TomCat39

I've been looking at engine specs for the 5th generation D series motors.

Block
Engine Code	Bore	Stroke	Deck Height	Rod Length	Displacement	C/R	R/S Ratio	HP/TQ
D15B7	75	84.5	207.45	134	1493	9.2	1.59	*102/98
D15Z1	75	84.5	207.45	137	1493	9.3	1.62	*92/97
D16Z6	75	90	212	137	1590	9.2:1	1.52	125/106

Piston
Engine Code	Piston Code	Dish/ Dome Height	Dish/ Dome Volume	Total Height	Compression Height	OEM Part #
D15B7	PM3	Flat Top	0	61.76	30.7
D15Z1	P07	7.05 Dish		57.65	27.75
D16Z6	P28	3.00 Dish	-10.1	60	30

I wasn't able to find much on the D15B8 and that block wasn't available in Canada so would be rather hard to come by for me.

Anyways, looking at this, the Z1 (vtec-e) motor uses the longer rods like the Z6 but the shorter deck like the B7.

I have 2 B7 blocks at my disposal, one in a car and one not. I also have a an OBD2 6th gen D16Y8 head at my disposal.

I was thinking I'd like to acquire a Z6 crank for the dual oil holes per journal and then use aftermarket Z6 rods which should be 137mm in length.

The difference in the FSM between the pistons is 15mm skirt and 16mm skirt on the Z6.

I was wondering if I ciould use Z6 or even Z1 pistons and still be okay with the shorter deck of the B7 or will I need to look into shaved B7 pistons or some aftermarket pistons to use the beefier longer aftermarket Z6 rods?

Is there other issues with trying to use Z6 rods int he B7 block? I'm doubtful I can find a Z1 block easily as it seems to already use the longer rods so may already have accommodations in place for them.

Right now I'm just researching the options for the B7 block I got sitting around and am not really familiar with all the challenges involved in changing things up. The only part I do know is aftermarket support for B7 parts is non existent so requires custom rods etc which is extremely expensive and not worth the costs. This is partly why I'm humoring the idea of Z6 rods in the B7 block, the journals are both 45mm so that part matches.

Not to sure on the mains though, didn't look at that part yet.

Any insight you can provide would be great, including anywhere the whole idea will fail or not work. Please explain where it will fail so I can understand the folly in my thinking.

Thanks again

TomCat39

A little more research shows that the Z6 crank will not swap into the B7 block without serious modification.

However, the Z6 and B7 big end bore is the same 45mm on the rods thus being the difference is the 134mm length to the 137mm length.

I'm hoping the extra 3mm reduces stress enough to allow the b7 block to safely rotate to 7200-7500 rpm without having to shot peen the rods.

Does anyone know what the dangers/limitations are of smaller diameter crank mains?

And I'm still wondering what piston would allow the longer rod of the Z6 to fit the lower deck of the B7. I know the lean burn dish of the Z1 obviously will but will the Z6 dish be better or is there aftermarket pistons that may be better suited?

And what are the other issues one would have with putting the stock Z6 rods into a B7 on the B7 stock crank?

The specs of the Z6 and B7 cranks (found on d-series.org):

The D15B7 is part of the following FSM specs (D15B7/B8/Z1 and D16Z6 spec sheet):

mithious

Well, I've got no insight here, but I'm interested...

What I do have is a fully disassembled Z6, if you want any of it (crank, rods/pistons, whatever) you're welcome to it.

Came out of my 'sol in fine working order and 250k, only the valve seals were leaking but I disassembled it anyway as a learning experiment. Ended up finding a Z6 with 160k and used that for my rebuild instead.

TomCat39

Would be interested in the Rods but a press is needed to get the wrist pins out without damage. There is a small chance that the 01-03 Civc GX pistons would work but I'm not sure, compression height is 3mm lower and there is a small subtraction of -4 to the dish/dome. On zealworks it works out to be 10.25 compression ratio with a D16Y8 head on the B7 block with the Z6 rods.

I'm still trying to learn what all the numbers mean and there doesn't seem to be any experienced engine builders to educate me on how all the numbers correlate.

mithious

I wish I had any info for you, but I'm still in the newb category. I have a love for the d-series having finished a successful Z6 rebuild (my first engine)... And I swapped a Y7 longblock into a wagon using all B2 components for my beater. But that's the extent of my experience. I've just finished piecing together a B18B1 swap for my ek, so I have some new things to learn...

