RunRyder - Tuned Pipe on Gassers any feedback?

rrTV-PHOTO

New HD TV

HOME rrTV-PHOTO GALLERIES MY GALLERY HELP-FAQ

myHOME PM pmRR MEMBERS 294 ONLINE 38 EVENTS SEARCH REGISTER START HERE

13 pages [ << < 9 10 ( 11 ) 12 13 NEXT >> ]

7356 views

POST REPLY

ZoomsHobbies	.	HeliHobby	.	Ron’s HeliProz South
	.		.

Gasser Model RC Helicopters > Tuned Pipe on Gassers any feedback?

Fixit
Key Veteran
Location: UK

Well you certainly amazed me that’s for sure, how you can remember, understand and write all that is beyond me, I’ve read it three times and I’m still trying to take it in.

07-17-2008 07:18 PM

HOMEPAGE

j.8
Senior Heliman
Location: Denmark

Hi

You can see a small animation of it here
http://en.wikipedia.org/wiki/Two_stroke

Regards Bo

07-17-2008 08:43 PM

AceBird
Elite Veteran
Location: Utica, NY USA

The animation is perfect because it shows how the fuel air mix excapes out the exhaust and then gets pushed back into the cylinder before the exhaust port closes.

Bottom line is you are super tuning the engine to run under a very narrow power band. If you vary the load conditions (like you do with a heli) the tuning goes all to hell.

Ace
What could be more fun?

07-17-2008 09:43 PM

Fixit
Key Veteran
Location: UK

Thanks for that j.8
What’s the reason for the unburnt fuel going down the header and then back into the chamber, is it just for more volume or is it to preheat the fuel?

07-17-2008 09:47 PM

HOMEPAGE

Fixit
Key Veteran
Location: UK

You just answered my question before I asked it

07-17-2008 09:48 PM

HOMEPAGE

C.A.P.
Senior Heliman
Location: custer park IL.

It's when I hear someone say that a 2 cycle is a simple motor I always ask how does it work???. That little clip shows it, But doesn't explain why ,Together, I think its right. It's just a mind stopper when you think how fast these thing run. There is a thing called notching the pistons or pulse porting that made the 250 run all day at 14,000 rpm, Yamaha use this on there TDB-1 250cc RACE MOTOR. TUNED PIPES WERE CALLED EXPANSION CHAMBERS. (The pipe reduce the amount of exhaust from leaveing the cylinder, buiding up compression in the upper cylinder & lower crank case). When I raced for them in the 60s. I had the first rocket bike made. we put the motor on a twin jet 100 frame. which was was a little taller and a little longer then a 20" bike but with shocks. the Rice Burner in the Trunk, Everyone called it. Use to put in the trunk of my car on the weekends and go street raceing H_D & anything else, and never lost in Chicago southside. Until I hit a car when a dum girl went through a green light, but that's another story. 12 second 1/4 mile was very fast back then, for anything that ran on the street. Just a little of my history. Wally

07-18-2008 02:05 AM

j.8
Senior Heliman
Location: Denmark

Hi Fixit
"What’s the reason for the unburnt fuel going down the header and then back into the chamber, is it just for more volume or is it to preheat the fuel?"

More volume/higher compression.

Hi C.A.P

Well I have once been so crasy and said thet a 2 stroke engien
is simpel, well that`s only in relation to the 4 stroke, witch
have more moving parts, so it`s mecanical simpel

I copyed this from a old Vario catalog

Regards Bo

07-18-2008 11:44 AM

C.A.P.
Senior Heliman
Location: custer park IL.

