OK I have a few question I have heard a multiple amounts of answers on this in different threads and such so I figured I would get all the info in one post....So here it goes....

OK out of the A6, Z6, and the Y8 which block is the best?

Out of the Z6 and Y8 head which one is better? Which one flows better that is?? Also is there another head that out flows either of these? I am talking SOHC vtec heads only here also well unless someone says that the A6 head flows better than the other 2 that is?? Or possibly another head like the Y7 maybe??

And I know that the Y8 intake manifold is the best out of the 3 as well so mainly I want to know which block out of the 3 is the best in stock form and which head is better also in stock form.

And another question I know that the A6 distr will bolt right up to the Y8 head and it has to be modified to fit onto the Z6 head but anyone know how the Z6 distr will bolt onto the Y8 head?? Same type of mods needed or? If I do decide to do a mini-me I want to swap over to obd-1 so I would have to use the Z6 distr right? or could I use the Y8 distr?

 

The d16y8 head has pentroof-style combustion chambers with generous quench zones. The quench areas help improve combustion, reducing the need for as much advanced timing and reduces the propensity to detonate. The 1992-1995 SOHC VTEC head had a circular combustion chamber that does not work as well. The newer head also raises the compression ratio by a half point.

 

taken from endyns forum:
"Dipstick is located on the side of D16Z6 blocks, while it's on the front (through the oip pump casting) of the Y8's. Aside from, that, I don't think there's any difference.
Best combination for flow is the Z6 head with the Y8 manifold."

also dont the z6 &y8 blocks have oil squirters for the pistons? where the a6 doesnt. also there is no good place to bolt a knock sensor on the a6 block...im sure it can be dont but no holes are currently the right size for a honda knock sensor.

from what ive heard the y8 head has a better cam then the z6. i think you can put the y8 cam in the z6 just have to use the y8 cam gear too (its different than 88-95). the y8 intake has angled dividers while the the z6 intake path has straight dividers. this helps the z6 breath better up top, while the y8 may have better swirl but diminished flow. as far as CR the chamber cc's are as follows:
a6 - 38.0cc
z6 - 34.6cc
y8 - 32.8cc
y7 - 34.6cc
you can always increase the quench pads by milling head, decking block, welding the head or using aftermarket pistons designed for this (ie: endyn/wisco).

depending on the head/piston combination the valve angles might not be right and the valves could hit the pistons if the valve reliefs are not in the right place. (ie: the p29 pistons are designed so the valves from a d16a1 head wont hit, so there is no guarantee that the valves from a d16y8 head wont hit if using the p29 pistons in a y8). as far as valve angles on any of the heads, i am not sure if any are the same or different, ive just heard to watch out for that. so if running high compression, always clay the combo.

always use the y8 headgasket, its 0.037" thick versus the a6 0.048" HG. the z6 is the same thickness as the y8 but twice the price from honda.

the y7 head has 1mm larger valves then the a6, also the smaller cc chamber. but i am not sure which will outflow the other. also i dont think the cams are interchangeable.

the y8/a6 and i believe y7 distributors bolt up the same. the z6 is different and doesnt fit without mods. but any other 92-95 obd1 dizzy (lx, dx, etc.) bolts up to the y8/a6 head. the y8 obd2 can be used as obd1 if your going with a p28 ecu.

as always dont take my word on everything, im just regergitating alot of info that i have found online. some is true and some may just be peoples opinion.


Modified by fastcrxsi90 at 2:21 PM 9/10/2003

 

Anyone else have things to add?

 

Z6 head better for turbo... Ported Y8 head flows the best out of all though. A Y8 chamber is much like a GSR chamber, whereas a Z6 chamber is much like a B16A, so I've heard. Also, the Z6 blocks are beefier than the Y8 blocks. There was an awesome writeup on the D series message board, maybe do a search on there. Stock for stock a Y8 head is better though.