300 hp should be easily had by adding a set gm cast iron vortec heads and suitable intake for those heads and a mild cam. Comp cams make few marine grinds and the gm lt4 hot cam is also an option IF you are setup for a roller cam
Well, that's what many think to be the case.
Look at the RPM whereby the horse power rating is taken.
How many of us operate our cruiser engines at 5,200 rpm?
Fact is, the Vortec cylinder head still offers a "wedge" area, and is where we want the "quench" or "squish" to occur.
A full dished piston underneath the wedge, can not offer this.
Unfortunately, that's what we'll most commonly find being used in the GM SBC.........,
that silly, stupid, no good, worthless full dished piston!
Here is an interesting article by Jeff Smith on the Q/E.
It pertains mainly to HP Automotive, but the Q/E or S/E applies to Marine just as easily and effectively....., in fact, more so.
Since the Vortec chamber is only 64cc, we still need a piston dish volume in order to control C/R.
However, we can create a squish area by broadening the ring landing area, allowing it to "mirror" the wedge area......, as shown below.
Something similar to this piston can be used.
Now we can end up with both the correct C/R, and a Q/E, and take real advantage of the Vortec design!
On a technical note..... a proper quench will allow for a point or two higher on C/R and without further risk of Detonation.
This build equates to a performance gain, all due to one simple change to our piston selection.
Cost difference is minimal......, machine work and set up time should remain close to the same!
Let your camshaft supplier know of your piston/cylinder head selection.
Edit:
No offense to any of you full dished piston lovers!
This is simply my take on this based on some 45 years involvement witht the SBC!
Read articles by Dennis Moore, Jeff Smith, John Erb, Mike Nixon or even some of the Mopar experts!
The Mopar guys also know about the "Wedge" Head and what to do with it.
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