Zenoah Glow fuel eng?

[bermudadude]

oh wait ,i thought u showed that engine u bought cause you where going nitro with THAT. ooh well yea if u use a tk and a custom head button its allot easier

 

[dwilfong]

oh wait ,i thought u showed that engine u bought cause you where going nitro with THAT. ooh well yea if u use a tk and a custom head button its allot easier

I thought about it and figured why waste the time with the 230.
Have a R254 eng I was playing with years ago I found in a box of stuff.
It will fit in the Zeagle rigger I built.

 

[LohringMiller]

Remember that my experience is with GASOLINE in Zenoahs. We always ran the zero drag seals, but I'm not sure they were a lot better than broken in seals. The RCMK case ran double front and rear bearings as does Quickdraw. This is to prevent crankshaft flexing. Some tests with an RMCK engine vs a Zenoah in a mono didn't show any advantage, but it stops magneto strikes in the flywheel. Double front bearings were really a help on the CMB 35.

The stock 50 mm rod is too short even with a stock stroke. I would go with a 55 mm rod. We did that with the gas scale two lap record 30 cc engine. It will need a spacer under the cylinder and a check on the new port timing. We ran around .010" to .012" squish clearance on most engines because it was easy. However, we ran .002" clearance on a Quickdraw before we got head strikes. I think less is better. Consider a toroidal head button design to place the plug closer to the center of the combustion chamber. Jim Allen was able to run a 1.2cc head volume on gasoline. You can try even less.

Below is the best empirical pipe and port design program available. You will need to carefully go through it to use temperatures and speeds of sound for nitro fuels. I think somewhere between 200 and 300 degrees C should be close. Gasoline usually runs 550 to 600 degrees.

Good luck.
Lohring Miller

 

[dwilfong]

Remember that my experience is with GASOLINE in Zenoahs. We always ran the zero drag seals, but I'm not sure they were a lot better than broken in seals. The RCMK case ran double front and rear bearings as does Quickdraw. This is to prevent crankshaft flexing. Some tests with an RMCK engine vs a Zenoah in a mono didn't show any advantage, but it stops magneto strikes in the flywheel. Double front bearings were really a help on the CMB 35.

The stock 50 mm rod is too short even with a stock stroke. I would go with a 55 mm rod. We did that with the gas scale two lap record 30 cc engine. It will need a spacer under the cylinder and a check on the new port timing. We ran around .010" to .012" squish clearance on most engines because it was easy. However, we ran .002" clearance on a Quickdraw before we got head strikes. I think less is better. Consider a toroidal head button design to place the plug closer to the center of the combustion chamber. Jim Allen was able to run a 1.2cc head volume on gasoline. You can try even less.

Below is the best empirical pipe and port design program available. You will need to carefully go through it to use temperatures and speeds of sound for nitro fuels. I think somewhere between 200 and 300 degrees C should be close. Gasoline usually runs 550 to 600 degrees.

Good luck.
Lohring Miller

Where can I get a longer rod?

 

[dwilfong]

OK I got this on the way.
https://www.ebay.com/itm/ADA-Racing...oah-F270-R290-Baja-5b-5t-/322188529562?_ul=IL

 

[dwilfong]

OK so let me ask this with the stock 26 Zenoah crank this long rod and a reduced weight piston. What is the mechanical RPM limits of this kind of set up.
I can change timing build a head and make any kind of pipe.
But how many RPM will this rotating assembly handle?
20000? 21000? 22000? 23000?
That is the question that needs to be addressed!
I do not need torque the Nitro will supply all I will need.
I need RPM's...................................
Crank flex will not be a problem as there is no flywheel to mess with.
Rotational weight will be reduced with two short side crank ends.
There will be no fly wheel to control just the small pully on one end of the crank.

 

[LohringMiller]

Quickdraws use the same crankshaft and 50 mm rod as Zenoahs. We could rev them to 25,000 rpm and maybe more. The same was true for the M&D cast cylinder on a Zenoah crankcase. The stock Zenoah's power drops off a cliff at 20,000 rpm. The rpm is limited by breathing. Closed transfers and better port area is the main difference.

The stock rod big end bearing has a limited life at over 20,000 rpm. See my article Big End Blues. Quickdraw and others have increased clearance and slotted the rod to help. We propped our 55 mm rod engine for around 18,000 rpm peak. That's a little above the power peak at around 16,000 rpm.

Lohring Miller

 

[dwilfong]

Quickdraws use the same crankshaft and 50 mm rod as Zenoahs. We could rev them to 25,000 rpm and maybe more. The same was true for the M&D cast cylinder on a Zenoah crankcase. The stock Zenoah's power drops off a cliff at 20,000 rpm. The rpm is limited by breathing. Closed transfers and better port area is the main difference.

The stock rod big end bearing has a limited life at over 20,000 rpm. See my article Big End Blues. Quickdraw and others have increased clearance and slotted the rod to help. We propped our 55 mm rod engine for around 18,000 rpm peak. That's a little above the power peak at around 16,000 rpm.

