Difference between merc 260hp to 230hp engine?

[hoverman]

I have a 1991 merc 5.7l v8 alpha 1 gen 2 and the dealer told me the serial # indicates my motor is a 230hp model. What is the difference between my 5.7 to a 5.7 that is rated at 260hp????

 

[Bondo]

Re: Difference between merc 260hp to 230hp engine?

Donno,... What is the difference,... 2bbl. Vs. 4bbl. Carb,..?? I think the EFIs were rated higher...

 

[hoverman]

Re: Difference between merc 260hp to 230hp engine?

mine has a rochester 4 barrel carb on it...are the merc 260's fuel injected???

 

[fyrfightr]

Re: Difference between merc 260hp to 230hp engine?

Possibilities,,
Older Merc 260hp was rated at crankshaft, yours should be rated at propshaft.
Newer engine are Vortec giving more HP.

 

[John_S]

Re: Difference between merc 260hp to 230hp engine?

You will have to spend some time on MercruiserParts.com and MercuryPartsExpress.com and try to find the differences. It might be just the intake manifold, carb jetting, and timing curve. Check the cam part numbers. I have seen people mention that, but I never saw a different cam part number to support that.

First varify what you really have at MercuryPartsExpress.com by entering the serial number. By '91 Mercuiser had changed model names to 5.7L (2 or 4brl), LX, and Magnum. The earlier 230 model ended around '86. That would have had valve cover bolts around the outside edge vs the center bolts of the newer engines.

FWIW: Most carbed 4brl 5.7LX and 350 Magnums were rated 250HP at prop. Vortec heads did not come out to '96. I don't think TBI or MPI was available in '91.

 

[thundercraft260]

Re: Difference between merc 260hp to 230hp engine?

I have a 92 merc 5.7L magnum 4 brl...and VIN indicates a 260 hp. I know for sure as I had a complete rebuild done on it back in June.

John

 

[John_S]

Re: Difference between merc 260hp to 230hp engine?

I have a 92 merc 5.7L magnum 4 brl...and VIN indicates a 260 hp. I know for sure as I had a complete rebuild done on it back in June.
John

If you look at service manual #17 which is for your vintage, it only indicates 250HP. 10HP would not be a very noticeable difference, and within the variance range of the rating system, anyway. 350 Magnum was more marketing than performance over the 5.7LX.

 

[hoverman]

Re: Difference between merc 260hp to 230hp engine?

according to mercury parts express they decode my engine serial # 0d612561 as a 5.7l 260hp mag alpha/bravo ...so it looks like i do have a 260 hp engine???

 

[John_S]

Re: Difference between merc 260hp to 230hp engine?

Can you tell if it has the high-rise dual plane intake manifold vs the low-rise?

 

[hoverman]

Re: Difference between merc 260hp to 230hp engine?

im new to boats i dont know even know what a high rise dual plane intake is??? can you shoot me some clues as to what to look for????? i really appreciate everyones help

 

[John_S]

Re: Difference between merc 260hp to 230hp engine?

im new to boats i dont know even know what a high rise dual plane intake is??? can you shoot me some clues as to what to look for????? i really appreciate everyones help

One is higher than the othr, but without a reference...
I don't remember the casting numbers, either.
If you remove the cover and flame arrestor and take a picture from the side, I could tell you.

If you are just being curious, than it really doesn't matter, just go out and enjoy the boat. If you are loking to make some upgrades, then worth some more discussion.

 

[hoverman]

Re: Difference between merc 260hp to 230hp engine?

i will take pics this weekend and post them

 

[captainmas]

Re: Difference between merc 260hp to 230hp engine?

I'm not sure, but I will ask my rebuilder as I have 351 fords that are 233 hp , but after the rebuild I will have 260/265 hp. My guess is the cam.

 

[John_S]

Re: Difference between merc 260hp to 230hp engine?

I'm not sure, but I will ask my rebuilder as I have 351 fords that are 233 hp , but after the rebuild I will have 260/265 hp. My guess is the cam.

But we are discussing a GM 350 -5.7L Gen I, and not a Ford 351 winsor.

 

[Don S]

Re: Difference between merc 260hp to 230hp engine?

In 1991, the prop shaft horse power of the 5.7 MCM engine with an Alpha I Gen II outdrive was 230hp. There was no 260hp ratings of the crankshaft.
In 1990 however, they had ratings for both Crankshaft and Propshaft, which was 260/230 respectively.
Same exact engine, just different rating systems