Phantom 25 - upgrade from 450R to 500R
 

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

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.

Hi!

Thanks. The oiled boiled when running WOT until I installed a oil cooler. Acceleration is a must over top speed. I estimate I will get 3-5 mph higher top speed. Curious about mid range fuel consumption and punch :)

Cheers Toffen

The 500R is surprisingly thirsty in the mid-range compared to the 450R. There are some threads here about it.

I just seen that Kong has a kit out for both that adds 150HP,,,,,,,, Yee Ha

Then add the MoTec ecu to that and it’s a 200+ hp gain.

So 500R heads on a 450r shortblock, or you mean a 450r lower unit on a 500r engine?

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

The release I read said that was with the MoTec ECU. I think it was 8K?

Yep

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.

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

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

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.

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

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.

I would run that 450R until it throws in the towel, unless you have to have the warranty. They are great engines and the resale isn’t good, so I’d squeeze every hour out of it. Just my 2 cents.

Of course a 15” 300R with side steering would be really nice. you’d lose some speed but have a really great handling boat.

450R resale price
 

Yeah, the 450R is quite a bargain now.

A friend picked up 1 new and 2 used earlier this week, and I was surprised by how cheap they were.

Great news for many people - it is a fantastic engine.

Hi!

Good points :)

Learned today that dealer price for 500R with R-Drive Sport is NOK 919,000. Last year it was NOK 745,000. The Norwegian Krone was less worth until recently. We paid NOK 12 for 1 USD. Now we pay NOK 9,5 for 1 USD. So hopefully the price will be better upon Christmas.... https://www.screamandfly.com/images/smilies/smile.gif We see what happens.

Cheers Toffen