what would be the difference between stock 225 3.0L EFI heads and 250 xb heads?
what would be the difference between stock 225 3.0L EFI heads and 250 xb heads?
The primary difference as far as I know is the CC. The 225 has CC of 73 and 250 XB has CC 0f 68. Hope that this helps.
so would the 250XB heads be a direct bolt on to a 225EFI? and how much benefit would come from the raise in compression?
Yes, they are a direct bolt on. Not sure as to a significant benefit without other mods as well? Not sure if anyone on BBC has tried that mod alone? If so, perhaps they will chime in? I would imagine that a little more compression would not hurt. Perhaps a little more "grunt" on the low end and mid range? There are a number of members here who have modded a 225 3.0L and seen major improvements. A number of significant steps though and a few(??) $$ invested. But, who does not to go a little faster? LOL. Just remember though, as the mods are implemented, you will be going from use of regular octane gas to premium.
well my motor was fitted with a brucato svs intake by the previous owner, and i have a fairly slow hull, so any further gain might be worth the effort.
I personally think that a compression increase (via heads) is one of the best "bang for the buck" improvements you can make. And yes- you would need to convert to high-test fuel in doing so.
That being said... I'm not one that modifies engines. Would be a very good idea to speak with Eric Simon... he's very familiar with 3L mods (that's his business)!
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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If I were going to changes heads, I would invest in a set of 300X heads, unless you have a buy on 250 XB heads.300X heads have a little smaller combustion chamber than 250 XB heads. You're going to have to run high test pump gas anyway, so you might as well take advantage of it. I've been running 300X heads on my 225EFI for three years without a problem with 91 octane fuel. I've read the plugs and piston tops numerous times during different times of the year, and show no lean symptoms at all.
Another option is to have your heads cut.
"Better to remain silent and be thought a fool than to speak out and remove all doubt."
how much gain did you see with the 300X heads, and what should i expect to pay for a set?
Are the heads, 300X or 300 PM found in the EFI motors? Just curious. Thanks.
You should look for a set of 300 promax heads, the 300x heads would make the compression to high. What year motor do you have?
1996 225EFI all stock except the svs intake. eric, i'll give you a call this week.
300 Pro Max heads. Be sure you have carbon fiber reeds or the motor won't live long. The 96 EFI did not have a good exhaust tuner set up. You may want to do something like a 300 tuner also to let it breathe.
Richard
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