3.0L Mercury on xb2002????

[garrett24]

Are there many people running 3.0L on an allison xb2002? I am inquiring for a friend who has an allison with a 260 on it but he has a 225 proxs with a sporty that he is wanting to put on the allison.... his main reason for the swap is reliability. He is always having to work on the 260 but the 225 is very reliable with low hours. He has looked into having the 3.0L cut down to help with the weight and on handling but is this a disaster waiting to happen? All help and advice is very much appreciated. Thanks

[RNM018]

They Rigged them with 3.0 OMC's , so weight wouldn't concern me .
My issue would be hitting the rev. limiter , with it strung out !
Not sure what the boat might want to do at that point .



Rich Martin 018

[David]

3L OMC was 450 lb, 225 Pro XS is 505 lb

I would not run a DI 3L on my SS, but that's just me.

[baja200merk]

Arent there heavy layups and light layups? Just move some weight up front to keep CG the same or close.

[john w]

Allison's don't like weight !!!!

[props4u2]

The XB-2002 is not a good canidate for the heavier engines due to it's narrow beam.

[albypine]

The XB-2002 is not a good canidate for the heavier engines due to it's narrow beam.
Why say that ? Has anyone tried less set back and more weight that kinda =more set back and less weight ... Or am I wrong for thinking out the box ?

[cltch]

I have no pony in the race, but it seems the gear case and rev limiter are more the concern as long as you use a short mid section to get the cog down. I'm just abbreviating what some have said on allison owners regarding this.... I currently don't have the funds, but would love to run an 02 or 03 with a larger motor.... You might want to search around over there...

[whipper]

Weight is a concern on any light hull. A non ratcheting gearcase would be one thing that would be rough. Comming of high speed with a 30+ pitch parachute isnt a good thing when your trying to drop your bow slow comming of speed with an Allison. Cutting to a 15 inch mid would be a great pluss with any 3.0 on any Allison. Light cowl like Mike Nasses also would be a good thing. You could probably get the lbs down to 450-460 or so with a little efford and a few more bucks. Bushes flywheel ect... A real good thing might also be one of DBR kits with a 7000 rpm limitter. You could lessen the parachute effect with the non ratcheting gear case buy running lesser pitch props that way. Another thing would be to run a 2.5 gear case that ratchets if theres adaptors available? Run with inflatable flotation in the setback to off set the idle stern depth and take off squat in the stern. Move the gas tank forward 5 inches or so to help with CG balance. Less setback as mentioned for sure. Anything is doable. You just have to use common sence more when trying speed runs. Theres lots of guys running smaller lighter high flying pad vee hulls than Allisons with 250 and 300XS or DFI power and loveing them. You just have to be very well aware of all the inherant dangers when doing this kind of upgrade. Not as safe as a 2.5 but theres bennifits to doing it. So I would try it if I had the funds to setup my GS that way for sure!! As you can see ive never given it any thought at all.:D

[baja200merk]

Weight is a concern on any light hull. A non ratcheting gearcase would be one thing that would be rough. Comming of high speed with a 30+ pitch parachute isnt a good thing when your trying to drop your bow slow comming of speed with an Allison. Cutting to a 15 inch mid would be a great pluss with any 3.0 on any Allison. Light cowl like Mike Nasses also would be a good thing. You could probably get the lbs down to 450-460 or so with a little efford and a few more bucks. Bushes flywheel ect... A real good thing might also be one of DBR kits with a 7000 rpm limitter. You could lessen the parachute effect with the non ratcheting gear case buy running lesser pitch props that way. Another thing would be to run a 2.5 gear case that ratchets if theres adaptors available? Run with inflatable flotation in the setback to off set the idle stern depth and take off squat in the stern. Move the gas tank forward 5 inches or so to help with CG balance. Less setback as mentioned for sure. Anything is doable. You just have to use common sence more when trying speed runs. Theres lots of guys running smaller lighter high flying pad vee hulls than Allisons with 250 and 300XS or DFI power and loveing them. You just have to be very well aware of all the inherant dangers when doing this kind of upgrade. Not as safe as a 2.5 but theres bennifits to doing it. So I would try it if I had the funds to setup my GS that way for sure!! As you can see ive never given it any thought at all.:D

