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Engine basics => Engine set up tips => Topic started by: Larry Renger on October 13, 2017, 07:41:53 AM

Title: OS FP15 Venturi
Post by: Larry Renger on October 13, 2017, 07:41:53 AM

I need to make a Venturi for an OS 15 FP. what is the stock diameter of the bore?

Thanks  H^^

Title: Re: OS FP15 Venturi
Post by: RandySmith on October 13, 2017, 10:14:36 AM

Quote from: Larry Renger on October 13, 2017, 07:41:53 AM

I need to make a Venturi for an OS 15 FP. what is the stock diameter of the bore?

Thanks  H^^

I have brand new ones at my shop, I will pull the boxes this afternoon or eve, and  post the size

Randy

Title: Re: OS FP15 Venturi
Post by: Dane Martin on October 13, 2017, 11:47:32 AM

Not to topic drift, however; Randy do you know if that will also fit the OS max III 15? I can post a pic or measurement. Thanks!

Title: Re: OS FP15 Venturi
Post by: Fredvon4 on October 13, 2017, 12:01:53 PM

Can't find it...but recently I saw a reference to ALL common OS base carb (case opening) sizes... some 6 mm, some 7 mm, and a lot 10 mm

On the couple of home made, wide open combat venturies I did for the ASP 25, I just miked the base of the included Carb and made it a very tight oversize fit on my drill press

Title: Re: OS FP15 Venturi
Post by: kenneth cook on October 13, 2017, 02:03:20 PM

              Larry, the throat size is .236". The spraybar for the LA/FP .15 is not the same as the .20-.46 spraybar assembly. It will fit but it will also take up more volume. The stock FP .15 spraybar is turned down. If your using the nozzle that comes with the remote assembly, this should be irrelevant. I have opened the throat to .250 for clown racing and it still worked fine on suction. Ken

Title: Re: OS FP15 Venturi
Post by: Larry Renger on October 14, 2017, 09:03:41 AM

Thanks to all of you!  H^^

Title: Re: OS FP15 Venturi
Post by: Brett Buck on October 14, 2017, 11:49:08 AM

Quote from: kenneth cook on October 13, 2017, 02:03:20 PM

              Larry, the throat size is .236". The spraybar for the LA/FP .15 is not the same as the .20-.46 spraybar assembly. It will fit but it will also take up more volume. The stock FP .15 spraybar is turned down. If your using the nozzle that comes with the remote assembly, this should be irrelevant. I have opened the throat to .250 for clown racing and it still worked fine on suction. Ken

  I would not recommend that for stunt!  As you found it works fine for level flight at high RPM, but for stunt, the stock venturi is absolutely as large as you would ever try to run and only then when you let it run to at least moderate-high revs by stunt standards.

   The very first engine in the "small engine" experiments was the 20FP, but what kicked it all off was a bone-stock 15FP in a (regular S1) Ringmaster, which David and I marvelled at when some gentleman brought it out to fly with us in Napa.

     Brett