MAX RPMS (max amount of time run there)?

[Ball Racing]

What is the longest amount of time you have ever run a A4 at you MAX achieveable RPM?
My boat I built , which can be seen in the 12.5mph thread, will "plane out"
But it takes almost all of the rpms you can get.
I changed props, and now can get 2,500 rpms, and back down, and still stay on plane in perfect conditions at 2,300 rpms.
I know max load-cylinder pressure is hard on any motor, but just curious as to how long you have kept your motor at full tilt??
I know in some Bad weather some of you have had to run your motors hard.
Just looking for feedback, and results of running hard.

Thanks

[Dave Neptune]

Prop?

Dan, you mentioned cyl preassure as a concern. Do you have a vac reading when you were running? I don't see any problems either way until you begin to approach the 3K threshold and if you are still not at zero vac~no worries. Some with the reduction units run and operqate at those RPM's and even higher with no issues. I think Hanley said he was now running at 2900 with a prop I gave him to try out. I run mine at 2200 (7" of vac) pretty much all of the time.

What is the prop you are using?

I also sent you a PM.

Dave Neptune

[Ball Racing]

I do not have a vacuum gauge installed yet,
But it only requires half throttle to achieve my results, anything after half throttle just does nothing extra, and thus would lose more vacuum.

[Mark S]

In 2009, around 8 hours from Wood Island south to Isles of Shoals, about 35 miles, headed, with a 13x8 prop at 1500 RPM; and in 2011, a little less than 7 hours, again Wood Island to Isles of Shoals, flat calm, with the Indigo prop at 1900 RPM. Also in 2010, motorsailing about 7 hours from Race Point north to Marblehead, about 42 miles, calm and then headed.

I can never find the northwesterly that others seem to find from Wood Island to Isles of Shoals, and it never matters which way I'm going between Marblehead and Provincetown, I'm always headed or there's no wind. Why is that?

Mark

[Ball Racing]

Were those your maximum rpms you could achieve?
Or just a backed off "cruise" rpm?
If you can run "Hours" at the most rpms you can reach is awesome, and shows just how tuff this engine must be.

[Mark S]

Those RPM were the maximum RPM I could achieve with the two props used. The boat is a Pearson 35 with 13,000 lbs. displacement, so there's a lot to push. I replaced the 13x8 with the Indigo in hopes of getting higher RPM, and I did with only a little loss of speed, but not as much additional RPM as I had hoped.

Mark

[joe_db]

My original A4 was run at 100% throttle for as long as the fuel lasted many a time and sometimes even more if we were adding gas underway. I am sure it did more than 24 hours at max RPMs several times.

What is the longest amount of time you have ever run a A4 at you MAX achieveable RPM?
My boat I built , which can be seen in the 12.5mph thread, will "plane out"
But it takes almost all of the rpms you can get.
I changed props, and now can get 2,500 rpms, and back down, and still stay on plane in perfect conditions at 2,300 rpms.
I know max load-cylinder pressure is hard on any motor, but just curious as to how long you have kept your motor at full tilt??
I know in some Bad weather some of you have had to run your motors hard.
Just looking for feedback, and results of running hard.

Thanks

[Ball Racing]

Wheres a good place to run a vacuum gauge, if your not running a pcv valve plate to tie into?
Does the scavage tube pull enough to test there?
Thanks

[Dave Neptune]

Mounting

I have my gage mounted to the manifold via a tee where the scavange tube ties in. I recomend using 1/8" copper tubing and at least 18" which will really smooth the needle out at lower RPM's.

Dave Neptune