Cox Engines Forum
You are not logged in! Please login or register! Guests are limited to posting in the "General Questions (Guest Posting Allowed)" section only. Becoming a member is fast, easy and FREE!


Do Killer Bee back Plates sold onlne give better perf? Babe_b10
Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Latest topics
» The Annual Worldwide Ringmaster Fly-A-Thon
by Kim Today at 1:21 pm

» Tee Dee .049/.051 tuned pipe?
by 1/2A Nut Today at 1:17 pm

» Rusty's Final Flight
by Admin Today at 12:01 pm

» Fox 35 with ST NVA
by Cribbs74 Today at 10:51 am

» Loco - motion
by sosam117 Today at 8:10 am

» My two latest planes
by batjac Yesterday at 10:29 pm

» TD pusher prop?
by batjac Yesterday at 10:14 pm

» K & B Greenhead's
by oldguy Yesterday at 9:38 pm

» RJ.bee rc cars build tee dee powered
by davidll1984 Yesterday at 8:24 pm

» Tee Dee 049 / 051 Glow Head ID
by dckrsn Yesterday at 3:52 pm

Cox Engine of The Month
September-2020
sosam117's

"Traded an electric charger for this "Complete" (original) Cox Thimble Drome Olympic .15 engine. Right corner is photo as received."



PAST WINNERS
CEF Traveling Engine

Win This Engine!
Gallery


Do Killer Bee back Plates sold onlne give better perf? Empty

Do Killer Bee back Plates sold onlne give better perf?

Page 1 of 2 1, 2  Next

Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Do Killer Bee back Plates sold onlne give better perf?

Post  SkyStreak on Fri Aug 07, 2020 1:48 pm

What makes the red KB one better.
I would like to buy a KB back plate and try it but I don't want to find its no different that what I have.
I have several of the beige back plates already.
SkyStreak
SkyStreak
Bronze Member
Bronze Member

Posts : 31
Join date : 2018-02-26
Location : Mo

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  getback on Fri Aug 07, 2020 2:20 pm

Hey SkyStreak ,, Here is some information you should read before proceeding with the purchase .. And as it state on Cox Internal. site
Features:
Complete back end
Larger, screen-less,
high-flow venturi hole
Includes all gaskets, reed, hardware
Brand new Original Cox item
Needle valve & reed retainer are current production It will bee with fine thread needle valve assy. and air in take should bee .082 " with no restricting screen (witch i dont think would matter that much .
getback
getback
Top Poster
Top Poster

2019 Supporter

2020 Supporter

Posts : 7177
Join date : 2013-01-18
Age : 63
Location : julian , NC

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  getback on Fri Aug 07, 2020 2:20 pm

Are you looking for performance ? Very Happy
getback
getback
Top Poster
Top Poster

2019 Supporter

2020 Supporter

Posts : 7177
Join date : 2013-01-18
Age : 63
Location : julian , NC

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  GallopingGhostler on Fri Aug 07, 2020 6:47 pm

Someone not long ago published directions on how to modify existing horseshoe backs to improve their HP production. I've found that the gray Sure Start backs are a bit touchy to try this. Trying to gently remove the spray bar in one caused the plastic to split, very brittle. The DuPont Delrin nylon ones are more durable.

I'd say if you want to try the KB one, go for it. There are a few other things to do to improve power, but the more free flowing KB back is a step in that direction.

Nice thing about the Coxes is one can do a number of things to improve performance without spending a bundle.
GallopingGhostler
GallopingGhostler
Diamond Member
Diamond Member

Posts : 2433
Join date : 2013-07-13
Age : 66
Location : Clovis, Nuevo México

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  roddie on Fri Aug 07, 2020 8:17 pm

SkyStreak wrote:What makes the red KB one better.
I would like to buy a KB back plate and try it but I don't want to find its no different that what I have.
I have several of the beige back plates already.

I'm not sure if the one's you're looking at have a fine-thread needle-valve assembly.. but a backplate/carb having a fine-thread needle-valve assy. has the benefit of having a finer-resolution tuning for the engine. If you plan to experiment with a pressurized fuel-feed (bladder); then the fine-thread NVA is a must-have.

Your engine should be built to make the best use of all the parts being used.. for what the engine will be used for.

