300X or Promax on a xb2003

[PaulC]

Im looking for some input, kicking around the idea of selling all my 2.5 stuff and swapping to a bigger engine on my xb2003. Was wondering would be a good option I really like the 300X or the newer 300 Pro XS. Just curious as to which is more reliable and will perform better. With a light fishing load. Thanks

 

[Darth VMAX]

300x is lighter, stronger and faster. Looks better too IMO. But it's way more thirsty than the opti.

480lb vs 505 lb advertised weight difference.
300x is more of a 315-320 hp motor and the 300xs is 305ish. 300x has more RPM's to play with too...

The 300xs may have more low-end grunt initially and I'm just basing that guess on how typically strong DI's are in general to EFI motors out of the hole.

 

[PaulC]

I keep seeing 300X's pop up for sale. Gonna try the 2.5 out until the 1st 1/4 of 2018 and see what i can do with it. Then ill repower with a bigger motor. Unless the deal presents itself to be to good to pass up then ill lock up a new motor sooner.

 

[David chris corr]

I have a 300pm,but not on my xb3,I'm putting my 250xb with 300pm alien cowling on the xb this winter,I like the 250xb with 300heads and ignition ecu,and i can fish bass tourney trails

 

[z06man]

Darth is correct 300X hauls the mail but a lot more fuel. XS sips fuel but will lose some top end.

 

[Jr in Jax]

I love my new 300XS on my Grandsport. Almost 10 MPG at 60+ MPG cruise speed while still in break in. Definitely over 100 MPH GPS at top.

 

[dubmoney]

Jr in Jax, did you ever get your GS over 100mph with your previous motor/motors? If so did you ever sand the lip?

 

[Cleavor]

Jr in Jax, did you ever get your GS over 100mph with your previous motor/motors? If so did you ever sand the lip?

I have, many times. GrandSport, stock 260 ROS, 8-9 inch set back Rapid Jack, 103 MPH GPS top speed so far. 95 - 100 every day living. I haven't touched the lip.

 

[Jr in Jax]

The best I got with the 225 Promax 225 ss was 95 GPS @ 6800 with 3 people and full fuel three times. With only 14 hours on the 300XS, the fastest I have been so far was 90.3 at 5000 by myself on a really rough/windy day [it was a little spooky]. With the 6350 redline I am expecting over 105 if I ever want to try it. It idles like a 4stroke, great fuel mileage and no smoke it really makes the boat more fun. Cruise speed is 73 @ 4000 RPM at 7 MPG. I just wish it could use 87 octane. I have sanded the lip very slightly and it now runs very flat with almost no trim which makes my Wife happy in rough water.

 

[dubmoney]

I just spent a week with at the Western Allison Rally, and ran mostly with Lars and Neil, and they both have 300xs motors. Lars on an xb21, and Neil on and XB2003. Both guys have been driving Allisons for 16 to 20 years. Needless to say they have there boats dialed in. I was envious of the way their boats ran. Neils xb2003 runs awesome!! He has an Giant Ultrex on the bow, loaded with fishing gear and I was wishing I could do the things he was doing. Granted, I have some work to do to make mine run at its potential, i.e. engine height, prop, and lip adjustments.

 

[whipper]

JR you make me envious and waiting until the day I make this engine swap also. 225 still lives so until then it works. It would be nicer to have a 300xs for water sports. Im sure the hole shot is unreal with the 300xs? What prop you running at 30? Oh wait let me guess a 30 chopper2?

 

[Jr in Jax]

James,
Right now the hole shot is only so-so so I went by Tim's at Performance Propeller since I had just gotten a new 32 Yamaha Drag 4 from him. He is going to get me a 30" Drag 4 [when the castings come in from Ca] that will match my 1.62 gearset better. He is also fixing my brand new 30" chopper II that was torn up when we hit the alligator in Dunn's Creek last month. The 32 runs great once it get out of the hole, I was giving rides at the rally with several people at 90 GPS.

 

[Jr in Jax]

He was talking about in the next two weeks. The castings are already overdue.

 

[whipper]

JR or Paul Question for ya about CLE 4 hole gearcases. My TM drive shaft has pitted so bad around the lower base seal its not worth sleaving and a new shaft is expensive. A buddy who i got the TM is trading me for the TM back as he has shafts and time to fix it a CLE 4 hole swept skeg case. Ive read a few things about them mixed reviews on Allisons. I will probably do the skeg mod but how would they be an a Grand Sport ya think? Ive heard about they blow out or something around 85 with out a cone to make them longer? Any thoughts on this? I could shave the blow out ring also to streamline it maybe?

 

[Jr in Jax]

The sleeve can be supplemented with epoxy filler for really bad shafts [like most of mine].

 

[xb03fs]

If you dont care about running over 95. The 1.75 gears on 3 liters work really well.