Strange cylinder

TDbandit Mon Jan 11, 2016 9:22 pm

Well looks like I got my hands on something odd again. Just picked up a cylinder which appears to be a custom, whats unique with this one is its three port schnurle ported and single exhaust and from the way it sits on the case, it's indexed as well. Here's the pics;

First one shows the exhaust it has a curious dimple in the middle of the top edge probably for timing

Other side of the cylinder, looks to have been once a slit exhaust with the way the slits were filled in. cylinder has no SPI.

A look at the ports, sorry best shot I could get you can just see the three ports two small bypasses and one large boost. going to be interesting to see how this one performs.

a side shot showing the single exhaust.

Wonder who did this thing *Scratches head* (The bandit is curious)

pkrankow Mon Jan 11, 2016 10:43 pm

Silver solder you think?

It is a well reported "fact" that "the exhausts are too big" and yada yada for optimum performance.

"Modern" engines run more bypass area and less exhaust area for their displacement gaining higher power from the volume...

I want to know if it performs exceptional or pretty standard, or rather mediocre. I feel slightly inspired, that looks like it may be a low budget, potentially high return modification.

Phil

coxaddict Mon Jan 11, 2016 10:51 pm

If you plan to run it, it would be nice to have a base line to compare vs. stock. I had a similar idea and even found some carbon rod to fit in the cylinder to protect the bore while silver soldering the exhaust port.
great find!

happydad Mon Jan 11, 2016 11:50 pm

TDbandit wrote:Well looks like I got my hands on something odd again. Just picked up a cylinder which appears to be a custom, whats unique with this one is its three port schnurle ported and single exhaust and from the way it sits on the case, it's indexed as well. Here's the pics;

First one shows the exhaust it has a curious dimple in the middle of the top edge probably for timing

Other side of the cylinder, looks to have been once a slit exhaust with the way the slits were filled in. cylinder has no SPI.

A look at the ports, sorry best shot I could get you can just see the three ports two small bypasses and one large boost. going to be interesting to see how this one performs.

a side shot showing the single exhaust.

Wonder who did this thing *Scratches head* (The bandit is curious)

p.s. try putting the cylinder in front of a flashlight with a piece of white paper over the flashlight.

Is it ground for RC Sleeve? The outside is shiny.

happydad

**RknRusty** Mon Jan 11, 2016 11:59 pm

Hey Dave, are you a member of Stunthangar? That would be a good one to paste over in Randy Smith's Engine Setup forum. Or in the 1/2A forum.

**Admin** Tue Jan 12, 2016 12:25 am

I'd like to see if there is any performance increase (or decrease) with this. It looks like silver solder, someone closed up the two slits, opened on the other exhaust and then cut another port in it. I know some could get unfinished cylinders from Cox to play around with different porting and exhaust configurations.

JPvelo Tue Jan 12, 2016 12:33 am

It's probably no good. You should send it to me for proper disposal.

Jim

**RknRusty** Tue Jan 12, 2016 1:46 am

If it's higher performance than a regular cylinder, you maybe shouldn't put it on a Tee Dee, because they already run close to the ball socket limit.

Oh, and thanks Jim, but I'll be glad to dispose of it, I'm much closer.
Rusty

badbill Tue Jan 12, 2016 12:28 pm

You must have a wonderful benefactor.....

1/2A Nut Tue Jan 12, 2016 4:29 pm

Looks like the original owner may have tried to use a tuned pipe.
It would require a single exhaust port and timing to be raised.
The exhaust port was filed on the upper top side then a groove added.
I wonder what the timing is now I bet he grooved it to hit the 180 deg mark.

TDbandit Tue Jan 12, 2016 4:57 pm

badbill wrote:You must have a wonderful benefactor.....

Yup

(Bandit)

TDbandit Tue Jan 12, 2016 5:09 pm

@ Rusty: Yup I am!

@Admin: I stuck it on my Tach race Reedie platform and ran a couple of tanks through it, needs break-in so I'm gonna do some messaging before I do anything drastic with it. It did start easily though and wants to turn up a bit also has different manners too other than a normal cox seems more steady. timing seems aggressive so it's gonna be fun to tinker with.

@1/2A nut: I agree, with the way it tries to run I bet it would take off with the right setup. I need to put a degree wheel on it and see come to think of it. Would like to find a pipe for it and try it out. Another thing that points to that possibility is the cylinder also has no SPI.

@Happydad: Very well could be might of been from a dragonfly or RC bee. I does have the stop that keeps the throttle collar from floating up and down.

