Mark, I have installed the Quicksilver OEM rubber plugs and will be testing in the next week.
Are you suggesting that I pre drill all 3 plugs to 5/16 on my bench and then run the first test. As I make drilling adjustments should I be drilling all 3 plugs to the next size at the same time?
Mo
First test should be solid plugs to get a bench mark. Take data: What is the current load in the boat...folks fuel etc.
Try to keep these parameters constant during all the testing. Ambient temp if you think it will change significantly during your tests.....hotter it is, lower HP your engine produces so sloppier the performance will be.
How long from firewall till bow goes down on hole shot? Expect numbers in the 5 second give or take area. Maybe not initially, but when we are finished; looking for less time actually.
Engine rpms during hole shot. I realize they will increase as the boat speed increases, but do the best you can to capture them initially when you firewall it and what they are when the bow goes down.
Boat speed as bow lowers.
Other thing that you might want to notice, is once on plane, how long does it take for the prop to lock up....rpms will drop and speed will pick up proportionally.....you won't get this data point with no holes, but after you start drilling, be interesting piece of info.
Once you have that data let's look at it and then start drilling holes. Yes, all holes need to be the same size at the same time to equalize the load on the props. Otherwise you will surely have some prop vibrations.
Trim is an important part of this so in each of your tests, take a run with the trim all the way in till the bow drops, and then trim the engine parallel with the boat and do the hole shot again. A lot of times I get a better hole shot with it level vs tucked in as the engine ventilates better and the rpms come up faster. Also, if the engine ventilates while you are shooting, the boat will porpoise somewhat and every time it does, it sucks in more air but rpms increase significantly and when the stern goes back down, the prop is spinning a lot faster and you get a jolt forward. Once we get this right and you experience it a few times you will love it. I do!
Then we will decide to move on and if so, drill out 3 ea. 5/16 holes and take the same data under the same conditions as best you can. We will look at the numbers and if it's time to stop we will. Otherwise we will increase 1/16" on all 3 plugs at a time and continue testing.
Or if you want to spring for another set of plugs, we can go overboard just to see the upper limit and come back if necessary. One thing I am particularly interested in is the change in hole shot rpms between each test. Interested in hole shot time also, but rpms is what I am really interested in. You want to get your rpms up to get your ponies pushing the prop, but as I said before, if they get too high it just signals that you are loosing too much thrust via excessive exhaust gasses over the blades and it will delay the time of the shot.
Let's make it happen.
Mark