OS.25VF exaust timing - I wish I knew it...

LAST EDITED ON Dec-02-03 AT 09:13 AM (CST)
 
As a newcomer in the pipe world and living at Rio de Janeiro I'm having

to figure it all on my own (with the help of the Stuka Stunt gang only).

At first it seemes pretty simple. but the more I work on it the more I

see it ain't that simple.

Does anyone know for sure thes exaust timing of the .25 VF?

Another question: Summer is here,and tempteratures will be around 100/

110 degress Farenheit. Shoud I raise the nitro contents to 12 or 15%?

Len seems to advocate higher nitro as the weather gets hotter.

Scott, do tou remember the ID of that venturi you made for Jerry Eichten?

Also, I ain't sure if my pipe is a Wergage or a Carbonmaster.

It has only (seems to me) one baflle. Does that chart Len posted ad Stuka Stunt Works apply for any brand of pipe?

I don't intend to put my plane in the air untill, as Brad says, I've "eliminated all the variables" I can.

TIA, and

God bless ya all!

In Jesus,

Ion

Len, please no jokes this time...

ION E-MAIL ME at [email protected]

Scott Riese

.
>
>It has only (seems to me) one baflle. Does that chart Len
>posted ad Stuka Stunt Works apply for any brand of pipe?
>
>I don't intend to put my plane in the air untill, as Bras
>says, I've "eliminated ass the variables" I can.
>
>TIA, and
>
>God bless ya all!
>
>In Jesus,
>
>Ion
>
>Len, please no jokes this time...
>
>

I do not know the timing on your particular engine, but the chart will apply to any brand of pipe. Measure to the first baffle, or, if there is no baffle, to the back end of the pipe. The speed of sound still remains the same no matter what pipe you are using, and that is what we are working with here.

You can determine the exhaust timing on your own engine:
Buy a cheap plastic 360deg protractor around 4-5" in diameter at your local office supply store.
Drill a 1/4" hole in the centre and mount it on your engine crankshaft, followed by prop to hold it in place.
Make up a pointer from 1/32" wire ond bolt it to one of the engine lugs. Locate the point of the wire next to the degree index marks on your protractor.
Place a length of fine cotton in the exhaust port of your engine and bring the piston up until it catches the cotton in the port.
Zero the pointer against the 0 deg mark on your protractor and tighten the prop nut to lock it all together.
Check again to see that you have a true zero when the piston is up against the cotton thread.
Now turn the prop back to pass the piston through Bottom Dead Centre and bring it up the other side until the thread is caught once more.
Read the degree mark at the pointer. It should be in the 135-145 range. Check it a couple of times until you have it right.
Add say 2 deg to the reading to allow for the thickness of the thread.
This then is the exhaust duration of your particular engine.
cheers