H23 Turbo 4gen

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Junior Member
Hey guys, i'm about to leave right but i wanted to get this in so i can see the replies when i get back. Anyway, there is a guy selling a 90 accord for $500 ( engine is pretty shot, just able to get to my house ). I plan on just leaving it in my friends backyard until i get up the money for the h23 swap. I looked on hmotorsonline and saw they have the h23 longblock for 1k. I'll be going turbo ( which is why i chose the h23 ) and stay around 6-7 psi for daily driveability until i can afford the money for a build up.

What i know so far thats needed for swap:
h23 longblock (duh )
need p14 ecu
you can use accord axels
wiring harness ( h23 wire harness i gather ? )
prelude driver side engine mount

What i want to know is what is needed to make this swap complete and run ? I think i have an idea of what is needed but i just need some help on anything i might be missing/spending money needlessly. I gather since the engine is non-vtec it will be a pretty easy swap. I'll be shooting for 200-230 whp to start at 6-7 psi so i would appreciate ALL THE HELP i can get to make this swap easy as possible. Thanks for all of your replies and i'll be back later on tonight to ans any further questions to help get this process done. Thanks again guys !


Junior Member
uhh... a lil help over here ?

oh yea, i know you can use the f22 tranny for this swap but is the h23 tranny better than the f22's for boost ?


Junior Member
Dohc, thanks for the reply. Since the H series tranny will be better i guess it would be in my best interest to go with the full swap from hmotors instead of piecing one together ? I thought getting the longblock with the other required equipment would come out cheaper but it seems i better just go with everything. Ok so heres another question for ya...

Do you NEED to resleeve to install forged pistons/rods for this engine ?

Also, can you use pistons for the h22 ? i looked on www.RACEENG.com and they only have pistons for the h22 ( crower has rods for the h23 ). Are these parts interchangeable ?

Thanx again !


WRX Sellout
Sounds like a full swap would be the way to go.

As far as I know, forged pistons require resleeving of an H-series block.

Pistons are interchangeable, but you'd probably want H23 pistons, since they're lower compression. H22 pistons are 10.2:1 and up. I believe H23 pistons are in the neighborhood of 9.5:1.


Junior Member
Cool, Thanx Dohc, looks like i'll just keep the engine out until everything is complete on it ( building, turbo addition etc ). I'll be asking a few more questions in the near future so thanks for the help.



Senior Member
I've been working off and on for the past 8 months on the same swap for my 1990 accord coupe. Last week I got the H23A w/ECU and harness for $400. It just needs new rod bearings(#3 spun bearing), about $80. Anyway, I didn't have the extra $200 he wanted for the tranny(will be using my F22 5spd), so the guy's still got it. Let me know if you're interested. It's out of a 94 Si w/90k mi. This way you could still get the longblock from HMO for $1000 and essentially have a complete swap for well under $1500. I've seen P14 ECUs sell all the time on eBay for under $50. Anyway, what kind of turbo setup are you going with? I've got:

custom made log manifold w/ext wastegate flange ($200)
.48/.48 A/R T3 ($80)
7lb Deltagate ($100)
custom Air/water IC fabricated from spearco-cored 88Tbird SC IC ($200)
cheap bosch/Saab BOV (free w/turbo)
12:1 Vortech FMU ($100)

all had for under 700 so far (plus 400 for motor, 80 for bearings). My goal is 250 WHP/220lbft, all for under $1500. I'll post pics when I get them.

One more thing: stock CR is 9.8:1 on an H23A1, pretty friendly for the psi you're looking at. I wouldn't bother with new rods & pistons.


WRX Sellout
Originally posted by nuc79@Apr 9 2003, 02:05 PM
I wouldn't bother with new rods & pistons.

Well, he said "to start". Those pistons and rods would be fine for those psi numbers, but anything more and he should upgrade.


Senior Member
Originally posted by dohcvtec_accord@Apr 9 2003, 04:18 PM
Well, he said "to start". Those pistons and rods would be fine for those psi numbers, but anything more and he should upgrade.

Very good point.


Junior Member
Well, thats a killer deal on that motor but i'll have to let yet another great deal slip away. The guy that was supposed to sell me the accord sold it to someone else, saying he needed the money desperately ( i told him he would have had to wait till the end of the month ). So there goes my 4gen accord out the window ( for cheap anyway ). But, i think it's alright i'd rather put it in a 5gen anyway :p ... So it looks like hoop ride city until i just save. I'll just have all the money in the bank and binge on a serious shopping spree for my own christmas gift :D.

Oh and for the turbo set up. Well, i was going to go ahead and follow this guy from honda-tech whole set up with his h23a1 ( well some mixing and matching anyway ):

h23a1 engine
nascar sleaves
9.1:1 je 30over pistons
stock rods with arp bolts
h22 oil pump
oem rings with total seal top ring
h23 head
5 angle valve job
new valve guides with seals
P&P head
1998 f22 tranny

airex fuel pump with the stock intank
s-afc fuel controler
f22 ecu re-chiped
Jackson Racing fmu 5:1 rise rate

centerforce clucth

turbo kit

Modified drag manifold
garrett t3/t04e 60trim .63 turbine
large front mount intercooler incon systems core
apexi BOV
XS manual boost controller

MSD Blaster Coil
accel 8mm wires
NGK plugs
Autometer Boost
A/F gauge
Greddy turbo timer
MSD soft touch rev control

3" Custom exhaust
3" down pipe

He's boosting 337whp 313wtq at only 12psi. I planned to just re-do this plan with a lil of my own parts. Looks like with all the money i'll save i can do it easily. Anyway, i'll be on here back and forth trying to learn more and more in the meantime.



WRX Sellout
Looks like a good setup. Although the rechipped F22 ECU seems a little fishy. And I'd definitely get rid of the F22 in favor of an H23 tranny. F-series trannies are poop.

And yes, 5th-gen Accords own j00!! :)


Back in the Game
h23 swap

I too am building an H23a4 swap for my civic. I am buying a t3/t4 turbo kit in the next month. But what I don't get is all you guys have such low horsepower and torque specs you are shooting for. Correct me if I am wrong but the H23a4 is pushin 160/156 hp/torque so if you put a turbo on that and a turbo back exhaust you should be pushing already in the neighborhood of 215/200 (ish) but on my swap I am not sticking with anything stock. The intake manny, throttle body, pistons, rods, fuel rail, and injectors will all be done. I plan on going an all venom high flow fuel rail and injectors, aem or venom intake manifold, forged H-beam rods (if I can find them), as well as forged pistons (if I can find them). I also plan on port and pollishing the head doing a 3 or 5 angle valve job, and aftermarket cam gears. I then plan on going the full 9 yards on the tranny and clutch as well with a racing clutch, lightweight flywheel, and a rebuilt h-series tranny. Just in your guys opinion how much power will I be putting out? I plan on boosting it around 10 or 15 pounds but I will have an in dash Hallman boost controller to turn it up whenever. I am shooting for at least 400/350 (ish) but I guess after I have it done and dynoed we will see.
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