Discussion on pipes for 100cc class motors

[Cooper 1]

so around 17"...?

[branwell]

Hi Cooper,

For props like the Vess 28B, NX28-10 standard series, Menz 28-10, I found the peak RPM at 16.5 to 17 inches as measured down the centerline of the header, from the header flange to its exit ( where it would connect with the pipe ). This number does not include .25" for the space in the coupler.

That said, I ended up preferring the throttle response and midrange with the header set at 17.25 which is where I flew it most, but at the end, before I moved on testing another system, was thinking about lengthening it another .5 inch to 17.75.

At the R we are talking about, 6500 to 6800 ish static, a 1" header change will move the power band up or down the rpm range approximately 230 rpm.



Branwell

[cjcyclesrc]

If you are testing to get a better understanding of pipes, you should go ahead and try a set of greve's while you are at it. They are shaped quite a bit different than the 1060's. I'm having great results with them. With the stock length headers they seem to like to be loaded in the 6000-6500 range. Transition is great I didn't even have to mess with a throttle curve. I thought they wouldn't make as much power as some of the others, but I'm not so sure about that now. I flew with Lee at the Joe Nall. We have very equal set up 110" Yaks. Mine has the old style DA and Greve pipes. Lee has the DA100L with RE-2's. Both of us were running a Mej. 28x10 and planes weigh close to the same. They were equal pulling out. Neither one of us could tell any difference in power between the two. I was really surprised. I wanted a set of pipes that would work good 3Ding so I went with the greve's thinking they didn't have quite the top end but better in the middle. Now I've come to the conclusion they make awesome top end power in the air also.

[branwell]

Hi Charles,

The Graves certainly are works of art, and given how different their design is, I agree, I'll have to get a set. Guess I wont eat next week.

As to power. From everything I've seen in real life and read online, it looks like many people just bolt their pipes on to whatever headers they happen to get, and as long as they don't run horribly, think they are good to go.

Given the number of airframes, propellers, altitudes, pipes, and headers, the number of optimized systems at the fields must be very very low, and I think this accounts for why the reports on pipes varies so much.

Some people say the 1060s are beautifully progressive, some say they are really peaky.
One fellow said the ES pipes where very peaky and the RE2s not. My experience was the exact opposite, but I optimized the headers for the ES, and not for the RE2s.
Some people say the Graves make no power, some say they do.

There has to be a reason for all the contradicting reports and I'll bet its primarily the header lengths are not optimized.

Thanks for mentioning the Graves.

Branwell

[cjcyclesrc]

	Quote: Originally Posted by branwell
	Hi Charles, The Graves certainly are works of art, and given how different their design is, I agree, I'll have to get a set. Guess I wont eat next week. As to power. From everything I've seen in real life and read online, it looks like many people just bolt their pipes on to whatever headers they happen to get, and as long as they don't run horribly, think they are good to go. Given the number of airframes, propellers, altitudes, pipes, and headers, the number of optimized systems at the fields must be very very low, and I think this accounts for why the reports on pipes varies so much. Some people say the 1060s are beautifully progressive, some say they are really peaky. One fellow said the ES pipes where very peaky and the RE2s not. My experience was the exact opposite, but I optimized the headers for the ES, and not for the RE2s. Some people say the Graves make no power, some say they do. There has to be a reason for all the contradicting reports and I'll bet its primarily the header lengths are not optimized. Thanks for mentioning the Graves. Branwell

That's what I did. Just bolted the pipes on and tried them before I made any adjustments. I would however adjust if i thought it was necessary. My plane is running so good I don't want to mess with it. You can tell with different load props if it's not in the tune range. I've tried a bunch of different props and my pipe set-up seems to top out at about 6600. I tried a Vess 27B and the performance suffered greatly with the lighter load.

Great info though. There are not a lot of good pipe comparisons. I like the fact you are optimizing each set-up. Do you plan to do comparisons in the air? Static results can vary from in the air feel of the system. It would also be cool to see the weights of each optimized set-up. The RE-2's weigh more than the greve's before you have to start lengthening the headers.

[branwell]

This go round, the testing will be limited to:

Finding peak on each prop by adjusting the header length and needles.
Then I fly the plane 3D and IMAC styles and again adjusting the headers to find where the power delivery hits a happy medium between all out power and smoothness of delivery.

The props I have to try are:

NX 28-10 standard
NX 28-12 standard
NX 27-12 standard
NX 27.5 contest.
Mej 28-10
Mej 25-12S 3 blade
Mej 26-12N 3 blade
Menz 28-10
Vess 27A
Vess 28A
Vess 28B

There are a few others I want to try including a 27-10, 2-10 2 blade and 26-10 3 blade Bielas ( spelling ). I am not a fan of 12 pitch props as I haven't found one yet that is slow enough on the downline for me.

