F22a with h22 or h23 block

[h3ll]

Hi guys,
i currently have f22a7 with 150HP in stock. It's EUDM with 9.8:1. Now it has h23 intake manifold with 60mm TB and 2.25" exhaust. It makes something like 160CHP. I'm now in progress in fitting k20a2 manifold with 62mm TB. So can someone advise me what block to choose? h23 (CR stays the same) or h22a2 with +500revs and 10.5:1 CR. Is it safe to rev stock f22 head past 7k rpm? It's not some big built for race, just simple daily driver with a little more fun and I like sohc, so full h22/23 swap is not an option (i just want to get more torque). So i think engine with bigger stroke is my choice? Or just get some higher CR pistons and stay with my f22?
Thanks for any kind of information.

[deevergote]

This has been discussed at great length on this site. Searching will yield many results.

It is a bad idea, unless you plan on doing some major headwork. The biggest issue is that the bore sizes don't match, and you will be leaving yourself a sharp ridge in the combustion chamber that will be inviting detonation. The F22A head on an H block isn't as bad as an H head on an F22A block (which is something people often want to do for a "cheap H22"), but it's still not the best idea.
Do headwork to enlarge the combustion chambers to match, and be careful with your installation, and it could work... but you'd be much better off just building up the F22 block.

People have revved the stock F22A head over 7k and reported no problems, but I wouldn't suggest it without a valve spring upgrade. Without a cam and port work, I'm not even sure it would make power that high, even with higher compression.

[Jarrett]

You currently have a 95mm stroke. The H23A is the exact same. The H22A is 90.7 so that's not an improvement in stroke.

Keep what you have and get forged pistons and rods and rebuild the bottom end. Or if you don't want to spring for forged pistons then K20A2 (or the European equivalent for the RSX Type S engine) pistons use a 4.25cc dome. They are an 86mm bore so you'll have to have the cylinders bored by 1mm and rotate them 180* in the cylinder because the rotate the opposite way in the K20.

The added compression will allow you to chose a nicer camshaft that will make good power. However, any aftermarket camshaft with move the powerband higher in the rev range so power down low will have to be helped by something else.

On an unrelated note, do you know what stamp is on the end of your camshaft in the F22A7? I'd like to know for sure if it's more aggressive than the one in the F22A6 over here.

[h3ll]

Yeah, i've found almost everything that I asked about in other threads. Sorry for that. Is there any OEM pistons of 85mm bore that yields higher CR and fits f22? F20 maybe? I just can't seem to find what CR I could be expecting.

Jarrett, I didn't check my camshaft. I'm interested myself. Can the stamp be seen just with the valve cover removed?

[Jarrett]

Easier than that. It can be seen with just the distributor removed.

There isn't really an OEM piston that will work with the 85mm bore of the F22A that you don't already have. Your pistons would actually be a decent upgrade over what we have here in the states. Ours are -15.6cc and make for an 8.8:1 compression ratio.

The only real piston choice we have is the 4G63 piston designed for the 100mm stroke of the 4G64. The only problem is finding one that is meant for high compression. The compression height on those are 28.73mm which is already significantly lower than the 30.55mm ours is and they are dished on top of that. I want to say I've seen a set for high compression before, though.

[Joey GT-R]

I think the obvious option here is F20B pistons. Using the ZealAutoWerks Calculator, on a stock F22A(I realize he has an A7 but bear with me) F20B pistons combined with F22/H23 rods creates a 12.67 C/R.....and with F23 rods he's at 11.99 C/R

The only other Honda engine I know of to come with an 85mm bore was the G25. But that's still only 9.0:1-9.6:1; and the 9.6:1 came out of the G25A4 which came in the USDM & CDM 95-98 Acura 2.5L. But I'm not sure on the specs of the combustion chamber and plus it's a 5 cylinder.

Why not just invest in some Bisimoto Pistons? Or bore your block and move up to K20 pistons?

