1996 Johnson 200-250 question. Can I make a 225 into a 250?

[cobbcfi]

I am in the market for a new powerhead and when ordering one it looks like the powerhead can fit a 200/225/250. What is it about my 225 that I can change to make it a 250? Is this possible and or worth it? It is in fact a 25hp increase.. Just wondering

 

[Faztbullet]

Carbs and porting..even though they list it will replace a 250 and it will the output will be low. The carbs have bigger venturis and ports are same as 225HO spec

 

[cobbcfi]

So I would need to buy a new set of carbs? Is it worth the money for the 25hp?

Oh I understand your point now I think.. Even though it will replace a 250 or a 200, if installed into an original 250 setup the output will not be the same as factory original whereas if installed on a 200 the output would be more than original? Is that correct?

 

[dingbat]

So I would need to buy a new set of carbs? Is it worth the money for the 25hp?

i looked into this on my 200.

My 200 measured 216 on a dynamometer. Buying a set of 225 carbs would net me 14-15 hp. Not worth the money imho

 

[cobbcfi]

Well I have never done anything with this motor and it has been flawless for 14 years.. That includes the carbs that have never been touched yet the bottom left carb was spewing oil/gas mix during normal operations but I am the kind of guy that "if it's running, don't fix it".. So if I head down the road of an obvious remanned powerhead, I might as well either rebuild/tune the existing 6 carbs or buy a set of carbs rebuilt that would make it a 250hp? I am going to spend the money anyways, should I go ahead for the 250hp or am I spending money for nothing?

By asking the question I think I already know the answer, stay the course and get my 225hp up and alive again but if the changes and costs to make it a 250hp are not so outrageous then I guess it is more of an extension of the "*****" for me to change the 225 decal to a 250 decal on the engine cover and show everyone that I have a 250hp.. Not that I really care..

 

[jimmbo]

You may also need a new exhaust tuner

 

[Faztbullet]

They don't have a tuner as the exhaust runners as cast into block..

 

[bob johnson]

They don't have a tuner as the exhaust runners as cast into block..

so how much of the extra 25 hp...comes from port differences? ....and just for comparison....if a guy just replaced his 225 carbs with 250 hp carbs...what would he gain...if anything at all??

I realize the result of the extra 25 hp comes from GETTING MORE MIXTURE IN< and GETTING THE RESULT OUT in combination


bob

 

[dingbat]

The hardest part of converting your 225 to a 250 is adding the two additional cylinders.

The 250 is an 8 cylinder. The 225 is a 6

 

[Faztbullet]

They make a V-6 250 maybe not in 99.....A 225H0 is a 250 with different cover as its 255-265hp at prop...As for swapping carbs it may have give a little more mid range grunt but would be to rich at WOT and need to be leaned out....

 

[cobbcfi]

So why does all of the "remman" builders list it for a 1996 Oceanrunner as either a 200hp/225hp/250hp. I am assuming it has to be the same block just different carbs.. What am I missing?

 

[dingbat]

1998 was the first year they made a 250 hp v-6. 1996 and 1997 the 250 was a V-8.

perhaps a 250 v6 block will fit a 1996 lower unit

 

[Faztbullet]

The V-6 and V-8 have the same foot print......As for listing as the same that up to reman company, as for real world there is a physical difference​

 

[jimmbo]

They don't have a tuner as the exhaust runners as cast into block..

What about the megaphones which extend down into the midsection? These are bolted on below the block

 

[Faztbullet]

What about the megaphones which extend down into the midsection? These are bolted on below the block

That is a exhaust can.. a tuner is like pic below......

 

[jimmbo]

Those are the megaphones, one for each side of the engine. sure don't look like they are cast into the block

 

[Faztbullet]

The v-4 and v-6 loopers use a foam cast block and the "hump" in the block is the cast in runners...each cylinder is tuned and that why they don't have a turner attached to bottom of adapter plate.The crossflows v-6 do use a tuner due the flat back exhaust as do Merc V-6"s

 

[cobbcfi]

Ok, sounds like I'll just stick with the 225...