H22/H23 blocks

[gunnmen01]

Are the h22 and h23 blocks the same other than the vtec oil passage? I am looking for a H23 block to build a motor, but need my lude to run until i get it built. I was wondering if i can use an h22 block instead?

[Prelewd]

http://www.jgenginedynamics.com/Short%20blocks

Just curious, what are you building? I'll trade your H22 for my H23... maybe.

[gunnmen01]

Im not building a h22, i just want to use the block if i can....that way i can build the motor and drive the car still....


gunnmen01

[del]

if i remembe right, i think you can swap heads. not so sure about the blocks.

i'll see what i can dig up.

(later in the day) so what i dug up was that no, the blocks aren't the same.

[gunnmen01]

So whats different? would i need to pluag the vtec oil passage? Or is there more to it?


gunnmen01

[drift]

H22 and H23 blocks are identical. the only components that differ are the internal rotating assembly, balancer shafts, timing cogs, crank pulley, and oil pan.

the H22 also has oil squirters.

the H23 block merely has a removeable plug in the VTEC oiling channel.

depending on what you're doing, you can swap H22 internals and accessories into an H23 block and stick a VTEC head on it and it's a 100% H22 motor, except for the stamping that says "H23A1".

on the assembly line, the blocks come out of the same casts... some turned into H22's, some turned into H23's. pretty much just the internals dictates the engine code.

[cero]

I could be wrong, as it's been awhile, but, as I recall, the h22's have an open deck design. My h23 block is sitting on an engine stand in my garage right now, and it has a closed deck. I don't know what difference that would make in this particular question, but, I always thought the two blocks were somewhat different.

[choweyt3t4]

only real difference is in the cylinder sleeves

[crj_lll]

Are the blocks identical or is there a difference in them such as open and closed deck design? I am asking to see if any displacement can be gain by using an H23 block over and H22 block with and H22 head?

[Prelewd]

The 4th gen H22 had a closed deck design.. they switched to open in 1997 with the new H22. That's all I really know about it, sorry I couldn't answer your second question. I'd like to know the same though.

[drift]

Originally posted by crj_lll
Are the blocks identical or is there a difference in them such as open and closed deck design? I am asking to see if any displacement can be gain by using an H23 block over and H22 block with and H22 head?

the displacement gain on the H23 is due to a stroked crank compared to the H22.

bore diameters are identical, along with deck height.

[crj_lll]

Does that mean the valve/piston clearance change from an H22 to and H23 since the crank is longer? Are the rods the same length?

[Prelewd]

Originally posted by crj_lll
Does that mean the valve/piston clearance change from an H22 to and H23 since the crank is longer? Are the rods the same length?

As taken from madh0 at nwhonda:
H22 rods are longer, and produce a lower rod/stroke ratio in the engine. The angle to the piston wall is greater, which puts more strain on the engine. The added strain will give you a broader torque range however. The piston speed will be higher with a longer rod as well.

[drift]

Originally posted by crj_lll
Does that mean the valve/piston clearance change from an H22 to and H23 since the crank is longer? Are the rods the same length?

please, dont ever waste your money going to school for an engineering degree.

on the H23, if the stroke is longer than an H22, but deck height is the same, the rod length would of course have to be shorter to prevent protrusion above the deck at TDC.

H23A1 block piston bore: 87mm
H23A1 block stroke length: 95mm
H23A1 rod length: 141.5mm
H23A1 rod/stroke ratio: 1.49:1


H22A4 block piston bore: 87mm
H22A4 block stroke length: 90mm
H22A4 rod length: 143.0mm
H22A4 rod/stroke ratio: 1.59:1


wrist pin placement also differs between the two motors. the combined rod and stroke length of the H23 motor is 1mm higher than the H22. therefore, the wrist pin location on the H23's P14 pistons are 1mm higher than the H22's P13 pistons to prevent the H23's pistons from protruding above the deck by 1mm.

[drift]

Originally posted by Prelewd


As taken from madh0 at nwhonda.com:
H22 rods are longer, and produce a lower rod/stroke ratio in the engine. The angle to the piston wall is greater, which puts more strain on the engine. The added strain will give you a broader torque range however. The piston speed will be higher with a longer rod as well.

that statement is backwards. a longer rod will decrease sidewall forces during crank rotation. it also slows piston speeds.

if you were to take a single crank, two differing rod lengths, and two differing block deck heights, the degree of angle acting on the rod when the crank is at 90 degrees BTDC will be less with a longer rod.

this means less sidewall force compared to a shorter rod on the same crank.

a shorter rod also means the piston speeds are increased as the rods base has to travel a longer distance around the circumference of the crank's rotation, in comparison with a longer rod on the same crank.

1.75:1 rod/stroke ratio is considered "square". it's a comprimise to give a decent amount of torque while preventing the loss of power due to friction from sidewall loading.

with a rod/stroke ratio of 1.49:1 on the H23 compared to the 1.59:1 of the H22, it shows the H22's rods being longer. this produces less bearing stress, less side force, and slower piston speeds. these are all the things you need to do to increase high-rpm capability and reliability at those higher speeds. slower piston speeds also allow for more efficent breathing, especially at higher rpm, as the piston doesnt drop too quickly to get an efficent fuel charge. the closer to 1.75:1 you get, the better your results. over that, you give up torque for higher rpm capability... this condition is called "oversquare".

the B16A features a 1.749:1 rod/stroke ratio. this is why it revs higher and produces power easily, as there's less bearing stress and side load friction. it can essentially breathe more efficiently... well enough to support high-rpm performance.

the F20C in the S2000 is a prime example. it's rod/stroke ratio is also 1.75:1.

so in closing, being undersquare (short rod, long stroke) will decrease performance by creating more side force and increasing piston speeds. this results in reduced efficiency at high rpm due to friction, breathability, and increased bearing stress.

being oversquare (long rod, short stroke) will decrease piston speeds, reduce side force, and reduce bearing stress... but at the sacrifice of torque due to the slow piston speeds at low rpm.

being in the middle at 1.75:1 rod/stroke ratio will provide a happy medium of both.