new gas pipes under construction

[Samuel Hagan JR]

I see a really cool looking pipe, what I don't see is a price.

After you spent several posts running me down, there's still something I haven't seen anywhere.
"PRICE"

Atleast this guy has something to show. All you are is mouth. Get your b/s out of here.

 

[Steve Seebold]

Steve,

I don't know if you are referring to me, but I haven't spent any of my valuable time in "running you down". I have to much work for nonsense such as this & I already stated clearly, "THAT NOTHING SHOWN IS FOR SALE"!!

Jim Allen

Sorry, I hadn't seen that.

 

[Jim Allen]

The new tuned pipe with a shortened header (.7500" shorter), 4 stages in the diffuser, a 2.500" major diameter, an 11* baffle, a .4062" ID X 6.000" long stinger & the HE19-A carburetor (19 mm; .7480" bore) look very strong on my dyno. The engine used is a 26 cc stroked to 27 cc rear exhaust QD. Don't ask about numbers as this will only start an agrument about what number is correct!

Jim Allen

 

[Jim Allen]

Tuned pipe programs are improving all the time. Take a look at this solid works program. It can be used for any shape chamber & it eliminates kenetic energy robbing longer length straight sections which are found in model engine pipes; except small size curvy pipes.

Jim Allen

www.youtube.com/watch?v=vcSQCDP48E8

 

[Terry Keeley]

Tuned pipe programs are improving all the time. Take a look at this solid works program. It can be used for any shape chamber & it eliminates kenetic energy robbing longer length straight sections which are found in model engine pipes; except small size curvy pipes.

Jim Allen

www.youtube.com/watch?v=vcSQCDP48E8

Cool!

 

[stan simpson iv]

Jim I have a serious question about pipes. The pipes you are making now have very sharp, and defined flat sections in all parts of the pipe and are pcs of art. Now some of your own older pipes I have seen and some pipes made today by other manufactures are what I call Speed pipes. They have a more round shape,some small in dia,some bigger in mid section's. Why are you making such a Radical change in your designs. Also what is the major difference that YOU see or think is better between the two. Im not into the Dyno stats...I want testing on the water. To me dyno is just another tool in the box for testing,lots of variables to take into account on the test stand. When the boat hits the H2O...all the theories are tested. The bs stops there. The water has ALWAYS BEEN the lie detector. Not slamming or downing any tests you have and are doing. What is better with your newer design?

 

[Jim Allen]

Stan,

"Curvy pipes" or tuned pipes without any straight sections in the exhaust header, diffuser, mid-section or baffle section have been used for many years on smaller displacement (.45 cu in) model racing engines because they are easy to machine on typical CNC type equipment. The improvement in how these type tuned pipes perform over straight section design pipes can be easily seen on the dyno, bench tests, at the lake & at FAI pylon racing speed events. I also believe tuned pipe manufacturers for our hobby are not interested in building the type of chambers found on some European type gas touring race cars such as those made by Samba. This is probably due to the fact that no one particular design would suffice & the market share is to small to warrent the necessary investment in equipment.

I have been building & testing machined & rolled type tuned pipes since the 1980's. As with any engineering sicence, time advances the technology. I havent attempted to make any machined large size "curvy tuned pipes" because of the difficulty that arises with boring deep bores. I have boring bares that can bore to depths greater than 12". However they cannot be used for smaller size holes. I also have the necessary CNC equipment available to do this type of work.

There is no doubt about the fact that no one size or type of tuned pipe can satisfy all the different engine sizes & types of running conditions possible with a model boat. At present I'm concentrating on pipe designs for oval racing, gas type engines, that displace 26 cc to 35 cc. Engine displacement dictates the displacement of the tuned pipe being used, regardless of the type of runing. The length & taper angles of the various sections, as well as what is done in the header section (still straight on every boat pipe sold) will make a siginificant difference in what HP increase can be attained.

Jim Allen

 

[Jim Allen]

Have any of the tuned pipe builders looked at what happens when there is no straight section in the header section or at the beginning of the tuned pipe's diffuser section? Also, what happens when the header itself is shortened before the first tapered sections of the tuned pipe & there is no straight section?

 

[Terry Keeley]

Nova Rossi makes (or did make) a header pipe that was tapered, it seems to work...

 

[Jim Allen]

Terry,

I'll be sending a print of the latest tuned pipe to Lohring Miller for analysis with his two stroke engine program. He has done this before on the pipe that is presently used on the oval rigger with surprising valid results.

