Z6 head on a Y8 block -- It doesn't run right, advice appreciated!
 

I built the motor a while back, after I lost my z6 built bottom end to a vitara wristpins C clip that decided it'd rather spend time in the oil pickup then on the pin.... Bottom line is, the old motor specs were as follows:

"stock" z6 with eagles / vitaras / titanium valesprings + retainers / drag mani / tial 38 / t3/t4 .48 57 trim / uber / 450's / walbro 255hp

I ran 22 psi or so, and it HAULED. It was estimated at around 350 wheel or so by a few different people, but regardless of what it actually made, it was fast as ----. It "blew" before I could dyno it. Then the wristpin thing happened, it fucked the bore on the #1 cyl, and I had a spare y8 block in my garage....

I yanked it apart, junked the z6 bottom end, swapped it with a y8 bottom end built exactly the same way, all new bearings / pistons / rods, but all the same.... Got the new ARP's for the y8, reused one of my z6 ones because you guys may or may not know how the y8 head is gay and has one bitch stud...

...and all of a sudden, I'm at least -100 hp. I actually managed to dyno this one -- and the ass dyno said slooow... the real dyno confirmed. ~230whp @ 22psi from that huge ass turbo.

SO, my question is: What the ---- is different about a y8 bottom end that all of a sudden my ------- car makes the same power it did when I ran a bone stock unopened z6 w/ a used volvo t3 .42/.48 at 13 psi?

The ONLY thing I can think of is cam timing. I've fucked with the tune to no avail, it won't do ---- + or - 15 hp at most... and I've learned about hondas, you can get some power in the tune, but chances are, when the ---- makes no power, it's never really the tune... I mean a bad tune may blow you up, but it's not going to be the difference between 230hp and 350...

Is the cam off? Are the marks different? What the hell could i have possibly done wrong that this thing blows my -------.


HELP!

Also, for all of you kind enough to read this and help, I have tons of d-series parts laying around ... so if your helpful, and you need something, chances are, I've got it if it's from a d!


Thanks,

Matt

Re: y8 head on a z6 block -- It doesn't run right, advice appreciated!
 

which crank pulley?

Re: y8 head on a z6 block -- It doesn't run right, advice appreciated!
 

are you using the Z6 timing maps? if so then that is your problem, JD posted a Y8 bin on the xenonignog site that is supposed to be pretty good timing.

Re: y8 head on a z6 block -- It doesn't run right, advice appreciated!
 

compare your timing to this map

Re: y8 head on a z6 block -- It doesn't run right, advice appreciated!
 

It was originally a y8 pulley, now it's the z6, and the timing map can't be the problem... the head is a z6, no?


Matt

Re: y8 head on a z6 block -- It doesn't run right, advice appreciated!
 

title says "y8 head on a z6 block" just figured it was a Y8 head :-\.

how are the 450's holding up at 22psi? just wondering because i'm doing a similar build and don't want to break the wallet with anythign other then blue tops.

Re: Z6 head on a Y8 block -- It doesn't run right, advice appreciated!
 

You are 100% right. I fixed it. The 450's should be good for ~300 - 350ish depending on fuel pressure. They did fine before, but as of right now, they aren't even close to maxed out.

Anyone, any ideas yet?


Thanks,

Matt

Re: Z6 head on a Y8 block -- It doesn't run right, advice appreciated!
 

Cam timing is fucked up.

Find factory manuals and figure out which marks you need.

Re: Z6 head on a Y8 block -- It doesn't run right, advice appreciated!
 

Has anyone else put a d together with the timing off a tooth? It's amazing that it could run seemingly so well if it actually is off. Anyone with experience on how they run if this is the case?


Matt

Re: Z6 head on a Y8 block -- It doesn't run right, advice appreciated!
 

I'm not 100% sure but you might have a 1/2 tooth error. BTW with cam gear you runing?
Steven,