Scott Little

New Project
I'm putting a H23A into my 94 Ex Accord.




Parts List(Roughly $2,500 in parts/shipping/taxes)
JDM H23A (Hmotors)$999
JDM M2S4 Manual Transmission(Hmotors)$750
Engine Intake Manifold Spacer(Ebay) $32.99
OBD1 P28 Chipped with H23A Baseline(www.phearable.net) $134.00 fyi I had the ECU laying around so add another $100-$200 for ECU
JDM H23A Exhaust Manifold/Downpipe(Hmotors)Modified to fit Accord. $70 at local muffler shop including 2 bungs, extra bung for Wideband
H22A Flywheel(Hmotors)
H22A Clutch(Hmotors)
H22A Pressure Plate(Hmotors)
Prelude Power Steering Bracket(Hmotors)
94 Accord Power Steering Pump(from original Engine)
94 Accord Alternator(From original Engine)
EGR from Original Engine
All motor mounts original 94 Accord, energy insert in front mount
JDM H23A Fuel Rail and Injectors, removed Resistor Box and wiring.
Earls Filter and AN Lines to Fuel Rail
Rosko JDM H23A IACV Adapter plate.(www.roskoracing.com May not be available on website yet) $35.00
Kaizenspeed H-Series Manual Timing tensioner V2(www.roskoracing.com) $125.00
F22b2 O2 Sensor from original motor
F22b2 Driveshafts/intermediate shaft
AEM CAI from Accord
Custom 2.25 exhaust with vibrant resonator
New Cone Filter(Autozone) $30
Accord heater/Coolant Hoses
H23A OBD2 Distributor(harness wired for OBD2)
H23A internal Coil/Ignitor
Gates T226 timing belt(Amazon) $27.24
Gates 41046 Water Pump(Amazon) $34.46
Dorman 917-006 Counter Balance Shaft Seal Kit(Amazon) $7.13
K&N PS-1004 Pro Series Oil Filter(Amazon) $5.38
Centerforce 50058 Clutch Alignment tool(Amazon) $5.95
Felpro/Camshaft Oil Seal(Autozone) $7.99
Prelude Ignition rotor(Autozone) $15.99
Prelude Duralast Wireset(Autozone) $30.99
1990 Accord Distributor Cap(Autozone) $21.99
Prelude NGK Copper plugs(Autozone) $10






I just finished the B20 Swap(for the second time) into my wifes Civic and for whatever reason cars just break whenever she drives them. So the same day that I get the Civic back on the road i get a call from her that my Accord is broken down. The transmission went out. The stock manual transmission that the car has had since i picked it up a few years back has always leaked, it got a little too low and seized up. I planned to swap it out with a M2A4 within the next few months anyway so it sucks but its not a disaster. I priced out the transmission at Hmotors for about 650. I pulled the old transmission from the Accord and as i was sitting there looking at the car i was thinking... well 3 more hours of work and the engine will be out completely, this would be a good time to swap out my 200,000+ mile engine. So i called Steve over at Hmotors again looking for a F20. He only had an automatic f20 in stock and the compression test showed low compression. Instead he gave me a good deal on the H23A. I wanted the H23 anyway but just didn't want to spend the extra cash. Big thanks to Steve over at HMotors for the help and good price on the engine and transmission.

I rushed over today and picked up the Engine, Transmission, Downpipe, good clutch, flywheel, pressure plate, power steering bracket from H22a and power steering pump from h22a as well that i would love to avoid swapping out if possible since i have a brand new one on the accord already. I remember when i was doing F22A swaps to H22A i was able to use the pump from the F22a but it didn't bolt up perfectly.

I want to get this thing dropped in right away but the first issue is that i don't have a clutch alignment tool. Just ordered on amazon for 6$.

Edit. to make sure I'm not spreading mis-information. The obd2 harness is a no go, it will not mate to the fuse box easily the plugs are missing, the plugs for the dash harness need the connectors swapped, you would most likely still need to swap over the wiring for the EGR, you may be able to repin the connector since the color seem to match up. The 3 pin IACV is a no go, you can wire it up without much issue, the colors match but the ECU would need additional programming/chip to make it work. Rosko will be putting selling an IACV adapter plate for JDM h23a soon and I hopefully will be testing the prototype in a few days. This will make this swap super easy for anyone doing it in the future. Ill take some pictures and post my findings once I get it.


Removing the needed wires and connectors from the JDM harness is the way this is normally done.


I am using the OBD2 injectors so I removed the resistor box wiring/bypassed it and added the OBD2 Injector plugs. I removed the wiring from the IAR And re-pinned the Ignition wire from the 2 pin connector to so it would match up with the OBD2 Distributor. I will be connecting the plug for the tach signal directly to the distributor later on. I also added the Knock sensor wire to the OBD1 Harness to a blank spot and will be patching that thru the firewall and to the ECU so it looks stock.

