Can I expect much more?
 

The numbers:
40 Excalibur
Notched Transom
Stellings 12" Boxes
IMCO Drives, shorties
1.5:1
18" X-Dimension, drives 4" Under running surface
650HP 700 Tq @5600 x 2

So far the boat has run 74.4 at 5000 rpms turning stock bravo 28's. Turning out. The boat planes very nice and has tons of excelleration, given the weight and age of the boat. It also carries the bow very high.

I have 1000 rpms before the limiter. Is it worth giving up the good cruise that i have now for a few more mph.

Have at it....Thanks.

Re: Can I expect much more?
 

Depending on where you want to run the motors, you could have a conserative Lab job done to the propellers. Only expect 200 rpm and you may loose little to nothing in the middle and could gain as much as 3 on the top.

We need to know the operating WOT range for your engines.

Re: Can I expect much more?
 

They were dynoed to 6000rpm. They peaked at 56-5800. I like to cruise at 3500-4000 (440 hp/650tq) and dont mind running 5000. It would be nice to know that at 5000 rpm that i have some left. Does that make sense? I ll try to post a dyno sheet.

Re: Can I expect much more?
 

You really should try to prop the boat out to the motor's power band. By propping it at an rpm that is too low you may have problems with detonation or burned exhaust valves.

I think 5000 is a little on the low side for a motor that developes peak HP at 5800. Maybe 5200-5300 may be the least you may want to go. A motor person may be able to answer this question better.

If you do decide to raise the WOT rpm a 26 pitch Bravo 1 prop would bring the rpm up about 300-400 from where it is now. Of course you will lose some cruise speed but with props it's usually about compromise. When you gain something on the top end you usually lose something elsewhere.

Matt