New Aritcle - thoughts on a Mercury Racing 3.4-liter R-series engine

[FBM]

FBM what are you doing? You doing your best to outrun that yellow boat on watts bar running a lil motor

Pretty sure we did, with an even lil'er mota

[FBM]

FBM you need to hang the little fella on a scale and get a true weight. Not sure what Merc has placed on the tag but the big 300 R weighs 561lbs

Will do, we are going to hang it on a 2 seater XB21 just to see how it does on a tournament rigged boat so I will throw it on the scales at that time.

I weighed a 250R with Darris back in 2018 and it was 560lbs, oddly enough the R cowl was 34lbs and the Pro XS cowl was 27lbs. I cant imagine the R mohawk weighs 7lbs...

[David]

90 plus with the 200R on the 21 Allison is impressive. For comparison, the 20 Tuff went 86 with a 225 Merc 4 stroke, and 81 with a flashed to 231 Yamaha 150

Overall length is similar: Tuff 21'10" Allison 21'2" (19'9" centerline)
The Tuff is narrow at 82" vs the Allison at 93"

The 200R results interest me more than the 450R, but I am curious about the differences between FBM's 450R 21 Allison and River Rocket's experience.

[hellbents-10]

That 225 on the 20 had a normal lower though so they couldn't raise it up. I bet a 25 would go 90 with a 200r, it will go 110+ with a 300r and little test time. I bet I could go 90 with a 200r on my 24, I would try it if it didn't have power on it haha.

[Greg G]

I still don't understand why they did not just offer a 225 R V6. Not many folks bought the 250 R V8 so not like it would compete with that model.

[John S]

Will do, we are going to hang it on a 2 seater XB21 just to see how it does on a tournament rigged boat so I will throw it on the scales at that time.

I weighed a 250R with Darris back in 2018 and it was 560lbs, oddly enough the R cowl was 34lbs and the Pro XS cowl was 27lbs. I cant imagine the R mohawk weighs 7lbs...

Has Allison been doing anything different to their XBs to accommodate the new motors? Or are they capable of handling the extra weight without anything design/ structural to handle it? Or is it just different setups?

Great reviews BTW, keep em coming.

[David]

I still don't understand why they did not just offer a 225 R V6. Not many folks bought the 250 R V8 so not like it would compete with that model.

Maybe they did offer a 225 V6, but chose to call it a 200.

[Greg G]

Maybe they did offer a 225 V6, but chose to call it a 200.

Not sure what you mean by that. The OEM has to stick with the +10% rule so the 200 can only make 220hp, where if they offered a 225 label it could make 247 which at least would equal the Promax and X back in the day.

[Speed Jr.]

People focus way to much on the sticker instead of the performance. Put that old 2.5L 225 PM on a loaded new XB21......See how it runs against a 3.4L 200R with a bigger prop spinning more blades.....The 2.5 is only relevant on lighter/smaller hulls. To get to top speeds with big props pushing real weight requires Torque. I'd much rather have the lower sticker number on the side of the motor to get cheaper insurance than have the big number and go slower.......

Jr.

[David]

The 10% is voluntary. It’s possible that the 200 R, or for that matter the 300R go past that. BMW under rated some of their car engines.

[FBM]

90 plus with the 200R on the 21 Allison is impressive. For comparison, the 20 Tuff went 86 with a 225 Merc 4 stroke, and 81 with a flashed to 231 Yamaha 150

Overall length is similar: Tuff 21'10" Allison 21'2" (19'9" centerline)
The Tuff is narrow at 82" vs the Allison at 93"

The 200R results interest me more than the 450R, but I am curious about the differences between FBM's 450R 21 Allison and River Rocket's experience.

River Rockets explanation is spot on. The 450 is too heavy and the AMS mid makes it even more cumbersome. The amount of hours I have invested in the setup from June 2021 until Nov 2024 is surreal...I'd hate to even try to put a number to it. I have an easy 15,000+ miles behind the steering wheel. The Allison has so many curved and cupped surfaces that were designed with 500lbs in mind and when you add 220lbs to that it really changes things. I was able to make mine great in a straight line but it really took the Allison out of the boat. The AMS complicates things like setback because a hydraulic plate is a must but due to the 5" built into the AMS you are limited to a select few plates. I tried multiple setback lengths as well and each time it changed the entire dynamic of the boat. The power steering was a huge issue, the boat was undrivable so I had to come up with a workaround for that. Just so many little issues that add up to be a major issue.

RR knew what he was getting into before hand. We installed a new 300R on his boat and so far its been 104.8 with room to grow.

Has Allison been doing anything different to their XBs to accommodate the new motors? Or are they capable of handling the extra weight without anything design/ structural to handle it? Or is it just different setups?

Great reviews BTW, keep em coming.

The XB21 series is built like a tank, Aluminum grid transom w/ studs instead of through bolts, aluminum glassed in anywhere something attaches (like the trolling motor). The boat handles the 300R with ease, and after 3.5 years of a 450R on the back of mine, there isnt a stress crack anywhere. I have put this boat through every condition imaginable. Our shop is located on Kentucky Lake and if the wind is blowing 30MPH, we are still liable to make a 50-75mile one way run for a tournament. Saying that, the weight of the 450 changes everything. It is just too much stern weight. The boat needs to be about 3' longer to float the weight better. It sits nose high at rest when compared to a 300R.

[John S]

@FBM Would you say the 300R is the ideal motor for the prosport? That has always been a dream cruiser for me. Kind of like an age appropriate next step up from my old XB-2002. I think it would make for a great cruiser/ beach hopper.

[FBM]

@FBM Would you say the 300R is the ideal motor for the prosport? That has always been a dream cruiser for me. Kind of like an age appropriate next step up from my old XB-2002. I think it would make for a great cruiser/ beach hopper.

IMO....Yes, the 300R pairs quite nicely with all models of the XB-21.

[John S]

IMO....Yes, the 300R pairs quite nicely with all models of the XB-21.

You mentioned the boat could use another 3’. Darris (and a million others) has been teasing the 23’ Grandsport since I can remember. Is a 24’ Prosport possibly in the plans? I looked at their site the other day, kinda made me sad the old models are all gone. I understand, but, ya know.

[FBM]

You mentioned the boat could use another 3’. Darris (and a million others) has been teasing the 23’ Grandsport since I can remember. Is a 24’ Prosport possibly in the plans? I looked at their site the other day, kinda made me sad the old models are all gone. I understand, but, ya know.

Darris is and has been actively working on a larger hull design for several years now. If it was done today they would still have to design the top deck layout, build molds, test, etc. I think we will eventually see a big GS, but its not going to be soon unfortunately.