I am no longer capable to search on this site so I'm just gonna start a new thread.

I have a spare h23 IM and am about to put it on a friends car with a f22 in it (Prelude S).

I heard of this before and I know it's a bolt-on, but I was just wondering about the secondary butterflies. Would you be able to keep those working or is that not possible? If not, would it be better to leave them in there closed, leave them in there opened, or just take them out completely?

And just to make sure I am correct on the swap, this is what I need correct?:
H23 IM
H23 gaskets
H23 throttle body
Extend sensors

 

if the ECu is programmed to work the secondairies than yes you can use them

 

It's going into my prelude with an F22a1, so we should just remove them completely then?

 

I have a spare P14, but that probably wont work on a sohc motor, : (

 

You would need some RPM activated switch for the secondaries. I am not sure completely how they are activated on the h23 mota.Unless your going to tune the intake manifold you may/may not see any increase in performance. If you plan for a FI setup you could remove the secondaries for a better air volume.

 

Thanks for the replies.

The reason for wanting to change it is due to spending some time in an accord forum and seeing a lot of them swap out their IM's for H23 IM's on their F22a1 and F22a4's along with the exhaust and claiming 15-20hp gains at the crank. Being advertised as one of the cheapest mods to do on F22a1's. Sort of like 'right after you do exhaust and intake and don't plan on messing with the header since you're going turbo...swap out the IM for an H23 one, besides extending some sensors it bolts up and by letting your engine breathe better it should add a few hp' Not dyno proven yet, but a lot of accord owners claim it added some top end power and sounded a little more aggressive too.

Paraphrased of course


We'll probably just remove the secondary butterflies since I am contemplating the turbo charged route.

 

One thing to think about. I think the h23 and the f22 use the same peak/hold fuel injectors. Just wanted to throw that out there. But I would double check.

 

I think there would have to be some tuning to see any gains with that manifold. What ECU are you using? There is a way to make some ecus control the IABs.

Check this out:
http://www.preludepower.com/forums/s....php?p=1729955

 

That's informative but it doesn't really state that you need to run a P72.bin file which is inherently VTEC. The P72 Bin file in nonVTEC apps will throw a VTEC spool code for there not being a VTEC solenoid. If you can live with the omnipresent CEL on the dash then it'll work fine otherwise get an adjustable rpm switch and wire it into the existing H23 IM IAB solenoid.

< has a P28 wired to use IAB and has nonVTEC using IABs.