new gas pipes under construction

[Jim Allen]

I continue to receive encouraging reports about the development of a suitable tuned pipe for 30 to 35 cc engines. Basic numbers for the initial development of such a chamber are proving themselves to be correct, making the direction of future changes much clearer. If a 20 + lb mono in oval trim can reach 65.6 mph at 20,100 rpm with the engine operating temperature below 200* F, I think it is safe to say we are headed in the right direction. There are still many changes & tests to be done in the future! Something new to be looked at is a mid-section that does not have straight sides????

Jim Allen

 

[Rudy Formanek]

Have you moved to silver solder(45%) from welding??

 

[Jim Allen]

Rudy,

All of my development type tuned pipes have silver soldered joints because this makes it very easy to disassemble & reassemble joints when making changes. Chambers with welded joints are difficult to cut at the welded joint! My chambers have .018" to .020" thick walls & interlocking joints. They are smoother inside & their joints are as strong as any welded tuned pipe! Photos should be posted left to right but are reversed.

Jim Allen

 

[Terry Keeley]

Holy smokes Jim, you hog those all out?

What material are you using?

Ever try a sharper converging cone? Something closer to 20* as Jennings mentions on pg. 62?

http://www.amrca.com/tech/tuners.pdf

 

[Jim Allen]

Terry,

Many of the pipes tapered sections are machined from thick walled A513- Type 5 Carbon Steel DOM (drawn over mandrel) tubings. Some tapered sections are rolled from .016" thick cold rolled sheet. Other straight sided sections are machined from thin walled (.040" thick) steel tubings. I have tested many different converging cone angles from a 20* to 26* included angle, as well as converging cones with two angles. A converging cone angle of 26* included angle will have a narrow but high power band. A converging cone angle of 22* included angle will have a wider but lower power band. Jennings book never talks about the necessary volume the pipe must have in relation to the engines displacement before anything begins to work properly. Also there is no mention of what takes place when the angle is increased or decreased. I wonder why?

Jim Allen

 

[Terry Keeley]

Whew! At least you're starting with tube.

Jennings says basically what you just said about different baffle cones on that pg. 62., I have found the same. I look for pipes that have sharp baffle cones, they add mph! Irwin's pipes all had sharp baffles.

 

[LohringMiller]

I've always had a hard time making rolled sheet pipes accurately enough in our small sizes. A comparison between a billet pipe and a rolled sheet version showed significant power loss. Below is a test of a billet pipe, a Need for Speed pipe and a fabricated version of the billet pipe on a stock Zenoah. The billet pipe is pictured. It has a variable position baffle cone we used in another series of test to look at changes in header length versus tuned length.

Lohring Miller

 

[Jim Allen]

Rolling tapered cones on a roller with straight rollers requires some practice. There are rollers with tapered rollers, but they are very expensive! The accuracy of the finished piece always depends on how accurate the flat sheet metal piece is. .016" to .020" material works the best. I spot weld rolled pieces to prevent any movement when silver soldering the linear joint. One thing to consider is the fact that the OD of the rollers determines the smallest ID that can be rolled. A taper attachment for a lathe saves much time when cutting longer tapered pieces.

Jim Allen

 

[Jim Allen]

I use a computer program to accurately determine the exact shape of each section to be rolled. Heavy paper is used before cutting any metal to insure the pieces will fit together. An extra .050" of material is added where necessary to provide a good silver solder joint. Notice how any tapered section needs to be twisted as it is being rolled. This technique takes some practice.

Jim Allen

 

[Jim Allen]

It's interesting to see the performance differences that are possible when small changes are made to similar type tuned pipes, which are being used on the same 26 & 27 cc size rear exhaust engines. The three pipes shown have different power curves, different peak HP amounts, different peak HP band widths & different over-rev characteristics. I believe all shown could be applied to oval type racing.

Jim Allen

 

[Rudy Formanek]

Did you run these on a dyno?? or on the water??

 

[Jim Allen]

Did you run these on a dyno?? or on the water??

Rudy,

I run everything on the dyno & then on the water. Sometimes the effect of small changes on things such as taper angle, section length, inside diameter, tuned pipe volume, stinger ID & length, header ID & angle & major diameter cannot not be seen on the water.

JA

 

[johnnyadams]

Are these available yet. Are they 7/8 or 1

 

[Bradley Ward]

There unobtainium

 

[Jim Allen]

Are these available yet. Are they 7/8 or 1

Definite progress is being made on a suitable tuned pipe for 32 to 35 cc engines. These chambers should be ready for sale in October or November of 2018, through Performance Unlimited. We have found that a 7/8" header causes high heat problems at WOT. This happens even when the chamber has an adequate volume, an adequate stinger ID & length, an adequate cooling system & a tapered header. Therefore, only a 1.000" header will be used on the 32 to35 cc size engines. The 7/8" header is still used on the 26 to 28 cc engines without any WOT high heat problems.