More airflow is good.. but remember; the reed is awesome when it's working.. but a tiny piece of grit ingested and getting stuck under the seat will end the activity and require removing the back-end of the engine to clean the reed/seat area. That's why Cox's sport-engines have a mesh metal screen in the air-intake.
roddie
roddie
Top Poster
Top Poster

Posts : 6927
Join date : 2013-07-17
Age : 60
Location : N. Smithfield, Rhode Island

http://www.stilburnin.com

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  dckrsn on Fri Aug 07, 2020 10:18 pm

Hi SkyStreak,
  Check here, https://www.coxengineforum.com/t6170-modifiying-horseshoe-backplates
If you're interested, I'll whip one up for you, under under one condition, you use it and keep us posted
on your progress. I'm not kiddin'. I was educated by St. Joseph nuns.
PM me your address, and I'll get t out by Monday. Totally gratis of course I Love This Forum!
I'm sure our brothers here can turn her into a monster.
Bob
dckrsn
dckrsn
Diamond Member
Diamond Member

2019 Supporter

2020 Supporter

Posts : 2265
Join date : 2010-10-21
Age : 67
Location : Long Island, New York

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  RknRusty on Sat Aug 08, 2020 1:12 am

The above is all good info for .049" and .051" cubic inch engines, but make sure you get the type that fits both your airframe's engine mounting area, and fits the application you want in performance. Fine thread needle valves will need to be found and scavenged from older engines, and we will help you with any boring of the venturi. As someone stated .084" is as wide as you want to go with suction fuel feed on an integral(built-in Bee type) tank style engine, and the bigger it is, the less user friendly it will be, as well as lower flight time due to it being thirsty. For a pressurized fuel system with a front rotary intake valve(like on a Tee Dee or Medallion .049), up to .150" wide is about as good as it gets before it becomes too finicky, and less power benefit.
Rusty

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Rest In Peace
Rest In Peace

2019 Supporter

2020 Supporter

Posts : 10869
Join date : 2011-08-10
Age : 64
Location : South Carolina, USA

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  SkyStreak on Sat Aug 08, 2020 9:57 am

Do Killer Bee back Plates sold onlne give better perf? Coxbac12
I found in some of my parts a back plate with no screen and it got me thinking that it was similar to a KB back plate.
I have an engine I've been experimenting with that so far I'm getting 17,000 with 15% and a 5x4 prop. Now that I discover this back plate I need to try it to see if it has any improvement on perf.


Last edited by SkyStreak on Sat Aug 08, 2020 8:28 pm; edited 2 times in total
SkyStreak
SkyStreak
Bronze Member
Bronze Member

Posts : 31
Join date : 2018-02-26
Location : Mo

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  Ken Cook on Sat Aug 08, 2020 10:31 am

Drilling the backplate to 11/64" or a #16 bit is about as large as you can take the hole size up too. Anything larger equates to problematic fuel draw. There's nothing very specific about the Killer Bee backplate that sets itself apart from the rest. It's been said the early versions came with a fine needle valve assembly but I've never seen one. In reality, if you want more performance, up the nitro.
Ken Cook
Ken Cook
Top Poster
Top Poster

Posts : 4032
Join date : 2012-03-27
Location : pennsylvania

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  balogh on Sat Aug 08, 2020 11:20 am

I have a few that I mounted on my active reedies and see a tad of performace improvement over the conventional horseshoe backplates. Probably the free flying reed under the reed retainer flanged cup with longer reed clearance than the beryllium allows easier and more  generous fuel-air mixture charge into the crankcase?
balogh
balogh
Top Poster
Top Poster

2019 Supporter

Posts : 3113
Join date : 2011-11-06
Age : 61
Location : Budapest Hungary

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  roddie on Sat Aug 08, 2020 6:40 pm

This is the backplate that I bought.. (less fuel-line and needle) coarse-threaded NV-body BTW..

Do Killer Bee back Plates sold onlne give better perf? 4-24-113

The air-intake is unobstructed.. (no mesh-screen) and looks (to me) to have a smooth-dished orifice; as compared to a "sport" horseshoe-type backplate that has a screen. You could look at it as a sort of "tunnel-ram" reducing turbulence in the venturi.

roddie
roddie
Top Poster
Top Poster

Posts : 6927
Join date : 2013-07-17
Age : 60
Location : N. Smithfield, Rhode Island

http://www.stilburnin.com

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  crankbndr on Sat Aug 08, 2020 7:57 pm

SkyStreak wrote:I found in some of my parts a back plate with no sceen and it got me thnking that it was similar to a KB back plate.
I have an engine I've been experimenting with that so far I'm getting 17,000 with 15% and a 5x4 prop. Now that I discover this back plate I need to try it to see if it has any imrovement on perf.


17K is a good number for that prop and fuel, 25 or 30 nitro will give a boost for sure. Getting over 18K usually takes some work.  The new old stock red backplates are brittle, I have cracked two. Don't honk down on the screws too much, they crack at the venturi. Another tip was to turn the fuel outlet in the spraybar a few degrees away from directly downstream of airflow in either direction, I think that one came from Larry the Renger himself. This is one of Matts EX engines, it has a Surestart cylinder and shortened, lightened piston to allow SPI. Cant see tach but turned 19K with standard head. High comp head and some tuning probably could get over 20K easy.


