OS 9B with Bellmouth Airhorn

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RaceMechaniX

RaceMechaniX

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Apr 27, 2007
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So I noticed OS came out with a trick airhorn for the heli motors and bought one to see if it would fit a OS 9B. Turns out it is roughly 1mm too large on the throat. The OS has a 17.5mm OD neck while the airhorn is 18.5mm ID. I machined a tube with the correct dimensions from some Delrin stock and make a simple piece to fill the gap. So now the 9B looks serious and will flow a little more air. The part number from Tower hobbies is: http://www3.towerhob...p?&I=LXBYZC&P=Z . The Throat lines up perfectly. Pretty easy to do to make your reliable OS9B flow closer to one of Charlie's Zoom Carbs.
gallery_4990_1585_383111.jpg


View before the airhorn was pressed on:

gallery_4990_1585_133077.jpg


View down the throat:
gallery_4990_1585_792719.jpg
 
Very nice idea Tyler. I've got a CMB90 with an OS9b and might try this myself.

DId you already try it out and did you notice any difference?
 
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Paul, I just machined this last night so no tests yet. I expect it will function identically as a 9B would will a little more flow at top end. For a 67 motor there will likely be unnoticeable gains, but on an 80 or larger 90 I expect top end to improve.
 
Ding Ding Ding, we have a winner. Yes, lower operating costs and huge tax incentives plus a 500,000sqft facility. Alex Borla of Borla Exhausts purchased TWM Induction several years ago and moved the equipment and the employees who wanted to move out to Johnson City, TN. Borla still has a R&D shop in CA. Johnson City is quite nice, just much quieter compared to CA. TG
 
Steve Seebold said:
RaceMechaniX said:
Steve, I used to have a very nicely equipped machine shop in Goleta where I worked before the equipment moved to TN. Most of the induction kits on the site I designed. http://www.borlaindu...me/Home-FR.html
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Why on earth would anyone want to move from CA to TN.
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Steve, some of us just want more out of life than California can offer. You have an open invitation to visit me sometimes in Tennessee. It may not change your mind, but I am sure that you will enjoy your visit. Charlie
 
So, before I forget, does the O.S. 9B bolt directly onto a brand-new CMB .67HR or .80HR?

I have two new CMB .80HR engines, are the stock carb's okay? How are most folks running their engines (or carbs)? trying to find out what is best solution (being that their are no more Orlic or Zoom carbs available).

Also, what is I.D. of stock .67/.80HR carb?

Appreciate your input
 
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