.6? I can't just pull it out.
Old 02-23-2007, 11:53 PM
  #65  
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Default RE: RC Car Actions "How to port a Nitro Engine"


ORIGINAL: nitrodoper

Hey Jim, how did you pull out the piston from the bluck of the K4.6? I can't just pull it out.
Yeah, the best way to get the piston out is to use teh trick with a zip-tie strap through the exhaust port. (Be prepared to lose the zip-tie as this trick will proabaly sever the strap especially if your piston and sleeve have a good pinch on them).

The trick is to, of course, take teh zip-tie strap, slip it through the block's exhaust port, and with the flywheel still on, turn the flywheel so that tha piston is going up. The piston will raise the sleeve significantly. If you cannot pull the sleeve out with your fingers, do not use pliers to pull it out. Continue to turn the flywheel and sever the tie-strap; the strap will be cut but the sleeve will continue to come up untill it is finally far enough out to pull with your fingers. Once the sleeve is out of the block, the con-rod will fall of the crank journal easily and the piston and conrod will fall out the top of the block.
Old 02-24-2007, 12:25 AM
  #66  
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Default RE: RC Car Actions "How to port a Nitro Engine"

I almost use the screw driver to push it from the back. I got it out now.

Thanks Jim precaite it!!!
Old 02-25-2007, 04:37 AM
  #67  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Won't taking metal off of your crank unbalance everything.

Is there a way to rebalance it?
Old 02-25-2007, 03:12 PM
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Default RE: RC Car Actions "How to port a Nitro Engine"

I got my os ported today man that thing is fast now
Old 03-01-2007, 09:50 PM
  #69  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Hi i've been following this thread for some time, am very much interested in learning this art, however am way behind on the subject, would really like a more in depth how to on the timing subject as well as how to port the engines, any related articles on the web anyone would be kind enough to point me to.

Engine porting / timing is not something I have played with, pretty much played with everything else on the car.

Thanks for the info
Old 03-02-2007, 12:51 AM
  #70  
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Default RE: RC Car Actions "How to port a Nitro Engine"


ORIGINAL: shesha

Hi i've been following this thread for some time, am very much interested in learning this art, however am way behind on the subject, would really like a more in depth how to on the timing subject as well as how to port the engines, any related articles on the web anyone would be kind enough to point me to.

Engine porting / timing is not something I have played with, pretty much played with everything else on the car.

Thanks for the info
I can explain how to calculate just how far up you would have to cut the ports to increase timing. The calculations are easy provided you know simple trigonomety (sines, cosines, tangents, and their arc-functions). If you have MS Windows XP, the in-computer calculator has a scientific function with trig functions on it and this will make the calculations a snap.

The hard part as far as employing clculations is measuring the dimensions accurately (for example, just how far down the piston is when the port in question begins to open).

Alternatively, you could use a degree wheel and eyeball the opening with a bright light to assist you in seeing just when the port in question begins to open. I personally prefer to calculate AND use the degree wheel and eyeball method together to verify both methods are giving accurate timings.

If you want, I can write up on instructional post on how to calculate timings and (hopefully) some of the better methods of determining when a port opens. Bear with me since such an essay will require me to draw driagrams and illustrations to assist the explanations.
Old 03-02-2007, 06:07 PM
  #71  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Savagejim, would love to read up on your information, that would be very kind of you to share. As far as trigonometery, no worries on that, have a scientific calculator in my toolbox
Old 03-02-2007, 07:42 PM
  #72  
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Default RE: RC Car Actions "How to port a Nitro Engine"

nitrodoper, anything in the engine thats hard to move, just add heat to it, I use a heat gun get it to operating temp in the 200 range and everthing just falls out easily. Use heat mittens when handling as I forgot that once.
Old 03-02-2007, 08:04 PM
  #73  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Just a question on the main crankshaft, those burrs in them are done to do what exactly, balance the crankshaft ? It's sort of similar to what I did on my Hyper50 heli engine due to the crank webbing inducing extreme vibrations.

Anyone care to clarify please whats the role of the burrs in the crankshaft ?
Old 03-02-2007, 09:43 PM
  #74  
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Default RE: RC Car Actions "How to port a Nitro Engine"

I guess when you say burrs, you are referring to the scallop shaped cuts on the face of the crankshaft. Those are turbo cuts that are meant to better help mix the fuel-air mixture (better atomize the fuel with the air), distribute the incoming charge more readily, and to help vector away some of the charge laterally in relation to the crackshaft centerline.

See my post in this thred: (It is post #5)

http://www.rcuniverse.com/forum/m_51...tm.htm#5196204

I hope this answers your question.
Old 03-03-2007, 06:19 PM
  #75  
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Default RE: RC Car Actions "How to port a Nitro Engine"

Thanks for the info savage, am still reading, here is some good information I also came across

http://www.rctech.net/forum/showthread.php?t=141508

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