Username Always stay logged in
Password:
Pages: [1] 2
  Print  
Author Topic: F2D FORA mods  (Read 11500 times)
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« on: May 07, 2012, 05:37:17 PM »

Here is the topic to share the ideas how to make your FORA run faster
all the feedback, notes, etc are very welcome
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #1 on: May 07, 2012, 06:04:54 PM »

Here is my notes.

I experimented a lot and here is what I do, I find the most productive in terms of what efforts you put in and what you get.

The bearings.

only a few people know FORA installs the most inexpensive bearings of their kind into FORA's engines (I guess it's one of the ways that helps FORA to keep the prices relativity low). The nose bearing either the rear one come with normal precision grade (tolerance). The nose one is Ukrainian (sometime it's made in USSR one  Cheesy ) and the rear - the Swiss one.

So the easiest way to increase your engine's performance - replace all the bearings to the higher precision bearings or at least the nose one (nose bearing replacement is a must! You may just replace it to any brand name bearing with normal precision if you don't find the high precision one). You may use the bearings with polyamide (nylon) either the steel cage ones - I haven't notice any difference in those. But keep in mind the bearings have to be made of Chrome Steel alloy.

You may also use hybrid bearings (ceramic balls + chrome steel rings), but I would recommend to use the hybrid ones as the NOSE BEARING ONLY. You might use it for the rear one, but there is a danger a ceramic ball might crack and blast, once it happens all inside parts are destroyed, since the ceramic bits have super hardness. And again - DON'T USE CHEAP NONAME BEARINGS, as it puts your engine into an extra danger if you install the hybrid noname bearings in there.

Make sure you put a bearing with the right ball clearance though. For the rear one it has to be C4 (in some scenarios C3 might work) and for the nose one - C3.
DO NOT INSTALL THE BEARINGS WITH NORMAL or REDUCED (C0 and C2) BALLS CLEARANCE, as it may cost you a motor.

As for the nose bearing you may use both open type of bearings: open or metal shielded one. Shielded bearing will perhaps work better with engines having a severe fuel leak from nose bearing while the engine run. Using the shielded bearing eliminates that problem, or at least the leak doesn't go that much. No worries about lubricating the shielded nose bearing, it still lubricates good enough as the shields still have a gap between the inner ring and the inner shield's diam.

To my experience getting good bearings installed increase the speed by 0.2-0.3 sec/10 laps
Also the higher bearing's precision is - the longer it's life and the plug's as well.

I experimented a bit with hybrid bearings - my best result: FORA rocket launched from 23.5sec to 22.8sec/10 laps with both bearing replaced by hybrid ones. But keeping experimenting at the end cost me three engines destroyed (!) due to cheap hybrid bearings used.

P.S. the balls clearance low to high:
C2, C0, C3, C4, C5

P.S.S. See the attached balls clearance table


* SKF bearing internal clearance.jpg (61.36 KB, 541x375 - viewed 374 times.)

* main bearing standards.jpg (111.74 KB, 1234x527 - viewed 393 times.)
« Last Edit: May 15, 2012, 08:13:12 PM by Yaroslav Melnikov » Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #2 on: May 07, 2012, 06:51:49 PM »

Crankshaft

I guess the pictures might tell much more than the words (the more so English is not my first language  Cool )
so enjoy the pictures:
http://aerohobby.ca/photos/index.php/Motors/FORA-mods

It's a lot of work, everything you see is done with "Dremel" rotating tool using grinding stones and polishing stuff as well.

To my experience crankshaft done that way cuts another 0.2-0.3 sec/10 laps


* IMG_8004.JPG (293.88 KB, 1419x1232 - viewed 386 times.)