(Bandit)

roddie Tue Jan 12, 2016 8:08 pm

1/2A Nut wrote:Looks like the original owner may have tried to use a tuned pipe.
It would require a single exhaust port and timing to be raised.
The exhaust port was filed on the upper top side then a groove added.
I wonder what the timing is now I bet he grooved it to hit the 180 deg mark.

It would be good to measure (if you have access to a vernier-caliper or height-gage) the amount that the port was raised from the base of the cylinder. It probably wasn't lowered.. because there's no SPI.. correct? If it's a screamer.. then you'd have a baseline to work from if you want to make another.

I often wonder what effect raising one exhaust port would have on a given Cox .049 cylinder? Would it scavenge exhaust toward the low-side? Or with your cylinder in question; what if the intake-port(s) were indexed 180 degrees from that single exhaust-port..? Might that set-up a swirl-combustion action?

As for the closed exhaust port.. I wouldn't be surpised if it was mig-welded.. and faced-off in a lathe.. (hence the bare-steel) If the PO had the tools to grind the intake port(s).. they certainly could have de-burred and polished the area inside of a welded port? I can't see solder holding-up. Thinking it would just blow-out from dis-similar heat expansion?

1/2A Nut Wed Jan 13, 2016 2:14 am

This method of modification adds rpm, typical props will not apply so well as the smaller thin and narrow bladed ones such as a APC 4.5x4 / 4.4x4 / 4.2x4 the upswing is you can exceed the 24k recommendations by Cox do to lower load on the socket and rod. Load limits are bumped to a safe 26k static perhaps a bit more and would be best to minimize the time on the bench at those rpms. Heat of course will have to be kept in check with a all castor blend preferably 20% - 22%. A Kern Craft or Kustom Kraftmans rear back plate .004 pressure nipple hole would be in order to feed the beast for rpm or a bladder. Am I seeing a 3rd boost port?? With a raise in the exhaust timing you would want to bring up the boost ports as much as possible to maintain best delivery of the fuel / air.

Once you feel a safe break in has been completed let us know what sort of rpm readings your seeing per prop.

faif2d Wed Jan 13, 2016 8:54 pm

20 years ago Richard Stubblefield was running a schnurle ported Tee Dee. I seem to remember that it ran really well in 1/2 a combat.

**RknRusty** Wed Jan 13, 2016 9:25 pm

faif2d wrote:20 years ago Richard Stubblefield was running a schnurle ported Tee Dee. I seem to remember that it ran really well in 1/2 a combat.

F2D, did you ever get a look at the porting on Richard's cylinders? I wonder if this one resembles his.
Rusty

faif2d Thu Jan 14, 2016 8:30 am

I never got a look but he told me it was schnurle ported. He may have also told me that it was from a blank cylinder from Cox.

getback Thu Jan 14, 2016 9:20 am

Were do you find these blank cylinders from Cox ? getback Huh...

pkrankow Thu Jan 14, 2016 11:05 am

getback wrote:Were do you find these blank cylinders from Cox ? getback

Hen's teeth.

There were very few of them, and not available to the general public, so they only show up when someone is liquidating a collection from someone who was able to get them.

Phil

**Admin** Thu Jan 14, 2016 2:12 pm

They pop up on eBay every few years and they don't sell for cheap.

happydad Thu Jan 14, 2016 5:10 pm

Admin wrote:

They pop up on eBay every few years and they don't sell for cheap.

Are those blank cylinders? Don't you have a smaller picture? lol!

I mean a close up of the cylinders?

happydad RC Plane

< (RC car emoticon)

**Admin** Thu Jan 14, 2016 7:37 pm

happydad wrote:
Admin wrote:

They pop up on eBay every few years and they don't sell for cheap.

Are those blank cylinders? Don't you have a smaller picture? I mean a close up of the cylinders?

happydad < (RC car emoticon)

Not my picture, it's the only picture I have from an old eBay auction years ago.

getback Thu Jan 14, 2016 8:42 pm

Well alright then !! Just something else to look for ,, This COX ENGINE story is really a lot longer than you can imagine going on and on on on ,, But is really cool as you learn more and more and more and is fun and I know you know what I mean Happy New Year

I just sold a engine that had a cylinder that looked like that but I think it had just been cleaned too much!! getback Very Happy

roddie Thu Jan 14, 2016 9:24 pm

A machinist could make blanks on a CNC lathe. You just need to know a person with the skills and access to the equipment. CNC precision is awesome.. and repeatable. If alternate than stock porting proves to yield an increase in performance.. it might be worth spending some $$ on custom cylinders. The grinding would need to be done by a skilled person too.. but all they need to know are the specs. for a proven design. It must have been exciting to work for L.M. Cox back in the day.. if you were into small engines!

1/2A Nut Thu Jan 14, 2016 10:20 pm

Here ya go

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