To all of y'all thanks again, L Renger and B Buck the 10-22 worked like the champ that it is, 2 O Z went about 5-6 minutes again
With due respect to Larry's experience, it doesn't need a heat sink, it is fine the way it is.
Note that we all should have learned something about this. It would have been easy to conclude that the fuel draw was inadequate, and it needed a smaller venturi. A smaller venturi would likely make it work with the original fuel, or conversely, it works with a larger venturi if the fuel viscosity is lower. Meaning, with *absolutely no other changes*, you could Get More Power by using a larger venturi (more air) and lower-viscosity fuel (more volatile contents) to get the same mixture.
Note also that an alternate solution would be to make the spraybar passages larger, so that enough of the thick fuel would still flow through it with the available suction, which would entail no loss of power compared to the "smaller venturi".
A third takeaway is that this also explains, to a certain extent, *why it goes lean when you load the engine (slowing it down)*. With a fixed venturi and a fixed fuel metering drag, slowing down the engine reduces the flow of air and thus the fuel suction, but the reduced fuel suction has more effect on the mixture, because the *
fuel flow goes down faster than the air flow*. Reduced fuel line drag, from either lower viscosity or making the passages larger, reduces this effect, and tends to make the engine
less prone to mixture changes as the load changes.
In case it is not obvious, what happens to a Fox 35 when you do a corner? The load on the prop increases, slows it down, and it goes lean momentarily. It's also part of why it runs differently and reacts differently when you run Fox Superfuel (29% straight castor), 29% 50/50, and 22%. It's not just the different cooling and lubrication effects, it's also a mixture change - despite the fact that the supply pressure actually goes up as you start the corner. This is, I think, about half the entire 4-2 break effect (the fast part).
As an example, this is why everyone concluded that the Evo 36 venturi was "way too big". The directions said to use Cool Power, which has something like 12% synthetic oil. Everybody "knew better" and ran GMA or something similar. Guess what, it won't draw thick fuel properly. In addition, you can get it to work on GMA with a smaller venturi - which cuts the power drastically since you are now pumping less air.
This is what David and I had found about fuel viscosity and fuel line drag over the past 10-12 years. You can greatly effect how the engine runs in the corners, and during maneuvering, by altering the fuel viscosity or fuel line drag. For smaller conventional stunt engines, it's a minor effect, but for very large engines with a huge air flow for a given fuel line/spraybar passage size, it can become a significant effect - no matter how many "engine experts" might think otherwise. Lowering the viscosity of the fuel, and/or running larger fuel tubing and larger spraybar bores, can have a *marked effect* on the way the engine runs in maneuvers.
Brett
Topic: Medallion wont start (Read 2096 times)