Jim Allen

 

[Jim Allen]

Did you run these on a dyno?? or on the water??

Rudy,

We presently have a functioning chamber that will be tested further on the water. The Performance Unlimited 35 cc engine has the necessary timing numbers, raised compression & tuned pipe design to move the peak HP point from 18,500 to 20,100. Doing this allows the same 20 lb Delta Force mono, with the same 7016 3 blade 395 propeller to increase its speed to 65 MPH. The boats speed, engine RPM & engine temperature at WOT are being measured real time. Further testing will be done in an attempt to raise the peak HP, at the same RPM number, but keep the engines operating temperature at WOT below 200* F. This will be attempted with a small reduction in the pipes total volume from 1010 cc to 952 cc.

Jim Allen

 

[Jim Allen]

This information comes from Les Smith of Performance Unlimited. It speaks about the progress of the 32 cc to 35 cc Pipe R&D work. This tuned pipe's design follows from the research developed over the last year.

"The R&D design and the testing of our new Stainless Steel Pipe is finally being finished....below is a synopsis of the R&D testing ...

The final results are more than impressive to say the least. Ray's 20 lb 53'' Delta Force Annihilator Mono started out with a top speed of 51 mph with a modified 30.5 cc engine using a QD Hot Pipe. He upgraded the displacement to a 35 cc engine and tried the following pipes from QD, Insane and Zipp Kits with no better performance than the 30.5 cc using a QD Hot Pipe, the JB pipe gave a little improvement over the others and all running in the 17k-18,600 rpms, however...the Pro-Modified 35 cc engine was producing the same power as the 30.5 cc, since the same prop was turning the same rpm as the 30.5 cc and the 35 cc was also showing a lot of increasing engine heat from the CHT sensor readings were going above 205° and then the performance of the engine was sluggish and the top end power dropped off.

We went through 7 different designs of the pipe as well as several different shapes, angles to mention a few and the performance of the 35 cc engine came alive and we kept testing in the direction of the performance increases and the CHT temps were monitored closely to insure no melt down will occur at WOT for an extended period of time that was way beyond any heat racing or marathon running time frame. The air temps in the 3 digits and altitude changes from sea level to Las Vegas did not hinder the performance gains with the new pipe.

Rays heavy mono now has a speed of 65.6 turning a prop with more pitch and rpms around 20k-21,400 with no over-heating and plenty of bottom end to more the heavy hull.

This pipe is not a spin off of a QD Pipe, Zipp Kits Pipe, Insane Pipe or a modified pipe from those on ebay as some have done to sell pipes by modifying them and claim this is the pipe for the 32-35 cc or to claim their pipe works on this size of engine.

In the R/C hobby most pipes will work across several different engine displacements, however only a pipe that is specifically designed for the engine and its displacement will work even better.

There are several guys that have been there when Ray first started the testing and have witnessed the performance improvements during the R&D testing and have visually seen the results of the pipes performance even during NAMBA District 9 races.

We are pursuing to have this 4 stage pipe stamped out of Stainless Steel and we decided on this method, since the inside of the pipe is smoother than a bunch of welded stages and the angles are radius to the other areas along the pipes length, so the pipe will have the welds similar to a QD Hot Pipe and have the flared diffuser that you can see without the welded stages and of course be lighter in weight too.

The 32-35 cc Pipe uses a 1" header

All clamps are Stainless Steel

Muffler on our pipe has an integral stinger

Weight of the pipe with stinger & muffler is 17 ozs

JB Pipe is 18.8 ozs and QD is 15.4 ozs

Below are photos of the visual differences between the tuned length and / or the pipes shape and length of the QD, JB and our pipe.

Top Pipe is Our Stainless Steel Pipe, Middle Pipe is a JB Pipe and the Bottom Pipe is a QD Hot Pipe."

 

[TomGracey]

Nice looking pipes

 

[Les Smith]

Fellow boaters.....It has been a long R&D testing journey and the pipes are in the final stages of the process of being welded up & post finishing.

Hopefully will have everything ready after the new year.

Below are the current pipes and the first WTC Pipe for the 35 cc and Kevin Maliner will be Testing this one in the spring of 2019 with his 35 cc engine and the other pipe is the standard  pipe that will also be available.

The pipes will have the option of an integral Stinger / Muffler that is 3x quieter than any available muffler without any performance loss.

These pipes require a 1" header and water-cooled flange

Pipes will come with the Heavy Duty T-Bolt Clamps that are Stainless Steel and not the zinc plated ones that others offer and sell.