Rick and others reading this thread, I contacted the builder, and after research on their part,
they guarantee 9.3 C/R.
Are you not curious as to what Quench dimension are they shooting for?
One thing that I am learning thru this process is that it can be complicated! There is not enough information readily available.
Your shop should have all of the information that they need.
If not, perhaps this is not be the right shop to be building this engine for you!
I did more research on the heads, and it looks like from the information I have found these heads were a good choice, here is just on of the explanations of these heads that I found:
These heads were made from 1987-99 with 1.94 intake valves and 1.5 exhaust valves.
For a 6.3L Marine build, I wonder why the shop would suggest the small intake/exhaust valve diameter!
Combustion chamber size is 65CC,
which would offer you the ability to get a reasonable compression ratio with flat top or slightly domed pistons.
Open up an On-Line static compression ratio calculator and plug in your knowns.
Flat top pistons with a 3.750" stroke and with 65cc combustion chambers comes out to be approx 11.4:1, of which is far too great for Marine use!
I don't want to say that these heads have good flow characteristic other than they are noted as "swirl port" heads. There are no port volume statistics on them.
I did some quick research myself.
The g
eneral consensus for the #14102193 is:
.... production start date 1987
.... small valves @ 1.94 and 1.50
.... good for small displacement engine.
.... light casting.
.... good for up to 4,500 RPM only. (you won't be into this RPM range)
.... sometimes mistaken for the 14102183
Swirl port heads were on trucks and boats mostly. The swirl port design was created to provide good fuel mixing and more swirl pattern as the flow enters the combustion chamber. This improves the fuel burn rate with a more complete combustion resulting in less un-burned fuel in the emissions. The focus here was on emissions but the same rules for port swirl apply to performance engines as well.
If you use these heads for a performance engine and do any modifications to them, I recommend you take them to a professional if you want any port work done. Hopefully they use a flow bench in the process because without incremental testing the swirl characteristics can be diminished.
Keep in mind that these head castings are likely thinner than most performance heads so you're limited on how much mterial you can remove to improve flow. Consider that an old 461 casting from the 60's weighs 47lbs bare (no valves, and rockers). If you weigh each of these heads and they come in less that that, then you are dealing with thinner casting walls.
I think alotta ppl get confused & get #'s twisted around. Ppl read or hear that swirl ports are no good for a high revving strip engine & then translate that into swirl ports are no good for anything. The 193's actually outflow Vortecs up to approx. 3500 rpm,then the Vortecs pass them & keep going. A set of stock 193's will normally run outta breath by 4500. Of course, other factors can vary that by a few 100 rpm. For an average street cruiser in the 300 to 330 HP range,they can be a good budget head. Before Vortecs came about, they were the best production iron head from GM to date,except for LT stuff.
I found this information in several places.
I find it interesting that these Hot Rod guys change from one cylinder head to another (as to see what differences they make), but NEVER do you hear them talking about changing piston profile to accommodate the different cylinder head chamber volumes!