yikes

I have a 1986 Daytona with twin 260 HP stock small blocks. At the end of last year I changed the drives and now have counter rotation Alpha 1s. I also went from the 20P 4 blade aluminums to 23P Mirage props. The boat is now running 61MPH at 4400 RPM.
I am considering a set of 21P Revolution 4 blades. Will I loss my speed by dropping the picth or will I gain by getting into the power range?
What is the optimum RPM?

throttleup

The range of your motor is 4400-4800 RPM. You are running at the low end of the torque band of your motor and probably experiencing decent cruise speeds for your set-up. However if you are looking for greater top end then you should increase your RPm to 4700-4800 RPM at WOT. You could drop down to a 21P or lab you 23P to do so.

Julie

bbladesprops

Actually you are on the high end of the torque band and the low end of the recommended WOT range below the max horsepower rating.

Your slip is low. Running the Rev 4 21's will more than likely not help the top end. They will increase acceleration, and keep you on plane at lower speeds and rpm's. Your top speed will stay the same.

If you are looking for top speed, Lab Finish the Mirage Plus 23's.

We have a set of 21 and 23 Revolution 4's if you would like to try them. I also have another brand of 21 4 blades that I think will work excellent on your application if you are interested.

yikes

Thanks for the info.
Sounds like I should forget the 21s and concentrate on adding some power and lab the props. The boat is bone stock including exhaust through the drives. I would like to get closer to 70MPH without major engine work. Exhaust, Ingition and Carb should help. I know I need some 383s but it's an old boat on a budget.
Should I wait until the engine mods are complete before I have the props done?
One of the props does not have a flow torque hub. Should I get another?

bbladesprops

Definitely do any engine mods you are considering before propping out the boat. Otherwise we will end up doing it twice.

The 21 Rev 4 may still be worth experimenting with when the time comes. Especially if you decide to wait on the mods.

We can supply you with a new Mirage but again, use what you have to begin the dial in process. No sense investing on propellers till the end. Props should be the final piece of the puzzle. When your ready, Let us know and can supply you with the test props you will need.

yikes

Thanks It wil give me a place to start and wait to do the props until I get more power.

DMAX

I'd go with a couple of 502s, hee hee. See ya at work.

throttleup

Yes, Brett is correct I should have said Power Band of the motor! Sorry.

Julie

yikes

Hey Ginger
Just trying to keep up with you guys. I think I'll have to ditch the GPS and get a happy speedo. Unless you want to trade a couple of 502s. Maybe we can go to Winny so I could keep up. 45 MPH!!!
Are you planning on Sebago? There are more pictures of your boat on their web site than the pace boat!
Start waxing.

DMAX

Hello Yikes,
As far as Sabago goes, we got a wedding in Colorado that weekend; but we're gonna go to Winni July 8th for the Easter Seals run. We'll hit Sebago some weekend in July to go through the locks; if you're interested let me know, maybe we can hook up.
Talk to ya later.