Want to convert Merc 1150 to 150 HP

[ben3843100]

Hello, <br />I have a 1975 Mercury 1150 I6 that I just toasted. (Overheated) I want to order a new powerhead for it and am wondering if I can convert it to a 150 HP by ordering a 150 hp powerhead for it. I assume I would have to rejet the carbs for the higher output engine, but are there any other differences in electrical systems, distributor, etc? Are the carbs totally different? If I'm going to put money into the engine I'd like to upgrade it in the process. Thanks in advance.

 

[The Marine Doctor]

Re: Want to convert Merc 1150 to 150 HP

You would be better off to buy a used 150 V6 engine. Rather than rebuild or repower with an inline Tower of Power.<br /><br />TMD

 

[briannh1234]

Re: Want to convert Merc 1150 to 150 HP

Ben -<br /><br />I have 2 of these engines apart right now. They look identical on the inside. The one difference I have found is the throat (opening) on my 140 carb is bigger that on a 115. I have been told that there is also a piece of the exhaust that goes in the center section that is different. I can't confirm the center section thing right now - the other center section is in Maine.<br /><br />I don't think you can modify 115 carbs to make 150 carbs. It would require machineing.<br /><br />If you must pursue this path than I would recommend that you look around for a totally blown (not rebuildable) 150 block that someone is willing to sell for parts. (including carbs)<br /><br />Good luck<br />- Brian

 

[briannh1234]

Re: Want to convert Merc 1150 to 150 HP

I took a closer look at the carbs I have. The opening's look about the same size. I could have sworn they were different... <br /><br />I checked my manual and it does show different jet's for different HP models, and different altitudes. At sea level the jet's go from .070 (90HP) to .082 (150XS short shaft). At the bottom the manual note's that some engines may have either .082 to .084 as standard. (140 and 150 long shaft).<br /><br />As for other differences between HP model's - I don't know. I have not found any yet. There may not be any difference with the exhaust either.<br /><br />If you decide to try this, let me know how it turn's out. Jet's are cheap compared to buying a bigger motor.<br /><br />Good luck..

 

[P.V.]

Re: Want to convert Merc 1150 to 150 HP

You should purchase the new "up-date' kit to do what you are seeking to do. The part number is "150 ELPTO" and it costs about $7700.00 Just thought I'd bee a smart-*** ! BTW, If you don't want any problems... stay stock! And unless you have too much money, time and patience, .... stay stock!!!

 

[briannh1234]

Re: Want to convert Merc 1150 to 150 HP

P.V.<br /><br />I am curious about your opinion.<br /><br />Do you know of some other change between the 90HP and the 150XS model? Do you know someone who has tried this? The manual I have shows shows them as all having the same displacement. Same proceedures for servicing all of them. It seems something should be different or all the original owners of these engines paid a lot more for a higher HP engine that just has different jet's.<br /><br />It is true that I don't have any money to waste on this. If you know what could go wrong, please let us know, before I order jet's and explode my motor. <br /><br />Thanks<br />- Brian

 

[mellowyellow]

Re: Want to convert Merc 1150 to 150 HP

upgrading from 115 to 135 is lots easier and more<br />reliable IMO.<br />good luck,<br />M.Y.

 

[Chinewalker]

Re: Want to convert Merc 1150 to 150 HP

The 150s were really quite refined - had to be to get that much power out of 99-cubes on a reliable basis. There is not easy bolt-on upgrade from 115 to 150. Much more attainable to go to 135 specs as per MY's suggestion...<br />- Scott

 

[P.V.]

Re: Want to convert Merc 1150 to 150 HP

Undoubtably, there are more differences than just carb jets and venturi sizes. Port sizing, height, and exhust tuner MUST also be consider'd. Really, you can install bigger carbs, etc... but you will AT LEAST have an engine that will not idle, difficult to accelerate, no top end...... you pick what features you want or don"t want and we will watch you post your problems here on the internet!!!!!!!!

 

[Mercury140-I6]

Re: Want to convert Merc 1150 to 150 HP

Hello:<br /><br />I had a 1979 Merc 115 and changed the Powerhead to a 1979 140 with NO problems at all. As long as you are staying with the distributer model, you shouldn't have any problems. Go on E-Bay and but some 1500 carbs. I have seen them on there ALL the time. As for mounting the block on to the mid-tower. ALL the inline 6 engines used the same bolt pattern and as long as you can get the same year, there is no worry about something not fitting. Your 1500 was only putting out 90 at the prop. The 1500 should get you about 135 at the prop. And remember that Mervury usually under rated the hp on these engines.<br /><br />Hope you get what you need to do this, and have fun with the new powerhead.<br /><br />Craig