Jim

 

[Terry Keeley]

Terry,

I'll be sending a print of the latest tuned pipe to Lohring Miller for analysis with his two stroke engine program. He has done this before on the pipe that is presently used on the oval rigger with surprising valid results.

Jim

Lohring's a sharp guy, I'm "harvesting" some of his dyno knowledge, lol.

 

[LohringMiller]

Thanks. You and others are doing a lot to keep the tradition of actually building things alive. Computers have helped a lot, but there's no substitute for putting tools to metal and seeing what you made perform.

Lohring Miller

 

[Jim Allen]

The two tuned pipes shown in the photo are similar, but they are used on different hull types. The chamber painted black is used on a rigger & the un-painted chamber is used on a cat. Both are used for oval racing. Their major diameters are the same, but the tuned length of the unpainted chamber is longer. This longer tuned length is because of the smaller included angle of the baffle cone used on the un-painted chamber. Also the unpainted chamber has no straight flex section & a much shorter flanged header section. Both chambers have a total internal volume that is approximately 24 to 28 times the displacement of the engine. A very important fact that allows the use of a long, small ID stinger for the maximum boost amount possible!

Jim Allen

 

[Jim Allen]

Some more two stroke tuned pipe building ideas.

http://l3s9113.zeus09.de/RD350/Auspuffbau_V2_englisch.pdf

JA

 

[Terry Keeley]

The two tuned pipes shown in the photo are similar, but they are used on different hull types. The chamber painted black is used on a rigger & the un-painted chamber is used on a cat. Both are used for oval racing. Their major diameters are the same, but the tuned length of the unpainted chamber is longer. This longer tuned length is because of the smaller included angle of the baffle cone used on the un-painted chamber. Also the unpainted chamber has no straight flex section & a much shorter flanged header section. Both chambers have a total internal volume that is approximately 24 times the displacement of the engine. A very important fact that allows the use of a long, small ID stinger for the maximum boost amount possible!

Jim Allen

Some good info there, thanks!

 

[Jim Allen]

All properly working tuned pipes will benefit greatly from having their fuel systems pressurized from the the normal pressure ( approximately 4 psi or 120 inches of water at WOT) contained in the tuned pipe chamber. This is the reason that a longer, smaller ID, stinger is desirable, but only possible if the chamber in question is of sufficient volume (approximately 24 to 28 times the engine's displacement). This applies to any type of carburetor, with or without a fuel pumping diaphragm. With this feature the fuel tank must be rigid & there is no chance of setting the boat on fire with a pressure line coming from the pipe directly to the rigid fuel tank. The rise & fall of the measured pressure varies directly with the engine's RPM's. Since the tuned pipes operating temperature is approximately 450* F at the pipe's mid section, a neoprene rubber line is used at the pressure nipple.

Jim Allen

 

[Jim Allen]

The machined adaptor in the photo allows a standard CC racing pipe to be directly connected to a QD header. Both the QD header (1* 44') & the adaptor (2* 16') are tapered inside. This gives four tapered sections in the diffuser section of this pipe with no flat section anywhere. The two pipes pictured are used on 25 to 27 CC engines operating in the 19,500 to 22,500 RPM range.

Jim Allen

 

[Jim Allen]

More work has been done on developing a suitable tuned pipe for 35 CC Zenoah engines. Because of the very poor design of the exhaust area between the exhaust window in the cylinder & the final round shape of the water cooled header, only larger size headers can be used effectively; typically 1.000" ID or possibly larger. Any header used, straight or curved, should have a tapered ID! The photos show the difference between the first pipe (black coating) that was tested & what is being tested presently (stainless steel). Both tuned pipes have adjustable length & adjustable ID stingers as well as adjustable tuned lengths. Small changes in the ID of any stinger will greatly affect the engines operating temperature at WOT. The same is true for the length of the stinger, except the effect is much less. Both pipes are being tested without tuned pipe fuel system pressure. Tuned pipe fuel system pressure will be added at a later date to improve the mid range throttle response.

Jim Allen

 

[Jim Allen]

delete

 

[Jim Allen]

The new tuned pipe's stinger was purposely designed to have a .562" OD. This allows the use of the clamp on muffler shown & gives the ability to easily reduce the stingers ID's in .031" steps down from .531", to .500", to .469", to .438" with K & S telescoping tubings. Stinger lengths will also be decreased as the ID's are reduced in .400" steps starting at 6.9" for the .531" ID down to 5.7" for the .438" ID. This method is used to determine the maximum length & smallest ID of the stinger being used. We also use a Trail Tech TTO Temperature Meter Gauge Sensor 742-ET1 for a 10 mm spark plug to monitor the engine's operating temperature.

Jim Allen