MTW RE 3 Tuned Pipes - What's the story.

[SleepyC]

A REPORT BY:
Reza Gholamipour



Dear Flying Giant members,

I recently had the opportunity to test MTW’s newest product - the RE3 tuned pipe - on my DA85, and compare it with a Greeve pipe. I would like to share with you my findings through 3 videos that I have made.

I would also like to say that I am very impressed with performance of RE3 pipe. Not only did the test find that the RE3 produces 300 more rpm on average than the Greeve pipe, but also has a very good mid range feel.

I found the sound of RE3 to be different than my Greeve and deeper in idle. Although this is more of personal preference since no DB meter was available, I like the RE3 sound much better.

The RE3 is a little shorter but larger in diameter (by 10mm) than the Greeve, but has a thicker wall that promises a longer lasting product when used in less than perfect conditions such as higher vibration applications.

I test flew my RE3 in my QQ-Yak 101 and could not believe the extra power and speed that I gained! I used full length MTW header and left 0.5” gap between the header and pipe at the coupler. I had tried shorter header lengths but didn’t have much success as engine would get really hot and mid range suffered! I will continue testing on longer header that MTW is making later but I truly believe the answer is right here with what I have!

Prop Mejzlik 26x10
Greeve 6700 RPM
RE3 7078 RPM

Prop Mejzlik 26x12
Greeve 6400 RPM
RE3 6700 RPM (Speed of the plane was probably close to 100 mph with this set up)

I test flew the plane, not to show flying skills, but just to show the slow and high speed capabilities of this set up. So forgive me if the flying is not too thrilling. I was able to torque roll and tail slide from 30-40 feet to the ground and do everything I would with a standard muffler. Please note the speed in rolling loops as the plane ascending and also how fast plane launches from hover and maintains speed until out of sight! I used no throttle curve, there was a little jump in 5000 rpm range on the ground but didn’t feel bad in the air at all. MTW RE3 seems to be consistent in RPM increase even when I changed the prop!

I also flew the Greeve set up with a DA85 in the QQ-Yak 101 and prefer the increased power and speed of the RE3! Mid range felt very close, but the edge definitely goes to the RE3.

Please let me know if you have any questions and also what you think about the videos and tests. I have made a conscious effort to be as objective as possible on these tests, and spent many hours to get everything to this point.

Quique also would like to share with you his experience with the RE3 and RE2 pipes. He is the first to fly these in the States I believe. Below are his words:

“In July*2008 I was contacted by owner of MTW and was asked if I would be interested in testing their new pipes for DA85/170. It took me like...... 0.03 seconds to say sure I would be interested as I love this kind of work. Few days after our conversation I got a set for the DA170 and a set for the DA85. I first set up my Yak54 120" with DA170 and from first run I could see a big future. After flying and working on header length I concluded the RE3 MTW pipe is the way to go! Later I installed one in my Python with DA85 and it was same great performance. After all the DA85 and* DA170 excitement it was time to put 4 of the RE2 in my* TI-12 with DA200 and boy how sweet that was!!.*

As you can see in*Reza's Video flying our 101 Yak54 with RE3, the engine runs clean with incredible power.

The pipe has a deep sound especially at idle and it is built very strong which I also think it will offer a longer life. Thank you, Quique Somenzini”

Here are the videos I made!

Video 1 showing Greeve and RE3 comparison and RPM reading on the ground:
http://www.rcmodelaviator.com/Videos/RE3vsGreeveV1.wmv

Video 2 showing flight performance of MTW RE3 with Mejzlik 26x10:
http://www.rcmodelaviator.com/Videos/RE3V26x10.wmv

Video 3 showing flight performance of RE3 and Mejzlik 26x12:
http://www.rcmodelaviator.com/Videos/RE3V26x12.wmv

Best Regards,
Reza Gholamipour

[SleepyC]

Pics.

[Unbalanced]

Nice report. Thanks for sharing.

[Reza]

Thanks Sleepy

Here's a little more that I would like to share for those interested.

I would like to talk about tuned pipes in general. Main purpose of tuned pipe is to increase your top end RPM to provide you with extra power for better performance of your valuable airplane!

I do not consider myself an expert in tuned pipe design, but I would like to share with you how a tuned pipe works, and what they do to boost our top end power.

