Im in the process of building up my H23A vtec and have some questions about piston to valve clearance with my specific setup.

H23V bluetop bottom end overbore to 87.25mm
Bnib oem Honda Type S pistons 87.25mm
Crower SS valves
Supertech valve springs and retainers (93lbs seat pressure)

I want to run Skunk2 Pro 1 cams and am concerned if I'll have clearance issues. The bigger stroke of the H23 crank will bump the 11.1:1 comp. of the S pistons to 11.68:1. Jus to be clear, once again, this is the H23V bottom end not U.S. H23a1 non vtec. The H23V bottom end uses shorter rods than the non vtec due to using H22 pistons from the factory.

 

bluehbcivic here might be able to help you

he has very good h22 knowledge and has used Pro1s

 

Hondatech needs to be like Facebook where you can tag people and get instant notifications lol

 

amen

 

There is a H23V thread in the Prelude forum. Check it out. Tons of information there.

 

You are gonna be ok, just check what your adjustment range is.

My engine is the H23A1 crank and rods, with jdm H22 pistons, so they actually stick out the hole compared to that setup, and I have PRO1 cams in it as well.

The exhaust pockets are very close though, so it takes a fair bit of attention to make work right, and ensure that your valve guides are in good shape!

Oh and for reference, use good cam gears, and loctite them! Mine had the exhaust gear slip at 7K on the dyno, and needless to say, I am now rebuilding my head! AEM or such with the big bolts, instead of the little allen keys on most gears, is the way to go.

 

Awesome, I appreciate the feedback.
Everything is like new or brand new. In fact on of the only used parts are the skunk2 cam gears I have. Hopefully they dont break...
Would you recommend cutting the pockets or should I be ok with just degreeing the cams and making everything tight and right?

 

I would actually look at getting some new mahle pistons instead. I had something to your build in my first build( Crower 2) and I ended destroying my motor because of the piston rings could not hold up. All the rings in one cylinder broke

 

I dont see how rings not holding up would be indicative of needing different pistons....

On that note, does anyone know where I can buy 87.25mm rings besides Honda? Unless theyre the only ones that will hold up. I was thinking about calling Mahle and seeing if I can buy just the rings from them.

 

normally you get a set of rings to the pistons, unless its from the same pistons(aftermarket) you are just replacing your rings for. I think I have read of people using mahle rings on Honda pistons but cant remember the thread.

You can try it but its just smarter just to get it all together.

 

Im not gonna use the Mahles unless someone can verify that theyll work on Honda pistons. Ill go oem if I absolutely have to....

 

Type-S Pistons should set flush in your set-up and fit fine. I personally have not run them so I cannot be positive, but I am close to positive. Ask ESP, as I am sure he has used this set-up. With a bigger cam like the Pro1, you will have P to V clearance issues if you fail to properly degree your cams or check your clearance. If you degree them and check your clearances you will be fine. The Type-S reliefs are better than the H23As and so you should have a little more wiggle room than you would if just running the stock bottom end.
The H22 Heads have P to V clearance issues when you run larger valves, so I hope that you are running OEM sized valves. If not, you can run bigger valves but you have to be sure to check valve to valve the clearance as well. Really you need to check the valve to valve even if you are keeping OEM sized valves.
Another thing to consider is that the H22 Head's OEM valve guides sometimes have some wear and that will cause clearance issues. The wear on the valve guides might not be apparent, but if you are running tighter clearances it will become apparent when you bend your valves/drop a valve. You will probably be okay, but its something to keep in mind. The stock bottom end on the H23V has some tight clearance and this valve guide wear becomes an issue in those engines running at high RPMS (especially on the exhaust side). Since you will have the Type-S piston you should have a little more room. Just double check your clearances and make a judgment call.
Piston, Rings- I would run the OEM, but that is just me.

