Header Question
 

Hi guys, I an a newbe to gas engins so I thought I would ask the experts being you guys a header question. I have a Areoworks 50 cc Yak 54 with a DL 50cc engine. I know its not a DesertAircraft but this was a gift from a friend. I purchased a K&S 1060 tuned pipe and a DA header 25mm drop with flex. The length is 8.5" . Some good old boys at the field say I need to use the 11" header. After doing some measurments I found that a 11" header is way to long for the Yak using the tuned pipe as far as fitting everything in the exhaust channel of the Yak. The 8.5" fits everything just about perfect with a little over a 1 1/2" to play with. I like to get you guys input on this. I know I am completly lost on this. Thanks

RE: Header Question
 

You made the comment, " I know its not a Desert Aircraft..." who cares?????? It's funny to hear about DA50's like they are some holy creation....yeah, whatever-you have a fine motor there friend so don't fall victim to a name brand, besides, we all know how your engine performs anyhow:D and I need not say anything else.

RE: Header Question
 

Great response flygilmore, but alas, not an answer to the question at hand.

to get back on topic:. What is more important, to tune the pipe to the engine, or to fit it in avaiable space. If you want to fit the contraption into available space, it is no use to ask about the consequences. You will find out about that soon enough.
If you want to do your engine a favour, use the 11" header length, and adapt your airplane to fit the items that your engine needs to operate to it's full potential. There are no if's and but's. Just do as you choose, and accept the results.

RE: Header Question
 

Thanks guys for the input. Like you say try and see if you like it.

RE: Header Question
 

I doubt your engine will like it with that short of a header, never run that engine, but I know what happens when you go to short on a pipe set up. As Pe mentioned, you will find out.

RE: Header Question
 

You won't like the results of running it on that short pipe.

Cut the airframe apart and extend the tunnel to fit the pipe in with the 11" header and tune it the proper way.

Don't take this the wrong way....... if you don't know that a tuned pipe must be "tuned" then you probably want to stay away from them or start doing some reading in this forum. A tuned pipe is NOT "bolt-on" power. It has to be tuned. That means checking RPM and then selecting the right prop and RPM range. Then adjusting and tuning the header/pipe system to perform best. Using a header that is too short will lead to a burned up engine if you run it too long. Thats no joke. You are taking a very severe risk running that engine with a pipe thats too short. It effects the pressure waves and sound waves inside the pipe. It won't be tuned right.

Sincerely dude.... do some reading or get the longer header. Or you could just forget the tuned pipe and just slap a pitts muffler on it. Just don't run it like that with the 8" pipe. You'll probably damage the engine.

RE: Header Question
 

Thanks again guys, I will give this a lot of consideration. I will take all the help I can get.

RE: Header Question
 

As an afterthought, tuned pipes have a second torque hump at 3/4 of top torque rpm that may save the day. So if we suppose the pipe/header is in tune for 10,000 rpm, there will be a second operation range at 7500 rpm, albeit at lower power output, more in line with canister output.

RE: Header Question
 

Just to clear up confusion (on my end) ... how is the header length determined? Do I measure the length of the tube (including the bend radius) or the straight distance from the exhaust port flange to the end of the tube? Thanks

RE: Header Question
 

for calculations, it is the distance from the piston face to the start of the tuned pipe first cone.
For discussions like this, we talk about the header only, without any parts of engine or muffler.