All motor Mike

We all know of the H22A Euro R intake manifold, the PDE and it’s typically thought to produce the “best” power of any OEM H series intake manifold. Now while this may hold true in peak hp, it isn’t necessarily the case in the lower to mid rpm range, where the duel runner P13 IAB manifolds found on a vast majority of H series shine. In fact, the common duel runner P13 manifold has been proven, with some minor polishing work to outperform the PDE(Euro R) manifold all throughout the power and only falling short in the high rpm range. Now there is 2 variants of the H series IAB intake manifold, the P13 and the PCBX. In reality there are actually 4 variants if you count the obd2 P13 and the regular PCB found on the F20B but due to similarities between them I’ll be going over only a P13 from a JDM h22A and a PCBX from a JDM H23A blue top.

Moving forward, in the early 2000s when I was first getting into H swaps, I had an excessively hard time finding any info on any intake manifolds other then the PDE and common P13, and almost everyone preached to delete your IABs. For a long time I used Euro R manifolds on various H series cars I build and deleted IABs constantly when I’d get a new H that I didn’t have a PDE or Skunk2 manifold for. As the years went on and I dyno tuned a number of cars, I started noticing something funny, functional IAB setups I tuned made better mid range power then those with them deleted by 5-8hp consistently and only lacked up top by 4hp max typically. Real world numbers always tend to argue with internet claims and I’ve found this is one of those instances. One thing that does hold true is that the PDE always makes 8-11whp more then a P13 IAB manifold when dyno tuned but again that’s peak hp and only in the highest rpms, dyno tuned IAB manifolds make more TQ low down and better usable midrange power for street driving. With all that said, there is a 3rd manifold that is a bit different from the PDE and the P13, the PCBX intake manifold.

So due to the lack of easily findable knowledge on the matter I felt I could shine a little light on one of the last scarcely reviewed OEM parts that is not nearly as appreciated as it should be. Some of you may have read my write up on the H22A7 exhaust manifold and why it is by far the best OEM H series manifold ever built, well here I will go over this little heard of intake manifold and give you a few reasons why you may want to choose it over a PDE Euro R manifold for your next build. This will be a long thread so I will begin with comparison pictures, P13 vs PCBX. Both are IAB manifold and look similar but I assure you they are absolutely not built equally. The PCBX is far superior in all aspects concerning quality and air flow which will be clear from these first few photos alone. I’ll go over the differences and why it’s the best OEM H series manifold imo in the following comments on this thread.

AllMtrRex

Love the thread. Brings back memories of what HT use to be. Are you dodge neon all motor mike?

I certainly appreciate this kind of information. I have moved away from OEM combinations but interesting info still.

All motor Mike

Now what’s instantly clear is the PCBX has much, much smoother casting as well as a larger upper plenum volume. I have to still take pictures of the lower runners but they are much smoother as well, the sensor in the far runner that always caused flow inequality in the typical p13 manifolds has been moved to the upper plenum to help equalize flow between cylinders. Also you can notice pictured above, that between the entrance of the runner on the P13 are a rough transition where as there is a “v” shape casted to smooth the air transition between runners on the PCBX. The PCBX also is lighter and has much of the unneeded metal found on the P13 cut out of it, making for a cleaner appearance. The IABs are the same between the P13 and PCBX, but more attention has been paid to port matching in the lower runners so little dead heading is present unlike its P13 counterpart which is notorious for having bad dead heads where it meets the runners after the IABs.

One thing that should be noted here is there was an apparent 10hp difference between the P13 and PDE H23A blue top and many have been arguing for years about what actually caused the difference and I think I know the real answer. So people at first said it was just that the PDE was the “euro r” head but actually many obd2 H series have the PDE head and they don’t make 10hp more then there P13 counterparts. What about cams you say? Well they’ve been measured and they both have the same typical JDM h22a cams. Pistons maybe? Nope they both share the same one off pistons, 10.6:1 cr. So what is it that caused the 10hp increase between the 98-99 P13 H23A and the 00-01 PDE H23A? It’s actually really simple when you tear both apart compare them and put some thought into it. Here is my theory since Honda never released a statement on what the extra 10hp was from: I believe that the combination of the smoother, better valve angled PDE head in conjunction with its far superior PCBX intake manifold and some revised ecu tuning resulted in the 10 extra hp. No big changes as most people originally where thinking, just a much better intake manifold and slight tweaks to the tune.

This brings to light another interesting subject and another reason behind this thread, if the PCBX helped make an extra 10hp on the H23A over its old P13 manifold, and the PDE “Euro R” intake manifold makes 8-11hp over the P13 manifold on typical H series setups, does this mean that the PCBX is in fact a direct rival performance wise to the PDE manifold? Only the dyno will tell so in time I plan to get some charts together for comparison between the PDE and PCBX but that won’t be for some time.

Ill get picture of the lower runners later and post them, as well as go over more differences so stay tuned.

All motor Mike

No I am not a neon guy, my dodge fix is with my 95 Stealth R/T Turbo lol but I don’t post anything about it anywhere. I am just a long time Honda builder who feels the need to continue to get information on rare oem parts out there as few people are contributing real useable new info these days. I have quite the collection of rare OEM Honda parts, one of my hobbys is simply collecting and often times not even using them. I have a few U2Q7s and even a hyper rare factory optional P2T4 LSD Accord sir trans in my collection that I am rather proud of considering so few where made that there is no real info available on it.

AllMtrRex

10-4. There was an all motor mike that ported intake manifolds for the 2.0-2.4 N/A engines and then moved on here and did some nice work years ago. I got you two mixed up.

All motor Mike

no worries, Mike’s a super common name unfortunately for me hahaha. I’ll try to make as good of contributions as he did regardless though 👌.

1996accordlx

Nice info! I have a P13 intake manifold I plan on running on my H swap for my Accord. I kept it (with functioning IABs) for that exact reason of making more streetable power on the low end. I had it ported to match my 68mm throttle body, and had all the runners smoothed and gasket matched. I would definitely look into swapping to the PCBX upper if it does flow better than the P13. And I've never cared for the look of the P13 upper, with the flat spot and stick on PGMFI plaque. Definitely looking forward to your dyno results.

Aradin

Just the thread I needed to see. Thanks for the info.

I have a PCBx manifold on my current setup and I've been on the fence about replacing it with a Skunk2. After seeing the differences over the stock P13 manifold here I think I would be better to just stick with what I have. It has a mild port job already but I think I'm going to really open it up and see what it can do.

All motor Mike

Thanks! Glad to add helpful info. Now in regards to the manifolds, the PCBX does flow far better then the P13 there is no question about that, if the entire manifold is used and tuned I’m sure you’ll see 8-11whp gains over the P13 just like the PDE manifold. The only remaining question that the dyno will answer is if the PCBX is in fact as good or better then the PDE Euro R manifold.
But on the subject of just switching the p13 upper plenum to the PCBX upper plenum, I’m sure there would be gains but the p13 lower runners are not nearly as smooth as the PCBX lower runners and the P13 has a sensor in one runner that impedes air flow which that sensor is not present on the PCBX lower runners. If you can get a PCBX upper plenum and swap them I’d love to hear if you felt results, I’m sure even the upper plenum improvements alone would help somewhat over the P13.

All motor Mike

of course! And to be honest after running 5 different setups with the skunk2 I’d say just port the PCBX and clean it up all the way, and send it. I feel there is no better alternative for a street build then a PCBX, the IABs are magic in the low-mid range and it can move a lot of air with ease. I’m confident that the PCBX is so smooth, the plenum is so big and the runners are so cleaned up that it can in fact out perform the PDE in street applications if properly tuned. Maybe it won’t make the same peak hp but I bet it’ll only be off by 3-5hp past 6500rpms max.

Now, for an all out race build like cams, real good header, 2.5”-3” exhaust, maybe pistons and head work then do Skunk2 with a matching 74mm, I’ve found that setup does good where the goal is high rpm power and you don’t care about city driving.

Aradin

I am boosted and soon will have a big stroke, big bore engine so it's a little different than a typical setup. I eliminated the IABs for simplicity and because it was nearly impossible to find a black box in working condition at the time. I also cut out the "webbing" for the iabs and did some minor port work to increase plenum volume and flow even further. I ran out of time when I was putting it all together so I didn't have a chance to work over the throttle body inlet or gasket match the lower runners. I'm going to go through it again when I pull the current F20B to replace it with my new engine. Should be pretty stout.

All motor Mike

I got ya, since you cut the webbing yeah just gut it the rest of the way, polish the heck out of it and port match, save you a bunch of money and perform awesome. Also, the black box is actually a commonly built aftermarket part if you look through muscle car magazines, it’s just a simple vacuum reservoir. There are some nice ones through Jegs or yearwood for cheap, you can also make your own pretty cheap just need a one way check valve and a bottle/canister to use. You just need the activation solenoid and a clean vacuum source to hook it up and an rpm window switch for tuning it separate from the ecu. People think you can’t run them without a ecu with outputs for it but that’s not true, a simple rpm window switch is all that’s needed.

snobordboy

I for one am interested to see the difference in how the IAT sensor is located and what it does for the airflow in the last runner there.

What is the chance that you have the ability to actually measure the volume of the plenum there, as the first picture makes it look like it is a bit larger overall.

Granted I am running a fully gutted out P13 manifold and 76mm TB, but still interested.

All motor Mike

Im actually working on building a home made flow bench, for now I’ll probably just get a CFM meter and check each runner individually to see what kinda flow readings I get.
The PCBX plenum is slightly bigger over all and each runner on the lower runners have a bigger inner diameter then on the common P13. It should be noted that the lower runners are a different PN from the rest, the typical P13 lower manifold is a P13 “HF1” or “HF2”, the PCBX lower runners are “P13 HF3” and are shared with the red top h22a type s engine that runs the “P13 HF3” upper plenum, a smoother version of the typical P13 upper. The HF3 lower runners are clearly much smoother then the HF1&2, also as I noted before the IAT is no longer present in the already slightly larger runners.

I believe Honda moved the IAT for a few reasons, it disrupted flow on the far cylinder port and got a reading only from the far side of the manifold instead of the center as would be ideal for a more average reading across the whole manifold. I got pics of the lower runners finally and will be uploading them shortly.

All motor Mike

Not the best pictures but I don’t have good cameras so I did my best. From this pics you can see the smoother runners on the PCBX lowers(HF3), very similar over all otherwise, however you can clearly feel a size difference in the ports just by putting your fingers in the runners. Also notice the difference in the flange shape, it’s because there is a chamber with a vacuum port built into the flang/cylinder head, I’m actually unsure of its function as I never pay attention to it or emissions stuff so I always just plug the port, chime in and tell me if you know it’s function. It shares a throttle body with the ATR/Euro R/Type S engines and some have told me the S2K TB is the same P/N but I haven’t looked into that myself, regardless it’s bigger then the other H/f TBs slightly, however it does taper to a smaller Inner diameter unfortunately.

*note that I have removed the IABs for this comparison.

JKaze

That left one looks exactly same as S2000 F20C’s 62mm throttle body, which is same base cast as ITR’s tb but without purge canister nipple on top and idle adjusting screw.

Gen2ITR

I think the biggest question would be: ACTUAL volume of the upper plenum. The lowers are virtually identical if memory serves me correctly. The only other concern is the IACV, but an adapter could easily solve that.
We did ALOT of testin back in the early/mid 2000's with cutting/porting the lowers and what "depth" was best....as well as plenum spacers... but I dont recall ever messin with the late model Upper.
Either way, its great to see some old school effort on this site again.....too many people just want to buy their power and forgo the steps required to earn it.

All motor Mike

the lowers are actually considerably different between the two, same basic shape though. The PCBX lowers that are marked p13 hf3, have no IAT in them, they are far smoother then the typical p13/hf1-2 runners and minutely bigger inner diameter where they meet the head. The flange it’s self is also different as it has a vacuum port connected to it for that rear vacuum pocket that I still don’t know the function of between the manifold and cylinder head. The holes where the EGR gases go back into the runners are smaller then the older ones too so that cause less turbulence inside the runners. Volume wise I am confident the PCBX is decently bigger, I’m gonna do a simple measurement with liquid and a big measuring container later this week, that will and least give us some idea of the difference for now despite my lack of better measuring equipment.

Bingli

Thank you very much for taking the time to post this information. I race in the Outlaw FWD class and cant afford all the aftermarkef piceses. I race the F22A and just bought an H22 JDM. Putting it in the car now and looking around for IAB info. I'm running a stand-alone harness and might have to delete it.

While I realize you will most likely never see this I'm grateful just the same.