 

So then yours uses custom rods?? The measurements taken in the H23A thread state the JDM H23A-V uses the same length rods as the USDM H23A1 and same piston compression height. The pistons have less dome than an H22 piston but much more than the dished H23 piston. To be clear, the Type-S and H22 pistons share the same piston compression height while the H23A-V does not.

https://honda-tech.com/forums/showpo...1&postcount=23

Given H23 measurements, that puts your piston 0.026" higher, or 0.020" out of the hole. Actual CR is closer to 12.2:1. Beware the combustion chamber has a minimum of 86.5mm diameter, so there's a chance the larger pistons sticking out will catch that ridge. Your pistons will be 0.006" away from the ridge with an OEM 3-layer MLS, while 0.030" is the min I'd recommend for 7000 rpm.

 

I have not had a chance to search yet, but I can sure tell you those rings wont last if your planning to push that motor.

 

The rod length in the H23A blue top is .020 shorter than the USDM H23A1. The H23A Blue top has a unique piston and rod combination.

No, it uses a different and unique piston, as HiProfile already stated accurately.

Are you saying that the OEM rings wont last in an NA application for the H series? I have not heard of that, but its good to know. Please confirm.

 

That is not what I am saying at all. What I am trying to explain is that when you begin to push the stock piston rings they begin to fail, which was my case. For basic builds they will work for sure, but when you begin to go into strong more compression and power pistons rings will fail. You guys can do some research and find out about them. Its not something fairly new at all.

 

Thanks for the clarification.

 

The h23v uses shorter rods and uses plain Jane h22 pistons. H23v pistons are very similar to h22a1 Why do you think Type S or any other H22 piston sits flush with the H23v rods? Theyre shorter than the non vtec rods to us the h22 pistons from the factory

Same wrist pin location and everything. Only difference is the dome and the skirt length
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So what rings would you recommend then?

 

No, they don't have a plain Jane H22 piston! LOL Its a completely different piston... Most obviously the skirts are different, but the fact that the valve reliefs are different and dome is different makes P2V clearances substantially different. Clearance with those pistons is a good bit worse on the exhaust side, especially if the valve guides are worn at all because the pockets are so narrow that the value might hit outside (or along the edge) of the pocket. They make the same compression and have the same wrist pin location (which means that you can use a plain H22 piston in the H23a) but it is an entirely different piston, and not a plain Jane H22 piston.
The reason why people think and say weird stuff about the H23A (like the pistons will not sit flush/they will stick out of the block, or they use the same rods as the H23A1) is because there is a lot of misinformation out there. They are very popular with certain drivers/shops but overall they are a pretty rare swap when compared to other H series.

 

As is noted, there is much information out there, some correct, and some, not so much.

That said, I think the OP is on the right track. As a matter of fact I sifted through all of the same info myself and came to pretty much exactly what he is doing, I even have that same set of pistons, and a set of the H23A bluetop rods in my garage, but decided not to bore the block yet.

The one person who has done a ton of measurement of the H23A, and properly is Rosko. He is the one I purchased my rods from, and I have verified the slight length difference against the H22A and H23A1 rods myself, and can do so and take a picture if anyone would like to see it.

Personally, I think that a properly gapped set of OEM rings will hold up fine in a ~11.6 to 1 engine with Pro 1 cams. It is not super aggressive, and there are guys running bigger cams and shaved heads, with stock bottom ends making a lot of power and having the engines last.

 

Well even if the are there own specific piston, they're damn close to h22 pistons. My old h22a4 side by side with the h23v, I had never noticed a difference besides part number.

 

At least someone hears me, haha I've been talking with Rosko about my setup for months and he's given me some good insight. I personally don't think, like you stated, that compression a half a point over stock Type S (11.1:1 and 11.68:1) is gonna wreak catastrophic failure on rings.

 

another quick question for you guys I bought the super tech 93 pound valve springs and titanium retainers for my h22 head and can't find install instructions anywhere to give to the machine shop. I need to know what is needed to be done to put them in

 

The shop should know how to install valve springs. If they don't, then take it to a shop that does.