Pond Skipper

For the Cox engine I am at the stage where the next step is to file the the top of the exhaust port at and angle and raise the port about .5mm to allow more boost into the cylinder.

I have a single bypass port cylinder in the mail coming from Portugal - if it is what I expect there will also only be one exhaust port from the photos it appears to be the case.

Here is the parts description:

Cylinder, Piston, Rod Assy Kyosho 049-1477 Cox f1 LARROUSSE ferrari F189 Single Bypass


If that doesnt pan out I have a cylinder picked out to mod it has two bypass ports and two TD style exhaust ports a non SPI
Here is the cut pattern will mod only one side facing the pipe the other side will be blocked off.

Pond Skipper

I have also noticed when the pipe starts to function it acts like a pump drawing more fuel air thru the carb. The NV setting on pressure has a small window from sweet spot.
Yes with boats all mechanical bugs / weak system components have to be worked out. I have ran mono's and outriggers on TD's and Queen Bee's. The TD's had more top
end speeds but the QB had a more robust crank case and could handle the Dumas 1/2A flywheel for more runs before over time it would waller out the aluminum crank case.
I had planed to use a bronze bushing but never sourced the part and drill bit size.The flywheel is a bit heavy I wanted to fabricate a lighter one. The surface drive outriggers went
fast compared to the submerged drive mono's. From about 17mph mono's to 26ish riggers on the same amount of power. I used exhaust throttles on the TD's for best power management. I am curious about the pipe length on your tunnel design did you fabricate the outboard or retro fit the engine to vintage unit?

Japanman

I made the outboard myself.
If I find the pipe, I'll measure it.
Funny thing I remember is, I ran incredibly high compression heads, like you would never get away with on a plane. But perhaps it was the water cooling, it ran sweetly like that, and the time a head plug failed and I used a stock cox head, it couldn't get planing the torque was so refuced.
it makes me wonder if the crank surviving the high rpms might have been from the extra high comp. ratio.

I had the same experience with the surface drive: night and day.

Pond Skipper

I could run higher rpm with surface drive the loads on the engine are less then with an air prop pulling a plane around. So the loads on the ball socket and piston rod made it possible. When I raised timing to 170 the combustion chamber was expanded so high compression head is a absolute must or the power loss is too great as you observed.
I plan to only run with one shim about 155 deg and do the cylinder mod is the best way to insure the pipe is boosting the cylinder. The Bolly Book stated tuned pipes will not function on anything less the 140 deg timing - if 2 shims gives me 170 odds are per shim its 15 deg.
http://www.bolly.com.au/book/Book.ph...er=6&Section=4

The engine was difficult to run at 170 deg the NV was way to sensitive with the Tarno Carb. I have a non SPI cylinder on 1 shim and so far it show promise. I am waiting for the single bypass cylinder to come in before I decide which cylinder gets filed. You had mentioned before you hadn't done any work to the porting, did you use a RC carb?

I plan to grind down some of the aluminum off the bottom of the glow head to seat it further down for higher compression to make up for the shim- I want to regain the same amount of compression prior to the shim.

With an outboard how did you manage to hang the pipe forward over the length of the boat?


Check this out I made a Micro Cracker boat with a TD .020 water cooled and exhaust throttle surface drive with a 20 mm surface prop

https://www.youtube.com/watch?v=gSqH9EZGKKc

Pond Skipper

This looks promising perhaps a 1/2A version.



http://www.rbinnovations.com/category_s/3.htm


https://www.youtube.com/watch?v=b8KKbmMtuGg

https://www.youtube.com/watch?v=3bi5h7Tf2BY

Japanman

Nice boat! I really wish I had video of the outboard boat running now.

I only used non spi cylinders, as at the time I thought it would be impossible to run a pipe with a spi cylinder- but Andy W was the first to prove norvels run on a pipe just fine, even though they have spi.

I didn't use base gaskets, for the reason you mention, instead I cut the exhaust ports higher. I thought at the time this would be important to increase blowdown time.

I have since run several 1/2A size motors on a pipe, and found that the idea of sub X port timing not working to be not true.
I suspect this comes down to the relative densities of air to the engine- as you get smaller, it goes up, so things change, like Reynolds numbers for airfoils.

yeah the pipe on an outboard was a bit of a headache! I made it in a curly S shape.

Pond Skipper

With SPI you have to either tune to the SPI or tune for the boost going directly into combustion chamber cant do both. The window for SPI is smaller than the later but can confirm it does work with a cox engine there is a small loss using a piped system once tuned it is regained and I have had 22k plus static with a APC 4.5 x 4
The SPI function acts like a vacuum and could actually be doing good work for such a small gap.
I think opening up the top of the exhaust port allows more window time for the boost charge.


Ahh ok figured you had something rapped around the out board engine. I have been using a hat mounted video cam will have to
find some water and get my mono uploaded on YouTube will message you if you like to check it out.

gmeyers

It's been a lot of years since this was posted and I'm looking for a pipe or pipes for my 1/2A engines and I have been unable to locate any today. Seems like Rossi, Profi, Macs, and others don't make them anymore and likely won't due to the electric invasion. Anybody know of a 1/2A pipe being available anymore ??