I have a P28 sitting here already so i will send it out to get chipped and have the H23A Baseline added.


I will be installing a spacer so I can remove the IABs.


I am using the USDM EGR since the JDM one is a 6 wire and wont with the OBD1 ECU easily. Its a simple swap.

I know i should be doing the Tensioner, Water Pump and Timing belt but i'm short on funds. You guys can all say i told you so in 3-6 months when i have timing issues. Ill pull the covers and inspect everything.

I am debating pulling the balancer belt, assuming it has one. That's something i have always done in the past but maybe ill hold off on that for now.

I'm excited to see how she runs, i have had a few really good H22A's in Preludes and at one point i had a short lived h23a hybrid that didnt last long. I was always happy with them.

Im not sure what to do about the downpipe. My DC header will not fit so i will be using the stock header/manifold for now. The downpipe has a different connector than what i have now so i was thinking i would try the Downpipe from my DC header. They roughly look like they will match up. The lower collector on the downpipe is super small, i remember the H22a ones being Huge but maybe they are just small on the h23a's. Ill keep posting as i do the swap and take pics where i can. This isn't exactly a rare swap but i wanted to do a thread on it anyway.

Scott Little

Forgot to add, i think i need to make a change to the Secondaries on the intake, i cant remember how i did it before but i may just remove them. Anyone have a better solution?

GhostAccord

Nice Pickup..... rather see H23A than H22 swaps


If you are keeping the engine stock internally, I would run the IABs tuned up on the P28 base map.

CiGHonda

I would be interested to see a "quick swap". Usually there are lengthy build threads, but I'd like to see a weekend swap to get it up and running ASAP.

Scott Little

Should be pretty quick to get up and running.


Edit. Just so no one is gets confused with my previous statements.
I am using the OBD1 Harness modified with the wires needed for the H23A. More information is in the first post.

holmesnmanny

supposedly hmotors guarantees all the sensors as being in working order

Scott Little

Yea I believe that's correct. They actually checked and replaced the ones that were broken. To be totally fair one of the sensors on the back of the block is broken but I didn't know until I attempted to unplug the harness. It may be the Knock sensor, hopefully I have a spare.


The wiring Harness is where I have some confusion and that is in no way guaranteed. Like I said earlier all of the Sensors are on the motor and wiring looks good to all of them. My concern was that there 3-4 bundles of wires that had the connectors cut off that I have no clue what they are for. I thought that some of them bay be for the Resistor Box but that does not seem to be the case.


I will have to compare the Harness on my OBD2 Civic and the connectors on the accord.

Aradin

You're gonna have a much easier time adapting the car harness to the engine...and not the other way around. The conversion harness you stated you bought is presumably for the ECU side of things, which will do you no good since your car is already setup for OBD1. I'm not aware of any other conversion harnesses. The plugs on the H23A harness that attach to the car side of the harness will be different. It's really not worth attempting to adapt the OBD2 harness to an OBD1 car.

I put one of these into my 95 back in August. Using the OBD1 Accord harness was the simplest. Extend wires for IAT sensor, run a Rosko Racing IACV adapter, use an OBD1 H22 dizzy(either internal or external, whatever matches your stock Accord harness for simplicity.), run OBD1 injectors, and delete the IABs since you won't really have way to control them if you're using a basic chipped ECU solution such as Crome.

Whoever makes your basemap will need to know the size of your injectors so get that sorted before you ship out your ecu. Low impedance matches the Accord harness and keeps the resistor box. I recommend at least 345cc minimum for this engine.

It appears you have the "lesser" performing of the two variants of this engine since you have the P13 head and intake. One downside of this is that the IACV is on the front of upper plenum instead of the rear like the PDE models. You may run into clearance issues with the IACV adapter but I'm not sure. If so, you will need to source an OBD1 H22 upper plenum.

You will also need to adapt the fuel lines to work with that stuff. The banjo fitting is different on the H23A and will require a modified stock fuel line. The return will also need to be lengthened.

If you want to retain powersteering you need to source a 97-01 Prelude bracket.

Highly recommend replacing the timing components and switching to a manual tensioner setup before dropping it in. The stock auto tensioners will fail at any time and I certainly wouldn't trust a timing belt that had been sitting for 10+ years after being run for 40-50k miles.

Good luck with the swap. There's more to it than I think you know about so far. These engines are pretty great but they're....temperamental. Don't go nuts and rev it like it's an F20B or even an H22. Mine ate 2 main bearings and spit out a rod due to the bearing shavings clogging up the wrist pin oiling hole 3200 miles after I picked it up from the importer. And that was only revving it to 7200.... Still a stout engine, but definitely not a high RPM queen. I have an F20B now and it's a complete dog under 4k rpm. The H23A definitely shines down low thanks to that long stroke.


