I was reading today on crvtec.com about the different strokes and rod lengths of B series engines. I noticed that the B18A/B has a 1.8mm longer stroke than the B18C and .9mm shorter rods. Seeing as how people have been known to put CTR and ITR pistons in their LS/VTEC's and B18A/B's I would assume that they B18A/B and C have the same deck height. Am I correct?

If the above is true, why not just take the crank and rods out of a B18A/B and put them in a C to get the extra displacement without have to do all the block and head work? Am I missing something, or will this work?

Kenton

 

Anyone...?

 

Yeah, the B18's (and B20B/Z) all have the same deck heights (about 8.340"). The B16 deck is 9mm shorter (about 8.000") and the B17 is somewhere in-between.



[Modified by Phantomcivic, 11:30 PM 6/3/2002]

 

i didnt think that mattered. maybe you mean they have the same rod length?

they fit cuz of the same 81 mm bore.

 

Just because a piston has the same bore as another, does not mean that it will fit in said block. Some pistons have different piston pin locations, which would cause the top of the piston to stick out of the block.

So instead of making an LS/VTEC with the LS block and VTEC head, you can just use the internals from the LS block and have a much easier job. This would prevent all external oil routing.

Kenton

 

Yes, it all fits like it was meant to be there.

 

Would the displacement change with the B18A/B piston/rod crank in a B18C? The bores are the same though is the stroke determined by the rod/piston's length of movement, or by the actual "height" of the cylinder? Basically, I'm asking if the stroke is determined solely by the crank/rod/piston, or by the cylinder dimmensions? I think it's the former based on the meaning of word "stroke".

Thanks

Note: genuine question.

 

The B17A deck hight is the same as the B16A, the only differences in the two motors is the stroke, rod length, and piston dome and the distributor does mount to a B16A2 and A3 but not an A1.

 

Yes, the displacement will change. The deck height and bore is the same for the B18A/B/C, so the only difference would be the stroke of the crank, and the length of the rods.

Kenton

 

The B18A/B has a larger displacements crank than the B18C.

An engines displacements is governed by the stroke displacement and the bore diameter.
the Block's height could be 5meters or 1 meter or whatever, it wouldnt change the displacement.

Hence, putting a B18A/B crank into a B18C would alter it's displacement

 

So, the stroke of an engine is independent of the rod length, and only dependent upon the crank? The stroke shouldn't change with different sized rod lengths and piston heights, right?

Sorry for the extra ?s.

 

yeah, that's right. Think of the crank as a circle of say 100mm diameter. If you attach a rod and piston to it, it doesn't matter what you do to the rest of the system, the piston will only move 100mm (assuming it was within the confines of a cylinder)

-Chris

 

Keep in mind though that although a longer rod doesn't affect stroke , it does affect clearances between rod and block, and piston and head.