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Engine basics => Engine set up tips => Topic started by: Balsa Butcher on November 04, 2010, 06:12:43 PM

Title: OS 20 FP Venturi ID
Post by: Balsa Butcher on November 04, 2010, 06:12:43 PM

Does anyone know the inner diameter of a stock OS-20FP venturi? I have not been able to come up with a number using the search function of this forum. I know they are still available thru Tower but wanted to check and see if I have one of equal diameter in my parts locker. I'm converting an R/C 20 FP to C/L per Brett specs.  8)

Title: Re: OS 20 FP Venturi ID
Post by: Kim Mortimore on November 04, 2010, 08:56:24 PM

Pete,
Brett's article on Heman's website says .259.  My mic says .256.
http://www.aeromaniacs.com/brett.htm

Would it be nosy to ask what plane you're putting it in?

Title: Re: OS 20 FP Venturi ID
Post by: Clint Ormosen on November 04, 2010, 08:57:24 PM

I have some of those venturi NIP if you want one.

Title: Re: OS 20 FP Venturi ID
Post by: Balsa Butcher on November 04, 2010, 10:28:44 PM

Thanks for that Kim, I didn't realize Heman had that posted there...great site! Plane, probably a trainer, we have been getting some new folks interested in the sport up here and I thought it would be nice to have a plane for them to try. Clint, I'll take you up on that offer. Put one aside for me, I'll give you a call 'bout delivery.  8)

Title: Re: OS 20 FP Venturi ID
Post by: Geoff Goodworth on November 05, 2010, 04:19:33 AM

Pete, I think they have varied over the years, but those that I have boiught from Tower over recent years measure 6.55mm dia or .258".

Title: Re: OS 20 FP Venturi ID
Post by: Balsa Butcher on November 05, 2010, 08:58:02 AM

Thanks all, the only ones I have on hand are larger, for FP-40's and the like.  8)

Title: Re: OS 20 FP Venturi ID
Post by: Kim Mortimore on November 05, 2010, 10:18:19 AM

The 20 venturi is being used by some in the LA46 when they have oodles of power and want a steady 4-stroke. It really sucks.  

Title: Re: OS 20 FP Venturi ID
Post by: Geoff Goodworth on November 05, 2010, 09:08:30 PM

Pete, depending on your intended use, further to Kim's comment, several people in Oz are having great success with the small venturi that used to come with the FP 35 and FP 40 on the LA 46.

There was an article in Stunt News some years ago by somebody who was enjoying success with FP 40s using the FP 20–25 venturi.

When Kim says 'It really sucks', I hope he means that there is a lot of suction and not the way the kids of today would be thinking when they say that.

I suspect that the FP 20—25 venturi is a little small for the 46 but a good candidate for slight opening up if you do not have any others to use.

Title: Re: OS 20 FP Venturi ID
Post by: Balsa Butcher on November 05, 2010, 10:58:35 PM

Geoff, G'day: The last one I had I installed in an FP-35. Tamed the run-away, still lots of power in a solid 4 stroke so I do agree with what you blokes in Oz have been doing. Unfortunately I do not have that engine here.

and Clint...I broke down and ordered a few .20 Venturi's from Tower but thanks for the offer, I'd hold onto the ones you have, they sound like a pretty versatile part.  8)