D15Z7 head to D16 mini-me advice

[Madact]

OK, so it may have been a touch imprudent, but I've just acquired a used D15B 3-stage (AKA D15Z7) head, complete but without manifolds or wiring (yes, it has the dual solenoids). Goodness only knows what condition, of course - I'll see when it arrives - and whether I can pull off the mini-me swap. This popped up for about the same price I could get a VTEC-E head, so I figured it may be worth it.

Anyhow, I'm aware I'll need to sort out engine management, linear O2 sensor, and wiring, but any experience or details with doing this swap - or something similar - would be greatly appreciated. I'd really like to get it done using OEM parts, nothing after-market if possible, with the possible exception of combining a lean-burn capable ECU with a separate VTEC controller for high RPM. The destination engine is a D16Y4 (very similar to the US D-series engines, except for lack of OBD ECU).

Some specific questions I'd like to work out (beyond the questions of ECU and wiring):
* What the effect (if any) on compression ratio will be.
* Whether I'll need to do anything special with the intake manifold - in particular whether I need EGR to take advantage of lean-burn.

[Ecky]

No specific experience with it, but after playing with some compression calculators I'm coming up with 12-13:1. What are your goals with this build?

Again, not a lot of experience here, but I haven't heard of any aftermarket fuel management systems that would be appropriate.

Taken from D-Series.org:

The trickiest thing about this engine is the tuning. Because of the multitude of valve operations, the ECU programming is complex. The P2J ecu is OBD2, so you can only run that with a stock-ish engine.

A standalone system is the only thing that could possibly do this engine justice, but an IMMENSE amount of tuning and dyno time is necessary to squeeze the full potential from the engine.

Personally, I'd see about finding a Z7 block to mate with the head. It's a fantastic engine.

[Madact]

Goal is fuel economy, naturally (for its own sake rather than economic reasons w.r.t. this particular mod, break-even point might be 5 years if there are no hitches, so it's not justifiable just from that). A little more top-end power wouldn't hurt, of course.

Since reading your post I've played with a couple of compression calculators (didn't know they existed ), but I suspect you haven't set it up to stock specs first? 12-13:1 doesn't seem very likely, unless you're starting with a *very* odd combination of parts in the first place. I really hope this is the case, anyhow

D16Y4 has a compression ratio of 9.4:1 ... the combustion chamber volume is quoted here as 32.8cc, but though this info has been repeated a few times on the net, I couldn't find source material confirming this. The guy posting here says the combustion chamber looks identical to a D16Z6 (34.6cc), which makes more sense... also, D16Y4 and D16Y7 share the same head code (P2A-2), and the D16Y7 has a 34.6cc combustion chamber. I'd go with this as the figure.

By the same token, the info I could find D15Z7 all said 32.8cc for the combustion chamber. The head casting for this is a P2J, same as the D16Y8, which also is quoted at 32.8cc, so this passes the sanity check.

Setting up a compression calculator for a stock Y7 gives a compression ratio of 9.39, which is a match for the Y4 by part numbers and compression ratio - swapping to a Y8 head (same volume as the Z7) in the calculator gives 9.72, which would let me keep running 'regular' unleaded safely ('regular' is 91 octane here). For reference, the D16Z7 compression ratio is 9.6, so this seems like it should be fine w.r.t. not hurting lean burn performance/reliability AFAICT.

Only way I could get the kind of compression ratio you mentioned was with a D15Z1 head (completely different spec. and casting), combined with some crazy mismatched pistons.

From the tables here it looks like the Z1 has *massive* piston dishing, to go with its tiny combustion chamber size (25.3cc, much smaller than any other D-series).

Let me know if you think I've gone wrong anywhere there!

[Ecky]

My mistake. I had used the Z1's numbers as I didn't quickly find anything on the Z7.

Might be interesting to try running on a stock Z7 ECU and see what it does.

[Madact]

I think that would be ideal - if I can find one. If I can match the injectors to get an extra 7% flow vs. the injectors on the Z7, it might not even realise it's running on a different block

Which leaves the problem of EGR of course, the Z7 definitely has this, but no Aus. Hondas do. I wouldn't be too concerned about it except that I've read that FE goes down on lean-burn Hondas with clogged EGR ports, which implies *no* EGR might be a bad thing.

I'm not in any particular hurry, so I'll probably just lurk and keep an eye on ebay for ECUs and manifolds... of course, getting shipping to Australia is often an issue with this sort of thing..

[some_other_dave]

Originally Posted by Madact

...('regular' is 91 octane here).

There's a good chance that is 91 RON, which is the same scale that most of Europe uses. The US uses an average between RON and MON (called "AKI" or even "R+M/2") which usually comes out 4-5 points lower for the same fuel. So your "regular" at 91 RON is about the same as our "regular" at 87 AKI.

I'm not sure that changes the judgement about the compression ratio and running on regular-grade, but it does mean you might need to take the difference into account when comparing things internationally.

-soD

[Madact]

Yup - looks like Australian fuel is indeed shown in RON.

Playing with the compression calculator, it appears using a D16Y8 gasket (0.037in), which would make sense as it matches the head casting, gives a 9.96:1 compression ratio. This is higher than most of the VTEC-E engines, but the D17 series, which is apparently specifically optimised for 'regular' (91RON / 87AKI) has a 9.9:1 ratio - including the VTEC-E variants. In theory, this could be worth a tiny bit of efficiency, but of course it could be possible only due to different cams and ECU... unsure about that.

[Madact]

And now I have it ... very much in "used / as is" condition (as expected), but no oil sludge I can see and a straightedge showed zero warpage from removal and shipping, so pretty satisfied.

Quite a bit of carbon build up (I would say excessive), appears to start on the sides of the intake, so I'm guessing caused / exacerbated by EGR. But the oil is clean and the valve seats of the part-open valves seem fine, so fingers crossed it hasn't caused issues. A cleaning is definitely in order though.

[Madact]

Some more photos showing
* Head codes
* The extent of carbon build-up on the valves/chamber
* EGR passage artherosclerosis - I've scraped it out a little on the left in this pic with a 3mm drill bit (gently, by hand!) originally the drill bit was a snug fit, so it had the effective passage diameter down to ~3mm

[vrmouseyd15b]

No EGR on my head! (moved hose to show off dual vtec solenoids)




This guy is talking about his dual vtec wiring (JDM p2j-j62 - about $50 on ebay here)
I've got a working econo/happy light thanks to that bit of info. don't know if these tricks will help with your z7 ecu (dont know the code?)

check this out: http://ecomodder.com/forum/showthrea...hat-30181.html


page 3 of this thread I share some more good stuff: http://ecomodder.com/forum/showthrea...tec-28808.html

hope it might help!

thanks,
Victor