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