Noob Questions about Engines, Heads, and Nomenclature

[serversurfer]

I recently bought a 1993 EH2 from a kid on Craigslist for $900, mostly because it was cheap and I needed a car. He told me that a "bigger" engine had been swapped in, but he generally didn't seem to know what he was talking about, so I didn't put much stock in it. Anyway, the car needed a ton of work before it would even pass a safety inspection, and as I'm short on cash, I decided to do the work myself, despite the fact that I had no idea what I was doing. Being quoted $450 to install a pair of calipers versus $80 to buy them from AutoZone is an excellent motivator, especially when I also needed a new lower control arm bushing and more!

So in the process, I learned about fixing and maintaining my car. It still needs more work, but at least it's roadworthy now. I've learned a bunch of other stuff, most of which I understand, some of which I think I understand, and a little that I don't understand at all. So, beginning with some of the stuff I think I understand, I have a few questions.

So, it turns out the kid was right about the engine swap (at least), and taking a wire brush to the engine block revealed a D16Z6 stamp. Now, my understanding of Honda nomenclature indicates this is a 1.6L D-series engine with a Z6 head? Is that correct?

Assuming I've groked that, I'm wondering about the head itself. From reading the forums here, I've gotten the impression that heads are fairly interchangeable. That being the case, how would I determine which head is actually on the engine? Clearly, changing the head wouldn't change the stamp on the block. Are the heads stamped similarly, and if so, where would I find its stamp?

Oh, and just to make sure I've got all of my nomenclature correct, the EH2 is the CX hatchback, right? :lol

 

[Blood_Shot]

it has a z6 swap from an ex civic

head will be stamped in the front above the exhaust manifold, should be p28

 

[serversurfer]

Oh, so Z6 just refers to the type of D16? Does Z6 have any particular meaning in and of itself, or is it more or less arbitrary?

The reason I thought Z6 referred to the head was because I saw someone else talking about putting a "Y8 head" on their engine, and I noticed that another D16 had a Y8 suffix, so I assumed that described the head itself.

 

[MistahJuice]

z6 is the type of engine its a D16 (D series 1.6L engine) and the z6 is basically just the last half of the name. so the d16z6 came in the 92-95 Civic EX and SI the D16Y8 came in 96-00 Civic EX

If that car is not an EX or SI then that means he swapped the engine in, I would make sure your check engine light is actually working/ a bulb is actually in there and make sure he wire vtec up correctly. Other then that enjoy the extra 25hp

 

[serversurfer]

The stock engine on the CX was actually 70hp, so I've got an extra 55hp.

The CEL is definitely functional; it's been on since I bought the car. I was actually gonna try to check the code(s) tomorrow, but we're supposed to be getting some snow, so I may put it off a couple more days. Kid said it was a bad O2 sensor, but who knows what's really wrong with it.

How would I make sure the VTEC was wired up "correctly"? I don't think the kid did the swap himself. I assume it was done by someone reasonably competent, though I suppose that may not be a safe assumption.

Edit: Oh, and the person talking about the "Y8 head"? Now I'm guessing that means the head from a D16Y8, but the head itself may be stamped Q72 or whatever?

 

[Blood_Shot]

yes, the head stamp is the same as the ecu in (when everything on the vehicle is OEM). Example, P72 head and p72 on a B18C1, pr3 head and pr3 ecu on a b16(as far as OBD0-1 go)

everyone just says z6 or y8 head because people cant remember all the actual numbers

so if I said a GSR head Im talking about a B18c1 head which is stamped P72

z6 head is on a d16z6 but is stamped p28, same with the y8 but no one every remembers the actual head code

confused yet?

 

[serversurfer]

No, I think I follow you. So the Z6 and the Y8 both have the same head, P28?

Is there a table that shows this information, and maybe explains the difference between the various heads? Are all of the D16 heads interchangeable? And could I put a B16 head on a D16, for example, or is the B-series fundamentally different from the D-series?

 

[Billy.]

no you can't match a b-series head to a d-series block, or visversa.

these links should help as far as identifying engine codes and technical specs

http://www.clubcivic.com/index.php?pageid=enginecodes

http://www.phearable.net/tech/wiring/ecus.html

 

[serversurfer]

Thanks, Billy. Bookmarked.

So what about the VTEC wiring? How do I make sure that was done correctly/at all? I'm assuming it was, because the kid was talking about how you could hear it kick in, but I've actually never had it up to 4800 RPM, partly because I'm an old man, but mostly because I don't want to push the engine too hard until I'm sure it's in decent shape. (Which may be another symptom of being old, come to think of it. )

Oh, that reminds me. I've still got the stock instrument cluster, so the tach shows a redline of 6500 RPM instead of the Z6's actual 7200 RPM. I assume that other than that, the tach is "accurate" and 3000 RPM is actually 3000 RPM and not "46% of the engine's redline" or anything crazy like that? That being the case, all I "need" is a set of gauge faceplates from an EX/Si, right?

 

[serversurfer]

Okay, now I have another question. Wiki sez the Z6 has a redline of 7200 RPM and a VTEC crossover of 4800 RPM, but the page Billy just linked shows values of 7600 and 5500. Anyone know which is accurate? I'm assuming Wiki is, since the Si faceplates I see on Amazon also show 7200, but I want to be sure I'm looking at the correct faceplates, etc.

Edit: Hmm. Wiki also shows an ECU code of P28, but it says the head code is P08. Is that right?

