Just got my header and I was wondering if it was ok to shorten the length?

the lenght determines the power band

HMMM. Maybe somebody with experience with the DA 50 can chime in and tell me what length seems to work best for 3D performance?

EDIT: KS Cannister.

12"

Laying a string along the header so you measure the length taking in all the curves it should be no shorter than 11"

Thank you.
Now the big question. Last night I trimmed the header. I just measured it and it's 10". The white nylon coupling I ordered is 6" long. Can I use the coupling to get back to 12" or would you guys recommend I buy a new header?
It would appear that the stock header length is just right. LOL

the powerband is gong to be aburt with a shorter header its your call in how u want to spend you $$$

Aburt?

Seems that the design of the plane will not llow for 11" of header. At 10" the exit is right at the front of the LG. 12" header would put me right on the back edge of the LG. I could use the white coupling to move it back 1" but that would give me 13" from the motors exhaust to the front of the cnnister. I guess that adding 1" would have the same effect as losing 1"?

I went through this on my DA-50. I'm running a KS86 (I believe) canister and the standard exhaust header. My problem involves a power band issue where it will jump from about 4,500 to 5,500 rather abruptly. After talking with DA, TBM, and making posts here and other places, here's what I've learned:

1. The shorter the header, the narrower the band (bigger spike in power) for a given size prop.
2. A bigger prop needs a longer pipe. A smaller prop can use a shorter pipe.
3. The stock DA pipe is 10.25" as measured along the curves on the centerline. This is the only header DA offers (from what I understand).
4. I am using a 23 x 8 prop. Using a 22 x 8 may solve my power band problem.
5. You shouldn't use the silicon union to extend the length of the header. It will burn through. If you want to lengthen the header, get a small section of pipe and two silicon unions.
6. My problem may be a rich low end. My cylinder head temp as measured after a flight while idling is 145*F MAX! I need to go leaner on the low end needle most likely. I should be hitting 180* or 190*.
6. The big caveat for me in all this is that adjustments on a fresh motor are tenuous. I only have 4 gallons through my DA. It's probably not ready for fine tuning. When I lean out the needles, my power band problem might go away.

I fly a 50cc Aeroworks 260 weighing in over 16 pounds. Vertical is no problem. The only 3D problem is that spike in the power band. I'm using a 23 x 8 Zoar prop.

Any update? I just bought a DL-50, DA header and MTW 75K canister, did your spike go away or did you work on the header length?

You should contact DL direct and ask them... as I have been told by DL users that the engines are totally different

As soon as DL has 9000 engines delivered to customers more info will come in regarding their performance with a cannister or pipe. Frankly the stock setup works so well most users won't go to the hassle of a longer system. It is quite loud though.

Basically, the exhaust port has the same dimensions as the DA (and a few other engines, btw). A 50cc engine "tuned" to swing a certain size prop in a certain RPM range and possessing a certain diameter header will ALWAYS require a certain length pipe.

Most of the "improvement" in power seen using a cannister arises because a cannister typically flows much better than the side-dump or pitts style muffler it replaced. Most of the cannisters don't give much of a "tuning" effect (although some do). In fact a sharp tuning peak is not desired because it makes the throttle more difficult to manage. We desire a nice, broad power curve without any peakiness.

Soarrich, you probably need to follow the experience of others who use a cannister on a 50cc engine and use the same header length. If your pipe tunnel isn't long enough it may be worth modifying to give you the exhaust length you desire. This should require only minor surgery on the airframe.

exeter_acres

Totally different, the DL doesn't shine, and being cast it's probably about half as strong.[X(]

BTerry

I'm 75% interested in a quiter motor, I hate loud anything, 25% interested in smoother powerband.

I was just looking at my installation, no tunnel, it looks like I may need an extra 2inches in headerpipe length, I assume that'll give me quiter exhaust with more grunt in mid-range?