I searched for this answer, but it was hard to come by, and i could not find a straight answer to my question. I have always noticed that the nonvtec engines have a longer stroke, and i have been told that results in more torque. This has never really been relevant to me because i always have had an H22. well i recently swapped in an F22B DOHC non vtec, and after driving it around for a week or so in my 5g prelude waiting to install my turbo setup, i am almost positive that the F engine has more usable torque in the low end, or atleast it seems that way. This put me off entirely as i expected the F engine to be inferior in every way.

Well recently i pulled up specs on the two engines (h22,f22B), and was comparing the stoke/displacement. I noticed that the h22 had a stroke of 90.7mm, and the f22b with a stoke of 95mm. Does this difference in stroke result in a more usable/streetable powerband for the nonvtec counterpart?

also, I have always read that the b18b engines lay down more torque than a b18c1 engine, and i figured that was do to the stroke. however, when i looked at the specs on those engines, i noticed that the b18b actually has more displacement than the b18c1 too. Then i went back and looked at the H/F engines and noticed that even though the stroke is longer on the F engine, it does NOT have more displacement over the h22 like the b18b does over the b18c, just a longer stroke.

Why is it that the B series engines have more stroke AND displacement for their nonvtec engines, while the F series (which is basically an iron sleeved H series block anyways) only has a longer stroke but equal displacement as the H22? is there an advantage/disadvantage to this? is this increase in both stroke AND displacement the reason the b18b creates more torque? does the longer stroke alone help the F22B? maybe using the B series as a comparison is not a good choice, but it seems like the closest relative.

apologies for this probably being hard to read. ive been searching for this information but just cant come up with it. thanks for making me smarter.

 

Without going into a very detailed explanation, the equation for torque (from a physical standpoint) is:

T = R*F, R=Radius and F=Force

(FYI there's another equation but don't worry about the details, you just need to understand the general concept)

To make this relevant to the question, stroke is twice the radius that the connecting rod journal creates when the crankshaft is rotated. Since this is a set distance in each respective engine F is the only independent variable and this dictates the amount of torque each engine will put down. Now F is controlled by combustion which is comprised of air/fuel being compressed and ignited. This is dictated by the cam profile and fuel maps.

In the instance of the B18A/B making more torque than a B18C, think about this. The blocks have the same deck height. If the stroke is changed but all else is equal (meaning the same amount of air/fuel is compressed the same amount and ignited), then by the equation T = R*F the B18A/B has the advantage because R will always be greater compared to the R of the B18C. Of course it's not that simple but you get the idea of why a bigger stroke is desirable.

As for displacement, that is a result of calculating volume. Without considering the volume of a combustion chamber, just think of this as:

V = pi*R^2*H, R = Bore/2 and H = Stroke

Again, with all things being equal (in this example Bore would be the constant, being 81mm for the B18A/B/C) as the stroke increases the volume increases. And again, it's not that simple but you get that main idea.

In the case of the F22 vs the H22, you have the F22 with a 95mm stroke and 85mm piston vs the H22 with a 90.7mm stroke and an 87mm piston. Do the math and you'll see how it is the F22 has a bigger stroke and yet still yields the same displacement as an H22.

So to conclude and attempt to answer your question, it's a combination of things that dictate the usable powerband but generally speaking think about that equation of torque. If F is equal, then the amount of torque generated increases as stroke increases. If stroke is equal then torque increases as F increases. If neither are equal, then their respective products will dictate which combo will put down more torque.