gjlude

So...the reason I have put this topic in the hybrid section is that the motor will use the f23a1 block with the f22a6 head.

I've done some research trying to find more information about enlarging the combustion chamber to match the bore of the f23a1 block of 86mm. I'm not a machinist so excuse me if I have the terminology wrong.

I've read that the "sharp" edge overlap can potentially cause detonation because it will become a hot spot. I couldn't find any technical papers on this, just forums. Has anyone had any experience with this phenomenon?

If this is not a factor, would it still be advantageous for me to enlarge the combustion chamber to match the block bore? I don't mind the extra work on the head, I just don't want to pay for something that is not critical in the motor's longevity.

Also, if it is critical that I match the bore, is that a task that any reputable machine shop could do? Or is it more of a specialty type work?

Thanks for any help.

gjlude

This is the thread I am "more or less" referencing...

http://cb7tuner.com/vbb/showthread.php?t=170763

Found one more link from h-tech. I've read a lot from this guy that is responding, he seems quite knowledgeable.

http://ht-archive.org/showthread.php?p=44445182

Anybody else have any hands-on experience? I feel like I've almost answered my own question. Haha.

gjlude

Found yet another discussion on this, and after reading it, it seems that it is just a "yes vs. no" argument that no one can come to the same conclusion.

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/mismatched-head-bore-cylinder-suggestions-2358965/

I guess another question would be, does Honda match precisely the combustion chamber volume bore to the block bore?

Still looking for some feedback...

hondasdohc

Maybe not this guy on here did that head swap to his f23 and he didn't mention the enlarging of the combustion chamber bore.

gjlude

Yeah, I talked to my local shop here and I was told that it wasn't necessary, but it would be a good idea to.

hondasdohc

I don't even think they do it either my boy did an lsv b16 head b18 block no problems so far. My setup has a 85mm f22a1 block and a 85mm f20b head and i was lucky to have this head it has the same bore instead of putting a h22 87mm head on it.

jonina

don''t want to get off topic but i have a question for you, why are people swapping f22 heads on thier f23 blocks? i am doing some research because i a planning on a f23 swap into my ek and i noticed that a few people swapped their f23 heads out for f22a6 heads

wolve

f23 head flow sucks
f22a head flow out of the box is quite impressive, but porting potential is enormous!!!

swapping f23 for f22aX head is like swapping a LS with a vtec head flow wise!

jonina

ooh, ok thank you

gjlude

Thank you for the information and insight.

You are correct, I have not specified my intentions for the build. It will be NA, and I am using k20z3 pistons. They have the same 4.25cc dome as the k20a2 type-s. This should give me a CR of around 12.3:1. I'm 500ft. above sea level, and I have access to 93 octane but will tune on 91 since only one gas station offers 93. As for spark plug/heat range and ignition timing...you got me there. I have not thought that far through. I'll do more research on those.

To be honest, I'm new at building engines, but I am being adventurous on this build. I'll take it slow - learning as much as I can. I also have access to a nice set of Starrett micrometers and dial bore gauge, but I realize that won't do me any good if I don't know what I'm doing.

I'm sure I will have several more questions as I go along. I've read through your engine build threads (except the k24 hybrid) and they have answered several of my questions. So, thank you for your knowledge.

ApexiChild

IMHO i'd perfer to have a smaller camber size vs. matched to piston size.

i would think the smaller the camber the better the fuel burn and more power.
just because the compressed air on the upstroke is crammed in smaller volume camber up top, fuel is injected, and power is unleashed downward.

a larger chamber would just mean fuel has to mix with air in a larger area of quence space.

maybe i'm just simplifiying it too much but imho you shouldn't waste money trying to open up the camber and spend money on nice injectors like ID/fic/bosh/ect..

ivan93egreppin210

good stuff. this never even crossed my mind when i decided to put the a6 head on my f23. good to know.

KPDSM

Hey guys
I've been online the past 3.5 hours looking - I know the rules to the forum(s) and have been searching for a pretty basic answer - I'm sure someone here knows...

Will the f22 head bolt directly to the f23 block with no modification? If there is a modification, what is it?

I'm working on a 5g accord - obd1, crome pro, (havent decided on p72 or p28 yet) - once I get this figured out I can either grab another f23 head or f22 head with ARP fasteners

thanks

unuselectus

We need to bring this thing back from the dead!

I have been following all things F-series for a while, but when ivan93egreppin210 built his motor, I was sold!

I hadn't even considered matching the block with the head... There really isn't any decisive answers on this build, unlike the unlimited LSV and K20/K24 threads.

If anyone has anymore thorough assembly and machining guidelines for this setup, PLEASE let me know. I'm about to purchase my parts, and I want to get this right the first time. ;-)

unuselectus

No F-Series build love...?

ivan93egreppin210

I never enlarged the combination chamber on my head. Never had any problems either.

ivan93egreppin210

And for the guy asking why we swap heads, this is mine with very little porting.

hondamark35

I matched mine just for peace of mind. it was very easy... if you're handy with a Dremel and have a steady hand.

I used the ball-shaped carbide burr and then cartridge roll to clean up.

marked out the material to be removed with paint pen using the original F23A1 head gasket positioned with the dowel pins. once the paint was gone, i just blended the cut into the chamber removing as little as possible.

I left the old gasket in place while cutting to protect the machined surface of the head from damage. also taped off the valves (removed rocker assembly so they would all be closed) to make clean up easier.