RE: Induction Timing

RE: Induction Timing
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RE: Induction Timing - 7/5/2007 8:08:11 PM

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Joined: 4/17/2007
From: wolves, UNITED KINGDOM
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I am a noob to modding rc engines but i am a mechanic by trade so i understand the importance of correct engine timing.I want to mod my vx.18. ive red how to port and polish and to give the crank a fang. but how do you know how much material to remove from the top of the sleve ports .it has been said to know this before removing any material.
So my question is how much material can you remove from the sleve windows and induction window on the crank for best performance or where can i find this info from.thnx once again very good reading.

< Message edited by paddy4511 -- 7/5/2007 9:54:56 PM >

(in reply to SManMTB)

RE: Induction Timing - 7/5/2007 8:33:13 PM

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From: Charlottesville, VA, USA
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Trial and error basically. Modding port timings changes the caracteristic of the power band so it all depends on what you like to do.
I bought a software called MOTA. It's 2 stroke engine simulator and I've learned a lot from just changing port configurations and port sizes. It gives you a feel for it and will clue you in on what to do.

Google MOTA engine simulation and you should find it fairly easy. It's around $185 or so IIRC.

(in reply to paddy4511)

RE: Induction Timing - 7/9/2007 3:47:35 PM

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From: wolves, UNITED KINGDOM
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Thnx SManMTB i'll have a look sounds like a good simulator

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RE: Induction Timing - 7/9/2007 4:33:28 PM

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It's awesome and WELL worth the money. Playing around with it gives you a good feel.
I entered all parameters for the OS RG and measured the OS-T2050 pipe and ran a simulation. It returned a max hp of just below 2hp close to the rpm stated by OS. Pretty damn good I must say since OS says it should have 1.9hp.

(in reply to paddy4511)

RE: Induction Timing - 8/25/2007 8:06:20 AM

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From: Toronto, ON, CANADA
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beautiful work SAVAGEJIM

this belongs on the first page
-bump-

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RE: Induction Timing - 9/19/2007 5:40:03 AM

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From: Palm Coast, FL, USA
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Sounds like your theory is sound because math is not only possible but it is the true means of which engineers use. Good job Jim, I sent this to a person who mods engines and asked him to take a look, I wont drop any names but I hope he post something here. It will be a treat for all!

(in reply to Codeblack)

RE: Induction Timing - 9/19/2007 6:21:57 AM

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From: , MB, CANADA
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Good luck finding a modder who actualy alters sleeve port timing..... at the very most the odd modifier may alter exhaust timing, but i know of none who will hand cut transfer and boost timings........ Myself As a hobby i alter the timing on all my modded motors, the only drawback is i create motors sometimes too powerful to even be usefull....

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RE: Induction Timing - 9/20/2007 2:25:49 AM

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quote:

ORIGINAL: FastRcCars

Sounds like your theory is sound because math is not only possible but it is the true means of which engineers use. Good job Jim, I sent this to a person who mods engines and asked him to take a look, I wont drop any names but I hope he post something here. It will be a treat for all!

Thanks, I hope he can find this useful when shooting for an induction timing that he knows would be more powerful.

Supertib is right: altering the timing profile to advance them is difficult. I use masking tape on the inside of the sleeve to mark how high I want to cut up, but just getting the masking tape into proper position is quite a chore in itself. What I have resorted to is oputting the masking tape just a little lower tghan I know where the cut goal is, then, with the sleeve and piston installed, I turn the degree wheel to the exact degree I want the port to open. The piston pushes up the tape to the exact lin to where the port needs to be cut up to.

I hope that little helps modders and amatuers alike in making how high in the sleeve to cut up.

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RE: Induction Timing - 9/27/2007 1:53:35 AM

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From: Fuquay, NC, USA
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Lots of good info here. Keep it coming fellas.....I'm absorbing as fast as I can.

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RE: Induction Timing - 9/27/2007 5:36:42 AM

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From: Saudi, SAUDI ARABIA
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quote:

ORIGINAL: Tubbed440

Lots of good info here. Keep it coming fellas.....I'm absorbing as fast as I can.

i thought i was the one digging for info!!!

Induction Timing eh? :lol: <--

(in reply to Tubbed440)

RE: Induction Timing - 9/27/2007 7:25:09 PM

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From: Fort Worth, TX, USA
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Once you have crank position locked for your new timing marks measure depth from top of sleeve to top of piston. Next, transfer the inside measurement to the outside of the sleeve, mark with scribe, and start cutting!

For crank induction, remove the carb, turn crank to new open/close timing and scribe a line on the crank. Remove crank, cut, polish edges, reassemble, and go run!

Works for me!

