ENG: H23 Intake Manifold Swap (56K die!!!)

[Clueless]

I was curious if you had a side by side comparison picture between the f22 and h23 TB....

[bboygreddy]

oh see u have an adapater that hooks from intake to TB, thats what i meant, due to the h23's tb being a bit larger

quick question where did u put ur vacuum hose, its the one that hook to the front right side of the a1's labeled i think cruise control vac, it comes off from the right near the brake cylinder thing. also did u hook vac #8 to anything?? heheh i love this swap man, at 4k it kicks in hard, excep twith auto 2nd gear is forver long

props to cokinut once again for the sweet write up!

[owequitit]

Good write up. It inspired me to do my own investigation.

1) The H22A Plenum is the same as the H23 and will also bolt on. I don't know about the H22 Runners for sure, because I didn't try it, but my impression from all of the info I have see is that they do not.

2) The H series and the F series IACVs are interchangeable. I am currently running an F22 IACV on mine.

3) The TB is about 5mm larger in diameter on the H series. With a very rough caliper measurement I got 57MM on the Accord and 62MM on the Prelude.

4) I used the F22A6 runners on my setup. Having gone from F22A4 to F22A6 to F22A6 with H plenum, I can say there is quite a bit of power locked up in the intake mani. It now pulls at 6700 like it did at 6300 with the A6 plenum. It sounds cooler and also didn't seem to lose any lowend.

5) I have a stock intake on my car. It will fit over the TB, you just have to fiddle with it.

[ehulst]

where did u put ur vacuum hose, its the one that hook to the front right side of the a1's labeled i think cruise control vac, it comes off from the right near the brake cylinder thing. also did u hook vac #8 to anything??

i mis understood your question, yeah the TB is a bit larger, but just go to the hardware store get a hose clamp cut the stock inlet and throw the clamp on there, i have yet to spend the $2.10 for my outlet..just plain lazy to drive to the end of my road to my hardware store..........

crusie control one look carfully i think u can see it in my pic, i took a T fitting from my old 86 carbed accord and threw the vaccum line into my Dual runners......i noticed an effect w/ cruise control slightly(slight[not noticeable to the passenger, only to the driver] pulls randomly sometimes adds like an increase of speed but nothing drastic like 0.5mph,you really gotta feel how the car's driving to feel this... i now understand why),how ever no loss of power...8 i pluged long ago but i think it was a mistake, i think that might be my idle problem in the morning....

[owequitit]

Why would you cut the stock intake tube? It works just fine with the H series TB. You can't go with much larger of an outside diameter, but with the stock H it works fine.

[TSM_Pikachu]

Got a quick question on this mod, I got a manifold but it did not come with the water housing or the Air starting valve nor did it come with a IACV.
Can we buy those separate at the stealership or what?

[TouringAccord]

Yes, you can buy them at the dealer, but they are going to cost you.

I found a complete thermostat housing (water housing) with coil attached on eBay for an H23A1. I got it for $.01 bid + $10 shipping. Don't know if you will find a good deal like that, but you could take a look.

Here is an idea of what you would pay for those parts from the dealer.
http://www.hondaautomotiveparts.com/...E+BODY+%282%29
starting valve = #14
IACV = #17

http://www.hondaautomotiveparts.com/...UMP-THERMOSTAT
thermostat case = #9
thermostat cover = #6
coolant temp sensor = #15

[owequitit]

Your F22 IACV should work just fine. My H plenum was MT, my IACV is F22 Auto (they have some functionality differences from the MT). It fit perfectly. I also have the H22 IACV but one of the coolant lines was pinched between the IACV and the F22A6 runners, so that is why I used the F22. I have also put an MT Accord IACV on an H22 plenum and it worked also. They are more plentiful and liable to be cheaper if you don't have one to use.

The Fast Idle valve isn't really necessary to the correct funtioning of the engine. It brings the idle up to prevent surging. You can either use the H22/H23, or you can block it off.

The thermostat housing from the F22 may work, but I don't know for sure.

[TSM_Pikachu]

Your F22 IACV should work just fine. My H plenum was MT, my IACV is F22 Auto (they have some functionality differences from the MT). It fit perfectly. I also have the H22 IACV but one of the coolant lines was pinched between the IACV and the F22A6 runners, so that is why I used the F22. I have also put an MT Accord IACV on an H22 plenum and it worked also. They are more plentiful and liable to be cheaper if you don't have one to use.

The Fast Idle valve isn't really necessary to the correct funtioning of the engine. It brings the idle up to prevent surging. You can either use the H22/H23, or you can block it off.

The thermostat housing from the F22 may work, but I don't know for sure.

Okay well that is my fault for not being clearer.
I have a 5th gen accord but am a former CB7 owner. I had to join for that reason, I beat the snot out of the CB7, left right up and down the block and it still ran hard. hahahah
I have a 95 Accord EX with a 5 spd F22b1 so will the IACV still work alright and then if the lowest temp around my area gets to about 43deg farenheit, you think i will be cool without the air starting valve? (I'm assuming the air starting valve is that fast idle valve you speak of)
The water housing is the thermostat housing?

