ExospeedAMcrx

I get this question alot and here is a comparision picture of both of the heads to help get an idea on this issue.

This is a D16Y8 combustion chamber


This is a D16Z6 combustion Chamber


Also for another comparison: the D16A6 head is similar to the Z6 combustion chamber, but here is one of our Exospeed heads with a welded chamber.

Spade

Great pics.


<---For those of you looking for great power in the upper RPMs out of the SOHC.

Z6 with the welded combustion chamber is the only way to go.

Aquafina

iTrader: (3)

Whats the theory behind this? So which one of the heads is better for power gains in what RPM range?

t0p_sh0tta

what are the benefits of a welded chamber?

ExospeedAMcrx

the welded chamber decreases the combustion chamber volume and increases the compression ratio of the setup.

-DC2-

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by exospeedAMcrx &raquo;</TD></TR><TR><TD CLASS="quote">the welded chamber decreases the combustion chamber volume and increases the compression ratio of the setup.
</TD></TR></TABLE>

because you're welding on the head, there's potential for warping. so, are new valve seats required?

kommon_sense

Here is a link with additional info on z6 vs y8

http://pub143.ezboard.com/fhon...topic

ExospeedAMcrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHCDX &raquo;</TD></TR><TR><TD CLASS="quote">

because you're welding on the head, there's potential for warping. </TD></TR></TABLE>

We have heads that have been welded since 1997 and still on the same block, never had problems after 100K miles. no we never had warping issues on any of the welded heads

-DC2-

on a stock internal z6, what CR will i see by having you weld the chambers?

i'm looking at other options of increasing my z6's CR to 12:1 with out large domed pistons (i will have a stage3 cam eventually, and i don't want to deal with valve/piston clearance issues)

also, what are the advantages of welding the chamber versus installing p29 pistons (if there are any)?

Marauder

Built a turbo engine for testing, and opened up a Y8 head to the open chamber like the Z6 head. Only added 2cc's to the combustion chamber.

-DC2-

yeah, the d-series CR calc says the diff in CC between the z6 and y8 head is 1.8cc/cyl.

even with pm6 pistons, 2layer HG and y8 head it only nets ~10.7:1

ladysman

I had to bring this back to life because of something I just recently noticed. I posted this first off:
https://honda-tech.com/zero...26986

Come to find out my head (which was originally ported by JG) has a welded combustion chamber. It is FOR SURE a Z6 head however.

My question is, is the sole purpose of welding the combustion chamber is to increase compression? By how much in general?

Guam_CiviC619

Taken from Sport Compact Car http://www.sportcompactcarweb....art4/

Some head specialists also modify the quench zones of the cylinder head's combustion chamber. The quench zones are the flat areas of the cylinder head where the piston comes in close proximity to TDC. Pentroof DOHC cylinder heads typically have four quench zones at the ends of the combustion chamber. Quench zones promote more complete burning and reduce the likeliness of detonation by increasing turbulence of the fuel air mixture as the piston comes to TDC by squishing the fuel air mixture toward the sparkplug and away from the end zones of the combustion chamber. This reduces the amount of fuel-air mixture near the ends of the combustion chamber where it does not completely burn (thus being wasted) by pushing or squishing it toward the centrally located sparkplug where it can easily be ignited. When heads have additional quench area, they normally need less timing advance to make power. Thus a skillful tuner can tune the engine to be further from the detonation threshold, making the engine more reliable.

The quench zones can be welded, milled and reshaped by hand to make them bigger, shaping the combustion chamber like a cloverleaf instead of the stock pentroof rectangle. This reduces the combustion chamber volume, increasing compression as well as making the quench zone more effective. This can also make the combustion chamber less likely to promote engine-damaging detonation because the turbulent air/fuel mixture squished by the bigger quench zones burns completely and smoothly. AutoPowerDesign's Stage 6 modification is a good example of a modified quench zone. In fact, AutoPowerDesign pioneered this technique for modifying four valve heads.