Sleeve Porting: What does what?

[Jim Allen]

Here is another picture. If you look closely, there are piston strikes at the outer most edges.

Jim

 

[BigChuck]

WOW...................... Looks like a QD HEAD,,,,,,???

 

[Marty Davis]

Jim:

What is the magic number for the protrusion of the plug into the chamber? Correct me if I am wrong, but the primary reason for the toroidal head button is to get the plug more central to the chamber. Why do you think that the design is so much better for eliminating detonation?

The image is really what I envisioned, I just couldn't determine the lines on the edges of the chamber. I see now, that you were drawing several different volume chambers.

I would like to draw one of these in AutoCad and then scale it down to consider the size form tool or ball mill that is appropriate for the little engines.

Are you going to post a drawing with dimensions for us to look at it more closely? I can almost do that with the drawing that you posted, but I need to know what ball mill diameter this drawing used in order to draw it.

Do you believe that the plug depth should be around the centroid of the chamber?

 

[Marty Davis]

Jim:

After drawing a few chambers, I can see that it is difficult to get enough volume in the chamber for a .21 engine with the large requirement of the glow plug.

How much have you been able to raise CR with this design head button without getting detonation?

With the EAS and my Cad, I can easily figure out the Trapped CR with various designs, but it is REALLY difficult to get enough volume.

VERY interesting discussion. I had actually drawn a toroidal button for my .67 engine some time ago. Never cut it....

 

[Jim Allen]

Jim:

What is the magic number for the protrusion of the plug into the chamber? Correct me if I am wrong, but the primary reason for the toroidal head button is to get the plug more central to the chamber. Why do you think that the design is so much better for eliminating detonation?

The image is really what I envisioned, I just couldn't determine the lines on the edges of the chamber. I see now, that you were drawing several different volume chambers.

I would like to draw one of these in AutoCad and then scale it down to consider the size form tool or ball mill that is appropriate for the little engines.

Are you going to post a drawing with dimensions for us to look at it more closely? I can almost do that with the drawing that you posted, but I need to know what ball mill diameter this drawing used in order to draw it.

Do you believe that the plug depth should be around the centroid of the chamber?

Start by placing the glow plug as close as possible to the center of the chamber. You will lower the plug's placement as you continue to raise the compression ratio. "This causes the initial pressure to rise more slowly, but it will reach a higher peak level. The higher level causes the finished burning process to take place in less time than with a hemi style head. If you can shorten the time to complete the burn there will be much less detonation."

"The CFD graphs show a higher cylinder pressure & a shorter burn time for the toroid shape. This means there is a greater efficiency for the entire burning process. The toroid can burn far more fuel in less time because of the greater efficiency."

"In a gas engine this type of head likes lots of advance & rich jetting for maxium power." In a nitro engine raise the compression & turn the needle much richer.

The diameter of the mill for the 26 cc gas engine with a 1.339" bore is .375". The diameter for the 15 cc nitro engine with a 1.126" bore is .3125".

The geometric compression ratio has been doubled in both types of engines without any detonation. Imagine what that can due for the bottom end & mid-range HP. The over-rev capability of the engine will also be improved providing there are large enough time area numbers to support high RPM's.

Jim

 

[Jim Allen]

WOW...................... Looks like a QD HEAD,,,,,,???

It is the toroidal head used on my 26 cc rear exhaust QD. The geometric compression ratio has been raised from 10:1 to 20:1. The engine makes more HP across the entire range than my 29 cc Pioneer. There is no washer under the spark plug & no silicone rubber "O" ring is used to seal the head. A precision machined brass washer makes a perfect seal that is unaffected by any amount of heat. The toroidal head & the engines pipe works best in the 20,000 to 26,000 RPM range.

Jim Allen

 

[dave roach]

Hi Jim

You have a PM.

Thanks

Dave Roach

 

[BigChuck]

WOW...................... Looks like a QD HEAD,,,,,,???

It is the toroidal head used on my 26 cc rear exhaust QD. The geometric compression ratio has been raised from 10:1 to 20:1. The engine makes more HP across the entire range than my 29 cc Pioneer. There is no washer under the spark plug & no silicone rubber "O" ring is used to seal the head. A precision machined brass washer makes a perfect seal that is unaffected by any amount of heat. The toroidal head & the engines pipe works best in the 20,000 to 26,000 RPM range.

Jim Allen

Thank you Jim, Thought that cut away was something I had seen before, but could not be sure. Interesting how some if the info that will help us move forward is already in front of us.

 

[Jim Allen]

WOW...................... Looks like a QD HEAD,,,,,,???

It is the toroidal head used on my 26 cc rear exhaust QD. The geometric compression ratio has been raised from 10:1 to 20:1. The engine makes more HP across the entire range than my 29 cc Pioneer. There is no washer under the spark plug & no silicone rubber "O" ring is used to seal the head. A precision machined brass washer makes a perfect seal that is unaffected by any amount of heat. The toroidal head & the engines pipe works best in the 20,000 to 26,000 RPM range.

Jim Allen

Thank you Jim, Thought that cut away was something I had seen before, but could not be sure. Interesting how some if the info that will help us move forward is already in front of us.