[owequitit]

Thanks for clarifying. I have bad news.

1)All US Domestic Market (USDM) F22Bx and F23 series engines have a completely different manifold flange design. An H23 or and F22A manifold will NOT work. All US F22B and F23 engines are single runner, so you will not be able to use any of Honda's dual runner stuff on the car.

Sorry, it sucks, but is true.

The engine will run fine without the Fast Idle Valve, it may just surge a little bit while it is warming up. I have never noticed it on any car that doesn't have one.

I don't know off the top of my head if F22A IACV will interchange or not. Your car is still OBD I so there is a chance it may work.

If you got an USDM F22B manifold and are trying to use that on your 95, then if your IACV has the same port pattern and bolts to the manifold, you should be fine.

[TouringAccord]

(I'm assuming the air starting valve is that fast idle valve you speak of)

just so you know. The air starting valve and fast idle thermo valve are two different parts. If you look at the beginning of this thread, the pictures are labelled to show the different parts.

The water housing is the thermostat housing?

yes

[TouringAccord]

I have bad news.

1)All US Domestic Market (USDM) F22Bx and F23 series engines have a completely different manifold flange design. An H23 or and F22A manifold will NOT work. All US F22B and F23 engines are single runner, so you will not be able to use any of Honda's dual runner stuff on the car.

Sorry, it sucks, but is true.

Sorry, but that is not true.

Yes, the flange designs are different. But you can make it work, it's been done before, there are some modifications that are needed however. I am currently about to start modifing the flange on my H23 IM to fit on my F22B1 head. Although I won't be using my F22B1 motor in an Accord.

If you would like some proof, here is a thread from a member on AccordinglyDone who fit an H23 IM onto a F22B1 head in a 5th gen Accord.
http://www.accordinglydone.com/forum...ad.php?t=11176

As you can see from that thread, you need to cut some of your flange and some of the thermostat housing due to the vtec solenoid being in the way. In addition, it would be a wise idea to do some porting on the intake side because the intake ports on the F22B1 head are smaller than the intake manifold runners.

Also, if you plan to use the bypass valves (a.k.a. secondaries) as they were intended, you will need the vacuum tank and sensor located under the intake manifold of the H23. You'll also need an ecu that will control the addition of the bypass valves. Or you can hook them up like others have done, like in that thread, but they will open up sooner than when they are intended to. You could also remove them from intake manifold altogether as some have done as well.

[owequitit]

Sorry, but that is not true.

Yes, the flange designs are different. But you can make it work, it's been done before, there are some modifications that are needed however. I am currently about to start modifing the flange on my H23 IM to fit on my F22B1 head. Although I won't be using my F22B1 motor in an Accord.

If you would like some proof, here is a thread from a member on AccordinglyDone who fit an H23 IM onto a F22B1 head in a 5th gen Accord.
http://www.accordinglydone.com/forum...ad.php?t=11176

As you can see from that thread, you need to cut some of your flange and some of the thermostat housing due to the vtec solenoid being in the way. In addition, it would be a wise idea to do some porting on the intake side because the intake ports on the F22B1 head are smaller than the intake manifold runners.

Also, if you plan to use the bypass valves (a.k.a. secondaries) as they were intended, you will need the vacuum tank and sensor located under the intake manifold of the H23. You'll also need an ecu that will control the addition of the bypass valves. Or you can hook them up like others have done, like in that thread, but they will open up sooner than when they are intended to. You could also remove them from intake manifold altogether as some have done as well.

Take it in the context of the post. With the right fabrication tools/money/skills, I can fab an LS1 intake manifold to fit.

Do you honestly believe that someone who doesn't know what a fast idle valve and an air boost valve is or does is going to do that???? Let's be realistic here.

Also, had you interpreted the post correctly, I thought it was IMPLIED that the manifold AS IS wouldn't fit. Of course you can change/modify the flange and or ports. Is it worth the extra couple of HP? IMO no.

Perhaps a better solution would be to just use the larger plenum SOHC VTEC F23 manifold with a larger TB. It would be a lot less fabrication, and may even produce superior results if done correctly. You could even port it or extrude hone and probably have even better results still.

Disagree with me if you want. It isn't feasible for a beginner. I can also tell you from an airflow/aerodynamics standpoint that the port match problem is causing at the very least some high rpm issues. A little turbulence is good, but you can tell just by comparing the pic of the H23 and F22 heads, that isn't "a little."

If you want proof, I have an aerodynamics text book for sale.

[owequitit]

P.S. You have to cut/trim/hack the manifold flange area, and then cut/trim/hack the thermostat housing support. Tell me there isn't a chance of reduced durability there.

[LX Rida]

Good write up. It inspired me to do my own investigation.

1) The H22A Plenum is the same as the H23 and will also bolt on. I don't know about the H22 Runners for sure, because I didn't try it, but my impression from all of the info I have see is that they do not.

So the H22A plenum will also fit the F22A6 intake manifold?