1999 2.5 200hp fishin motor modification?

[86vintage]

With the steel bore what is a the best to do when porting, without goin overboard? I was going to CC the heads to 145 Lbs combression. Bracato PCU. Looking for 62-7000 Rpm, someone told me not to spin a steel bore past 6500, is that true?

What did Mercury build these 2.5 steel bore out to for max stock HP was it 240 hp?
I heard the scream of 2.5 at 120 mph on the Ct river and now I am addicted!!
I can't trade out for a race motor cause I have 3-200hp steel bores. 1 Together and runin strong and two apart ready for me to get to business!

Any tips or expierences you've had would be apreciated.
Happiness is "trimmed out and runnin smooth and fast"
James
86vintagehttp://forums.screamandfly.com/forums/images/icons/icon14.gif

[TheRickster]

Do a search on here for "Port Map" .. John Has posted several port maps on here , 245-260, 280 as well as his 330hp map I think...

Rick

[Fish]

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=69958&highlight=2.5+mods

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=57686

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=56233

[86vintage]

Whats the limit with a steel bore. I will take all the neccasary steps to make sure it stays together but I don't want to build a granade - want a motor I can check yearly ie combression / leak down. Have a reliable steel bore. Curious what people spin a steel bore to (RPM)?http://forums.screamandfly.com/forums/images/icons/icon10.gif
Thanks for the lead!
James
86vintagehttp://forums.screamandfly.com/forums/images/icons/icon14.gif

[rhickox]

Depends on what material the pistons are(cast or forged). Rule of thumb has always been 7k on a cast piston and whatever you want to turn with a forged piston. There are a lot of considerations you need to make as to how much you want to spend and how fast you want to go. Probably best to talk with a reputable engine builder and let them make the decision. John Marles would probably be the one to talk to about a steel sleeve 2.5... BUT OTOH, 7K I think is the magic number for a GOOD CAST PISTON 2.5.... Hope this helps

[The Big Al]

The 6500 rpm limit on steel bore is a recommendation if you retain the oil injection.

7000 rpm steel bore all day long no problem. Just remove the oil injection.

[86vintage]

First thing to go! trin to get that racer look! Need to go back and freshin my mind with your reed valve shoot out - That was a great! I appreciated that work you did.
8k the place to be max - OK.
Merc Builds the 2.5 steel bore, out to what HP?
Thanks,
James
86vintagehttp://forums.screamandfly.com/forums/images/icons/icon14.gif

[us1]

My steel bore Mod-U race motors turn over 10,000 RPM and can make around to 360 HP.

[rhickox]

I wouldn't be turnin no cast piston 8K very long.:eek:

[us1]

Forged pistons are a must for high RPM.

[rhickox]

Top Pinned ones at that!!!