Grandsport engine options

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simpson_3

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I've been looking to possibly buy another Allison and I have a few questions about engines for the Grandsport and possibly an XB21 prosport (center console). If I'm looking to set either of these boats up for long distance river cruising without having to sacrifice top end speed, what would be your preferred engine for either of these?

I have tons of experience with the 225 promax's and have had great luck with them but my concern is I feel they wouldn't carry the weight well if I'm going to make a long trip and want to carry a bunch of fuel as well as passengers.

I've seen quite a few Grandsports with 250 xs and 2.5xs optis and was wondering what you guys thought of running a heavier engine like that? This may sound crazy but ideally I would like to run a 300X SS and have the gearcase converted to ratcheting. I ran a 300X on a different boat of mine and it's an absolute powerhouse. Weight never seemed to bother that engine and it loved high speed cruising. Not saying a 225 promax isn't good for high speed cruising but the 300x does it better. The 300X weighs about 475lbs and if I run less setback I feel I could make this work. Am I crazy for thinking this? I'm not looking to set and speed records but would still like to be able to run 100. What kind of MPG would a 300X get?

Now for the XB21... what kind of mileage would I get with a 300X? How does an XB21 MPG compare to a Grandsport? Does anyone know how fast an XB21 is with a 300X? I haven't seen many people run these engines on these boats which kind of surprises me. I've only seen 250 and 300 opti's or the new four strokes.

Any info would be much appreciated! Thanks
 
Ally-Sun

Ally-Sun

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simpson_3 said:
I've been looking to possibly buy another Allison and I have a few questions about engines for the Grandsport and possibly an XB21 prosport (center console). If I'm looking to set either of these boats up for long distance river cruising without having to sacrifice top end speed, what would be your preferred engine for either of these?

I have tons of experience with the 225 promax's and have had great luck with them but my concern is I feel they wouldn't carry the weight well if I'm going to make a long trip and want to carry a bunch of fuel as well as passengers.

I've seen quite a few Grandsports with 250 xs and 2.5xs optis and was wondering what you guys thought of running a heavier engine like that? This may sound crazy but ideally I would like to run a 300X SS and have the gearcase converted to ratcheting. I ran a 300X on a different boat of mine and it's an absolute powerhouse. Weight never seemed to bother that engine and it loved high speed cruising. Not saying a 225 promax isn't good for high speed cruising but the 300x does it better. The 300X weighs about 475lbs and if I run less setback I feel I could make this work. Am I crazy for thinking this? I'm not looking to set and speed records but would still like to be able to run 100. What kind of MPG would a 300X get?

Now for the XB21... what kind of mileage would I get with a 300X? How does an XB21 MPG compare to a Grandsport? Does anyone know how fast an XB21 is with a 300X? I haven't seen many people run these engines on these boats which kind of surprises me. I've only seen 250 and 300 opti's or the new four strokes.

Any info would be much appreciated! Thanks
Click to expand...

Having had both of these boats in the configurations you are inquiring into minus the 300X, I figured I would give some input. Yet it all depends on what you want in a boat.

As for the GS, the best combo is definitely the 2.5L combo. Albeit, the 225 ProMax and above. It's balanced well, has the ratcheting lower, and light. Yet as you know with the ProMax they like their gas. The ultimate 2.5L on the GS IMO would be the 200XS Opti. That gal ran like a raped ape and sipped fuel. Good luck finding one of those. Yet even if you do parts will become more and more scarce. Especially on the Sportmaster lower unit end. Again, IMO, I loved the 250XS Optimax on my GS. It was great on fuel (@9mpg) handled well and reached mid 90's on a pretty conservative height setup. Guys got trips with them and higher engine heights. I was happy on the conservative side. I never had any issue at all with the non-ratcheting lower. In fact I could ease her out of high speeds better than the ProMax. Never chop the throttle and all will be just fine. If a major failure took place that may be a different story. Yet thats with any engine if the bow drops. The only bad trait with the 3L on the GS is she will sit about 2-3" lower in the rear while idle in the water. If I had passengers sitting in the back while resting in the water and a big wake came from the stern. I would have to get them to stand up and move as far forward as they could to keep water from coming in. Honestly a Merc 150 4 stroke would be a consideration for me on the GS now. Getting upwards of 10 mpg, cruising on a tank of fuel all day and them some, smooth, great torque, quiet, reliable, and hitting 80 mph sounds like a fantastic combo to me. I think Tim Powell had a couple in stock. One of his customers put one on a XB2003 after having a ProMax for years and absolutely loves the 150! I loved my GS and there is not a better looking Allison out there IMO. Yet knowing what I know now and what I use my boat for. I would look for an XB2003 over a GS because of the front deck area.

The XB21 ProSport is an absolutely amazing hull!!! I had the 250XS on it at first and I loved it. Then I saw the opportunity to get a 300R and I took it. The 300R took the XB21 to a whole new level! The 250XS did well and ran up to 90mph. Yet the 300R is a power monster, smooth, and much quieter. The XB21 300R combo does everything better than the GS with the exception of the launch and light snappy feel when doing so. Once on plane there is no comparison. It rides better, handles rough water much better, and is absolutely on rails up to 100mph. Plus the room and ability to walk around and relax on the spacious front and rear deck is fantastic! The boat sits much more level and is 10 times as stable when idle in the water. The wind protection is great but not as much as the GS. Which isn't all bad at times. Yes I ride a lot in the winter and stay plenty comfy, but i do get a touch of breeze now and then from a strong side wind. Which in the GS you hardly feel a breath of wind. While that's great in the winter, on a smoldering summer day in the upper 90's it leads to hot sweaty ride at times. As far as fuel mileage, when cruising at best I am around 6.5 mpg with the 300R as I was with the 250XS Opti. I know a guy who has a 300X on his XB21. He said she runs in the mid 90's and isn't looking for every mph. He summed it up though in one sentence. On his lake she will pass everything but a marina with a gas pump! If it's an XB21 you decide on give Tim Powell at Fastbass Marine a call. He is a bit southeast of you in Kentucky.

All in all both are amazing hulls! I came out of Hydrostreams and Checkmates. So when I got my GS I thought I had died and gone to heaven. Yet if heaven... has a heaven I reached it when I got the XB21. haha!
 
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Lotus 50

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I think the 200XS would be perfect and I saw one for sale on Tuesday at Top Gun Marine in Ontario. He has it for sale on the Allison stuff for sale site on Facebook,

My SS2000 has a 200XS and it works fine with 4 men in the boat.
 
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Brandon2684

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I have a Grandsport with a Merc 150proxs four stroke. Runs 81mph and it’s a nice setup.

Really no complaints. But I suppose if I had to do it all over again I’d get a 150/175 Yamaha SHO and flash it. Now you have a mid 90mph boat that has all the benefits of a four stroke and still sub 500lbs. I believe there’s aftermarket solid mounts for it and I’m sure can cone the stock case or put something else on it. That or get a v6 225 Merc four stroke and same thing with the case and mounts just be a bit heavier I believe around 510-520lbs if I remember correctly.

Either way you’re going to have to make some modification. Even for me with a Merc 150proxs I had to cone the case. The ride like panda with a stock case deep.
 
Wave to Wave

Wave to Wave

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Ya, the 150 Merc, or the Yamaha 150 / 175. Advantage of the Yamaha 175 is it comes with the 1.86 gears and without a tune is making about 190 HP.
 
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