[Accord problems]

f22c

would the f22c or f20c pistons be a better choice than the k20 ?
http://en.wikipedia.org/wiki/Honda_F20C_engine

[Jarrett]

Alright everyone, settle down with the piston recommendations for a second. Joey, the combustion chamber of the G25A is roughly 50.5cc just like ours. In many ways it's like an F22A with another cylinder. The bore is 85mm but without knowin the compression height or the dome volume then it's an empty suggestion. As for the F20B pistons, it's a start but clearance could be a problem. People run 31mm pistons in H23A1 bottom ends with a 53.8cc H22A head on top with minimal issues. But the F20B dome is even bigger and you're talking about squeezing it into a 50.5cc combustion chamber. The K20A2 pistons also have a big dome but drop the compression height by .5mm to give that minimal bit of clearance. Yes you have to bore but on old cylinders you probably should be anyway.

Accord Problems, the F22A cannot be bored to 87mm. Those are not options.

[Accord problems]

what is the max bore a f22a can handle ?

[Jarrett]

86mm but failures have happened there also. The one I know of was a boost build, though.

[Accord problems]

ok thanks for the info .

[deevergote]

Anything more than a slight overbore of stock sleeves can be disastrous.


Jarrett, you may know more about it than I do (as I know little...) but is the F22B DOHC's higher compression due to the head design, or are the pistons different?
Another potential option would be the F20A, which I am quite certain has the same head as the F22A, but the F20A has 9.5:1 compression. I don't know enough about the engine to say if it's due to the stroke, or the piston design... but it's worth looking into.

[Jarrett]

There is some suggestion that the F22B has a smaller combustion chamber. In fact, PirateMcFred got really upset with me one time for stating otherwise. However, the pistons have different casting numbers on them and are noticeably less dished. I've seen them in person. We also know F22As in other markets to have the same 9.3:1 CR as the F22B DOHC so it stands to reason that the pistons are different.

The F20A pistons could be an option but I don't know anything about that piston besides the bore. I suppose I could calculate dish volume as the combustion chamber, headgasket thickness and stroke are all known.

It's important for everyone to remember that simply calling a piston a XX.X:1 CR piston is an incorrect way of labeling it. A piston with a flat top with achieve a much higher compression ratio in an engine with a 95mm stroke than it would in the same block with an 88mm stroke and accompanying rod length change.

[deevergote]

Quite true. This is all going beyond my own experience, so I can't do much more than guess.

It's entirely possible that the extra 10hp that the F22A7 makes could be attributed to the higher compression pistons. I don't know the F22A7's CR, and I can't find a reliable source that lists it at the moment. If it has the same pistons as the F22B, that could explain the higher output, and eliminate the F22B pistons as an upgrade option.

[PR CB7]

You currently have a 95mm stroke. The H23A is the exact same. The H22A is 90.7 so that's not an improvement in stroke.

people swap heads on h23vtec, because of the head, honda made ma motor like that because of the head
there's only so much a non-vtec head can give you

There isn't really an OEM piston that will work with the 85mm bore of the F22A that you don't already have. Your pistons would actually be a decent upgrade over what we have here in the states. Ours are -15.6cc and make for an 8.8:1 compression ratio.

with the h22 head and a f20b piston you WILL be at 11.7 comp
the f20b piston fits perfect

Alright everyone, settle down with the piston recommendations for a second. Joey, the combustion chamber of the G25A is roughly 50.5cc just like ours. In many ways it's like an F22A with another cylinder. The bore is 85mm but without knowin the compression height or the dome volume then it's an empty suggestion. As for the F20B pistons, it's a start but clearance could be a problem. People run 31mm pistons in H23A1 bottom ends with a 53.8cc H22A head on top with minimal issues. But the F20B dome is even bigger and you're talking about squeezing it into a 50.5cc combustion chamber. The K20A2 pistons also have a big dome but drop the compression height by .5mm to give that minimal bit of clearance. Yes you have to bore but on old cylinders you probably should be anyway.

Accord Problems, the F22A cannot be bored to 87mm. Those are not options.

the g25 piston does work, 85mm bore, a dome of -10, compression height of 30.5
it does work in reality, the reason the numbers are different from a f22b is because IT was meant for a 5 cylinder, but it does work

H3ll if you swap to a prelude vtec head, you'll have better piston options, if you are in the process of making a k20a2 manifold fit to a f22 flange, you have the capability to do this swap

granted the manifold will perform better on a vtec head, being that the manifold doesnt have a cooling passage going to the T-stat, its already casted in the head