[goneflyin]

Ready to fire up now.
200 with lightened cyl's, should be a bunch smoother (and a lot quieter) than the 170 on pipes. And 2 lbs heavier.
Still needs baffling- haven't got that figured out yet.
Don

[Cougar429]

It looks so much like the installation on a real plane I would suggest doing the baffling in a similar manner. Most standard installations duct the air to the top of the cylinders with a dam at the rear and outside edges, (fit tightly to the underside of the upper cowl) to direct the air downwards and out the aft lower edge of the cowl.

Since yours is a radial style cowl that may be a bit difficult, but not impossible. Good luck.

[TBrum]

Looks great Donny!!

You'll be blown away by the difference in the mid-range of the quads!!

There are a lot of great posts on FG of ducting that hangs off the firewall and wraps around the quad cylinders for one-peice cowls (I'm in the same boat as you for my 58% Pitts / 3W220!!) I'll see if I can locate the posts and will post them here for you!

Cheers

Trev

[goneflyin]

Thanks for the replies guys,
Trev, you're part to blame for this you know.
I was thinking of making it out of thin aluminum, but lite ply would likely be more suitable. The cowl is really wide so it's going to be a huge baffle.
Trev, did you have to play with the sync (throttle sync) of the two carbs on your 4 bangers?
Thanks
Don

[scaleguy]

Don,

That's sweet but that Yak really NEEDS a 3 blade to make it look right!

next thing you know we are going to be looking for old VW Beattles to steel there 1300cc engines for our 99% Extras and Yaks!

[TBrum]

Originally Posted by goneflyin

Thanks for the replies guys,
Trev, you're part to blame for this you know.
I was thinking of making it out of thin aluminum, but lite ply would likely be more suitable. The cowl is really wide so it's going to be a huge baffle.
Trev, did you have to play with the sync (throttle sync) of the two carbs on your 4 bangers?
Thanks
Don

LOL... I feel bad that I influenced you!!

There's a few on FG that basically build a rectangle over top of the quad cylinders that hangs off the front of the fuse and butts up against a big flat baffle that seals off the front of the round cowl. I believe they have made them out of thin aluminum also with a carbon fiber round plate to seal off the front.

For synching the carbs, for set-up I now run (2) separate fuel tanks on the quads - each tank is completely separate from the other and each tank feeds a carburator. After you go out and fly, check the tank levels when you land to tell you which carb is richer/leaner than the other.

After a bit of tweaking, you'll be able to get nearly exact fuel consumption between the two carbs.

From my testing, I found that no two Walbaro carbs are the same - I guess it's just manufacturing tolerances!

That being said, I know Wingburner and I set up his DA200 on one tank and I believe he's still running it in the same configuration with 0 issues... like yourself, he can set-up an engine and had no issues with carb synch at all (perhaps he can comment!)

Cheers

Trev

[bigguy]

Don,

Looks sweet.

For baffeling ideas. Here is a picture of a 200 on another round cowl Yak.

[goneflyin]

That's sweet but that Yak really NEEDS a 3 blade to make it look right!

Thanks Jim, yep there's a 3 blade at home to try. It's just that the 30-12 is a good break in prop.

Trev, very good ideas there, interesting with the two tanks. It's currently got only a single tank. I wondered if you've been tuning by cyl temp or plug burn. I use a manometer set and airflow meters to tune multi-carb car engines here at work, but it's all a bit big for the aircraft motor.

Also thanks Ralph for the photos. However it really sucks to have to cover up all that pretty bling with a wooden crate!

Don

[wingburner]

Sweet engine..The 200 is the only engine of DA's that I have liked. It's actually quite powerful and very smooth..

As far as tuning I have been doing mine by ear only...As was mentioned factory setting mean nothing...Both carbs on my engine are set leaner on Lo and High needles.

Trevor and I have been discussing baffling somewhat..We both believe that his Mintor and my DA are running too cool (mine does not have the milled cylinders)..The air temps where I live are seldom over 80..

I recently sent my 200 back because the gaskets on both carbs were leaking. While in there it had a crankshaft upgrade and they said the engien looked great...But I noticed it could still be leaner and I believe it's running to cold.

You'll love it...So far the Mej. 31/12L EVO..30/13L EVO..29/12/3..MSC 32/10..are my favorites..All around the Mej. 31/12L is my favorite for my style of flying...It's whisper quiet with the right prop...Enjoy it!!!

[goneflyin]

Thanks Jack.
good notes in there...
I also have a 30-13L that was awesome on the 170. The Mej's are pretty hard to beat.
Apparently the milled 200 is a bit harder to keep cool, or more accurately stated is less forgiving of imperfect cooling setups.
Hope the extra 2 lbs on this airplane won't be too noticeable. I don't 3D this airplane so what the heck.
Don