JDM D15B and D15Z1

[N2UAD]

My stock 92 VX will need an engine rebuild someday. Compression is getting a little uneven between the cylinders. Running just fine but MPG going down a bit. Already cleaned intake, EGR, replace O2 sensor, etc.

I see that you can get a particular JDM D15B that the sellers (I've seen 3 for sale on websites) claim is a replacement for my D15Z1 engine. Is this true? Is there no difference? Or am I better off rebuilding what I have?

Thanks...

PS - I've searched the forum and can't find a direct answer to this question.

[GasSavers_Erik]

I don't know the answer to your question, but it is possible that you just need a valve job. Repeat your compression test but put a tablespoon of engine oil in each of the cylinders. The compression will be much more even if the piston rings are at fault. If the compression values are still uneven, then it is likely that several of your valves/seats aren't sealing properly and need to be resurfaced at a shop. Around here, the machine shop would charge less than $150 for reconditioning the head (you would need to provide the valve stem seals). Pulling and replacing the head would likely be a simpler job than swapping engines.

[N2UAD]

Yeah, I did not yet find out what's going on. Whether it's leaky valves or the rings but I'd bet it's a valve or two. But with 230k miles I'd be willing to just rebuild the engine to make sure that I have no problems for as long as I own the car.
But then I saw these D15B engines. From what I've read there are different variations of this D15B and one of them can be used in place of the D15Z1. It would take less time to swap the engine than to rebuild it.
But the devil is in the details. Without details on this D15B engine I'm not going to consider it as an option.

[norurb]

It might cost you less if you can verify the cylinder head is at fault for your uneven compression. I say this because it looks like you could pick up a rebuilt cylinder head on ebay:
http://cgi.ebay.com/ebaymotors/92-95...item56420015e4

While you are at it, change the head gasket, timing belt and water pump. If you can do the work yourself it may cost less than $300 to do it all.

[tony_2018]

Quite simple, you're looking for a d15b vtec-e motor, I'm sure the vx was a vtec-e motor so if you can find one than you're good to go. Make sure its the 92-95 d15b vtec-e. This info is from what I have been researching for the past few weeks. I want to build my mom a 4dr ek with a vtec-e motor, run a p28 programmed with the correct mapping and she should be fine but I'm still researching.

[TwoGlassEyes]

Tony is right but the issue is a little tricky unfortunately. VX motors were D15Z1 as you know. The JDM D15B is a 3-stage VTEC motor; it has the FE of the D15Z1 when you want it, but also has the VTEC for power at high RPMs. However, Honda stamped other motors as D15B in other markets that are not 3-stage and not VTEC-E. You have to make sure it's JDM. If the seller won't say or doesn't know, don't buy it.

[add|ct]

How can a 3-stage VTEC-e D15B(?) series have the same FE of a D15Z1 when it's not mounted to the taller geared tranny? Is that the motor that came stock in the CX, just without lean-burn?

[TwoGlassEyes]

Originally Posted by add|ct

How can a 3-stage VTEC-e D15B(?) series have the same FE of a D15Z1 when it's not mounted to the taller geared tranny? Is that the motor that came stock in the CX, just without lean-burn?

Well, I misspoke: The 3-stage VTEC-e does not have the same FE as the D15Z1 and for the reason you mentioned, the tranny. But it has more FE than the straight VTEC engines. This is not the motor that came in the CX, as that motor did not have VTEC at all. The JDM D15B 3-stage was what they used in the JDM version of the Civic HX, which was the generation after the VX. The USDM HX did not have the 3-stage VTEC-e engine, but did feature 14" rims that look very much like the 13" VX rims.

[add|ct]

Ah, cool. Thanks for clarifying and explaining that. That's pretty awesome. I was thinking the D15B in of itself was still 5th gen.