RE: RC Car Actions "How to port a Nitro Engine"  
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RE: RC Car Actions "How to por... - 6/16/2008 5:10:31 AM   
SAVAGEJIM



Posts: 4315
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From: behind my 'puter, USA
Status: offline
quote:

ORIGINAL: Over_revO

Hi guys,

i thought i should share some pictures of a OS .18TZ i have modified 3 weeks ago.
Mostly flow mods except for the crankshaft.








Wow! very clean work! very nice indeed. I really like your polishing work.

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       Post #: 476

RE: RC Car Actions "How to por... - 6/16/2008 11:02:12 PM   
Duke Cummings


 

Posts: 6
Joined: 5/26/2008
From: , GA, USA
Status: offline 		very nice !

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       Post #: 477

RE: RC Car Actions "How to po... - 6/17/2008 2:19:02 AM   
PENGUINBLASTER!!!



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From: , AFGHANISTAN
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RE: RC Car Actions "How to po... - 6/17/2008 2:37:01 AM   
JB COMP



Posts: 4029
Joined: 11/23/2006
From: Navarre, FL, USA
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quote:

ORIGINAL: PENGUINBLASTER!!!









This is supportive criticism. So don't get mad at what I'm about to say.

You cut way to much off.

On your intake ports you put way to much angle. They're suppose to be aimed at the top corner above the boost port.

On the boost port you cut a lot away and its going to cause turbulence in the fuel flow.

live and learn that's the only way

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       Post #: 479

RE: RC Car Actions "How to po... - 7/2/2008 2:12:19 AM   
rccheech



Posts: 424
Joined: 8/2/2007
From: Roseville, MI, USA
Status: offline 		Does anyone here have any pics or info for wich ports to mod and how to mod on a RBS7 sleeve???? I have a couple of older WS7II sleeves to practice on and they are identicle. Any help would be great.

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       Post #: 480

RE: RC Car Actions "How to po... - 7/5/2008 4:18:03 AM   
supermod


 

Posts: 117
Joined: 8/6/2007
From: lisbon falls, ME, USA
Status: offline 		nice work rev.

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       Post #: 481

RE: RC Car Actions "How to po... - 7/5/2008 5:05:09 AM   
Over_revO


 

Posts: 57
Joined: 5/4/2008
From: Longueuil, QC, CANADA
Status: online 		Thx guys

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       Post #: 482

RE: RC Car Actions "How to port a... - 7/20/2008 7:26:36 AM   
Keith_Jones


 

Posts: 4
Joined: 3/8/2008
From: Jeffresonville , GA, USA
Status: offline 		I joined this so I could get in on this porting discussion because I'm interested in doing one of these little motors. I'm very experienced with outboards but they are just a little different.

First, am I missing something or are ya'll doing crazy stuff with the backside's of the exhaust ports, if so, why?

On a motor that does not run a ring, has anyone cut the bride out of the exhaust port since it's not needed to keep the ring from popping out and hooking the port.

Does anyone have any blowdown numbers they find works better.

I notice on these, they seem to bring the transfers in first, on my outboards I sometimes bring the boost in first and the transfers in approx 2 degrees after the boost. Has anyone tried that?

I see one sleeve someone added finger ports to, did they make a big difference and where do you bring them in? I usually bring them about 1 - 2 degrees before the boost so they will give a good pull on the boost when it opens.

I also see ya'll doing a lot of grinding on the crank to get the charge around the rod. What do you do about balancing the rotating system afterwards?

Also, with all the grinding ya'll are doing, are there any tricks to stuffing them to make up for the lost crankcase volume you're getting with all the metal you're removing?

I know I'm asking a lot of questions but I have an old OS 40 SF motor apart right now that I was gonna play with and see what I can do with it. If you want to turn a 200 hp 3.0 carburated Johnson/Evinrude into a 300+ hp monstor motor, I could answer most any question you might have but don't know anything about this little things, yet.

< Message edited by Keith_Jones -- 7/20/2008 7:29:43 AM >

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       Post #: 483

RE: RC Car Actions "How to po... - 7/20/2008 10:51:18 AM   
chookman46


 

Posts: 36
Joined: 6/4/2008
From: Queensland, AUSTRALIA
Status: offline 		You can have a look at this forum it has a bit more info on timing changes. It does cover a few of your questions.

http://www.rcuniverse.com/forum/m_7452102/mpage_1/key_/tm.htm

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       Post #: 484

RE: RC Car Actions "How to po... - 7/20/2008 6:43:30 PM   
JB COMP



Posts: 4029
Joined: 11/23/2006
From: Navarre, FL, USA
Status: offline 		I'm not real sure on the port (transfer and boost which is better to open first) I just cut them the same. The carnk I heard if you don't cut the trailing edge is doesn't hurt the balancing as much. I heard you can't balance a single cylinder engine either, so I don't worry about it, but I don't go crazy with the cutting like some do.

