DA + MTW Pipe tuning

[jaguar bone]

I have a new DA50 with a MTW tuned pipe on an EF YAK.
I have never used a tuned pipe before. The K&S header length has not been shortened - and all is installed as STOCK.
I will be using Lawnboy at the recommended ratio with Xoar 23 x 8.

MY QUESTION:
How will I know if the tuned pipe requires 'tuning' ? What will the symptom(s) be?
I have not started the engine yet - wanted to this weekend but, if I need to make a length adjustment, I think it is best done before I heat the coupler up!?

I'd call DA today but - closed on Sat!
Would it be okay and run it for the first time knowing I may have to make a length adjustment later?
Come to think of it, should I have used a silicone coupler in lieu of the Teflon that is normally used (and that DA sold me) - or does that even matter?

Okay- Let me come clean on this - I choose the Tuned pipe ONLY because DA was out of the K&S canisters at the time. Tuned pipe alternative was considerably more money, but my building schedule dictated that I GO for IT!
_________________

This is my second DA but I used a K&S canister on the other set up and is working like a champ.

[cyco]

youll find the right lenght by trying. a 23x8 should nearly run 7000, i think.
purpose, to be sure not getting to hot, measure the engine temp.

i would decrease the header lenght in very small steps, measuring temp and RPM and go flying - then you directly see if you have a perfect throttle transition.

thats the easiest way to find out.

another way is to measure the reference pressure with water -but thats very complicated...

ehm, a silicone coupler doesnt hold, Teflon is right. but usally the pipe is hold with silicone tubes at the end and at the beginning where the header is coupled (behind where the clamps are), too.

Regards, Chris

[jaguar bone]

	Quote: Originally Posted by cyco
	youll find the right lenght by trying. a 23x8 should nearly run 7000, i think. purpose, to be sure not getting to hot, measure the engine temp. i would decrease the header lenght in very small steps, measuring temp and RPM and go flying - then you directly see if you have a perfect throttle transition. thats the easiest way to find out. another way is to measure the reference pressure with water -but thats very complicated... ehm, a silicone coupler doesnt hold, Teflon is right. but usally the pipe is hold with silicone tubes at the end and at the beginning where the header is coupled (behind where the clamps are), too. Regards, Chris

Thanks cyco!
I'll call DA tomorrow too - maybe I will get lucky and they can tell me a targeted starting length range.
I take it when you say very small steps, you would mean 1/8" increments or so?

[Bill_Higgins]

The best length is anywhere between 10.5 and 12 inches (measuring through the bends). Anything shorter than 10.5 and the midrange runs the risk of becoming "peaky".

Bill Higgins
Desert Aircraft

[jaguar bone]

	Quote: Originally Posted by Bill_Higgins
	The best length is anywhere between 10.5 and 12 inches (measuring through the bends). Anything shorter than 10.5 and the midrange runs the risk of becoming "peaky". Bill Higgins Desert Aircraft

I trust " measuring through the bends" don't measure along ht e bends and all - go c/l of head to pipe connection?Thank you!!

[Flyinrazrback]

Take a piece of string, cut it to 12" and run it from the flange down the middle of the pipe around the bend and mark where it ends. He says 10.5-12" for the length, so the 12" length would be best for larger props like the 23x8 and a little less rpms and the 10.5" for more rpms with a 22x8" or such.

[jaguar bone]

	Quote: Originally Posted by Flyinrazrback
	Take a piece of string, cut it to 12" and run it from the flange down the middle of the pipe around the bend and mark where it ends. He says 10.5-12" for the length, so the 12" length would be best for larger props like the 23x8 and a little less rpms and the 10.5" for more rpms with a 22x8" or such.

Whew! Gosh am I thick or something? Thanks FRB
Got it - measure the entire lineal distance from start of pipe to end - as if straightened out.
Just did a quickie and its close to 10.5" !! Hurray! I maiden Thanksgiving weekend - if I can stay away from the field Friday!

[Flyinrazrback]

Try a 22x8 as well, with the header that short it may not like the larger load 23x8 Xoar. Try a Vess

[jaguar bone]

Well as it is said - the devil is in the details - and I uncovered a few nasties with the test run today. (what a brilliant idea to do this before driving 1.5 hrs one way to the perfect "maiden" field; just for a lost flying day!)

These issues will need to be fixed and addressed before the YAK makes the "leap".
The potentially worse on the list is two holes in the recycled header that I supposedly had braised closed.
The job did not hold up. (a friend at the field does this stuff in his job).

I may end up using a through bolt and lock-nutting it down. Not sure if this is a serious no-no with a tuned pipe or not? (man don't you just love being in control and ignorant all in the same responsibility?!) Any comments or concerns?? Will a#8 bolt obstruct the tuned pipe effect at all?

One of the wing bolt holes needs moved a tad - and I may change the way the wing is bolted down.
My fueler is VERY close to being positioned below c/l of the tank! It almost syphons out when you take the fuel filler nozzle off. I never even thought of that potential muck-up! I have one idea for reducing the syphoning 'condition'-but if that doesn't work- I will have to live with it ; unless I get an idea on one of the message boards I post on! I'm surprised I have never read of this problem happening to anyone else before. Surly it can happen VERY easily! Maybe I'm the rare type that will actually TELL on ma-self?
With the 3W the fill tube is closed off when you screw the cap back in place. The cap has a rubber pad that seats against the copper tube in the unit. Now I can't have fuel flowing out into the cavity of the fueler unit and on the fuse till I get the cap screwed in place!

Hope you all had a great Thanksgiving!
Oh - The DA- sputtered on fourth flip with choke on- and started right up on fifth flip- just as predicted and promised in the manual. Ran like a 1st CLASS CHAMP!! I love DA's product!