It really sucks fuel

crankbndr
crankbndr
Diamond Member
Diamond Member

I Support My Forum

Posts : 2549
Join date : 2011-12-10
Location : Homestead FL

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  1/2A Nut on Sun Aug 09, 2020 12:20 am

High static rpm with a mylar reed / Killer Bee backplate & crankcase
but not the piston and cylinder.



Best peak 24,790 / 7.1oz thrust / 106 mph pitch speed / 93.3w
Nelson plug / 25% nitro / HQ Carbon 4x4.5 prop


intake variable per throttle barrel
mylar reed



Best peak noted at 23,336 rpm
APC 4.1x4.1 / peak rpm hit 91 mph pitch speed


Small Cox Logo  Thumbs Up


Last edited by 1/2A Nut on Sun Aug 09, 2020 10:56 am; edited 2 times in total
1/2A Nut
1/2A Nut
Diamond Member
Diamond Member

2019 Supporter

Posts : 2929
Join date : 2013-10-20
Age : 57
Location : Brad in Texas

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  crankbndr on Sun Aug 09, 2020 8:02 am

WOW!! nut= speed demon!! Cool, glad you never sent any engines to the old tach races.
crankbndr
crankbndr
Diamond Member
Diamond Member

I Support My Forum

Posts : 2549
Join date : 2011-12-10
Location : Homestead FL

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  1/2A Nut on Sun Aug 09, 2020 10:22 am

Thank you,
I do plan to build a test plane for Cox reed engines .049 - .051
Will be fun to discover what is possible with RC Reed Speed.
They have a unique sound compared to TD engines.

Small Cox Logo Thumbs Up
1/2A Nut
1/2A Nut
Diamond Member
Diamond Member

2019 Supporter

Posts : 2929
Join date : 2013-10-20
Age : 57
Location : Brad in Texas

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  aspeed on Sun Aug 09, 2020 11:01 am

Almost sounds like a threat to start an online RPM contest with a standard unmodified propeller/fuel mix. Maybe the APC 4 1/4 - 4 prop or something similar that is readily available still. Reedy and rotary class. Bragging rights, no cash is best. I can not say much about the KBee backplates, but imagine the carb bore is just slightly larger than the others. I only have one separate white backplate and pulled the needle assembly to file the bore a bit bigger. That would be the older G clip copper reed. Maybe the mylar reed with the newer retainer is faster. IDK.
aspeed
aspeed
Platinum Member
Platinum Member

Posts : 500
Join date : 2013-01-18
Location : Leamington Ont. Can.

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  1/2A Nut on Sun Aug 09, 2020 11:45 am

Lol Alan true, sunny

The RC carb by eyeball looks like a reasonable intake dia. of course it was made to feed the thirsty TD engine.
Does not seem to be a issue with the reed valve. APC 4.1x4.1E is plenty stout to handle the engine, the thinner
blades let the reed engine gain some fresh new useable performance compared to the fat bladed IC props.

Small Cox Logo Thumbs Up
1/2A Nut
1/2A Nut
Diamond Member
Diamond Member

2019 Supporter

Posts : 2929
Join date : 2013-10-20
Age : 57
Location : Brad in Texas

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  crankbndr on Sun Aug 09, 2020 12:32 pm

i have tried some crazy stuff with KB backplate, this one failed. It did run 19.5K on 25% and a 5/3 gray cox prop. Standard head.
Too much vibration in the intake.

Do Killer Bee back Plates sold onlne give better perf? Kb_bac10
crankbndr
crankbndr
Diamond Member
Diamond Member

I Support My Forum

Posts : 2549
Join date : 2011-12-10
Location : Homestead FL

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty where did you get the syringe?

Post  happydad on Sun Aug 09, 2020 8:02 pm

crankbndr wrote:
SkyStreak wrote:I found in some of my parts a back plate with no sceen and it got me thnking that it was similar to a KB back plate.
I have an engine I've been experimenting with that so far I'm getting 17,000 with 15% and a 5x4 prop. Now that I discover this back plate I need to try it to see if it has any imrovement on perf.


17K is a good number for that prop and fuel, 25 or 30 nitro will give a boost for sure. Getting over 18K usually takes some work.  The new old stock red backplates are brittle, I have cracked two. Don't honk down on the screws too much, they crack at the venturi. Another tip was to turn the fuel outlet in the spraybar a few degrees away from directly downstream of airflow in either direction, I think that one came from Larry the Renger himself. This is one of Matts EX engines, it has a Surestart cylinder and shortened, lightened piston to allow SPI. Cant see tach but turned 19K with standard head. High comp head and some tuning probably could get over 20K easy.