 

[95CTR]

as far as getting the face of the EX/Si dont worry about it, im not sure which cluster you have, (maybe a VX or DX?)

but it has been swapped because the CX cluster didnt come with a tach (how ever all automatic civics did.....which i think is a crock of s*** but what ever)

just think of it as a safety zone if you let a friend or relitive drive the car at some point, if they decide to have fun with it they'll think thats as far as it goes so you dont run the risk of them hurting anything lol

 

[Billy.]

No don't replace the faceplates. The gauge cluster SHOULD be accurate. As for the redline descrepancy, it's possible that the actual redline and published redline are different. For instance, a B16A2 has a redline of 8200rpm which is a fuel cutoff point. The gauge cluster on a civic si shows the redline as 8000rpm. The Z6 probably has a fuel cutoff at 7600rpm.

 

[serversurfer]

as far as getting the face of the EX/Si dont worry about it, im not sure which cluster you have, (maybe a VX or DX?)

Looks like it may be a DX/LX automatic cluster. At least, the tach matches the redline that Wiki reports for the D15B7.

just think of it as a safety zone if you let a friend or relitive drive the car at some point, if they decide to have fun with it they'll think thats as far as it goes so you dont run the risk of them hurting anything lol

Good point.

No don't replace the faceplates.

Any particular reason I shouldn't?

The gauge cluster SHOULD be accurate.

Okay, so 3000=3000? Excellent.

As for the redline descrepancy, it's possible that the actual redline and published redline are different. For instance, a B16A2 has a redline of 8200rpm which is a fuel cutoff point. The gauge cluster on a civic si shows the redline as 8000rpm. The Z6 probably has a fuel cutoff at 7600rpm.

I thought redline and fuel-cut were different, with the redline being the maximum recommended RPM, and the fuel-cut being the "Okay, this guy's an idiot" point. For example, for the D16Z6, Wiki shows the redline as 7200 RPM — which matches the Si tachs I've seen — and a fuel-cut of 7411 RPM. For the B16A2, it shows a redline of 8000 RPM and a fuel-cut of 8450 RPM.

 

[Billy.]

Any particular reason I shouldn't?

I thought redline and fuel-cut were different, with the redline being the maximum recommended RPM, and the fuel-cut being the "Okay, this guy's an idiot" point. For example, for the D16Z6, Wiki shows the redline as 7200 RPM — which matches the Si tachs I've seen — and a fuel-cut of 7411 RPM. For the B16A2, it shows a redline of 8000 RPM and a fuel-cut of 8450 RPM.

To remove the faceplate on the gauge cluster requires removing the gauge needle. When you pop off the needle the small shaft pin will unwind and become uncalibrated, and is almost impossible to recalibrate, and the delicate pin can be bent or broken.

I don't specifically know the redlines for D-series but I was mistaken about the B16A2. Thank you for correcting me. The gauge cluster shows a redline of 8000rpm, but the engine has an actual "redline" of 8200rpm, and the fuel cutoff is about 8400rpm. So you see there can be some descrepancy on who you are talking to and their definition of redline.

 

[2slo4u]

i wouldnt worry about redline too much, shouldn't be bouncing on redline anyway
and its a good thing you haven't been beating up on it too much cause if it was a bad o2 sensor, the bad signals of a/r could mess up your motor if driven too hard

 

[serversurfer]

To remove the faceplate on the gauge cluster requires removing the gauge needle. When you pop off the needle the small shaft pin will unwind and become uncalibrated, and is almost impossible to recalibrate, and the delicate pin can be bent or broken.

Oh, okay. That does sound like a PITA. Thanks for the heads up. So if I want to "correct" my gauges, I should just shop around for an entire EX/Si cluster and replace the whole thing?

The gauge cluster shows a redline of 8000rpm, but the engine has an actual "redline" of 8200rpm, and the fuel cutoff is about 8400rpm. So you see there can be some descrepancy on who you are talking to and their definition of redline.

Not to be pedantic, but if the gauge shows a redline of 8000, why do you think the "actual" redline is 8200?

i wouldnt worry about redline too much, shouldn't be bouncing on redline anyway

Yeah, I don't plan on taking it right to the limit on a regular basis. Mostly, I'm just curious about how all of this stuff works, but the OCD part of me is a bit annoyed that the gauge is "wrong."

 

[Billy.]

Oh, okay. That does sound like a PITA. Thanks for the heads up. So if I want to "correct" my gauges, I should just shop around for an entire EX/Si cluster and replace the whole thing?

Not to be pedantic, but if the gauge shows a redline of 8000, why do you think the "actual" redline is 8200?

Yeah, I don't plan on taking it right to the limit on a regular basis. Mostly, I'm just curious about how all of this stuff works, but the OCD part of me is a bit annoyed that the gauge is "wrong."

If the gauge cluster is significantly off it's probably due to some outside factor, like tire size or tranny speed sensor. If you can't live with it, you'll need to swap the whole gauge out, or find a complete cluster.

8200 is the published redline by honda for the b16a2. 8000 is probably some conservative number they show on the cluster

 

[serversurfer]

No, no. The gauge is giving accurate readings. What I mean by "wrong" is that my tach shows a redline of 6500 RPM when my engine has a redline of 7200 RPM. Stuff like that just bugs me. Anyway, my speedo is wonky and only works intermittently, so I'll probably keep an eye out for an Si cluster. Low priority though; it doesn't bug me that much… yet.

So, what about this "VTEC wiring"? What am I looking for, exactly? What will happen if it was done wrong, or perhaps not at all?

 

[Billy.]

If done incorrectly i believe the worst is that vtec won't engage. You'll feel power loss in the upper rpm's. If done correctly you should be able to hear the changeover point. It's more pronounced if you have a short ram intake and/or exhaust system.

 

[serversurfer]

Okay, cool. Thanks for all the hand-holding, gang.