The picture is what you are looking at instead of reading the print, The color of the SPENT EXHAUST should have been changed to red. (NOT GREEN), The ports are angled to redriect the new fuel mix to carb side of the combustion chamber helping push the spent fuel out. But does not do it completly. When using a stock zenoah muffler this does not happen very much so you will see very little to no carbon build up in your exhaust port. When using any other muffler that reduces noise. You are causing back presure and building up heat. Which causes the spent fuel to burn even hotter turning it into carbon. and the engine to run hotter also. So the picture shows a expansion pipe where the exhaust expands in the larger chamber then hit the restiction end of the pipe. (where the exhaust tail pipe is smaller then the intake manifold pipe). Building up presure and pushing back into the combustion chamber. (THIS IS SPENT FUEL) causing more compression in the upper cyinder and lower case with a tuned pipe (expansion chamber) pushing in more fuel air mix in the combustion chamber. THERE WILL MUCH MORE OF THIS. Then when using a stock Zenoah muffler. As there is nothing in the muffler to slow down the exhaust from leaving. If you look at the airplane motor against the heli. You will see a deferent muffler one with two tail pipes (air) and one with one tail pipe(heli), Because the air will not be subjected to the same power needs as a heli. There is two tail pipes and less back presure and less hp made. EVEN THOUGH THE MOTORS ARE THE SAME. Because heli's need more hp to maintain proper head speed. There is only one tail pipe building up more back presure making more hp. Only after you realy read up on the motor. and work on them for a long while do thing start to fall into place. Learning any subjust is a discipline. You never fully under stand until you do it for a while. But understanding the basics of this motor will help you keep the the only thing, and I mean the ONLY THING that will slowly and sometimes very fast kill this motor. IT IS HEAT. Knowing what causes heat. And knowing what your engine temps will make your engine run stronger longer. These engine will run almost forever (HOT TO A POINT)and not tuned correctly. But running them WITH A GOOD COOLING SYSTEM AND TUNED CORRECTLY, Is what a Pro does. AND THATS ON ANY TYPE OF ENGINE MADE. and what everyone should do. and will give much more reponses and hp without a lot of over building. WALLY

07-18-2008 02:31 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Quote
What’s the reason for the unburnt fuel going down the header and then back into the chamber, is it just for more volume or is it to preheat the fuel?

With a two stroke there is a point where both the exhause and intake ports are open at the same time. This will always happen with a two stroke and that is why they waste fuel when compared to a 4 stroke.

Ace
What could be more fun?

07-18-2008 05:48 PM

TooBizzy
Senior Heliman
Location: Georgetown, Ohio USA

They don't really waiste fuel compared to a 4 stroke. You usually get way more HP out of a 2 stroke compaired to the same displacement 4 stroke. Plus it fires every stroke, not every other stroke.

To answer the question:

Quote
What’s the reason for the unburnt fuel going down the header and then back into the chamber, is it just for more volume or is it to preheat the fuel?

When the intake port opens and forces fuel/air into the cylinder, at the same time you get this back feed of pressure from the header. These two gases are forced into the cylinder at the same time to get more volume/pressure. Kind of like the long post explains, its like super charging the motor.

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

07-18-2008 06:46 PM

C.A.P.
Senior Heliman
Location: custer park IL.

ACE I understand why you are making that statement!! But a 2 cycle does not waste fuel it is the best fuel burning engine out there WHEN RUNNING COOL. if you read further in that clip. The new fuel mix does not leave the cylinder, just If the engine exhaust port timing is correct. The spent fuel may come back in a little. I mean very very LITTLE. (This cause a ruff idle with a tuned pipe,increasing you idle will help). With a lot if back presure. This is the pulse you feel when put your finger over the exhaust port manifold and hand turn the engine. A build up of presure then a feel of a vacuum because of a fast release of presure. It's a small pulse, imagine how small that pulse gets at 12,000 rpm. A human would never be able to feel it. Also the pulse for the carb created by the up and down movement of the bottom of the piston. This is not the same pulse. That pulse is created by vacuum and compression. And that also become just as tiny. The pulse on the exhaust side is made by compression only and fast release of compression through the tail pipe. Gives the feel of a vacuum. That what I mean the engine is not simple to understand. The piston movement is doing so much more then just move up and down and pasting over ports. The placement of the ports is the most important thing in the design of the motor for the use you are going to put it to, If you want power on the high end or low end , the design of the piston as where the piston pin is closer to the exhaust from center of the piston will give more torque on top end. the closer to the intake from center will give more torque on the low end. it just what rpms the motor was made to run at, and where the torque is needed. Just like a pistons in a car and in diesels. If you have un spent fuel entering the exhaust port or valve chamber in 4 cycle you will have a back fire. Because the fuel that is not spent will fire because of the great heat and compression there. This what will happen on a 2 cycle to some extent. I'll explain what piston porting timing does after I take a nap. (a beer or both) By the way I have mention piston port timing to a number of people to see what there reaction was. And the only one that understood what it does and wants to try it is Billme, And is the only one that seem to under stand what real happens, when you turn those needles with a cool motor. Bill does not have have his head up you know what. EVEN THOUGH HE IS SO MUCH MUCH MUCH MUCH OLDER THEN ME. He CAN HEAR!!! listen, learn, evaluate and test to a standard, as a true engineer. (that I have talked too) (by 3 years and thats older at our age. )

07-18-2008 08:19 PM

C.A.P.
Senior Heliman
Location: custer park IL.