Lohring Miller

Yes I remember talk about the big end getting blue from heat.
I think I got in to it with Les about trying a full complement like the nitro eng use.
That was some time ago getting old and forget full........LOL
I will reduce the piston weight as much as I can and use the longer rod.
May even try the full complement needles in the big end will see.
If I can run at 23000 I will be happy

 

[LohringMiller]

As I said in my article, I like Jim Allen's solution of two needles per retainer slot. My only rod failure was actually a retainer failure that allowed the needles to skew, breaking the rod. Jim used heat treated C-350 maraging steel for the retainer and M-2 reamer blanks for the needles. See below

Lohring Miller

 

[dwilfong]

As I said in my article, I like Jim Allen's solution of two needles per retainer slot. My only rod failure was actually a retainer failure that allowed the needles to skew, breaking the rod. Jim used heat treated C-350 maraging steel for the retainer and M-2 reamer blanks for the needles. See below

Lohring Miller

View attachment 290830View attachment 290832View attachment 290833

Yes I was aware of what Jim had done.
BUT reality is that is not a option unless you have it custom made.
So how much side clearance for the rod is required?
Also how much end clearance for the crank when assembled in the case?
I can adjust all this as needed when I build the crank up.
I can also slot the big end of the rod if need be.
Want to make this as user friendly as I can and cost affective.

 

[dwilfong]

Quickdraws use the same crankshaft and 50 mm rod as Zenoahs. We could rev them to 25,000 rpm and maybe more. The same was true for the M&D cast cylinder on a Zenoah crankcase. The stock Zenoah's power drops off a cliff at 20,000 rpm. The rpm is limited by breathing. Closed transfers and better port area is the main difference.

The stock rod big end bearing has a limited life at over 20,000 rpm. See my article Big End Blues. Quickdraw and others have increased clearance and slotted the rod to help. We propped our 55 mm rod engine for around 18,000 rpm peak. That's a little above the power peak at around 16,000 rpm.

Lohring Miller

I would love to read the article BIG END BLUES but my computer will not let me in to the NAMBA web sight. It said I am blocked.
Tried every thing I know and can not get unblocked. It is the ONLY website that I can not get in to.
Can get into the member.namba.com to pay up but nothing else.
Can you send it to me in a Email?
[email protected]

 

[David Ashcroft]

OK I have spent some time going over my options on the best way to go.
As usual DAM the torpedo's full steam a head........
So this is what I have planed and will need as much help as I can get.
Will use a RCMK R254 crank case with a Tiger King top end kit.
This way I can make my own head buttons.
I am thinking about using a stock Zenoah 26 crank to keep the rotating mass as small as I can.
So what rod is the best as far as strong and light?
What rod bearings work the best?
I will use two rear half 26 cranks and run a pully on it for the starter.
I will build up the crank my self.
Also what about this 0 drag seal?
Will run my own design full complement bearings one on the front and one on the back.
O and who has the easiest pipe program on line to get a feel for where to start off with the pipe build up.
I remember one of the gas boat forum had one with cone templates?
So lets here it the good the bad and the ugly.............LOL

Forget the zero drag seals ,overrated and can leak

 

[Wasted wages]

Aren't they just a regular shaft seal with the spring removed ?? can't create that much drag...

 

[dwilfong]

I never seen one my self.
Have one coming from Gizmo motors to check out and see what is what.
On the R254 crank case the back side has a cone casting on it no seal needed.
The front side has 2 bearings and the out side one is a sealed bearing.

 

[LohringMiller]

Zero drag seals are low clearance bushings. The latest are designed to fit inside the rubber seals. Originally they were designed and tested by M&D. I'm sure they dynoed them, but I took their word that they were better. The link to the Propwash no longer works. I'm not sure why. Below is my article on big end bearings. I think slotting is the first step. The piston end provides guidance so the side clearance is fine. See Gizmos rods.

Lohring Miller

 

[dwilfong]

Well here it is the crank build up with the 55mm rod.
I used the caged bearing that came with the rod kit for now.
Want to keep it simple at first to see what is what.

I used two short ends from two different stock cranks.
I slotted the 55mm rod in my cheepo mill with a Dremel thin grinding disk spraying CRC to keep it cool.

Here is it next to a CMB 1.01RS

With out all the ignition crap it is the same size.
Will see what the weight comparison is when it is done.
Still bouncing a round what to use for the crank bearing set up.

 

[Wasted wages]

Man, that looks like a huge wrist pin hole..
Does it run on rollers too ?

 

[dwilfong]

Man, that looks like a huge wrist pin hole..
Does it run on rollers too ?

Yes it has a caged needle bearing also.

 

[Wasted wages]

Are you going to add a slot or oil holes on the wrist pin side ?

 

[dwilfong]

Are you going to add a slot or oil holes on the wrist pin side ?

No it dose not move that much.