Difference between Honda D15B6 HF and D15B8 CX? - Fuelly Forums

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Old 06-01-2006, 11:07 AM   #1
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Difference between Honda D15B6 HF and D15B8 CX?

I've researched this and have come up with a few things:

1. Both motors are rated the same hp and tq at the same rpm, same displacement, # of valves, etc.

2. The B6 (HF) was produced in 88-89 w/ 62-hp and 90-91 w/ 70 hp. The B8 (CX) was produced in 92-95 w/ 70 hp.

3. The only difference I've found is the HF had 2-valve relief pistons vs. the CX's 4-valve relief pistons (which is odd considering both have just 2 valves per cylinder)

4. The HF was obd0 while the CX had the newer obd1. (what changes were made?)

My questions are, what would keep me from swapping parts between the two (esp. ECU's, electronics, etc), what are the advantages/disadvantages to upgrading to an obd1 system and what all is involved? This has been irking me for quite some time, and the main holdup in my "should I rebuild my B6 HF engine or go to D15Z1 VX w/ obd1 and VTEC-E and all that fun stuff. Mak
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Old 06-01-2006, 01:55 PM   #2
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I think my cx engine have 2 valve relief pistons...

Anyway, I think they're the same, I've heard there is a cam difference, but for all intensive purposes, same engines, same exhausts, same intakes.

Go d15z1.
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Old 06-02-2006, 08:03 AM   #3
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I seriously want to go D15Z1 if the install isn't too much of a hassle, wiring wise. I have never swapped out anything that didn't live in there before so different engines w/ different obd is a big ? mark for me. I need a tutorial/faq on obd0 to obd1 swaps, plus non-vtec to v-tec-e, if it exists. The cost will be about the same, complete rebuild vs. used motor, assuming I can find one that isn't in need of a rebuild itself. Mak
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Old 06-02-2006, 08:48 AM   #4
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The CX motor had 2 valve relief pistons in early 92, and then they used the DX PM3 piston (4 valve relief). Another difference - the HF has roller rockers, the CX doesn't.

Here's a thread on sohchonda that details some of the swap information btw obd 0 and obd1: http://www.sohchonda.com/forums/inde...wtopic=8868&hl=

There's a link in there to a harness that makes the conversion much easier.

If you upgrade to OBD1, you also have tuning options (if you happen to have the chippable P07 ECU) - Crome, uberdata, etc - www.pgmfi.org. I've got to run, but I'll post some more info when I get back from lunch.
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Old 06-02-2006, 08:52 AM   #5
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Don't know if this will help, but I used to have a VX and retrofitted the harness to run a 4-wire o2 sensor...maybe you could read this thread and do the reverse of what I did...anyhow, there's lots of good info in there on pin locations at the ECU for a 5-wire o2 sensor. Here's a link to the thread:

http://www.honda-tech.com/zerothread?id=295330

Quote:
Originally Posted by civicminded
you also have tuning options (if you happen to have the chippable P07 ECU)
I was told there wasn't such a thing as a chippable P07...something about the fact that there's an additional processor chip on the board to run the wideband. I posted a picture on here of my P07 board somewhere...
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Old 06-02-2006, 10:44 AM   #6
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Yes, there is a chippable version (the one I have unfortunately is the wrong type):


If you can't read that (pic is reformatted), try this link: http://www.pgmfi.org/twiki/pub/Library/P07/P07top.jpg

The board labeled 02D01560-1500 is VX specific and can't easily be chipped.
The board labeled 02D01720-1500 or 02D011F0-1500 are also used for P07 boards and are identical to the P28 ECU (which is chipper friendly).

I wonder about the 4 wire switch on the P07 though - I've done the re-wiring on my VX to a 4 wire, but I'm running a P28 and a D16Z6 now. Would the switch to the narrow-band not effect the efficiency? I would think that you would want better accuracy on the lean-burn mode than a standard lambda could provide.
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Old 06-02-2006, 11:08 AM   #7
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Taken from our beloved sohchonda.com:http://www.sohchonda.com/forums/inde...showtopic=1722

Quote:
Engine Designation= Stroke, Con-Rod Length, R/S Ratio:

-D16A1, A6, Z6, Y5, Y7, Y8= 90mm, 137mm, 1.52
-D15B1, B2, B6, B7, B8= 84.5mm, 134mm, 1.59
-D15Z1, JDM D15B VTEC= 84.5mm, 137mm, 1.62*

More info (taken from a post by Mista Bone):

ALL 1.6L rods and the JDM D15b motors have 48mm big ends.

ALL USDM D15b1/2/7/8 and D15z1* (VX) motors have 45mm big ends.

HF D15b6 and EDM type D13/D14 have 42 mm big ends.
So note that the rods (and crank) are different for the HF (B6) vs the CX (B8).
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Old 06-02-2006, 11:10 AM   #8
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Quote:
Originally Posted by civicminded
I wonder about the 4 wire switch on the P07 though - I've done the re-wiring on my VX to a 4 wire, but I'm running a P28 and a D16Z6 now. Would the switch to the narrow-band not effect the efficiency? I would think that you would want better accuracy on the lean-burn mode than a standard lambda could provide.
I'll have to check the board number for my P07...it definately has a blank spot on it for a ROM.

The writeup I did on converting the harness to work with a 4-wire was so that I could use the VX harness in the VX chassis with a B18A1 engine swap converted to OBD-1. This was back before I was really efficiency conscious, so I yanked the Z1 out and got rid of it in favor of the B18A1. The 4-wire conversion was so that I could run a P06 ECU without a CEL. I was just suggesting that the thread I posted had a lot of good pin information for converting a 4 or 1 wire harness to a 5-wire harness (in case you don't have the VX harness).
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Old 06-02-2006, 11:13 AM   #9
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Quote:
Originally Posted by civicminded
EDM type D13/D14
What? D13...as in 1.3L D-series honda engine?
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Old 06-02-2006, 11:45 AM   #10
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Yeah - there are other markets besides the USDM. Seems the rest of the world gets a lot more flavors than we do. That's a European Domestic Market (EDM) only set of engines.

And yes, I'm thinking a D13 would be a nice gas mileage engine too. Or a high-revving motorcylish SOHC!

I think if you want to get the most from the Z1 swap, the wide-band 5-wire O2 will need to be in there.

Funny thing about performance vs. gas mileage is that I want both! LOL I know, I know just not at the same time.
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