Xtremeracing

Stock RPM is 5450 , the newer motors that merc is building now ( newest generation) have been as high as 610 hp could be more but thats what I have seen.

thirdchildhood

iTrader: (6)

So you are running them right at the rev limiter? I am tachless right now until I get the AGI box and wiring sorted out. I am bumping the rev limiter warning horn on a good day though. I have been told to run my 525 at 5,400 rpm. Mine is an '07 vintage engine, I don't know what upgrades have been done since then. 610 hp!!

Xtremeracing

There is a lot that can be done, but the biggest thing to get the HP is to take it to 510 CU and the intake. Porting work to the intake and better air flow would be the best bang for ur buck .

BRUCE SEROFF

I was led to believe The HP is rated the prop shaft, not flywheel . so 525 at the prop should translate to around 550-560 at the flywhee.

correct me if im wrongl

onesickpantera

iTrader: (1)

Mercury makes this clear as mud. The mercury racing engines(aka blue engines) are rated at the crank, HP500 was rated at 500 at the crank and 470 at the prop. The Mercruiser engines (aka black engines) were rated at the prop, 502 mag was 415 pshp.

The confusing part is the blue engines always put out more hp than advertised and the black ones put out less. So, in reality the blue hp figures seem to be closer to the pshp and the black closer to cshp.

The 525 came along and had much higher hp than advertised and made it even more confusing. I assume they rated it at 525 to avoid hurting the 600 sales, as hp was down on those the first year(or maybe two?)

I have never heard of a 525 making 610hp stock. Most dyno sheets show 540-560.

2 Trick Rick

Depends if that Flywheel is aluminum or not..

Xtremeracing

The new generation hand built 525 are coming from Merc at 600 and better. SBI had 2 sets of SCL motors dyno after the Worlds in 2010 and both were just a little over 600 and both stock. Not really sure what the changes are but they are making more HP, we tried to find out and had a few ppl look in to it. Same parts so not 100% sure just what has changed.

thirdchildhood

iTrader: (6)

ECM programming maybe?

Xtremeracing

The ECM does not cerate HP all it really does it cerates RPMs. There has been a lot of dyno testing done on motors and they make the same HP with or with out the hot ECM. The advantage is that u will get better respone in the rouch u can run a small wheel at higher RMP and still run the same speed as u would if you only turned it at 5450.

Xtremeracing

An alum fly wheel does not create HP but it does help in acceleration. The only thing it does is allow the engine to spin easier being lighter and that will give u more acceleration, but not more HP.