Checklist for Si to vtec swap

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ludemandan

New Member
I'm putting a JDM engine into my 94 Prelude Si. I'm in California so I have to be very cognizant of smog issues. So far I have tracked down:
-JDM H22a engine
-P13 ECU

Still need:
- Gauge cluster

Anything I'm forgetting?

Dan
 
An H22 transmission isn't a necessity, but you'll probably want it for the gearing...
 
Are you doing it for the gas mileage or because you're concerned about the longevity of the motor? If it's for the mileage, well, that's your choice. Go for it if that's what you want. If it's because you're concerned about the motor, don't be. If it wasn't perfectly acceptable for the motor to be running at 4,000 rpms consistently then Honda wouldn't have offered that transmission gearing as an option. The engine is meant to rev higher, it's not some big old V8 that red-lines at 5-6k rpms...
 
It's for gas mileage. Don't worry, I don't think high rpm is bad for it. I've done about a dozen track days with my car, no concerns. It's just that now I have a motorcycle, so I don't need top performance from my car anymore. I love a good flossing session but I don't like winding it way up when I'm on the freeway for an hour.
 
Ah, ok. In that case then you're well on your way. Are you comfortable with adding wires to your harness? If not, you might want to look into Rywire for a VTEC subharness.

Other than that, you're pretty much good to go with the stuff you listed. Just make sure the motor you get is OBD1, that will make things super easy for you...
 
I looked at the gearing charts again and decided to go with the JDM tranny. It has shorter street gears but a longer 5th, which is perfect. It was the usdm vtec tranny I wanted to avoid.
Old tranny: M2S4, New tranny M2A4

Gearratios.jpg


I'm supposed to pick up the swap today! We'll see how it comes out.
 
How did it work out? I would have advised that you get the m2b4 (LSD)... I like the way that transaxle feels... same gearing as jdm vtec tranny... and it is true the usdm vtec tranny had the shortest gears... I had an H23 before my swap and I used to twist 3000 right at 60mph, now I am doing about 62-3 at 3000... not a lot of difference, but my mileage has not gone down even though i have been playing with the vtec since it's new to me :)
 
I LOVE the M2A4 tranny. It's the gearing I've always wanted, short of adding a 6th. I could have paid an extra $400 for the M2B4, but I'm just not into spending money on car performance enough to buy an LSD. The motorcycle cured me of that.

Anyway, swap went great, I've been driving it ever since. A couple of little problems though. The engine has some serious hesitation right in the middle of the rpm range, especially prominent in 1st and 2nd gears. I'm planning to run a Sea Foam treatment and see if that clears it up. Also, I sprung a coolant leak somewhere the other day, so I'm filling up the radiator with distilled water before every trip. But that just requires some servicing.
 
My h22a definitely had some carbon buildup the cold idle has been smoothing out little by little as it runs. Motorsports shop said I didn't need to do anything except run it but I am been considering doing something to clean it up anyway. I almost thought I had noticed just a brief moment of hesitation from time to time right around 3k, esp in lower gears.... wonder if my problem is similar to yours (considering my engine was built in sept 94, and is supposed to be <25k... of course it's gonna have some carbon from sitting around in Japan going to grandmas house twice a year). I have not tried the sea foam treatment, have you done it before?

I don't know why honda never saw it fit to add a gear to these trannies... they wouldn't even need to shorten the gear ratios, just add it at the top as a true overdrive... you would only need to be doing about 50ish to use it anyway.
 
There's nothing subtle about the hesitation my engine gets, it's almost like it shuts off for a second when it hits 3500 rpm in 1st sometimes, if I'm at mid throttle especially. Anyway, I used seafoam once on my H23, didn't notice much of anything, but I also didn't use a lot of it. The car ran great for a few years afterward until the bearings seized.
 
Good luck with that... I would tell you to try an eCtuned p06, but I am not sure it would be very easy to pass smog tests. Doesn't sound like the ECU is at fault anyway. Has to be frustrating to have that kind of problem with a new swap.:(
 
sounds to me like its a timing issue,timing balance issue or some kind of major intake or exhaust leak...possibly a knock sensor issue maybe??? ive heard that some have em and some dont. could also be a spark issue or somethin. troubleshooting sux,i feel your pain.
 
dubgkizzle said:
sounds to me like its a timing issue,timing balance issue or some kind of major intake or exhaust leak...possibly a knock sensor issue maybe??? ive heard that some have em and some dont. could also be a spark issue or somethin. troubleshooting sux,i feel your pain.
Click to expand...

And it sounds to me like you didn't check the date on this thread before you hit "reply"...
 
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