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       Post #: 485

RE: RC Car Actions "How to po... - 7/21/2008 8:07:24 AM   
chookman46


 

Posts: 36
Joined: 6/4/2008
From: Queensland, AUSTRALIA
Status: offline 		Not sure about all of your questions but havee yet to see a abc nitro car engine that has a bridge in the exhaust port. Maybe there are some out there somewhere but. As long as you dont go too wide cutting the port its shouldnt matter.

The best way to reduce volume again is to add an induction ramp on the inlet of the crank shaft. It does reduce the volume and creates a smoother flow into the engine. Also some bore out the crackshaft past the inlet port and add the ramp to fill the machined area. Sorry I dont have any pics to explain this, hopefully someone else can help me out here if not i will endeavor to get some.

As for balancing assuming the engine is somewhere in the ballpark to start with its like JB COMP said. If you cut some turbo scoops on one side grind some off the back behind the big end journal to even it out(not enough to weaken it though). The same if you put a lead on the leading edge of the counterweight grind some off the trailing edge.

(in reply to JB COMP)
       Post #: 486

RE: RC Car Actions "How to po... - 7/21/2008 7:51:38 PM   
j_blaze



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From: Tampa, FL, USA
Status: offline
quote:

ORIGINAL: rccheech

Does anyone here have any pics or info for wich ports to mod and how to mod on a RBS7 sleeve???? I have a couple of older WS7II sleeves to practice on and they are identicle. Any help would be great.


you can look at the friction marks on the sleeve itself where it is discolored. it shows you the flow of the fuel and where it helps to open her up. i just "trimmed up" my S5 and threw it in a buggy and it screamed, it always ran in a truggy tho, that test will come this week. the dark spots under the ports were clear as day so i just trimmed right over them. i noticed tho the front of the ports had more angle than the backs in the staining. like the back went straight up and the fronts had the slight angle towards the back. also there was some staining going from the exhaust port around to the side ports, normal? i did not touch those. i also did not do the button head yet. good luck with the 7, i don't think that motor needs any modifications tho.

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RE: RC Car Actions "How to po... - 7/22/2008 2:01:18 AM   
Keith_Jones


 

Posts: 4
Joined: 3/8/2008
From: Jeffresonville , GA, USA
Status: offline 		I know this is a car forum but since this is on porting I was wondering if anyone has info on a Thunder Tiger Pro 46 they would be willing to share.

Possibly a port map (eithier in degrees or distance measurements down from the top of the sleeve) and a good crank opening timing. A few photo's of what you did to the crank would also be nice. I'm not wanting too radical because the plane I will be running it on is not exactly the smallest, lightest thing flying (Skyraider Mach II) but I think it would be a nice practice piece to try some mods on.

I pretty much have anything and everything in the way of porting equipment from tiny carbide burrs to 1/4" shank burrs, stones, sanding drums and just about any type die grinder made including most of CC Specialties plus I have access to CNC mills. Skills and equipment is not a problem. I've tried my computer based program I use for my outboards but it's not liking these little motors so I'm trying to take a short cut on the learning curve. Also, since these little motors wouldn't even spin my dyno (rated to 600 hp) so that's no good to me either.

How you cleaned up an OS Hyper 50 Heli engine would be nice. If the Pro 46 turns out, I will probably try to clean the 50's up.

PM or email would be fine.

One observation I've made is ya'll are polishing everything. When doing larger engines on the flow bench, my velocity numbers are always better with an 80 grit finish then a polished finish when working on the intake side were there is a fuel air mixture. Is the polish suppose to be better in these?

(in reply to j_blaze)
       Post #: 488

RE: RC Car Actions "How to port a Nitro Engine&... - 7/23/2008 2:38:30 AM   
kersplat


 

Posts: 60
Joined: 8/29/2004
From: Lancaster Park, AB, CANADA
Status: offline 		Hey Downunder,
Is that a Taipan 2.5 with the degree wheel attached to it? Lovely

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       Post #: 489

RE: RC Car Actions "How to por... - 7/23/2008 3:40:28 AM   
kersplat


 

Posts: 60
Joined: 8/29/2004
From: Lancaster Park, AB, CANADA
Status: offline 		Just another opinion here, Guys, some of you have to stop cutting through the liner. If you grind the liner and taper it too much into the chrome plating, it can chip and peel. Just a thought.