Well then, I guess if would be okay to tell you that the engine doesn't use any type of diaphram pumper carburetor. It uses a .725" unrestricted bore, needle controlled air bleed, barrel type carburetor. Tuned pipe pressure of 120 in of water (4.32 psi) pushes the necessary fuel the same way it does in a big bore nitro carburetor. 26,000 RPM means nothing to a system such as this.

Jim Allen

 

[BigChuck]

The pipe pressure I was not aware of.............Thanks. The big bore barrel carbs I was............not to the size how ever, .625 was the largest in the information that I had.. Again thank you for your input.

 

[Glenn Quarles]

Does the use of the turbo plugs with it's smaller "foot print" in the bowl make it easier to design around on the smaller motors?

Glenn

 

[dwilfong]

This tool in a lathe will make the button with a 50% squash in a .21

using a .21 button for size comparison.

David

 

[Marty Davis]

This tool in a lathe will make the button with a 50% squash in a .21

using a .21 button for size comparison.

David

What is the tool size and where did you find it?

 

[Marty Davis]

Jim:

After drawing a few chambers, I can see that it is difficult to get enough volume in the chamber for a .21 engine with the large requirement of the glow plug.

How much have you been able to raise CR with this design head button without getting detonation?

With the EAS and my Cad, I can easily figure out the Trapped CR with various designs, but it is REALLY difficult to get enough volume.

VERY interesting discussion. I had actually drawn a toroidal button for my .67 engine some time ago. Never cut it....

Think outside the Square Marty

Are you working with a flat top piston ?

Greg

Yes, flat top Christy piston.

 

[dwilfong]

This tool in a lathe will make the button with a 50% squash in a .21

using a .21 button for size comparison.

David

What is the tool size and where did you find it?

.120 this is what I use to make all my head buttons. makes a perfect radius cut. There are diffrent sizes.

MSC bottom of page 677. http://www1.mscdirec...31166&PMCTLG=00

 

[bob miller]

Everyone has an opinion and a procedure, this is mine.

On breaking in an engine it basicly comes down to load, heat and plenty of oil. No point in running the engine in without a load. Put a smaller prop on the boat, take off the water line, keep it rich without being slobbering and run it. Let off the throttle for a few seconds to let the engine breath and the internal temps neutralize. Let the extra fuel cool it. Do not even start the engine the first time without preheating the engine. It can be damaged almost instantly. Once the fit is damaged then it is all down hill from there. Add extra oil to the breakin fuel, up to 5% and gradually decrease the amount until the engine is broken in. It can be raced using these conditions. Run it, run it and run it.

It will thank you.

chares , how do you preheat your new motor when you are at the pond ready to run ?.....thanks....bob

Charles

 

[bob miller]

Everyone has an opinion and a procedure, this is mine.

On breaking in an engine it basicly comes down to load, heat and plenty of oil. No point in running the engine in without a load. Put a smaller prop on the boat, take off the water line, keep it rich without being slobbering and run it. Let off the throttle for a few seconds to let the engine breath and the internal temps neutralize. Let the extra fuel cool it. Do not even start the engine the first time without preheating the engine. It can be damaged almost instantly. Once the fit is damaged then it is all down hill from there. Add extra oil to the breakin fuel, up to 5% and gradually decrease the amount until the engine is broken in. It can be raced using these conditions. Run it, run it and run it.

It will thank you.

Charles

charles , how do you heat your new motor when at the pond ready to run ?...thanks.....bob

 

[Martin Hamilton]

On rc car motors its standared procedure to preheat motors during entire break in period,they either use heat guns or they have heater jackets (same principle as tyre warmers but higher temps) that wrap around the case.They heat to around 190-200F before attempting to start & then do a heat cycle on the motors running for around 3 mins then letting the motor cool,making sure the piston is at bdc when motor stops & not at or close to tdc.Once fully cold they go through the procedure time & time again varying & increasing the rpm during stages until the motor is fully broken in.Its also common to replace the rod after break in period.The old way use to be to break in letting the motor sit at tickover for long periods but now they run in at much higher rpm.I know Nova offer pre broke in motors for car use but not sure if thats just on certain models but obviously you had to pay extra for the motor. Martin.

 

[Jim Allen]

Mitch,

You have a message.

Jim Allen

 

[Charles Perdue]

Everyone has an opinion and a procedure, this is mine.

On breaking in an engine it basicly comes down to load, heat and plenty of oil. No point in running the engine in without a load. Put a smaller prop on the boat, take off the water line, keep it rich without being slobbering and run it. Let off the throttle for a few seconds to let the engine breath and the internal temps neutralize. Let the extra fuel cool it. Do not even start the engine the first time without preheating the engine. It can be damaged almost instantly. Once the fit is damaged then it is all down hill from there. Add extra oil to the breakin fuel, up to 5% and gradually decrease the amount until the engine is broken in. It can be raced using these conditions. Run it, run it and run it.

It will thank you.

Charles

charles , how do you heat your new motor when at the pond ready to run ?...thanks.....bob

Hello Bob, I have used a heat gun and propane torch (Yea, I know) but I made a pouch of doubled up fiberglass sleeving with lead shot in it and the ends folded over and fastened leaving enough of the sleeving to make handles. Heat this with a propane torch and then lay it on the top of the engine. Works quick, slick and safe.

I think that I will have to redo the heat pouch by putting the shot inside of a fine weave fiberglass pouch made with like 3oz cloth and stapled together then put this inside of the FG sleeving to help keep the shot in place.

Charles