Offshoreonly.com - Phantom 25 - upgrade from 450R to 500R

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- - Phantom 25 - upgrade from 450R to 500R (https://www.offshoreonly.com/forums/general-boating-discussion/385908-phantom-25-upgrade-450r-500r.html)

Quote:

Originally Posted by Markus (Post 4930532)

Head means powerhead, which is an outboard term for what inboard people would call engine.

Huh I am surprised the race teams are running 450r lowers for reliability sake.

They have a smaller diameter.

If you care about speed, rather than reliability, that is the kind of choices you make.

Quote:

Originally Posted by Markus (Post 4930618)

They have a smaller diameter.

If you care about speed, rather than reliability, that is the kind of choices you make.

Yep, makes complete sense. Someone should build some better strength lower shafts at that diameter for the racers, get the best of both worlds.

Quote:

Originally Posted by Twodocs (Post 4930310)

Driveshaft is larger, so current prop would have to be cut.

Do you have any steering issues with current setup that a camber would help?

Some of the race teams are running the 450 lower with 500 head, but I personally wouldn’t want to do that unless you have a lot of props.

Partially true.

Yes the 500R prop shaft is larger than the 450R. If Toffen will be keeping his Max5 props, or any prop that uses a hub insert, there is NO cutting required. You would just buy the 500R prop hub from Mercury and put it into the Max5. Only 450R cleavers would require modification to fit the 500R prop shaft.

Hi!

We are now closer to a 500R with 20 mid section, R-Drive Sport with cambered skeg. Hopefully it will last some years, since I am soon a pensioner :)

I will kee you posted about the swop.

Here are the engine history of the Phantom 25 between 1985-2026:

Johnson GT 3,6 V8 300 hp
Promax 300 X
2 x Merc 2.5 EFI SS with Brucato SVS
Verado 350 Sci
Verado 400R
Mercury 450R

Cheers Toffen

I was told Merc updated the 450R lower internals at some point. Most my friends have never broken a 450R lower ever and they run hard. Some over 650hp.

Here you go Toffen. Pocket $125K and do this rebuild
RameyRacing Stage 1 Upgrade – for Mercury© 450R - RameyRacing

Quote:

Originally Posted by Markus (Post 4930618)

They have a smaller diameter.

If you care about speed, rather than reliability, that is the kind of choices you make.

Who's running the 5.4 on 500Rs? The R sport is faster on a cat, runs higher and holds better. On a single V, nobody is racing that here in America, but I'd still go with the 500R case.

Quote:

Originally Posted by Toffen (Post 4930301)

Hi,

Hope you are well.

Its my 5th season with my 450R now. Still running Max 5 ST 15,25 x 27 with great performance. The warranty expire next summer, and I will try to sell my 450R and upgrade to 500R next year.

My current 450R has a 20 inch leg and Sportmaster straight skeg. I have installed an oil cooler to keep the steering oil not too hot. I consider to buy a cambred skeg for the 500R. I run my 450R propshaft 1,5-2 inches above the bottom, and I wonder if the R-Drive Sport lower unit is the correct choice for the 500R? The R-Drive seems to have a smaller skeg than the R-Drive Sport drive. My Phantom 25 is 40 years now, and straight V. No pad or steps.

The Phantom 25 runs approx 94 mph at 6250 rpms with the Max5 15,25 x 27. If my calculations are correct, I can use the same prop on my new 500R, spinning it to 6600 rpms? Estimated top speed around 98-100 mph.

Have a great day!

Cheers Toffen

R Sport and definitely cambered skeg. You should be running a cambered skeg on the 450 too

Quote:

Originally Posted by WavetoWave (Post 4943859)

R Sport and definitely cambered skeg. You should be running a cambered skeg on the 450 too

I was silly enough to buy one 450R with straight skeg. Puts lots of strain on the steering, but the boats run good despite the straight one.

Cheers Toffen

Quote:

Originally Posted by Toffen (Post 4943913)

I was silly enough to buy one 450R with straight skeg. Puts lots of strain on the steering, but the boats run good despite the straight one.

Cheers Toffen

Had an offshore sportmaster (straight skeg) on a 2.5 260 on the Hydrolift Sportcat for a while. Hated it and bought a fishing Sportmaster with cambered skeg.