Hi All!
Thanks again for posting. I'll clear a few things up.
850cc racer - No not Northern Territory.....Riverland, South Australia. We have enough trouble dodging logs let alone 'crocs'!
The boat is sitting flat in the picture as we are in one of the tight twisting creeks. My 'navie' is at the front to help get the boat to turn through the twisty bit. As soon as we hit the open water he moves back to the back seat with me to get the nose up. Not much boat in the water then!!
In the photo, you can make out the mouth of the creek with the River in the back ground, so we have just come steaming into the creek as the photo was taken to get around a couple of logs.
Cav Plate
is and must be level with the planning surface of the hull. Can not run surface piercing props.
This year we ran standard class with an Alloy prop (10 1/4 X 15). Now planning to jump up to run 'Sports' and will use 10 X 17 OMC stainless. Must run though hub exhaust prop NO CLEAVERS.
As for trim, standard class must run fixed pin. We ran it on the 4th pin setting which was pretty good for both open water and in the creeks. For Sports Class, we are setting up a manual hydrolic pump type trim system so will run anywhere from 1st pin to 5th pin and beyond.
David L_6 - Rev Limiter is not an issue so we can discount that. It will rev to whatever you like depending on the prop on the bottom.
Can not run external exhaust but porting as far as I am aware is not restricted in our 'Sports' Class.
So any porting I guess comes down to creativity and alot of engineering/mechanical know how. Finger ports though....I have no idea what that means.
You are spot on though about not wanting to sacrifice bottom end torque for outright top end speed. There needs to be a compromise for sure.
Mark 75 - Yeah compression sure helps which can be helped with some new rings. That and a little off the head maybe.
Can run oversize pistons as long as they are "factory specification" and "Mass produced" (ie: Can not have three pistons made - must be available to the public).
Fuel, 98 oct unleaded with Octane Boost (which doesn't help much from what I read). Avgas is available and allowed in 'Sports Class'.
Hope some of that lot helps. Cheers Haych
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