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Author Topic: K&B 4011  (Read 4112 times)

Offline Motorman

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K&B 4011
« on: August 26, 2015, 01:35:50 PM »
Building a Humongous for old time and I have allot of K&B 4011 stuff left over from racing days. I know they are heavy but hoping that might not be a problem on a big short nosed plane. Anyway, all my engines are loaded for bear so I'm looking for some advise on setting one up for stunt.

The stock timing on the crank is typical RC for good idle and I've increased the duration. Would that have much effect, what are good stunt numbers on the crank timing? Mine is 35/65.

Do you raise the transfer timing for less blow down?

All my head inserts are full race 14:1 but I can bore them out. Do you need to open up the stock head or just add an extra gasket? Anyone know a good compression ratio for stunt?

Should I just copy Fox35 numbers?

Any prop/fuel/rpm suggestions?

Thanks,
MM   

Offline Tim Wescott

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Re: K&B 4011
« Reply #1 on: August 26, 2015, 02:57:12 PM »
There are a huge number of answers on the 4011 out there.  This is one place where doing a search will net you lots of info:

http://stunthanger.com/smf/index.php?action=search2;params=YWR2YW5jZWR8J3wwfCJ8YnJkfCd8MTAzLDUwLDc2LDExMCwxMTEsNCw2Miw4Nyw2NywzMCw5NCw1Myw1Nyw5MiwyMSw4OCw5Myw1OCwzLDYxLDQ1LDQ2LDgsNjYsOSw2NCwyOSw2OCwyMCwyNiwyNSwyNCwxMDIsMjMsMjIsMTUsMTEsMzcsODUsNDQsOTcsNzIsMzUsNTIsOTUsMTA1LDEwNCw3OSw0MiwxMDgsNzQsNjksNzAsNDksODIsNDgsMzIsOTYsNDEsNzUsODksNDMsMTA3LDgzLDg0LDEwNiw0MCw5OCw5MCwzOSw3Nyw3LDI3LDI4LDE0LDE5fCJ8c2hvd19jb21wbGV0ZXwnfHwifHN1YmplY3Rfb25seXwnfHwifHNvcnR8J3xyZWxldmFuY2V8Inxzb3J0X2RpcnwnfGRlc2N8InxzZWFyY2h8J3w0MDEx;start=0

I did the search looking for the thread when I asked about the engine:

http://stunthanger.com/smf/index.php/topic,15633.0.html

I ended up trading it for an LA 25 (which still flies my Flight Streak).

Personally, from everything I've read about it, I'd put it back to as stock as possible and just fly it that way.  Run it it a wet 2, like you would a 46 LA.  I'm not sure it'd have enough beans to fly a Humongous if you turned it into a Fox 35.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Ken Burdick

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Re: K&B 4011
« Reply #2 on: August 26, 2015, 03:20:21 PM »
looks like you are trying for more rpm from what you've done. I imagine a stunt motor would like more torque and bottom end then the reverse. Put it back to stock or as close you can get. The head can be shimmed back to a reasonable compression for this application. I th H^^ink the engine will like a good slug of castor oil in the fuel 20%+ so you should be able to haul the Huge pretty well with it. If you just don't like it, try an la 40-46. I'm not a big fan of the LA series, but they seem to do ok for ots.
Good luck
 D>K

Offline Steve Helmick

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Re: K&B 4011
« Reply #3 on: August 26, 2015, 05:10:20 PM »
The late & great Jim Thomerson flew his Hugemongoose with a #4011 and liked it. I started with a #4055 in mine, and found it gutless and went to the .46LA. I don't know how heavy Jim's was, but mine was about 50 oz. I could see a stock #4011 doing ok with the right prop...maybe an 11-4 APC or TT 11 x 4.5. When the crank snout breaks off, it won't be good. I'd consider a ST G.51, or a Magnum .46/.52/.53 or TT .46, etc. What else you got?  ??? Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Motorman

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Re: K&B 4011
« Reply #4 on: August 26, 2015, 06:55:55 PM »
That's funny, I did a search and got nothing anyway, thanks for the link.

Steve, Did you break the crank on a rear valve? mine are front valve.


MM 

Offline Steve Helmick

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Re: K&B 4011
« Reply #5 on: August 26, 2015, 08:06:12 PM »
Well...mine were actually .35's...same dumb prop driver. Later ones had a split pin through the prop driver and end of the crank snout, same as the front intake 4011. They broke off at the front bearing. They didn't like being crashed, even on soft grass.  n1 Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Motorman

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Re: K&B 4011
« Reply #6 on: August 27, 2015, 12:18:57 PM »
Oh I see, you're talking about the small front valve case. Mine are the heavier front case with the collet drive. I'll be ok while crashing.

Did another search and apparently a Stan Powell would do some kind of mod to the transfer ports but couldn't find the numbers. What's a good blow down timing for stunt, should I copy the 4050 timing?

MM
« Last Edit: August 27, 2015, 02:57:27 PM by Motorman »

Offline Dennis Toth

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Re: K&B 4011
« Reply #7 on: August 27, 2015, 05:22:57 PM »
MM,
The K&B 40 works fine for Stunt, it was used to win the world championship by Les McDonald. Do a search for Stan Powell (he set up the K&B's for Les) and it will give you some idea of the set up. In the stock form it has lots of power works well on 10% N fuel with 22% 50/50 oil on a 11x5 APC. Mike K used one in his Humongous and reported it flew well. I have one in my YAK-YAK Bipe, on the 11x5 APC, tongue muffler, set for a rich 2 cycle and it is great (even starts with a spinner flip).  You can also use a 10 1/2"x5 prop if you need a little quicker lap time.

Best,     DennisT
« Last Edit: August 28, 2015, 07:37:54 PM by Dennis Toth »

Offline EddyR

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Re: K&B 4011
« Reply #8 on: August 28, 2015, 01:15:50 PM »
The motors built by Stan were hand built. It was nothing like a stock motor. One place to look is the standard bypass is to large for stunt use. It can be made smaller. Sleeve timing and on and on.
Ed
Locust NC 40 miles from the Huntersville field

Offline Steve Helmick

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Re: K&B 4011
« Reply #9 on: August 28, 2015, 01:46:21 PM »
Oh I see, you're talking about the small front valve case. Mine are the heavier front case with the collet drive. I'll be ok while crashing.

Did another search and apparently a Stan Powell would do some kind of mod to the transfer ports but couldn't find the numbers. What's a good blow down timing for stunt, should I copy the 4050 timing?

MM

AFAIK, the #4011 was the small/fragile front end and Dykes ring in the .40, and after that, they made the #4050 and #4055 (which was what I had, ABC P&L). I don't know if the #4050 (R/C version) and #4055 had the same cylinder timing. But those engines are ungodly heavy for a .40. Mine was not a bad runner, but didn't put out the grunt that the .46LA did.

I usually used a Taipan 11-5 on the #4055 and maybe that wasn't ideal; tried some BY&O props from Clarence Bull, but I don't recall anything helping as much as the change to the .46LA/APC 11.5 x 4. I used a MACS Muffler on the .46, and an RSM tongue muffler on the K&B. I tweeked the stinger on the MACS Muffler a little to clear the wing. That was a nice combination, particularly for OTS and Profile.

The Hugemongoose will come out tailheavy without serious building care, so a heavy engine isn't a bad thing. Dave Royer flies his with a big Merco. I believe it's a .49, which was built on the same case casting as their .61. Nice setup; he usually wins OTS around here.  D>K Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Dennis Toth

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Re: K&B 4011
« Reply #10 on: August 28, 2015, 07:48:24 PM »
The trick to getting the stock K&B 40 to produce power for stunt is the 2-2-2 run set up. Unless you do lots of mods (as done by Stan Powell for Les) it won't run a reliable 4-2-4. But kick up the nitro and get it in 2 cycle and you have the horse of a different color. For the 4011 I would go with the 10 1/2 x 5 (you could pitch up an APC 10 1/2 x 4.5). For the 4055 you could do the 11 x 5 on 10 -15% nitro. Venturi is around 0.280" with an ST NVA.

Best,    DennisT

Offline Motorman

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Re: K&B 4011
« Reply #11 on: August 31, 2015, 05:06:41 PM »
Ran the engine today. Fox superfuel 5/25, APC 10.5-4.5, .290 venturi, 85F, 13000 rpm no muffler, 12300 full factory muffler. I was surprised it didn't rev higher given the power these put out when configured for racing. One thing was the compression ratio was too low. I had a head that was cut down for racing so I put a spacer on it and it was too thick. Would not hold the leanest full 4 stroke without flaming out. I'll take out the spacer and use a .005" gasket and see how it needles. Love the look of that Los Angles class muffler. Anybody know size and how many holes in a tongue muffler for that size engine?

Thanks,
MM

Offline Motorman

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Re: K&B 4011
« Reply #12 on: September 01, 2015, 02:32:16 PM »
Took the spacer out and put in shims for a .011" deck clearance. Engine had more power at 13000 with the muffler and it needled so much better. Next step build the plane!

MM

Offline Balsa Butcher

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Re: K&B 4011
« Reply #13 on: September 02, 2015, 12:57:08 PM »
With that prop you won't need more than 10,200 to 10,500 rpm for good lap times with a Humongous so power will not be a problem if 13.000 is what you are getting. The question is how does it run at those lower RPMs? 8)
Pete Cunha
Sacramento CA.
AMA 57499

Offline Motorman

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Re: K&B 4011
« Reply #14 on: September 09, 2015, 05:07:12 PM »
Thanks for those numbers, gives me something to work with.

I just scored an 8011 off ebay for $10 so I'll be building a second engine. Had to order bearings and gaskets for it but other than gummy castor it looks fairly new. Made a special tool to drive the pin out and the crank polished up real nice. The 8011 doesn't have muffler lugs so I'll be using a 4011 case but, the smaller front end saves 1 ounce.

MM


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