Pond Skipper

RECORD Tuned pipes for engine 0.8 сс micro
I have 7 of these used with many engines all on video
AP .061
Norvel .061
SH .07
Picco .05
Sportwerks .05
Fuji .05
Cox TD .051

https://www.ebay.com/itm/RECORD-Tune...53.m1438.l2649

aspeed

Brad, you know that is over $1,000 worth of pipes here? In a pinch they can be butchered/McGivered together from CO2 cartridges and tubing.

gmeyers

Thanks - I'm thinkin over

Pond Skipper

Alan these pipe are very light weight only 11.5g a Co2 cartridge weighs a ton.
I bought mine from Speed Domingo on ebay $65 a pop plus shipping.
About every 2.5yrs. ish he buys engines and pipes some extra's go onto
ebay to help pay for his hobby order. He has a connection over there.
As I recall mine was 74 shipped to the door so around $518 in 1/2A
pipes. Right now the only way to get one is the link provided or you
buy from Alberto you can call him ask him to order you the pipe (949) 425-1362
He is out of California.
Will take about 35 days, I bought one from his site once. now $97.95
When I bought one from him they where 80 a pop.

• Model: PRO-08cc-TP
• Shipping Weight: 0.5lbs
• -1 Units in Stock
• Manufactured by: Profi Engines

Profi .8cc Speed Engine Pipe Only [PRO-08cc-TP] - $97.95 : Hobby Club

Here engine and pipe
http://www.hobbyclub.com/index.php?main_page=product_info&cPath=44_202&products_id=1610&zenid=656f35814db7ba596b51b3edaa9ef4bd

That's it the only two ways of getting the pipe the only 1/2A pipe worth buying currently.

aspeed

We lose 37% on the exchange rate here, for shipping too. It pretty much doubles the price of things you take for granted. The Australians and others face the same problems. I still have my old CS pipe but am always thinking of different solutions like mousse cans, silicone baby snot suckers and CO2 cartridges. Yes some are steel.

Pond Skipper

Dang Alan that truly bites!
You have the lathe on tap is there anyway to spin a multi piece tuned pipe that screws together?

I played with the cartridges back in the day for cooling a E motor in a boat servo valve controlled to dump Freon through the cooling coils.
The heat would frost up the coils it worked rater well with a 05 can motor of the day. But servo weight bottle weight water cooling won the
day was just a geek thing to do. Later I mess with 900 size can motors those big monsters of the day made servo and bottle ok to use
plenty of power to offset the add on feature.

I wish there was a way to make aluminum pipes without the need for special machine action, I would be all over it. Alas best one can do is
carve up wax pipe and mold over with carbon. High heat epoxy has proven to work, I need to man up and do a TD .02 pipe in carbon just
to get a feel of what it takes to deal with the process. Deflection bounce is important steel pipes do that the best. One thing carbon has
going for it is heat stabilization aluminum pipe sure do look pretty though and that's tough to beat.

aspeed

I made a mold of a CS pipe. It's a 2 piece mold but is just from the outside of the pipe. I was thinking of filling it with wax and turning an inlet and outlet tube from aluminum and figure how to attach them in the wax, then cover with a high heat epoxy/glass. Probably will never do it, but did make the mold. It has a few big bubbles in the surface..

Pond Skipper

Having both pipes the CS pipe is 80% the quality of the Profi. Weight is more finish and design is less.
Certainly gets the job done it's a colder pipe due to the short stinger with a bit more ID. The tappers
are not as good and a press fit adapter. With today's tech the match makes this a better pipe for a
.074 / .09 having said that the SH .07 kicks arse with the Profi pipe.


Published on May 11, 2019
Stock test with APC4.5x4 / 98 mph pitch speed /25.84K rpm 12.4oz thrust / .203hp - 152w / est. 33k ish unloaded to 130 mph PS
These are getting rare to see running just try doing a search on Youtube for a G&Z engine... nada. Stock tuned pipe that came with
the engine, speed spinner removed for a typical smaller dia. bullet spinner. 25% nitro / 20% castor.

aspeed

GZ videos are rare. First time I ran mine, I am not sure there was even an internet.

Pond Skipper

Yes hearing one run was a treat, I did not push the NV was after a bit of break in time prior to filming.
I could not find any vids bench or in the air of a G&Z in action. Doing a search per name and by GZ.
Of course now if you do a search my video will show up keeping the memory alive for those who
enjoyed them in the past.

I decided to run it with the APC 4.5x4 which is likely the prop I would flight test it with but also to
keep the rpm's from jumping up too fast during break in. The 4.2x4 will get a turn with a bit more
fuel through it yet. I am curious how the pipe function will perform with the added rpm will give a
more realistic power reading. I expect around 170w given the pipe will be kicking in well. Not bad
for it's vintage and carries it's extra weight well with the more restrictive RC carb.

aspeed

IIRC Carl Dodge was running the CS (GZ) for his 1/2A speed attempts. Around 140 mph. I think at around 40,000 rpm on a single blade prop. I have not run mine for many years with a pipe. I remember as it hit the pipe that the needle was ineffective. Like it could not richen out enough. Kind of typical pipe behaviour.