There's a ton of info about them in the "H23A mystery engine" thread in the Prelude sub-forum. Check it out if you want more info.

Scott Little

EDIT... OBD2 harness was not the way to go.


The JDM Harness that came with the engine is the complete harness from the Sensors to the ECU. I plan to just pull the OBD1 Harness and use the OBD2. The OBD2 Harness is a 1 piece setup unlike the 2 part OBD1 harness. I plan to use the OBD2 harness with the Jumper to OBD1. I know its an odd way to go about it but assuming there isn't an issue I am overlooking I think it will be fine. Honestly... I do feel like I'm missing something. I'm wondering about the wiring for the cluster comes in, maybe that it one of the plugs near the Driver side where the resistor box it, maybe that's one of the missing connectors that ill have to wire back in.



Edit. Euro R adapter will not work with PCB manifold. You need the one for the JDM H23A that Rosko will be releasing soon.
I do have one of those Rosko adapters from when I put the F23 Manifold on the f22b, that can be part of my plan B. Using the OBD2 Harness I "should" be able to use the OBD2 Injectors, no need for the Resistor box and also use the OBD2 Distributor without any modification or jumper harnesses.


I assumed I would need to delete the Secondary's, I'm not sure how I am going to do it, are they just vacuum driven?


I honestly didn't investigate the difference between the 2 Models, I just assumed It was the P13 head and I never validated.


As for the fuel lines I already have an Earls filter and am using AN lines so I'm sure I can sort it out. Return line will be easy. I was going to mock it up once I have the engine in and see where everything lands.


I have the Bracket and a matching pump but again I would love to keep the Accord pump if possible since its new, we will see.


As for the tensioner and belt... well we will see, I don't have the cash at the moment but if it takes me longer than expected and I get another pay check ill get them ordered.


Yea I read a few threads about it already. I'm not going to go crazy with it.

Aradin

It's still wise to use the OBD1 harness I believe. You're more than likely going to have issues otherwise.

The IABs do have a vacuum related actuator but they are also driven by a signal from the ECU. Additional components need to be soldered into an ECU that is not a P72 or P13. I deleted them with a spacer I found online for <$35. The H23A has plenty of torque so they're really not needed if you value the simplicity more.

The P13 model, which you have, has the older head and intake design. It came on the 98-99 models of the engine. Easy to identify by the upper plenum. PGMFI & IACV on the front of the plenum, P13 model. No PGMFI and IACV on the back of the plenum, PDE. The 00-01 models received a PDE head and slightly different upper plenum. The PDE head has magnesium coated cams, a factory port job and has a better valve angle that improves flow over the P13 models. They were rated for the same power though. Doubt the difference would be noticeable on the butt dyno.

For the PS, you use the 97-01 Prelude bracket and the Accord pump.

It's wise to go ahead and replace that stuff now. Wait a little and spend the extra now, or wait a lot and spend a lot more later when it pops.

Scott Little

Ok I see the problem with the OBD2 Harness. I have never actually removed the ECU side of an OBD1 Harness before. The fuse box connections are definitely an issue.


I have not given up completely but most likely the OBD2 Harness idea is dead.


Yea I think that's how I did it before, I just ordered the spacer and removed them.


I was curious about Ghosts comment.
"If you are keeping the engine stock internally, I would run the IABs tuned up on the P28 base map. " Can you give me a little more information on this?


I'm going to do an inspection on the tensioner and belt and see where it lands me. I need the car running as soon as possible.


Ill look at the tuck Harnesses and see how they are routed, maybe ill figure out what I want to do.

Scott Little

I want to use the OBD2 Injectors. If I modify the harness to for the correct plugs and Bypass the Resistor box I should be good to go right? No issues with the OBD1 ECU?

Scott Little

Just a note, I gave up on using the OBD2 Harness. Why re-invent the wheel and make things harder than they have to be. I diced up the OBD2 Harness for spare parts, should be nice and clean when I am done.


I did screw up and remove the OBD1 Injector plugs from the plastic mount and tape and now I don't know the correct order, hopefully I can find the color pinout.
Should be interesting getting a few things wired properly but hopefully it will be good to go before the alignment tool arrives.

Scott Little

Just ordered the spacer on Ebay. Should be here in a few days.


I also was attempting to figure out how to wire the 3 wire IACV but I'm honestly thinking whats the point. I have the Rosko adapter already so I might as well just use it .


Anyone have instructions on how to wire the 3 wire to OBD1? I may want to still try it but maybe not.

