So H23 IM on F23 head has been done with the transition plate. I picked up a Blacktrax H23 with two spacers in a trade and I'm wondering how it might work for my application. I know the Blacktrax manifolds don't dyno so well (+2-3 hp) with H22's, at least from what I've read, but I'm curious if the extra stroke of the F23 will help suck harder on this manifold and actually take advantage of the extra plenum and runner volume. Guess I'll have to test it to find out, but what's your gut feeling? 11.5:1 CR and Bisi stage 2.5+ cam

 

I've never taken a look at an F23 intake ports, but if they're anything like the f22b1 ports, they are freaking SMALL compared to the ports on the h23 runners. You'll have some unwanted turbulence there so I don't think the h23 IM will have that much of an effect on power.

 

Turbulence should be minimized by the transition plate 3/8" aluminum sheet blending the two shapes, plus the ports on my F23 head were already semi H23/H22 shaped. There will be a smooth CNC'd transition plate made, its actually at the shop right now. Turbulence will not be a big problem, if at all. Check AFACCORD's thread about H23 IM on F23 head to see what I'm talking about, and remember his efforts were effective even thought it was pretty DIY rigged together. Also, take a look at the ports of the head in my thread, and note the head flow CFM and I think the head will be "thirsty" for some serious intake hence my intention for a better IM.

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/300-cfm-f23-head-pics-added-2463843/

 

obx h23 itbs

 

Michael's F23 head is the most modified one I've seen and if you're pushing a bit of power then the H23 IM might benefit you but on my F23 cranked, 2,307cc F22B DOHC engine with an H23 IM, the H23 intake manifold worked fine for 200whp.

Gut feeling is that it might be worth it if you're making enough power to have the original TB and IM as a restriction. I don't know what you're using for an exhaust system but IME it has a huge role in making that last bit of top end power so if you're on the stock exhaust and cast header or POS DC off the shelf style I wouldn't mess with the intake side much.

Here's a couple of my engines that benefited from a custom header and retune using stock IMs and TBs:
H22 Type S:

K20/K24 hybrid


Sort the exhaust first.
-P

 

Thanks Pirate. I guess I shoulda mentioned I've already discussed header plans with SSR. They might just make me their H22 header with the ports realigned to F23 0----0--0----0. They said to just send them a flange and they'll make it. Paired up with 3" exhaust should be a sufficient exit.

 

and yes.....holy crap what a difference after custom header. far more critical indeed. I wonder what your G23 would've done with a custom header.

 

Not that it's on topic or anything but I assume that if I didn't build the whole engine from nothing for less than $1000 and used parts it would have done better. The next build is waiting in the wings and should address some of my prior cost-cutting devices.

 

IMHO, since the design of the H23 manifold is VERY similar to that of the H22 IM it will be a restriction around the 200whp mark, more so if you rev it higher than 7k.

The reason I say this is because a EuroR has gains everywhere over a worked(gutted plenum, runners cut into 4, deleted iab plate) H22 IM with a bigger tb. That's on a stock H22. The gains are more significant as power output goes up.

I'd look into getting a plate made for either K series or H series manifolds.

 

I dunno about K-series but the Euro-R didn't really change my power band. Granted I didn't take my own advice and optimise the exhaust system:



Man, that's a dirty engine bay...

 

hmm, the heads DO flow differently. They have diff sized valves and valve angles, so that's a huge difference.

How much for one of those plates, if you don't mind me asking?

 

I don't think that the heads flow that differently. And while the valve angles might be different I doubt that it matters that much. FWIW the valves are the same size as the F22A SOHC and are only 1mm in/ex smaller than the H22.

I made 2 adapters and have sold both. Sorry. I don't mean to be Mr. Killjoy. I'm basically going to swap to a "mild" H22 head and refresh the bottom end on my "G23" with nice pistons. I think it will be an interesting experiment to compare the G23 power band to the G23 VTEC on Type-S cams. I'm hoping I get as much or more torque but I assume it'll be a trade off. More power but less torque. We'll see.

 

yeah. like pirate said... check out a plate/adapter to get a K-series manifold on there. I know QSD currently makes one for the h22. Not sure how different the h22 and f series intake flanges differ.

 

gonna stick with it and see how it goes, i do not see how a gutted h23 manifold with adjustable plenum size could be a restriction. i have fallen in love with the euro r design and straightness. gonna grab one for my h22.

 

I don't think it's a matter of the gutted part, I think the plenum is too big for NA, or just not designed properly.

 

Point taken. We'll see I guess. I'm told my CNC'd adapter/transition plate from manifold to head has been completed. I'll pick it up sometime this weekend and snap some pics of the setup. I'm fairly certain the manifold will work SLIGHTLY better with the F23's longer stroke and the head certainly outflows a stock H23. This is also a Vtec engine with much more duration than any H23, and similar to some aftermarket H22 cams (254 @ .050 INT.) Power will carry well into the 7's and Bisi told me it wouldn't surprise him if it made power to almost 8K with the right intake and exhaust.