Greg Dunham (aka RRRevinrude) runs an xr02 with a 3.0 OMC and a non ratcheting case. Well over 100 with a 30 it did nothing funny when he let out.

allisons dont like weight but they make a River racer and a comp version. If you put a 3.0 on a comp and move the batteries etc. to the bow wouldnt it weigh the same as a river racer w/ a 2.5 and have the same cg. I dont understand how the boat would know the difference :confused:

[bep078]

The 3.0L Merc will not only increase weight on the stern but will also have a higher center of gravity which on a light boat will have a more then proportional increase in stability issues when compared to a heavier boat.

[john w]

A 3.0 L OMC weighs around 450 lbs, thats not to bad. I tried a 3.4 L Etec 250 HO about 525 lbs on my ally xb2002 comp, the boat would not air out properly. The ass end never lifted correctly. Darris, said it will not work, that's it, would not discuss at all.

[XstreamVking]

Or put a 2.5 200hp opti on it. The 200's are really closer to 220 hp and are 430#s I believe....Run what ever gear case you want and get reliability and good performance/

[ssv1761982]

I tried it on a xb2003 and did not like it. I came in to 5.5" setback. The rub rail was under water. I didn't put much effort into moving batts and other stuff. It just felt 'pig' like.

[Ted Stryker]

The potential problem cannot be fixed with any modification of weight forward or aft... The problem is the high CG during an aggressive hook or an aggressive intentional turn, and potentially rolling the boat over..

I have rolled an xb02 up vertical on it rubrail in a 40 mph intentional turn, it was knife edging to the point the gear case was dry and I acually fell out of the seat and into the drink.. I came up to find my boat stalling down, but due to some weird little damages I can't be 100% sure it didn't roll over while I was eyeballing fish -- although I think it was just extremely close to rolling...

In the even that it had a higher CG by 1 billionth/gram I'm certain it wouldve rolled for sure... A guy may operate one rigged as such for 2,000 hours without any mishap, but all things we have to weight out the risk...

Your gonna find alot of different opinions by asking a mixed crowd and I'm in that broad generalization also, but the man that has forgotten more than any of us have learned yet warns against it... The history sheet of Allison Boat.Co states that I have no grounds to second guess what they didnt have to guess on...

[whipper]

Greg Dunham (aka RRRevinrude) runs an xr02 with a 3.0 OMC and a non ratcheting case. Well over 100 with a 30 it did nothing funny when he let out.

allisons dont like weight but they make a River racer and a comp version. If you put a 3.0 on a comp and move the batteries etc. to the bow wouldnt it weigh the same as a river racer w/ a 2.5 and have the same cg. I dont understand how the boat would know the difference :confused:

Im just saying the optimum setup. Like Ted said the {high CG} for roll over hence {why I said carbon fiber cowl and 15 inch mid}. That brings all that down. I also am not disputing running the non ratcheting gearcase because alot of my friends run stock XS 250 and XS300 mercs on there Allisons and like them. Theres no problem comming of the throatle at 100mph with a non ratcheting gearcase slow. But Ill bet you money your buddy doesnt chop the peddle from 100 with a 30 on. He eases out for a bit and knows when he can and cant lift the foot. Theres lots of guys with Allisons that can chop the gas from 90-100 with a ratcheting gearcase. Mine included. Ive also like Ted drank the water beside the helm on my GS and thats was with a 360lb 2.5 on the back. I all for experimentation. Thats why we are mostly hear. But {WHEN} I strap a big block 3.0+ Merc,E-Tech,or Yamaha 300 on the back of my GS, those are some of the things i would be looking at after many years of reaserching the does and donts and Talking to Darris and many others about it. Anything is Possable. The main reason for Darris putting out the warning is for liability. Because he knows not everyone will take the extra percations that make doing this a little safer. Know ones saying it cant be done.Garret asked for opinions so thats mine:]