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Cantard
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Discussion Starter · #1 ·
We was discusing engine load versus rich/lean. Interested in info and solutions...under load rich, less load but still wot = lean.
 

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Cantard
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Discussion Starter · #3 ·
Ive torched a piston from nothing more than a gear change. And it happened in a heart beat.
Say you where running the same gear...what would you do? I know I could log book prop to.......(for you gears)
 

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Say you where running the same gear...what would you do? I know I could log book prop to.......(for you gears)
anything you do that loads the engine harder will have an effect on the cylinder temps. The A/F remains the same, but the cylinder temps can shoot up. Thats one reason the dyno jetting tends to be a little rich over what performs the best in real use. The engine is simply loaded harder on the dyno than you can repoduce in the boat unless you gear it to hold a given RPM lower than your peak HP.
If we run the thing at near HP, and then make a change to a lower RPM gear, I better take a good hard look at the plugs, or I risk a piston melt down. Not sure this applies to the drag boys or river racers that make 500 to 700 ft blasts, but a hard loaded circle boat is at risk.
Its hard to log the prop/gears to a specific Air Density. It could take years get enough data to utilize. Just not enough races under all conditions. But in general, if we are loading the hell out of it, I fuel it.



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steelcomp was here
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Let me help explain here...what Paul was telling me was that under load in the corners, it's pig rich, but get on plane and up in rpm going down the straights, it leans out to where it should be. I think it might be sloshing fuel through the ven tubes in the corners, becuase dynamically, there's no reason for it to richen up in the corners at lower rpm. Oh, and same throttle position...WOT all the time.
 

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Let me help explain here...what Paul was telling me was that under load in the corners, it's pig rich, but get on plane and up in rpm going down the straights, it leans out to where it should be. I think it might be sloshing fuel through the ven tubes in the corners, becuase dynamically, there's no reason for it to richen up in the corners at lower rpm. Oh, and same throttle position...WOT all the time.
Oh, well thats a horse of different color. I agree 100%, except the part about WOT all the time and the Gs in the corners. Are we talking about the same Paul?
I could possibly be a air bleed thing, but I doubt it. You would have to prove it on a dyno where the load pulls the Rs down without disrupting the fuel in the bowls.
I agree, its most likely a dynamic effect. We experienced a simailar thing with the carbs side ways and fixed it with some road race floats and a little installed a little modification, but effective just the same.
If the carb is mounted conventionally, circle track floats may help. If its a side hung float, errrr, its tuff going.



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