I'll then swap out the DA to the BME 116 and run the key tests again to see if the motor has any effect on the pipes characteristics.

Branwell

[Cooper 1]

thanks for the info Branwell time to find some extentions...and tune them pipes

[Rickster]

I have 3W106CS on 12.75" headers and K&S 1060 pipes.. I turn a Mej 28X10 @ 7000rpm on the ground in good air...

Transition is very good now that I have a CH Ignition. It seems the 3W ignition advanced the timing at the same time the pipe resonace came in and really put a jump in the throttle curve..

Rick

[danielph]

When you've flown them both and have your answers, I get the one that you like the least right? ;-)

[branwell]

Hi,

I got 8 flights on the DA100L / 1060 combination today with 11.5 inch headers and a .5 inch gap.

The 1060 has .75 inch more length to half way down its convergent cone than the RE2, so it would be about equivalent to flying the RE2 with a 12.25 inch header.
The 1060 has 3.25 more length than the ES, so to be equivalent, the ES would need to be on 14.75 inch headers.

According to the math ( not the same as reality I'm sure ), with the exhaust timing of the DA, it should put peak tuning at 7550 ish. Given that many props unwind 1100 to 1300 in the air, I though this as good a length as any to start given the rpms we run.

I was at the field to dial in a new airframe so did not focus on the pipes, but I can say with the three props I tried, the Vess 27A, 28A and Mej 26-12N three blade, the 1060's where noticeably less "pipy" than the RE2s on a sister airframe with the Vess 28A. Very progressive ramp up to boost making throttle management in 3D very easy.

While I am looking forward to getting testing underway, looking at all the pipes, headers and props, I'm thinking I need the Eagle Tree system to keep me honest and not get too lost in subjectivity, sooooooo, I don't plan to do much testing until I get one in a few weeks.

On a side note. Weight.
I started flying the 110" Yaks on the 4.5lb BME 116 which is a brute of a motor even before you put pipes on it. The extra 1lb of the DA, and 1lb of the pipes ( wont count the headers as they weight the same as the mufflers ) is very noticeable in 3D. The maneuvers happen faster and take more space. The bottom line is if you are serious about 3D, adding the weight of aluminum pipes needs to be factored in. Even on a 110" airframe, extra weight is tough to hide.

Branwell

[Bat Fastard]

sub...

[wolfejohne]

branwell

Any up date on the testing. I am real intrested in you DL100L testing, I am down to selecting the pipes and headers.

Thanks
John

[branwell]

Hi John,

Unfortunately I did not get the quantity of testing done I had hoped this summer and did not get to run the ES on the DA in the air.

However, I did run the RE2s and KS1060's and ended up sticking with the 1060's.

Once the header length was set ( 11.25 on the 1060s and 12.25 on the RE2s ), there was not much in it.

The 1060s have a little more top end ( 50 ish RPM ) and the RE2s a little crisper feel right off idle.

The midrange was great on both. No burbling and no pogoing in torque rolls with any of the 17 props I tried.

The RE2's have a little bit of a zing sound to them where the KS are just mute. I don't know which is quieter, but prop noise is by far the dominant noise in the air.

With the timing set from the factory, there was some evidence of knocking ( sounds like rocks in the pipes ) with regular gas. Reducing the timing solves it, but hurts the midrange and top end.
Running hitest with the timing as it is from the factory givens the best mid and top end.

With both sets of pipes, the engine runs a pretty consistent 170 degrees as measured upon landing ( not the most accurate ) and when I took the heads off to inspect last week, there was no signs of heat related color on the piston skirts and no hard carbon.

On props, I ended up running the PT 28-10 as it's the quietest of the props I tried that still pulls well. The motor turns it 6650 on average hot.

Branwell

[Bam Bam]

I learnt alot from your testing branwell and are now using the RE2's on my yak with the DA.
I am wrapped with the performance and extra power of the pipes over the cans i had.
Also i am no longer using a throttle curve mix as it's perfect now without it.
Best thing i ever did! also it may sound funny, but even though i can feel alot more power with the pipes, the engine runs slighlty cooler now! Dont ask how, but it does!

[drewbags]

	Quote: Originally Posted by Bam Bam
	I learnt alot from your testing branwell and are now using the RE2's on my yak with the DA. I am wrapped with the performance and extra power of the pipes over the cans i had. Also i am no longer using a throttle curve mix as it's perfect now without it. Best thing i ever did! also it may sound funny, but even though i can feel alot more power with the pipes, the engine runs slighlty cooler now! Dont ask how, but it does!

Are you using the RE2s on your EF YAK? If so what prop and header length have you found that works best? I am toying with the ide of putting them on my YAK so interested in any feedback.