HP on Marine Power engines

[adamsjstt]

I have the MP340 HP in my RZ2 and am curious what MP does to there engines to produce the 360 HP engine. Is it as easy as replacing the cam or more like bored out cylinders? I believe they both use the same block right?

[chpthril]

I think its the same displacement, so bore and stroke are the same. It can be as easy as tuning the ECM to get a few extra HPs, but I do not know exactly what MP does to get more out of the same 5.7L engine.

[dom w. forte]

I was told that they changed the rocker arm to rollers and changed the ratio to increase cam lift, and that gave them 20hp.

[adamsjstt]

I was told that they changed the rocker arm to rollers and changed the ratio to increase cam lift, and that gave them 20hp.

Would 20HP be worth the cost to change out the rocker arms to rollers?

[Timmy!]

That 360hp is also a closed cooling system engine too. A nice set of roller rockers in a 1.6:1 ratio will be about $160. It might rev a little smoother/faster with some good rocker arms. They may already have 1.6's in there, hard to tell.
http://www.summitracing.com/parts/CCA-1605-8/?rtype=10

If you change them out, you might want to replace the push rods and lifters too.

[dom w. forte]

The 360 hp that we saw were not closed cooling.

[chpthril]

Wasnt the standard closed-cooling engine like 385 or 390 HP and was the 6.0L block?

[Timmy!]

Oh, I thought the 360HP was the 6.0L closed cooling engine. My bad! Sorry for the confusion.

[adamsjstt]

Ill wait to see how the performance is with ballast and 10 passengers but it seems reasonable.

[dom w. forte]

The 6.0l is closed cooling, thats what powers my 20i ski team boat, they were 380hp until 2005, and then went to 400hp and now PCM, is 409 and 450.