< Message edited by lsurber -- 9/27/2007 7:30:35 PM >

(in reply to Mohammed T)

RE: Induction Timing - 9/27/2007 9:12:29 PM

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From: , UNITED KINGDOM
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quote:

ORIGINAL: lsurber
Once you have crank position locked for your new timing marks measure depth from top of sleeve to top of piston. Next, transfer the inside measurement to the outside of the sleeve, mark with scribe, and start cutting!

I see where your coming from and yes if the top of your port was square that's an accurate method.However i think the profile of the port should direct gases with minimal airflow disruption,invariably meaning the inside edge of the port will be the opening point(highest)and the outer will be lower(measured from top deck/piton crown@tdc).
I think the method that SavageJim has posted above(edge tape up cylinder with piston using d.wheel)is an excellent method,just ensure the sleeve is totally grease free and press the tape down firmly so it wont move then re-check

quote:

ORIGINAL: lsurber
For crank induction, remove the carb, turn crank to new open/close timing and scribe a line on the crank. Remove crank, cut, polish edges, reassemble, and go run!
Works for me!

I agree can't go wrong with that

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RE: Induction Timing - 9/27/2007 10:19:15 PM

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From: Fort Worth, TX, USA
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If you measure the incidence angle of the port and sleeve wall thickness then use the law of sines you can determine where to transcribe the line!

SinA/a = SinB/b =SinC/c

Note: A and B will complement each other so you only need to find one and you know the other!

C=90 degrees

Sorry, sometimes I assume too much!

It's also easier for me to cut referencing the outside rather than the inside of the sleeve!

Personally, I just make a good guess!!!!!!! LOL!!!!

Tape inside is also an excellent idea to avoid flaking the plate! If you do make timing changes to ports you may end up with a paperweight if the plating comes off!!!!!!

Lee

< Message edited by lsurber -- 9/27/2007 11:03:16 PM >

(in reply to Anthoop)

RE: Induction Timing - 9/27/2007 11:02:10 PM

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quote:

ORIGINAL: lsurber

If you measure the incidence angle of the port and sleeve wall thickness then use the law of sines you can determine where to transcribe the line!

Sorry, sometimes I assume too much!

It's also easier for me to cut referencing the outside rather than the inside of the sleeve!

No mate i had already "assumed" that you could take into account the sleeve wall thickness and the proposed port angle and using mathematics it would be easy to calculate the desired height/depth of both the inside and outside of the port.However how do you propose to see where to cut on the inside of the sleeve if your mark(lower) is on the outside?Do you have some devious means of scribing a line on the inside?

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RE: Induction Timing - 9/27/2007 11:05:32 PM

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Joined: 6/22/2007
From: Fort Worth, TX, USA
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No, I don't do all that stuff, just eyeball it and work slowly!!!! LOL!!!!

(in reply to Anthoop)

RE: Induction Timing - 9/29/2007 5:34:25 AM

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Joined: 1/21/2007
From: Palm Coast, FL, USA
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Jim, I think this is a good tip but there is no way to match a cnc machine and some one who has been a Machinist for 25 years, cnc programmer, and has a Fluid dynamics engineering degree. I do not know why he has not posted here yet; (other than being busy workin on the big boys toys.) Here is a pic That looks cool and shows the difference between cnc modding and the good old fashiond hand job! Do not get me wrong I have been doing HiPro work on hot rods for years and it takes a combination. IE: machines to punch out the head to desired specs, then by hand to finish the porting and polishing.
The main thing everyone should know is "be very careful when opening crank window and after porting the rest you will need to rebalance! Many trics to this But one hand method I have seen that does work will require a little fabbing. First make a jig that will hold the crank with the bearings on it and will fit on an ultrasonic. (small machine that cleans jewelry and such.) make sure bearings are very easy to turn (new and well oiled) straps will wrap arround bearings (also make sure you have clearance ie: crank will not touch anything other than inner race of bearings.) and as the ultrasonic vibs rotate crank in 45 and 90 degree increments. Watch the crank after each reposition and the heavy part will rotate to the bottom after a few seconds or so, after it stops mark heavy part on crank on the counter ballance weight (big part all arround where rod connects). Grind a LITTLE off heavy side at a time rechecking often, When you can put the crank in any position and it does not move its Balanced!
Remember bearings do have resistance so this is not perfect but it will work and if you want to get technical and be a big time perfecto after the crank is done, balance the drive washer and flywheel. Simply put them on the crank (1 at a time) and do the same as before only drill small hole in the side of drive washer to remove weight and for the flywheel... Well it depends on the wheel I am sure you can find a way to lighten the heavy side. FastRcCars

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(in reply to SAVAGEJIM)