So I've done quite a bit of research today and I haven't been able to figure something out. I realize there are a couple of critical differences in D series motors, displacement, VTEC/non and number of valves. The only differences I've come to find are in the cylinder head. Are there any differences in blocks though?

 

Are all women the same? (Not mentally haha - we know that answer.)

D15B7/2 - has a piston cc of = -1.5
D15Z7 - has a piston cc of = -16.1

I am not exactly sure what you are trying to get at - but the bore's and strokes are the same of 75mm x 84.5 mm... There are engines that use the later style big rod end and later rods (mainly JDM D15), a lot boils down to the piston. The deck heights are the same of 207mm...

So, NO - they aren't all the same. Unless you are asking about the block itself and not the short block... Then Yes - from what I have seen they are the same.

 

Thanks for replying, you're about the only person I can get a response from. I was asking earlier about my D15B6 and trying to do a full restomod on my CRX HF. I used to have a Prelude and I knew it had a stock H22A4 and typically would beat GSR's with their B18C's in a race but I never concerned myself with all the variants. Despite knowing enough about my Prelude, I didn't really go to school on the D and B series engines.

Pretty much what I wanted to know was, assuming we are talking the same language, is the short block (just the block, no head assembly, pistons, oil pan, etc) the same or which one is identical to the D15B6 or is there one? Mine has 202k miles and if I could get a D series short block thats under 30-40k miles I'd just use a newer block instead. I see the bore and stroke tends to be the same for most USDM D-series models...

Is this making any sense yet?

 

Just for future reference...

Long Block = Valve cover to Oil pan Complete (but doesn't have to include intake or exhaust manifolds)
Short Block = Complete bottom end (NO cylinder head)
Block/Bare Block = Empty block except Main Caps (NO pistons, rods, crankshaft, ect...)

The D15B6 has only 2 valve reliefs cut into the pistons... The D15B2 piston looks very similar in the top end dome aside from having the 4 valve reliefs cut in. I haven't ever cared to physically measure them as D15B6 isn't exactly supported (I think they stopped making over sized pistons) anymore. So I would assume you could easily use a B2 block instead - your compression ratio would be slightly lower in the process though. You would need to cc the pistons to see exactly how much lower - but I doubt it would be anything to worry about.

Just so you get an idea of what I am talking about...

D15B6


D15B2

 

Ok perfect, that clarifies quite a bit.

So I figured out all D15Bx engines have a 75mm bore and also the same stroke. You mentioned the D15B2 as a good alternative (bare) block and fortunately, they are still available through OEM Honda parts dealers as part 10002-PM5-A03. Though expensive this is exactly what I am looking for. Assuming I could get the pistons (or use the pistons I already have) from a D15B6 and also a new D15B6 8-valve cylinder head and other required parts, then put them on the D15B2 block, I would essentially have a new D15B6???

Also, is OBD0-OBD1 compatability going to be an issue in the long run? I assume that relates only to fuel control. I will be quite candid and honest to say I have only a rudimentary understanding of how electronic fuel control works but I assume the fuel control unit that is in my car already will suffice as the timing belt, cams, etc. are the only thing that physically controls the whole combustion part of the engine.

Once again, I appreciate all the help. I am wanting to make the most authentic restomod I can with the parts that are still available.

 

I said they have the same bore and stroke in the first post... :wink:

I would say your logic is sound when it comes to building/rebuilding the engine.

Where did OBD-0 to OBD-1 come into play? You never said anything about this before... what exactly did you have in mind? A D15B2 is an OBD-0 engine.

 

is there a reason you want a new d15b6 engine? my d15b6 lasted 310,xxx miles, you've got a ways to go.

 

You should know that you can't go by that in the slightest. There are WAY too many variables when it comes to how long an engine will last. If you don't understand, I can spell it out for you in detail...

 

Exactly, mine only had 150,000 and it spun a rod bearing because the previous owner didnt ever take care of it. It ran like crap didnt have an air filter and they didnt change the oil in it ever. Just topped it off every 200 miles or so.