TOOBUZZY you are as close as you can get. The spent fuel enters the exhaust manifold. The part between the end of the cylinder and where the exhaust pipe starts. that where the two gases meet. And the presure starts to builds there. As the spent fuel would hamper the new fuel mix from firing right. LATER WALLY

07-18-2008 08:22 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Quote
ACE I understand why you are making that statement!! But a 2 cycle does not waste fuel it is the best fuel burning engine out there WHEN RUNNING COOL. if you read further in that clip. The new fuel mix does not leave the cylinder, just If the engine exhaust port timing is correct.

That happens under absolutely perfect conditions and that rarely occurs for long especially in a helicopter doing gyrating 3D maneuvers.

Many people have a rough time tweaking the needles without a pipe. For most people flying helies I would suggest you forget it.

Ace
What could be more fun?

07-18-2008 09:51 PM

C.A.P.
Senior Heliman
Location: custer park IL.

Tuning a cooler motor with top head fin at 175degs and lower, You will find it very easy ACE. The cooler you can keep it. The easier it's to tune.And stay tuned. Try a new fan, with money back if you don't like it. And you will understand like Billme. Other wise we will be talking in circles over and over. And you thoughs will be on facts not guesses. you have learned a discipline, in the machining you know the only way to know something is to do it your self. Wally

07-18-2008 10:57 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Quote
you know the only way to know something is to do it your self. Wally

Amen to that

Ace
What could be more fun?

07-19-2008 02:08 PM

gorn
Elite Veteran
Location: Western Australia

well, right when I was about to take my pipe off for good, Shiro comes through with some advice.
I was very sceptical that what he suggested would make much if any difference.
But what the hell, I'll try one last thing.
He suggested using 2 Zenoah exhaust spacers at the header/motor.
I was using only 1.
We have the same gear ratio, muffler/header,engine.
Only differences were he runs a higher oil content and the extra spacer.
I was tearing my hair out with needle settings, as nothing at all seemed to work consistently.
So I found a car exhaust spacer which is twice the thickness of the stock one, but had cooling fins on it

So an hour with Dr Dremel and we have a new shiny spacer.
Normally if I can see more than a wisp of smoke from the pipe, it will just burble unhappily and not make any real power, and eventually settle down on the ground lol. Very frustrating.
This time I left it rich, fair bit of smoke, and up she goes.
Im waiting for it to lose power or something! lol
5 mins passes with a kicking tail and some vibes in the vertical fin, she smoothes out, less smoke (ahhhh that will be the header bolts loosening lol). I land at 10 mins, kill throttle immediately.
Plug showed what I thought, not overly lean, but not ideal either.
Snug the header bolts up for the last time, and Im done.
I still cannot believe that it made that much difference.
Its been raining a lot so I havent been able to test again, and frankly Im expecting the thing to be a pig again.
Just because with this new header its always been that way.
I tell you what Shiro.....if this is the end of my hassles.....I'll do a little dance around in celebration of your advice

Yes I have a wacky sense of humour too

You need it in this hobby.
Cheers

If you bling it, they will come :D

07-24-2008 05:32 PM

Dr. Fibinotchi
Key Veteran
Location: Sioux Falls SD

hmm

Gorn,

glad to hear. Thats a good idea to add volume. Are you still having problems with the bolts coming loose?

-Cody

All that a man achieves and all that he fails to achieve is the direct result of his own thoughts

07-24-2008 05:40 PM

gorn
Elite Veteran
Location: Western Australia

Hi Cody
Thanks...
The bolts never came loose with this pipe, except for 1st flights.
Just snug em down while hot, then forget em.
Not like the bloody Hatori!

If you bling it, they will come :D

07-24-2008 05:48 PM

gorn
Elite Veteran
Location: Western Australia

The only bolts that were coming loose with this combo, were the clamps holding the pipe to the boom and the rubber coupler clamps.
All fixed now

If you bling it, they will come :D

07-24-2008 06:07 PM

Shiro Muji
Senior Heliman
Location: Japan

Gorn: the rubber coupler that was included in the pipe was no good. I replaced it with a steam hose with braided steel inside see the pictures. never over tigthen the pipe side for it may be deformed. I use a made in germany clamp used by cars, it seldom comes loose.

Maxum with Hanson 3D Max, Maxum Nitro, Maxum 30.5cc modified engine, RH Generator, Sceadu .50Hyper

07-25-2008 01:08 AM

13 pages [ << < 9 10 ( 11 ) 12 13 NEXT >> ]

7356 views

POST REPLY

Century Helicopter	.	MTA Hobbies	.	Model Rectifier Corp
	.		.

Gasser Model RC Helicopters > Tuned Pipe on Gassers any feedback?

UPDATE SCREEN PRINT TOPIC

Advertisers

Subscribe to This Topic