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Cox Engine of The Month
starting a pressurized Cox
Page 1 of 2
Page 1 of 2 • 1, 2
starting a pressurized Cox
Hope this works
fit90- Diamond Member
- Posts : 1341
Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
Nope, computer is smarter than I am
fit90- Diamond Member
- Posts : 1341
Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
Follow these instructions
http://coxengineforum.forumakers.com/t367-how-to-post-an-image-in-a-topic?highlight=Image
http://coxengineforum.forumakers.com/t367-how-to-post-an-image-in-a-topic?highlight=Image
Re: starting a pressurized Cox
I hope this works this time
Sorry, not yet
fit90- Diamond Member
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Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
"The video you requested is not available"
Are you sure you don't have the video listed as private only?
Are you sure you don't have the video listed as private only?
fit90- Diamond Member
- Posts : 1341
Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
This is a lot of work!!! If anyone thinks it's not hard being dumb they are wrong! Just ask me.
fit90- Diamond Member
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Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
fit90 wrote:This is a lot of work!!! If anyone thinks it's not hard being dumb they are wrong! Just ask me.
Hey, you didn't know, you found out how, and you did it.
Nothing dumb there.
Bob
dckrsn- Diamond Member
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Join date : 2010-10-21
Age : 71
Location : Long Island, New York
Re: starting a pressurized Cox
Hey, Bob, I posted a comment on your video. That's a fast freakin' little Surestart "Type" engine. I almost ducked under my keyboard! What's that thing tach out at?
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: starting a pressurized Cox
It's turning just a little over 19K in the video, probably around 19.2 to 19.3. I am hoping to get this one to top 20K. I am using straight Sig Champion 25% and a Cox 5X3 stiff grey prop. I drilled out the venturi with a #10 bit, used a 128 tpi NVA from a 290 engine and opened up the spray bar hole a few thousandths and put it on an engine with a polished KB crank, SPI piston/cylinder and Galbreath head and Nelson plug with one gasket.
fit90- Diamond Member
- Posts : 1341
Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
fit90 wrote:It's turning just a little over 19K in the video, probably around 19.2 to 19.3. I am hoping to get this one to top 20K. I am using straight Sig Champion 25% and a Cox 5X3 stiff grey prop. I drilled out the venturi with a #10 bit, used a 128 tpi NVA from a 290 engine and opened up the spray bar hole a few thousandths and put it on an engine with a polished KB crank, SPI piston/cylinder and Galbreath head and Nelson plug with one gasket.
IT'S ALIVE! Nice work.
Bob
Last edited by dckrsn on Sat Jan 21, 2012 10:23 pm; edited 1 time in total
dckrsn- Diamond Member
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Join date : 2010-10-21
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Location : Long Island, New York
Re: starting a pressurized Cox
What angle do you position the spraybar orifice, stock straight ahead, or do you aim it off-center?fit90 wrote:It's turning just a little over 19K in the video, probably around 19.2 to 19.3. I am hoping to get this one to top 20K. I am using straight Sig Champion 25% and a Cox 5X3 stiff grey prop. I drilled out the venturi with a #10 bit, used a 128 tpi NVA from a 290 engine and opened up the spray bar hole a few thousandths and put it on an engine with a polished KB crank, SPI piston/cylinder and Galbreath head and Nelson plug with one gasket.
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
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Re: starting a pressurized Cox
Angry little cox motor,,nice work on the vid and engine.
PV Pilot- High Tech Balsa Basher
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Re: starting a pressurized Cox
The hole in the spray bar is facing directly into the back of the engine.
fit90- Diamond Member
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Re: starting a pressurized Cox
.
Last edited by Mudhen on Mon Nov 15, 2021 9:06 am; edited 1 time in total
Mudhen- Gold Member
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Join date : 2011-09-19
Re: starting a pressurized Cox
Thanks for the input on the spray bar angle Mudhen. I remember reading something about that a while ago but could not find the info. I also learned that making the venturi and spray bar hole larger are only effective up to a cetain point. This NVA flows so much fuel under pressure that the needle setting is ultra sensative. I think I will redo the backplate and try the angled spray bar.
Thanks again,
Bob
Thanks again,
Bob
fit90- Diamond Member
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Join date : 2011-08-11
Location : Naples, Florida
Re: starting a pressurized Cox
Bobfit90 wrote:This is a lot of work!!! If anyone thinks it's not hard being dumb they are wrong! Just ask me.
That certainly explains why I'm worn out at the end of the day!! Spent the whole day working at being dumb and was too dumb to figure it out!!!
MudMudhen wrote:
......... more thorough atomization........... For a pressurized engine, your mileage may vary. But it is worth experimenting with various angles..........
You've brought up a valid point.
Certainly for a normally aspirated engine, the old Bernoulli velocity/pressure principle dictates positioning to minimize pressure at the spraybar hole for maximum fuel draw. OTOH, pressurized engines don't need a vacuum to draw fuel, but good fuel atomization is important. Burn surface plays a big part in everything from gunpowder to solid rocket motors, so better atomization means more burn surface, which should transfer to a better flame propagation rate, i.e., more rpm. Dumping fuel into a high velocity air stream would, I think, help atomization. For a pressurized engine, I wonder what effect having the spraybar pointed directly into the airflow would have? Either way, various spraybar angles can't help but be a player in squeezing the last 100 rpm out of the motor.
Re: starting a pressurized Cox
For years and years, the general consensus(still) around the drag racing community was that the more you can atomize Nitromethane, the more power you can get out of it. They have perfected the top end or second system nozzle orifice sizes to the point of shooting a fog type mixture into there motors. They have even gone(years ago) to adding a high speed pinch valve,,for a quick leanout,,to get that extra burst of power.
I was thinking of a couple extra pinholes around that spray bar, to break up those droplets even more.
Just some food for thought, and fun.
I was thinking of a couple extra pinholes around that spray bar, to break up those droplets even more.
Just some food for thought, and fun.
PV Pilot- High Tech Balsa Basher
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Join date : 2011-08-11
Age : 57
Location : The ragged end of the Universe.
Re: starting a pressurized Cox
All this has me thinking to the point that I just ordered some more NVA's from Texas Timers. Unfortunately, I will be busy the next few weekends. But, when I get some more time to play with this I should have everything I need right at hand.
fit90- Diamond Member
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Re: starting a pressurized Cox
Glad I asked about the spraybar because I'm planning to build two Killer Bees as close to identical as possible for the Com Bats I got for Christmas. I'd like to try different positions if it can be fiddled with without loosening the spraybar too much.
Once I got a new red KB backplate with a loose spraybar that turned with the needle. I cleaned it of all fuel and JB Welded it but it came loose again. Maybe it can be re-positioned and then heated and the plastic will cool and grip it.
Once I got a new red KB backplate with a loose spraybar that turned with the needle. I cleaned it of all fuel and JB Welded it but it came loose again. Maybe it can be re-positioned and then heated and the plastic will cool and grip it.
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: starting a pressurized Cox
Back up again
fit90- Diamond Member
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Join date : 2011-08-11
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Re: starting a pressurized Cox
Come again?fit90 wrote:Back up again
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: starting a pressurized Cox
RknRusty wrote:Come again?fit90 wrote:Back up again
Instead of putting a link to this thread in the "Medallinon .15 side nipple" thread I was just lazy and bumped this thread back up.
fit90- Diamond Member
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Join date : 2011-08-11
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