It really sucks fuel


crankbndr: where did you get the syringe? I like the idea. Small fuel supply, and calibrated.

if only i had time to run some engines. i am still on garage cleaning duty. i recently put some old 128tpi needle valve assemblies into some new KB backplates. haven't had a chance to put one onto an engine assembly yet.

happydad. RC Plane Old Bugger United States
happydad
happydad
Diamond Member
Diamond Member

I Support My Forum

2020 Supporter

Posts : 1545
Join date : 2012-05-28
Age : 75
Location : Escondido, CA

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  crankbndr on Sun Aug 09, 2020 8:37 pm

Hay Happy, unfortunately I have have been around a lot of nurses and hospitals. Those syringes are full of saline so I either ask for a few or steal some or both. lol!
crankbndr
crankbndr
Diamond Member
Diamond Member

I Support My Forum

Posts : 2549
Join date : 2011-12-10
Location : Homestead FL

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  SkyStreak on Sun Aug 09, 2020 11:22 pm

aspeed wrote:Almost sounds like a threat to start an online RPM contest with a standard unmodified propeller/fuel mix.  Maybe the APC 4 1/4 - 4 prop or something similar that is readily available still. Reedy and rotary class.  Bragging rights, no cash is best.  IDK.

I think this would be a great idea. Keep it simple though limit it to parts that are Cox production parts.
SkyStreak
SkyStreak
Bronze Member
Bronze Member

Posts : 31
Join date : 2018-02-26
Location : Mo

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  Oldenginerod on Mon Aug 10, 2020 7:11 am

SkyStreak wrote:
aspeed wrote:Almost sounds like a threat to start an online RPM contest with a standard unmodified propeller/fuel mix.  Maybe the APC 4 1/4 - 4 prop or something similar that is readily available still. Reedy and rotary class.  Bragging rights, no cash is best.  IDK.

I think this would be a great idea. Keep it simple though limit it to parts that are Cox production parts.

Best to check the archives for the old Tach Race threads. We've done it all before. The whole thing was a huge drain on the host and interest has all but died out. Looks like the interest might be returning. Back then, because the runs were controlled by one person then it was all fair and above board, hence it had significant prizes. (I won a NIB Black Widow for my Mouse entry. By the way, I think I'm still unbeaten. 24,100 rpm on a tanked reedy Thumbs Up )
There was some talk about a "proxy" tach race, which is maybe what you guys are talking about. The idea would unfortunately be open to corruption, plus a lot of variation in fuels, props climate etc.
Oldenginerod
Oldenginerod
Top Poster
Top Poster

Posts : 3116
Join date : 2012-06-15
Age : 57
Location : Victoria, Australia

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  aspeed on Mon Aug 10, 2020 9:16 am

Oldenginerod wrote:
SkyStreak wrote:
aspeed wrote:Almost sounds like a threat to start an online RPM contest with a standard unmodified propeller/fuel mix.  Maybe the APC 4 1/4 - 4 prop or something similar that is readily available still. Reedy and rotary class.  Bragging rights, no cash is best.  IDK.

I think this would be a great idea. Keep it simple though limit it to parts that are Cox production parts.

Best to check the archives for the old Tach Race threads.  We've done it all before.  The whole thing was a huge drain on the host and interest has all but died out.  Looks like the interest might be returning.  Back then, because the runs were controlled by one person then it was all fair and above board, hence it had significant prizes.  (I won a NIB Black Widow for my Mouse entry.  By the way, I think I'm still unbeaten.  24,100 rpm on a tanked reedy Thumbs Up )
There was some talk about a "proxy" tach race, which is maybe what you guys are talking about.  The idea would unfortunately be open to corruption, plus a lot of variation in fuels, props climate etc.
If there are no prizes, then you are only cheating yourself. Maybe a picture of the the tach. I am sure someone would be cutting the prop down. Nitro content could be an issue if not available. I can rarely get 15%, unless I mix it.
aspeed
aspeed
Platinum Member
Platinum Member

Posts : 500
Join date : 2013-01-18
Location : Leamington Ont. Can.

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  1/2A Nut on Mon Aug 10, 2020 10:57 am

Hi Rod,

What prop did you use to get 24.1k rpm with a tanked reedy mouse entry and % nitro used?

Small Cox Logo Popcorn
1/2A Nut
1/2A Nut
Diamond Member
Diamond Member

2019 Supporter

Posts : 2929
Join date : 2013-10-20
Age : 57
Location : Brad in Texas

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  SkyStreak on Thu Aug 20, 2020 7:38 am

They say not to go over .082 ventury on a tanked engine. How do you calculate the intake size on a horseshoe bake plate. The spray bar divides the intake.
SkyStreak
SkyStreak
Bronze Member
Bronze Member

Posts : 31
Join date : 2018-02-26
Location : Mo

Back to top Go down

Do Killer Bee back Plates sold onlne give better perf? Empty Re: Do Killer Bee back Plates sold onlne give better perf?

Post  Sponsored content


Sponsored content


Back to top Go down

Page 1 of 2 1, 2  Next

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum