Just curious

Sitting here with it raining and a little bored I have been thinking about my next haulout. Hopefully I wont need to do any major engine work. I've noticed the cautions to the 5.7 guys about quench area and was wondering if this is a problem with the 454 BB motors? I see rebuild kits fairly reasonable with hypereutechnic pistons but not sure these would be a good option.

Doing some reading and may have answered my own question. Seems the 88 454/350hp motor used open chambered heads.

Mike, the SBC and BBC cylinder head combustion chambers are quite different from one another.

A Quench Effect or Squish Zone primarily applies, and is most beneficial, whereby the main combustion chamber is of a wedge shape and with a large quench surface off to one side.
This Quench surface must be "mirrored" by the piston deck in order to create a quench effect or squish zone.
The goal is to eliminate any areas for the gases to hide from the main flame front.


As for cautions pertaining to the SBC when used in a Marine application, one needs to understand that most of these OEM SBC being slated as "Marine" Engines, are fitted with a full dished piston.
The dish within this piston deck cannot possibly mirror the quench surface!
As a result, we end up with an area for the gases to partially hide from the flame front!
This exaggerates the potential for the dreaded "Marine load destination"!

The Marine industry's remedy for this is to hold back on Ignition TA (total advance).
The result is reduced "Detonation" potential, but it leaves us with a lazy LPCP!
(LPCP = location of peak cylinder pressure)
A lazy LPCP leaves torque on the table!

With the big block Chevrolet, you don't need to concern yourself with this.
However, any measures that can be taken that will help to force the gases out into the main flame front, will be nothing but a benefit to the Engine's performance!




Side note:
Detonation and Pre-ignition are two very different phenomena.
Ignition induced "detonation" raises it's ugly head in the form of second and third shockwaves, and high cylinder temperatures that perpetuate one another!
Detonation can be extremely damaging to the gasoline Marine Engine.

Side note #2:
I have heard people ask; "if the GM style full dished piston is not a good choice for a Marine SBC, why does GM and why do many Rebuilders continue to use them?"

The answer is simple, and it can be reduced to "bean counting"!
One piston part number fits all eight bores!

Depending on the style of piston, a more correct "quench" build requires 2 or even 4 piston part numbers.
This also requires the assembly person to pay particular attention to the assembly of the pistons onto the connecting rods.
Short of that, and paying attention to the piston deck height and compressed head gasket thickness...., no other changes are required!
For any good machine shop (who is worth their salt), this should be very easy for them to do!



And BTW, General Motors' very first series of SBCs incorporated a flat top piston.
The flat top piston created a quench effect in this series SBC.
General Motors screwed this all up in the early 70s....... but that is another story for another day!


The quench effect is also useful with the 335 series Fords, and the Chrysler wedge head engines!
The Chrysler Wedge Head boys have been using a Q/E for years!




.

Thanks Rick for a thorough explanation. I understand the concepts just not familiar with GM motors.