Still, I'm really interested in learning more about OEM engine component swap compatibility... d-series stuff is so cheap and easy to find, I wouldn't mind hacking something together with longer stroke and/or better compression, just for fun... If I could figure out what's reliable...

I don't have access to a press, but I could ship the rods/pistons together. I believe you're in Canada also, shipping should be reasonable - it's not a problem. They are in decent condition. I can snap a few photos after work tonight to make sure you'd want them.

TomCat39

That would be awesome. A lot of my research is taking me to d-series.org with Mista Bone and his Beast7 and such but they know all teh ins and outs.

One question about the rods, did you keep the caps together with it's respectful rod? Definitely can't mix those up even if both rods are the same stamped number. Mix matching rod caps or any bearing cap for that matter is a pretty big no no.

And yeah I'm in BC Canada. They just shut down our pick n pull too, so it limits our options a bit for self serve salvage.

Oh and by the sounds, you've got more experience than me already. I've managed some suspension related swaps, seat swap, new head gasket and head swap, timing belt, axels, valve lash adjustment and replaced various seals like valve seals etc.

If I actually managed to reduce my oil consumption (did a 45 minute engine flush today) I'm contemplating a poor mans rebuild on what ever rod is lightly knocking when cold by rolling the bearing out and puting a new one in with the engine in the car. This is with the hopes I'm getting to it before the bearing is bad enough to mess with the journal so I can stick to the proper color Honda bearings. The numbers and letters are right there on the crank and rod, sort of hard to mess it up if it's still factory surfaced.

I'm basically fairly mechanically inclined and enjoy the theory of it all. I admit, my theorizing sometimes isn't even close to how it is, but it's fun making the journey and learning where my thoughts went awry.

The biggest challenge is getting all the various tools needed to do the jobs. some of them are not even remotely close to being affordable on a tight budget.

JRCivic1

Compression height is the distance from the piston pin center-line to the top of the piston. This means that using a longer than stock rod requires the use of of an equally shorter than stock compression height to maintain your piston-to-deck clearance. You can alter these two values slightly to add/subtract compression... but I caution you, decreasing piston-to-deck clearance increases the risk of valve-to-valve and/or valve-to-piston contact. If you notice, the compression height on the GX piston is 3mm shorter than the P28 piston, and since the rod you are choosing is exactly 3mm longer than the stock D15B7 rod, the math works out perfectly.

TomCat39

Thank you, thank you! I suspected as much but wasn't quite sure if the compression height directly related to wrist pin location.

I thank you greatly for this piece of information. I believe the D15B7 uses the PM3 Piston which has the 30.7 Compression height while the GX's piston is 27.7 so like you said, it works perfectly.

That only leaves the concern of the smaller mains of the B7 crank compared to the Z6 crank. With 5 main bearings, can the rpm be safely taken to 7200 or 7500 without concern on the smaller main journals?

JRCivic1

I don't see why not. Smaller main journal engines have been revved to 7500+ RPM throughout Honda's Racing history. I wouldn't put a Turbo on it... there is simply less bearing surface area to deal with load, shock and detonation. All motor... give it a whirl.

TomCat39

That's good to know.

More research shows the GX block and head is pretty much the same as the D16Y8 as far as architecture goes. I was just looking at pics of the piston top and looking at my junker Y8 head and it will be a close fit with the dome.

I realize that it will be close enough that I should clay the setup to be sure of clearance.

Now the real important question is..... With a fresh hybrid engine build, how do you go about seating the rings prior to tune, or how do you go about tuning prior to seating the rings?

I mean with a static and effective compression ratio of 11.62:1 I don't see how you could go about seating the rings properly with any stock 5th gen ECU and I am doubtful there is a basemap already available for this hybrid build.

How do the pros go about fresh "prototype" builds and seating rings?

mithious

Ha. Well, they just shut down MY pick-n-pull. Cuz I live in Vancouver. (well Surrey) shipping might be a bit cheaper huh?

I was careful to put the caps back on where they belong, but it's been a while since I took it apart, I honestly can't be positive. But I've found if you really examine the rods/caps you can be pretty sure you've got the right ones.

Here they are anyway if you want em. Realizing this was a good running engine, I'm thinking about putting it back together... The only thing that stopped me was the seal groove on the crank was starting to get a little excessive...

As for the tools, I hear you man... I've spent a ton this year. Selling my first project car helped cover that cost, except I immediately used it to order all my B18 parts...

TomCat39