I am trying to look for this information myself, but according to crower rod lengths:
D-series c-to-c is 5.394
B16A c-to-c is 5.290
B18A/B c-to-c is 5.394
B18C c-to-c is 5.433

Am I missing something, or am I just misreading your post? Please let me know what you mean as all my research leads me to believe that the only rod longer than the D series is the B18C

 

My mistake. It's not the rod length; it's the bore/stroke ratio (I checked with my dad on this too).

D16A6/Z6/Y7/Y8/etc: 0.83333...
B18A/B: 0.91011...
B18C: 0.92891...
B16A/B: 1.05195...

The closer this number, the less lateral pressure is applied to the cylinder walls. This partially explains why well-tuned and balanced factory engines such as the B18Cx and B16A/B's can acheive such high rev. numbers and still be perfectly stable and reliable in the long run, and also explains why, stock for stock, B-series motors are more ideally suited for forced induction than D's.

 

Those Crower lengths you listed aren't stock lengths.

Center to Center:

B18Cx: 5.429"
B18A/B: 5.394"
B16Ax: 5.290"
D16Y7/Y8/Z6/A6: 5.394"

 

Yeah I didn’t think they were stock, but I knew they would be close as you cannot really deviate from stock too much without changing other components.

Kappa, with all due respect, I am not trying to argue with you, but I don’t see how bore would affect side wall force(mechanically). It is all about geometry. The real determining factor on side wall force is rod length and stroke. If you think about it, since stroke is determined by the crankshaft’s moment arm(moment arm center to center = ½ stroke), since it is the distance between the center of the crank and the center of the moment arm(pivot point of the connecting rod) that moves the rod up and down. One would say that at TDC and BDC there is 0 force applied to the sidewall. By the same token, when the moment arm is at 90 degrees(or mid point between TDC and BDC) it has maximum force applied to the sidewall. The larger the distance between the center of the crank and center of the connecting rod (what actually determines your stroke) the larger the sideways force applied(due to the larger angle of the connecting rod of the piston). The same goes the other way, the shorter the rod(like you had mentioned before) the same effect will happen. Without getting into too much technical mathematical terms here is the way I see it. If the total force applied to the piston due to the combustion is F, then with disregard to thermal, frictional, and other losses that force will have to be distributed either down or sideways right?

So F = Fside + Fdown
or
F = F*sin(angle) + F*cos(angle)

See animation:
http://auto.howstuffworks.com/engine4.htm

When the piston is at TDC the connecting rod at the piston end is straight up and down(angle is 0). So there is no sideways force. (note sin of 0 = 0, and cos of 0 = 1)

So F = Fside + Fdown
or F = F*sin(0) + F*cos(0)
F = Fdown

However when the piston is ½ way down, the angle of the connecting rod at the piston is the greatest so you have the highest sideways force. The larger this angle the more force applied sideways. What determines this angle is (like mentioned before) the rod and stroke lengths (rod/stroke ratio).

Actual force is:

F = F*sin(angle) + F*cos(angle)
Or
F = F*(1/2stroke divided by rod length) + F*(rod length divided by ½ stroke)


Bore size will just increase your displacement which will contribute to the amount of force applied in general(as in a larger F in the equation above). This has to do with the ability to add more air and fuel, not because of the geometry of the set up. So in a sense, the least amount of sidewall force comes from smaller strokes with longer rods and smaller bore, but that also comes with less total power. There is a happy medium in there some where and that is what has to be considered when building/designing your set up.

With that said do you happen to know the stroke of the engines mentioned?

 

From all the research I have done I still don’t see how rod angle would be any more an issue on a D series than a B. I have found that the B16 has a worst rod angle than D-series and if I am not mistaken it has a higher compression ratio(not verified) so stock for stock it would have a more limiting factor than a D series when force induction is considered. With a worst angle and higher compression ratio you are limited by both fuel quality availability (octane) and possible side wall stress.
So like md420 mentioned, he feels the oiling issue is what is bad with these engine,… unfortunately I have one of these. I will see what can be done to remedy this known issue even though I have gone through 200K miles without any oiling issues (however naturally aspired). I am planning on boosting and a better oil pump is first on my list as well as seeing how to fix this bearing oil restriction. I guess I have decided on rocking the D and I’m looking at all possible problems I may encounter and try to fix them before they become a problem. I had already decided if I go any more than 6-7 psi, sleeves, rods and pistons were a must since even though I have good compression and less than 10% leakage, I am pretty sure the bottom end is pretty tired. Especially the way I drive Cam, springs, valves and P&P were secondary.

 

The best way to go on it is boost your OBD2 D, then start a build on a Z6 obd1 block or buy a JDM D15B vtec swap and build it. The issue is not worth fixing when you can just pick up a block a couple years older(for the same or lower price I might add) and not have to fix anything.

 

Thanks, Z6 block it is! In that case, I might just skip the sleeves as well, like you had previously mentioned and just go with the rods and pistons(possibly lower compression ones).

 

Yea sleeves are a good part to add only if you plan on going into some really really big numbers IMO. I can see the point of some saying you can never prep a build up too much for any amount of power but it also gets to a point to where it is a waste of money if you never use it. It would be like buying a T70 for a D16, you will never realize the ability of the turbo so why go that big. Anything under 350 or so whp and you will be safe, even after that point with a D it starts getting to where it will not be daily driver freindly if you know what I mean.

 

what are the advantages over a jdm d15B vtec swap vs a Z6? I'm assuming the OBDII compter and wiring can still be used right?

 

Better rod/stroke ratio and more so setup to rev high. The only thing when building custom pistons have to be made but when you get down to it the cost is not really to much higher than pre-made "blanks" or "slugs". I would not run this engine OBDII unless you plan on running some kinda of management that will give it better fuel maps because it is alot more aggresive from 4000rpm to 8000rpm than your average D series.

There are 2 different JDM D15B's though, 1 is a regular sohc vtec(what I am talking about) the other one is a 3 stage vtec like the D16Y5. You can tell the difference a number of ways.

JDM D15B 3 Stage Vtec

2 VTEC selinoids
Intake manifold is stamped Pr3
Uses grey/alum. looking valve cover like the D16Y5/7/8

JDM D15B

1 VTEC selinoid
Intake Manifold stamped P08(same head and intake manifold as the obd1 Z6)
Uses a black crincle type valve cover like the 92-95 dx/lx but it has VTEC on it istead of just 'Honda'