Aradin

You can't. That's the point of the adapter, to be able to use a 2 wire.

Scott Little

I assume the point of the adapter is to make things plug and play but maybe this is something more than just simple wiring issue. If this wont work its because the ECU just communicates differently. There is a lot of conflicting information out there. Here is what I could find.


OBD2 3 Wire.(The 3 wire IACV has one wire for power, the second wire for ground, and the third wire for idle control from the ECU.)
-Blk/Blue ECU
-Blk Ground
-Yellow/Blk Ignition power. On JDM OBD2 Harness it was wired with the Injectors


OBD1 2 Wire(The 2 wire IACV uses one wire for power, and the other wire is for the idle control from the ECU)
-Blk/Blue ECU A9
-Yellow/Blk A25 I read that it should be A23 but A23 is PG1 which is a ground. A25 is IGP1 which is Ignition Power.


Wiring should be simple.
-Blk/blue to Blk/Blue
-Yellow/blk to Yellow/Black
-Black... Ground.

Maybe ill just build an adapter harness to test it. Unless the fact is just that the communication between the ECU and Valve on the blk/blue wire are just not compatible.

Tachi

I think that yours was a high mileage engine or something else went very wrong. 7200 was the stock redline when the engine was bolted to an automatic transmission back in Japan. The rods are actually shorter than a H22's and reportedly the crankshafts are the lightest of the family. These engines, on stock cams at least, should be just as good for 8000 rpm as a normal H22, provided everything else is squared away.

Aradin

They were designed for a broad power range, not high rpm. 8000 is definitely not a good idea on one. Pop on over to the mystery motor thread and look at all the people with piston to valve contact issues when revving them high. There's a well known problem with the exhaust valve reliefs on the pistons being very inadequate.

And yes, the cranks weigh in at 34lbs IIRC. The rods are obviously a shorter design to work with the increased stroke. They're a one off 141mm rod which aren't actually that strong. They're missing quite a bit of material where it matters around the big end and in the pin area as well, presumably to save weight. Which to me was a strange engineering decision because the F20B rod is the opposite. It's a linear amount of material from the pin to the rod cap, and there's more material on the top side of the big end for strength but that's besides the point.

The motor I had was probably already hurt when I installed it honestly. I got it from an importer that I won't name. The first time I changed the oil it was full of stripper glitter from the bearings. I wrote it off and the motor took a dump within a few hundred miles. Regardless, I've been involved with a few of these over the years and they've all failed catastrophically when taken outside of their intended RPM range or other abusive conditions. As the old saying goes, just because you can doesn't mean you should. I'm not saying they're bad or anything, they're great engines. They're just not perfect.

Tachi

Then I've been misled by the blue-top cam dyno thread and the people therein. Or are they doing that because they're drag racing and all their engines have popped by now? [sorry to derail from OP]

Scott Little

Spent the whole morning on the wiring harness. I got rid of all of the splices that were done in the middle of the wires and extended everything I could so that all of the wires should originate from the spot where the engine harness and ecu harness connect. I still need to add the Knock sensor but I think that's it.


I'm thinking of just removing the, I believe its called the IAR since its not used on the new motor and re-pinning it on the ecu side for the Knock Sensor. Any thoughts on that?

GhostAccord

IAR? intake air resonance solenoid?

If it's a wire that you no longer need. Sure you can re-pin it for use with another ECU circuit. As long as it is the same gauge wire/size pin.

GhostAccord

As far as the IAC valve goes. I believe the 3 wire uses PWM for the valve operation, where as the 2 wire uses a grounding circuit in the ECU for operation.

Scott Little

I thought the knock was a 2 wire setup but since its just 1 wire I found an extra port on the harness and I'm patching it thru that way. At least there wont be any confusion in the future that way.




Ghost,
For the IAC what does that mean as far as using the 3 wire? If its grounded, has ignition power and the black/blue wire is connected in theory could it work or am I just not bright enough to understand what your comment was saying? I suppose the smart question would be to ask what PWM is.

GhostAccord

If you are using the stock 3 wire IAC ECU you can wire it up. If you are using a 2 wire IAC ECU, the 3 wire solenoid will not work. They use 2 different circuits to control the IAC motor. PWM is pulse width modulation, it uses a chip on the ECU that regulates the signal voltage to the IAC motor. The 2 wire ECU does not have this chip/circuit.

Now if you are running a chipped OBD1 ECU. I believe there are some options to add PWM control. But IMO it would be easier just to use the adapter plate and run the 2 wire IAC valve.

Scott Little

Thank you Ghost. Yea I am definitely going with the 2 Wire setup. Its funny how I spent hours reading posts regarding this and no one ever provided this information. I'm glad you are reading my thread.