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Twin vs single outboard setup

Old 09-09-2002, 06:01 PM
Thread Starter
Join Date: Oct 2000
Location: Norway
My Boats: Phantom 25 (1985) w/Verado 400R
Posts: 600
Default Twin vs single outboard setup


I know we have discussed this topic before, but I hope you all can look at again.

I have a Phantom 25 with a Promax 300 1999 model running 78 mph in spring (75 mph in the summer). 7,5 inches setback, blueprinted Tempest 26 spinning 6.000 rpms. Torquemaster lowerunit.

I am looking for more speed. I have 4 options:

@ Buy another Promax 300 second hand, and add this to my 1999 model Promax 300. Since the boat is only 5,5 feet wide, I am afraid it will be a little tail heavy.

@ Sell my Promax 300, and buy a new Promax 300X. Speed will increase somewhat - approx. 2-3 mph according to my calculations (30 hp extra over the old 300) making in excess of 80 mph.

@ Sell my Promax 300, and buy two 2.5 EFI engines. Since these engines are lighter, the balance of the boat will approx. the same as one Promax 300 (7,5 inches setback) if 2-3 inches setback.

If I am correct the 2.5 EFI should be as strong as the old Promax 300. Is this correct? Do anyone have any dynoresults? What about longvity for the 2.5 EFI compared to the Promax 300?

Could the less weight give a better speed for the 2.5 EFI's compared to the twin Promax 300's?

@ Sell my old Promax 300 and buy twin Promax 300X. Expensive solution, and still uncertain if the boat will be a handful to drive in high seas despite trimtank in front.

I am a little confused here! Phantom 23 (new smaller model) is raced with twin installations (2.5 EFI) in the race circuit in Europe with great results. Even twin Yamaha/OMC 225 work fine ...

The big question is ofcourse: is the extra cost of a twin installation worth the money over a single Promax 300X....?

Cheers and thanks,

Toffen is offline  
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