SBC Vortex heads
 

Has anyone CC'd the combustion Chamber on stock cast iron 6.2L Mercruiser Vortex Heads? Would like to install some aluminum heads for better flow with out increasing/decreasing the compression ratio.
Thanks

The Vortec heads have a 64cc combustion chamber.

An engine with a small duration camshaft and one with under, say .510 lift, won’t really make anymore power with a different head than the Vortec.

The GM 86-95 center bolt tpi heads, well, very different story.

The 906 vortex head has about 63cc/ 64cc. The site One Dirt did an article in 2010 saying that the heads support 480hp out of the box.

I read that article two days ago. Very interesting, but skeptical of the 480 HP potential. My understanding is that the intake flow with the valve opened at .500 on a stock head is around 197 cfm and exhaust at 128 cfm. That equates to a flow of 65%. Using these numbers, the head has a Potential of 409 HP. BUT when you take into account the 64%, the actual HP is much lower..

Of course I don't have a flow machine and I'm taking the word of someone else flow numbers. It's a shame that One Dirt never posted the flow numbers of any head. That would have been an eye opener... Thanks for your time. Great article....

So SB, your saying that a vortex head that flows at, lets say 64% and an aftermarket head that flows at 80%, there will be no change in HP with the came cam? Either way, would I have to remap my ECU if I changed to an aftermarket head? I have know Idea what the lift is on a 6.2L 320 hp engine is. Do you? This is what I have. A Mercruiser Camshaft 862562T1. Same cam found in Black Scorpions.

IMHO I think we may be missing something obvious. Application, a near 500hp output may be possible but at what rpm? ( hot rod article says 6200 rpm )I'm guessing the conversion should be more about torque at around 5000-5500 rpm( re hot rod 405hp at 4900rpm). . And in addition the cost per hp, if it cost $1500 to swap even cheap heads and the make 10 hp at maximum speed is it really worth the effort? Just thinking out loud.

This is what we (oso peeps) feel is used as the Merc cam:
https://www.offshoreonly.com/forums/...-cam-spec.html

That thread is inquiring about a cam part number 86602T01 which he says equates to the 395 cam because he checked it.

As you can see my part number is different. Also my engine is stroked with a 3.75 crank making it the 6.2L 377 cid.

It did mention the comp cam that I'd like to put in my engine. That's the reason I wanted to compare the two.

Dave,
One thing that nobody else has mentioned is the fact that if you go with an aluminum head you should be able to bump the compression up some and still use the same fuel. That will let you use a bigger cam and use the extra flow. Otherwise I think you are wasting your time switching heads.

Billk,

The engine is supposably at 9:1 compression now. And there isn't much non-ethanol gas at 90 or 93 octane. So I'm looking to keep the heads at the same combustion chamber CC, put better flowing heads on and a better cam. Hence why I was hoping someone with no part number of my cam and give me specs. So I can compare.

And then there is the weight savings from going to aluminum. 100 lbs off the ass has to help in its self. 292's are ass heavy.

Not sure how that has anything to do with it ? Octane is Octane, period. We have had nothing but 10% Ethanol fuel here in my area for at least 25 years now. It simply has not been an issue except maybe in equipment that is stored for very long periods of time (2-3 years and more ) without being run.

What BillK is trying to tell you, is that you can get away with a higher compression ratio and still be safe with the aluminum heads. One attribute being they dissipate heat better.
Research it a while.
And not sure you're going to find anyone on here with the specs to the cam number you've posted.
The typical response to all the 6.2 upgrade threads is; Leave it alone.
Not many people fool with the 6.2's other than just run them.
Mostly because they pretty much need a complete redo so to speak.

BTW, what do you plan to do tune wise, exhaust, if and after you do swap heads and cams?

Link to one of the best 6.2 builds on here, probably the only one. LOL
Even if you're not going that whole route, It's informative.
https://www.offshoreonly.com/forums/...d-project.html