SWAMPHUNTER45 said:
As far as numbers go well PROOF IS IN THE PROP
Swamp,
Ya'll's Camaro must be putting too many smiles on your face, I mean that's a LS Slogan :fishing :stirpot:
SWAMPHUNTER45 said:
It would spin a 2 blade (76) inch NGQ pitched around 3 ya don't see many of the 540 gang doing that. Generally they are 72 inch blades.
My AV spins a 72" NGQ pitched on 2 and I will take on your whatever caddy any day of the week, usually I have to go in, make a few passes to mash the grass down (laugh a bit :bom: ). Next I have to get all the women off the damn overloaded thing and drop off my rider to shake the grass rake so my stern heavy buddy can get back to the main trail. :slap:
So let's talk Torkey.
The measure of spins "X prop at Y pitch" is only a measure at one point and that is it. Further, that measure is only valid for a specific boat or as a stand alone on a test stand with no boat. Prop Inlet conditions mean a lot more than outlet conditions, but that is a different discussion.
HD,
There is no doubt that a dyno run gives a whole bunch of useful data for many applications, but at the end of the day, the prop is the dyno of interest. Take two engines, both identical except one has less rotating mass (inertia). Standard dyno runs, slowly increasing the engine load, basically steady state, are not going to show a difference, but the low inertia motor will throw the prop better hands down. Most people would say the low inertia motor makes more torque. I would say they both make the same Pork, but one is more Torkey.
The slow grow dyno run gives a PORK curve. The Pork curve measures Pork vs. RPM for the engine at WOT. That's a max PORK curve, but its also a Hp curve in disguise (seriously, what's the difference? RPM is already part of the curve??). Throw Hp through a gear box (or axle gears)and you got Pork. Pork is most useful towin my airboat to the launch. Towin that big sail down the highway while cussin yankees, well my turbos are gonna be spinnin and the diesel is gonna make Pork, the only way you know you are making more pork is watching the boost gauge. That's some damn Pork :violent1:
For an airboat application, you definitely want Hp/Pork, start there. But everything below max Hp/RPM is response. Torkey is a measure of how the engine responds instantaneously. Torkey is torque vs time (in milliseconds) as opposed to torque vs. RPM. Torkey is taking flight in an instant. How much torque does the mill make flat off the bat in the first 2 seconds when you mash the gas? That's Torkey.
So mull that over and figure out a way to compare/tune Airboat mills. If you think about it, you will understand why the dedicated airboat builders don't waste money on dyno runs or publish data, who would understand it :dontknow: