D16y8 vs D16z6
 

Just wanted to do a D16 comparison.

I was wondering if you guys can add some things to the pros vs cons list that I was making for these two motors. I was looking at them in relation to my '96 Si. I'd like to know what the real differences are between the two. Obviously I might be wrong on a few, but please feel free to correct it.

D16y8:

Pros:
- many aftermarket parts
- easy and low cost to repair
- reliably boosted at low psi
- low cost replacement (~$500)
- can keep OBD2 ECM for '96 Si
- better flowing intake manifold design
- better flowing exhaust manifold

Cons:
- can't tune OBD2
- weak oil pump
- weak rod bearings
- boost can be risky due to above
- worse head design

D16z6:

Pros:
- OBD1 can be tuned
- many aftermarket parts
- easy and low cost to repair
- stronger oil pump
- stronger rod bearings
- can handle more boost, more reliable to boost
- low replacement cost (~$500)
- better head design

Cons:
- slightly less power that y8
- need to get OBD1 ECM
- need to get harness for OBD2-OBD1 conversion
- more restrictive intake manifold design
- more restrictive exhaust manifold design

What else?

RE: D16y8 vs D16z6
 

the y8 has steel shift forks compared to aluminum on the z6 the steel are way stronger

RE: D16y8 vs D16z6
 

all it takes is a chipped ecu and a conversion harness to convert to OBD1.

The y8 also has known bottom end oiling issues...

RE: D16y8 vs D16z6
 

z6>y8 nuff said..............only thing i like about the y8 is the combustion chamber in the head.....

RE: D16y8 vs D16z6
 

And there isnt such a thing as an '96 Si

RE: D16y8 vs D16z6
 

The '96 EX Coupe in the US is called the Si in Canada. Maybe should have mentioned that. It has a D16y8.

RE: D16y8 vs D16z6
 

I don't think the oil pump is the problem with Y series, it's small oil passages. Also I don't know about the Z6 oil pump either.

They both make about the same power. 2HP is negligible.

No ODB converting is necessary with the Z6 if you just get the OEM harness (which may be included with the swap, as well as the ECU).

You're right about the stock exhaust manifolds.

The head design is better on the Z6 from what I've seen, but the Y8 intake manifold is better than the Z6.

Will add more later, gotta run.

RE: D16y8 vs D16z6
 

That's interesting, because I've actually heard it the other way around. That the flow on the y8 is better

RE: D16y8 vs D16z6
 

Yeah, i think kedawei is confused, it has been pointed out many times the y8 combustion chamber is a step up over the z6, but id still go with the z6

RE: D16y8 vs D16z6
 

i still love the z6 over the y8, just seams more user friendly

RE: D16y8 vs D16z6
 

z6 here too

RE: D16y8 vs D16z6
 

my Z6 loves the 10psi im throwing at it every day.

RE: D16y8 vs D16z6
 

I got a D15 that's better than both of them :D

RE: D16y8 vs D16z6
 

Yea, but I can go start my Z6 right now. (and drive it lol) [sm=exactly.gif]

RE: D16y8 vs D16z6
 

You got a JDM D15B right? Weren't the D15's made from 92-95 virtually identical to the z6's, and weren't the D15's made from 96-00 virtually identical to the y8? From what I've read, the 96-00 D15's are only 3hp more and 5trq less than the y8, so not much difference there (D15=1493 cc, D16=1590 cc). What makes it better than the y8 or the z6?

RE: D16y8 vs D16z6
 

I've read the Z6 flows better at higher rpms, and it seems most people I see running D-series motors use the Z6 head. The only application I've seen the Y8 head used well was in the Pinks Full-Race Civic.
It had very aggressive porting though, so high rpm flow was no prob.

The JDM D15B is my favorite D-series motor though. I can't claim it's the best, because I haven't seen enough dynos of them or other D builds. They really seem to have potential though. Shorter stroke, long D16 rods, just seems like a better design. Torque would be lower with them in lower and midrange rpms, but I think it could follow through the high end much better. Might make up for it. I'll find out when I get mine, I guess. :D

RE: D16y8 vs D16z6
 

More favorable r/s ratio.
More willing to rev and make power higher in the rpm's

I have drove and worked on more Y8's and Z6's then I would even like to remember. This engine pulls harder than either one of them to me. I layed down 122 or so whp and like 114wtq with it with crap ebay bolt ons. That is around 5 to 7hp more than any Z6/Y8 I have ever seen lay down with really high priced name brand bolt ons. I boosted a Y7 which the bottom end is exactly the same as the Y8 with 7psi from a T25 and drove easy on it and treated the engine like gold. Well it spun a berring and crapped a rod into the oil pan. I have hit close to 1 bar on this engine and drove the piss out of it and never had any problems at all with it. Never.

RE: D16y8 vs D16z6
 

If you wanted to get replacement parts for your motor, (i.e. alternator, head gasket, spark plugs, etc...), can you get the same parts that you would get for a z6 or y8 (within the corresponding years)?

One other thing.... If the z6 is better than the y8 for the various reasons stated, would the D15 from 92-95 be better than the D15 from 96-00 for those same reasons?

This is really great info. Thanks for the input everyone.

RE: D16y8 vs D16z6
 

Exactly what Marty said. Shorter stroke with long D16 rods. :drool:

As for parts, I'm not sure. I have a feeling parts from several D-series motors are interchangable with it though, and most if not all parts from a Z6 probably are.

I've read of rare OBD-2 D15Bs (post 96), but for the most part they are OBD-1 (pre 96).

RE: D16y8 vs D16z6
 

The D15B is a oddity so to speak, not that it uses advanced parts or anything like that but here I'll lay it our to you somewhat.

The USDM D15's do in fact have smaller rods vs the D16's. But here is the thing about it, you can not use the crank from a D16 in the jdm D15B as the crank mains are smaller in the JDM engine just as they are on the usdm engines. But here is the kicker, while the crank mains are the same on the usdm and jdm d15 the jdm d15b has the same rod mains as the U.S. D16's. What does this mean?

It means that unlike a USDM D15 you can buy and use D16 aftermarket rods on the JDM D15B. Also to be noted you can not use any off the shelf aftermarket D16 pistons though. The deck is shorter on the D15B there for the piston will actually buldge out of the block smacking the head.

I will write more just give me time.

RE: D16y8 vs D16z6
 

Sounds good.

I'd like to know more about the D15 to keep this as an "option" should I ever find myself in need of a new motor. It would be great if most of the parts are interchangeable with the D16's if I ever decide to go that route and needed to get replacement parts.

Correct me if I'm wrong, but the 96-00 D15B is the 3-stage VTEC motor right? I remember reading that before.....(think I should have changed the name of this thread to D16y8 vs D16z6 vs D15B).....

Thanks.

RE: D16y8 vs D16z6
 

Yes the 96-00's have 3-stage vtec like the d16y5. The JDM D15B has a P08 head in other words the same as the Z6. There is conflicting reports about the cam inside the head though. Some say it is slightly more aggressive but I have had a D15B and Z6 cam sitting in front of me and the lobes are cut the same so i think that is bs. Like I said when I have time I'll sit down and make a large post about the differences. I know you use a Z6 timing belt for it, the rods in the D15B are actually D16Z6 rods, and the pistons have a shorter profile.

RE: D16y8 vs D16z6
 

No to thread jack, but are there updated rod bearings that prevent them from failing as often as the stock bearings?

Also, can the oiling issues be fixed in any way? My engine has about 120k miles on it, so a rebuild is not too far off so I would try to fix those problems if I was already in the motor.

RE: D16y8 vs D16z6
 

Is there any ways to adress this issue?

RE: D16y8 vs D16z6
 

no it is the oil passages but it is hit and miss. I think it affects the 96, 97, and 98 models more so than the 99/00 models. Also it's not just the Y8 it is all the Y series engines from 96-00

RE: D16y8 vs D16z6
 

How much and in what ways will this affect my car based on performance and reliability? my car needs to be reliable and now i'm a little bit worried.

RE: D16y8 vs D16z6
 

Hit and miss. Your engine may be fine and you may throw a rod. Can't really say. For Marty, it was a "miss" for his Y7.