hello HT members.which 1 is best?? i curently have a 92 civic si with a d16z6 vtec and was wondering if their would be a noticeable difference if i would swap a d16y8, d16a6 or a d15b7 wit a d16z6 vtec head or would my current setup which is a d16z6 be best?? thanks alot guys..

 

or a d16z6 head on a d16a6??

 

any help guys?

 

If you already have a d16z6, stick to that. The z6 head with a y8 or a6 block combo has slightly higher compression, but you're digging a grave if you use the y8 (oil pumps suck). The only combo that will be a noticable power difference is going to a D15 block or non-vtec head - a decrease in power.

For the price, a used JRSC would be your best option. It would also be far less labor intensive.

 

truth...stick to the d16z6. they are tough motors and they run better than a d16y8 IMO

 

if this is your only "mod" you plan to do just stick with your motor and spend the money on some boltons or somthing, d16y8 block would actualy lower your compression becasue the z6 makes compression with a higher dome piston and high cc head volume the y8 has lower head volume cc and lower dome pistons if your gonna go with boost use a y8 block with a ported and shimed pump, arp rod bolts and head studs, and you have an awsome turbo motor that can easily handle 15psi provided you have a good tune

 

You must not have looked at P28 (Z6) and P2P (Y8) pistons side by side like I have. The Y8 has a smaller DISH (did you mean inverted dome?) yet a higher comp hieght, the combined result is still higher compression. THe Y8 head also has larger quench pads, which leads to a lower-cc chaimber - which obviously leads to higher CR. The Y8 head is also known to flow less, if you want to get real picky.

Low pressure is not the reason the Y8 pump sucks, shimming hasn't solved everyone's problems, sir. FYI shimming only helps with pressure after the bypass opens around 3k rpm. A turbo will 'steal' oil pressure from idle to redline.

And FYI rod bolts only help keep the rod endcap held on at high rpm's. 99.8% of D16 rod failures has been from bending under load, since you need SERIOUS mods to make any power above 8k (on a real dyno, not an *** dyno).