* IMG_7998.JPG (200.67 KB, 1198x956 - viewed 353 times.)
« Last Edit: May 07, 2012, 07:33:22 PM by Yaroslav Melnikov » Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #3 on: May 07, 2012, 07:57:57 PM »

Connecting rod

here is another part might be modified relativity easy.
It's a connection rod. Having cut some extra metal from the rod and shaping it elliptical in section - we reduce the con.rod's mass which accordingly reduces the pressure to the cylinder's wall the piston makes while the engine runs. Shaping the rod elliptical and polishing it helps to reduce the friction of fuel mix flow into the combustion chamber.

to my experience no difference in level speed, but slightly more power in sharp turns (less RPM loss)


* IMG_8019.JPG (186.33 KB, 1187x905 - viewed 358 times.)
« Last Edit: May 15, 2012, 08:15:23 PM by Yaroslav Melnikov » Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #4 on: May 08, 2012, 10:00:09 PM »

Looks like you need a special tool to remove the front bearing nut?
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #5 on: May 09, 2012, 05:21:23 PM »

Looks like you need a special tool to remove the front bearing nut?

Yes and No. To get the nose bearing retainer off you would need the tool is sold in our store:
http://aerohobby.ca/store/index.php?main_page=product_info&cPath=14&products_id=75

But you still can use a coin with sharp edges, the coin should be a right diameter to fit the gap at the retainer tight enough. One more tip - much easier to do it while the crankshaft on. Also if the retainer seats tight - you might need to heat the crankcase to 140-150C it helps. MAKE SURE YOU LOOSEN THE RETAINER AT CLOCKWISE DIRECTION! As the idea of unusual retainer's thread - to self-tighten as the prop rotates anticlockwise.
Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #6 on: May 09, 2012, 10:32:58 PM »

I realized after I looked at the tool description on your site that this is a very handy tool.
Fortunately I had already purchased one from you!
I was able to replace the nose bearing on one of my 2012 Foras last night using this
tool, but still found I had to remove the crankshaft & heat up the crankcase.
Also noticed an increse in crankshaft end float due to the higher clearance (C3)
Bearing I used.
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #7 on: May 10, 2012, 02:43:46 PM »

I was able to replace the nose bearing on one of my 2012 Foras last night using this
tool, but still found I had to remove the crankshaft & heat up the crankcase.
Also noticed an increse in crankshaft end float due to the higher clearance (C3)
Bearing I used.

it's normal, it should float a bit. What brand name bearing did you use by the way? Was it shielded or open?
Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #8 on: May 10, 2012, 09:59:20 PM »

Not sure of the brand but I was told it was Japanese.
The bearing I used was the metal shielded type but I removed the inner shield.
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #9 on: May 10, 2012, 10:32:41 PM »

Not sure of the brand but I was told it was Japanese.
The bearing I used was the metal shielded type but I removed the inner shield.

try to find out the precision of that bearing as well, mate. Should be ABEC (1,3,5 etc) as if it was ABEC-1 it wouldn't make much sense to replace the bearing though. The high precision ones start with ABEC-3 and up. For instance ABEC-5 is two times more precise as ABEC-1 in terms of production tolerance. I will attach the ABEC chart tomorrow in my "bearings" post so you could see the difference.
Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #10 on: May 10, 2012, 10:47:08 PM »

Ok I was told bearing precision is ABEC-4 & manufacturer is Sapporo.
Cheers.
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #11 on: May 10, 2012, 11:17:03 PM »

Ok I was told bearing precision is ABEC-4 & manufacturer is Sapporo.
Cheers.

Hmmm... There is no ABEC-4. The tolerance comes as the follows: ABEC-1, ABEC-3, ABEC-5, ABEC-7

The retailer either BS you, either just doesn't have a clue what is selling  Grin

Sapporo brand doesn't look bad to me though...
Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #12 on: May 12, 2012, 04:31:56 AM »

Contacted the supplier again & they told me they were P6 whch by your chart is ABEC-3.
Logged
Yaroslav Melnikov
Administrator
Full Member
*****
Posts: 119



View Profile WWW Email
« Reply #13 on: May 13, 2012, 09:12:14 AM »

Contacted the supplier again & they told me they were P6 whch by your chart is ABEC-3.
oh, that make sense then
I like another more Sapporo brand of another kind though...  Grin


* sapporo-premium-beer.jpg (122.61 KB, 800x518 - viewed 324 times.)
Logged
AdzNadz
Newbie
*
Posts: 24



View Profile Email
« Reply #14 on: May 13, 2012, 10:17:04 AM »

Haha yeah nice one!
The girl with the fish tattoo....Huh
Logged
Pages: [1] 2
  Print  
 
Jump to: