RCU Forums - View Single Post - Throttlability of 1/2A Cox (and Norvel too) engines
Old 01-15-2005, 08:52 PM
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meowy84
 
Join Date: Oct 2004
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Default Throttlability of 1/2A Cox (and Norvel too) engines

Ok, ok, I know this subject has been beat to death already in other posts but i STILL have more questions and comments so I thought I'd throw them out there for the guru's. As some may know I'm 'researching info' on building some carbed/exhaust throttled Cox engines (both reedie and TD) in the single configuration and also in the flat twin configuration and eventually if all looks good to culminate in a Cox 5 cylinder radial. My ramblings may be disjointed so bare with me.

Here's what I learned and what I still wanna know. As a few of you have commented, building a r/c carbed Cox reedie (or TD) is not as simple as it may sound (especially compared to the larger engines). Some mentioned that a combination of throttling methods might give better results so I have decided to give the engine (Cox reedie ot TD) as many advantages as possible and use a combination of an r/c carb (one from an AERO/AME .049 engine that I just happen to have) and an exhaust throttle. Also, for best results Wink mentioned that the reed valve should be as close as posible to the end of the crank to essentially minimize the crankcase volume, thereby allowing better inflow of fuel charge when the reed valve finally opens.

Anyways, while I'm trying to concentrate on Cox engines at this point I also have a NIB Norvel .061 Revlite r/c engine and a NIB Norvel Cmax .061 engine with the muffler rod-throttle setup. I haven't ran either of these engines as of yet but was wondering if those who've ran either of the Norvels could fill me in on the general idle rpm of these engines? What do these engines idle at? I recall 7,000 rpm being thrown around as the idle of a lot of the 1/2A engines. Is it possible to reduce this any further (to the level of .10-.15 r/c engines which I assume idle at around 4,000 rpm or so?)? Again, someone suggested that I use the r/c Revlite with the t-shaped throttled muffler from the Cmax to further reduce the idle rpm and improve the response throughout the rpm range. This leads me to another question. How does the idle rpm of the r/c Revlite compare to the idle rpm of an exhaust throttled Cox .049 reedie or Cox TD? I realize that these (Norvel and reedie Cox) are two different engine designs but let's assume all other things being equal and comapre just the lowest reliable idle rpm figures.

Also, what about the progression and responsiveness? With 1/2A engines should I expect better throttling qualities with an r/c carb (as in the Norvel or others of course like AP, etc.) or with an exhaust throttle ring type of device?

To summarize my main questions then: (1)idle rpm of Cox engines? (2)idle rpm of Norvels? (3)responsiveness with carb vs. responsiveness with exhaust throttle?