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,

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

i know its ricey but i use an adjustable gear and i can tell the difference if i ---- with it plus/minus a few degrees
no power really gained or loss just where its at
most likely your timing is retarded so you band is way lower
just my theory :S

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

It'll run, and run pretty well with it off a tooth but it will have nothing for power. I was trapping 95 mph on 10 psi on SOHC engine, that's down about 5-6 mph from what it should've been.

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

And on that note--- were you retarded, or advanced? I'm taking a crap shoot on which way it's off. I can't think it straight.


Matt

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

Any updates, did you find out what it was.

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

I dyno'd my D16z6 build a few times after i installed a timing gear, we couldn't get it right. I was using a t3/to4e turbo.

ONe easy solution... buy a timing light from Walmart... look at your timing w/ the light, then return it.

I could only get 230hp with my timing gear off a tooth (looking at the gear from the driver side... the gear was turned clockwise (retarded) one tooth)
The worst problem we had was that the timing gear was made by ssautopoo... a friend had it lying around... and i figured we'd try it out... ABSOLUTE ----... the degree marks are WAY off.



We fixed it, and i pushed 340hp after we were comfortable with the dizzy, and cam gear. Oh yea... we went back to the STOCK cam gear, and slightly advanced the timing w/ the dizzy.

This was @ about 18-24 psi. (i dont remember exactly)



That is exactly your problem. You sparks are going off after your pistons pass TDC... It runs great, very conservative, and will run a long time, and get GREAT spooling because your thermal's are still expanding into the exhaust runners, and into your turbine... but ---- for power.
Triple check your timing gear. my bet is your retarded one tooth. Pay attention, cuz w/ the y8 block, you may not have the same marks on the timing belt cover ??? not the same marks that the z6 block has.

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

I think you are right. LOL. 230whp at the same boost is what I made. I already took it apart and put it back together, but I must be missing something. I'm going to advance it a tooth this weekend and I will let you all know!

Matt

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

Wasn't posted on here that with a Z6 head you need to use a y8 cam gear, or an adjustable. maybe it was the crank gear. I heard that it has to be compesated for, sounds like you already have the right idea though. :y

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

Run the Z6 gear on the Z6 head.

Keep in mind that the Y8 crank pulley's timing mark is at 12 degrees, not 16. Mark the Y8 pulley @ 16 degrees, or run Z6 pulley, etc.


Best all-around thing to do if you are doubting mechanical timing is to center your distributor, and check timing. If it isn't dead on or pretty close, you need an adjustable gear. You can set your mechanical timing by adjusting the cam gear until you hit 16 degrees timing at idle *with distributor centered*.

Aside from fiddling a few things to get your engine in synch, there's no difference in the tune since you're running "the same" pistons and head.

PS - is this the Z6 head off your old build? Did a machine shop pressure check it?

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

It is the same head from my old build. I didn't bother pressure checking it, because it had been newly rebuilt and checked on the old motor, and only went about 20k miles. It was running fine on the old motor until the day I stripped it down, even with the wristpin eating my bore apart :-\

I had the z6 crank pulley on-- and a warning to you all if you try this: The z6 pulley will hit the timing cover on the y8 block. That caused my z6 pulley to FALL OFF on the highway... and melt the plastic until it did. Luckily I had tools with me to re-attach it, and since have switched to the y8 pulley... But the key in my crank got eaten alive-- took some rigging to get it back together.

I'm going to try advancing the cam like general consensus says I should -- and I'll let you all know. If it doesn't work out, I'll build yet another D. I have enough parts for 2 motors laying around... so, while were on the subject... Let me know if you guys have any d's around.


Matt

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

Don't advance your cam. Check your cam timing via timing light trick I mentioned - that way you actually know what is going on instead of adjusting things blindly.

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

I had to read your post about 10 times before I realized what it is you meant... but now that you restated the timing light part, it makes perfect sense. Not bad, JD... Not bad at'all.

I'll keep you all updated. I'm hoping to do this come 5'o'clock :)


Matt

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

I've gone back to ------- with this after over a year, and I still can't figure it out. How would the fact that the timing mark is off on the y8 effect the initial timing of the motor (timing belt). Isn't the only mark we are concerned with when doing this the TDC (arrow) mark on the crank?


If nobody knows, oh well. Then we'll convert this to a for sale thread.


Matt

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

you want the tdc mark when you're setting up your mechanical timing for the belt on your cam, but to set your distributor timing you need the xx btdc mark. If your dist. isn't synched correctly your timing maps in the ecu will be all fucked and off and could ---- you for power.

Did you ever do a compression and leakdown test on this thing?

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

Yeah compression was good all around, I forget what it was, but all within 5psi or so, never did leakdown.

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

Start from the beginning.

What crank pulley, what lower timing cover?

What cam gear.

What is your ignition timing at idle set to in the .bin, and has the ignition timing been set to this exact spec with a timing gun?

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

Y8 crank pulley, z6 cam pulley, y8 lower timing cover, no upper timing cover.

Thanks guys.


Matt

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

Set ignition timing in the ECU maps to 12 degrees. Check ignition timing. With distributor more or less centered it should align with the marks - does it?

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

I think this is the same problem i'm having. lots O boost, but no power.

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

For D-series 2-3 degrees can make a difference in no power and good power. Another 2-3 degrees can destroy the engine. Welcome to small bore grenades.

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

Which mark should base timing align with? And are the other 2 marks + & - 4*?

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

Standing on the driver's fender facing the crank pulley, the marks will appear:


14-12-10-------------0


That's the cluster of three marks and a short distance to the right of those the single solitary 0 degree aka TDC mark.

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

Excellent.