In general the power potential of a 2-cycle engine depends largely on its combustion and exhaust cycle; the more efficiently fuel is burned and the faster the exhaust gases can be scavenged, the more power an engine will produce. A tuned pipe does that by converting exhaust energy into a sound wave and then into more sound waves that produce pressure. When a tuned pipe is properly matched to a 2-cycle engine, there's an oscillation in the pipe between negative and positive sound waves. The low-pressure, negative (vacuum) sound wave arrives at the exhaust port as it begins to open and helps to scavenge (pull out) exhaust gases. The high-pressure, positive waves arrive at the exhaust port as the piston begins to close off the port, and this action pushes spilled, unburned fuel back into the cylinder just before the combustion cycle begins. As mentioned, the spilled fuel is inherent to the 2-cycle design: The exhaust window and transfer ports (intake) are open for a fraction of a second at the same time during each cycle. Thus installing a properly matched pipe dramatically increases the efficiency and overall power of a 2-cycle engine by utilizing these sound waves for maximum efficiency and power.

So in simple terms, as I don’t want to make this a boring article, the faster gases exit and the more efficiently the engine burns the fuel, the more power will be produced. A good tuned pipe will push back some of the unburned fuel into the cylinder and will increase the efficiency.

The key to all this is the port timing of the engine and correctly tuning the pipe length for optimum (desired) performance.

Tuned pipe mid range may not always be the best but can be improved through trying different pipe lengths. But at the end of the day you need to make sure that your tuned pipe does its number one thing: That is increasing the power of your gas engine!


Now I would like to talk about what factors are involved other than the tuned pipe. I am sure you have read that some people are complaining about their tuned pipe performance where some others have no problem using the same tuned pipe and engine! Why is that? Well, weight of the plane for one and the desired RPM missing the optimum range of that tuned pipe combination!

Let’s say you have a relatively light airplane that will hover at 4000 rpm with a particular prop/engine/pipe combination. Your tuned pipe provides the useable rpm in that range with no issues, but has a non-linear jump in RPM from say 5000-6000. Guess what? If another plane is heavier it will require a greater RPM in hover to support the additional weight. And in that RPM range that he is missing, the pilot will have a harder time hovering because now he needs to modulate the throttle faster in the range of 4000 and 6000 to make up for the loss in mid range power. Or the length of the header will need to be readjusted to gain the range of RPM needed, and perhaps sacrifice the top end a little.

There is a limit to all you can do with a tuned pipe: You can’t shorten the header distance too much because you would not only loose RPM in the midrange further more but also you can potentially destroy the engine by making it run way too hot! As hot exhaust gases are being ‘trapped’ by the header/pipe and not scavenged from the engine.

[Reza]

I also would like to Thank my good friend Jim Brown for helping me in the installation of this pipe! I am moving to a new place and I could not do any work in my very small shop, Jim is always there to help out if he can.

Thanks Jim!

[WOODisGOOD]

http://www.bukupower.com/animateCorrect.html

[Reza]

Here are the videos I made but these FG links

Video 1 showing Greeve and RE3 comparison and RPM reading on the ground:
http://www.flyinggiants.com/gallery/...hp?photo=54716

Video 2 showing flight performance of MTW RE3 with Mejzlik 26x10:
http://www.flyinggiants.com/gallery/...hp?photo=54717

Video 3 showing flight performance of RE3 and Mejzlik 26x12:

http://www.flyinggiants.com/gallery/showphoto.php?...
Right click here to save the video

[twostroke]

Reza, what, if any, is the weight difference per pipe?

Thanks!

[Reza]

Less than 2oz per pipe! It has a thicker wall but it's shorter so its not bad at all! What I noticed my CG didn't seem to change from muffler! At least my trim didn't change! You're welcome!

	Quote: Originally Posted by twostroke
	Reza, what, if any, is the weight difference per pipe? Thanks!

[Carlos Vargas]

really nice report, thanks Reza, i am running my 170 with Greeves, i think is time to feel something new

[Reza]

You are welcome Carlos and Thank you for kinds comments.
I have plans to do the same testing with DA170, hopefully I'll be able to do that as well.

	Quote: Originally Posted by Carlos Vargas
	really nice report, thanks Reza, i am running my 170 with Greeves, i think is time to feel something new

[flynz4me]

Holy cripes Batman that is some pullout!!!

[amoss]

Just watched the videos, and I'm very impressed! Thanks Reza for taking the time to do these tests and sharing them with the rest of us. Based on what I saw, I may using this setup in my 101.

[Rush7]

I run the RE2 pipe on my DA 50. I have ES Composite pipes on my DA 100. I like the sound of my RE2 a lot better than the ES pipes. Just personal preference.

That was some insane pull out power.

[Reza]

Rush7, I agree with you. Sound of MTW tuned pipes are different, a little deeper in low end, more pleasant to ear at least mine