Hey guys, I am having my JDM H22 rebuilt and I was thinking about upgrading the pistons while the rebuild takes place. What advantages can I expect if the rest of the motor stays stock.

I am going to have the main and rod bearing changed if they look bad.

Are these pistons worth it if the rest of the motor stays stock????

 

i thought it gives high compression?

 

Type-s pistons will raise the compression to 11:1 from USDM 10:1 or JDM 10.6:1. That equates to about 10HP. If you upgrade the pistons with the OEM type-s rods then you'll get a little more HP., becuase a little less friction from the type-s floating wrist pins vs. USDM pressed-in wristpins. The Type-s wrist pins are held in with circlips on either end. I am pretty sure that the only difference in the rods is the wrist pin journal is *slightly* larger diameter. If you change nothing else then I would not think that it is worth it. I'd rather spend the $$ on tuning a stocker, or intake/exhaust. my 2 pfenig
the Pirate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred &raquo;</TD></TR><TR><TD CLASS="quote">Type-s pistons will raise the compression to 11:1 from USDM 10:1 or JDM 10.6:1. That equates to about 10HP. If you upgrade the pistons with the OEM type-s rods then you'll get a little more HP., becuase a little less friction from the type-s floating wrist pins vs. USDM pressed-in wristpins. The Type-s wrist pins are held in with circlips on either end. I am pretty sure that the only difference in the rods is the wrist pin journal is *slightly* larger diameter. If you change nothing else then I would not think that it is worth it. I'd rather spend the $$ on tuning a stocker, or intake/exhaust. my 2 pfenig
the Pirate</TD></TR></TABLE>

I thought JDM rods had floating wrist pins...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point2 &raquo;</TD></TR><TR><TD CLASS="quote">

I thought JDM rods had floating wrist pins...</TD></TR></TABLE>

JDM rods have pressed wrist pins.

 

In order to run Type-S pistons you HAVE to have floating wrist pins. You can rebush your pressed pin rods to become floating compatible

 

so a type s piston will fit in a jdm motor no problem, just bolt in no machining neccisary?

let me know

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike95lude &raquo;</TD></TR><TR><TD CLASS="quote">In order to run Type-S pistons you HAVE to have floating wrist pins. You can rebush your pressed pin rods to become floating compatible</TD></TR></TABLE>

Ok, I have NO IDEA what floating wrist pins means. So does that mean I have to buy new rods too??

If someone could post pics of what my JDM wrist pins look like and what floating wrist pins look like that would be GREAT!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike95lude &raquo;</TD></TR><TR><TD CLASS="quote">In order to run Type-S pistons you HAVE to have floating wrist pins. You can rebush your pressed pin rods to become floating compatible</TD></TR></TABLE>

How much does this cost to do?? I don't want to spend too much money on it if the gains will be negligable.

 

Do you have a jdm motor or usdm motor?
the gains will depend on that, but even with a jdm motor your looking at 10hp through out. and with the help of cams and other mods, will make the motor really strong. possibly over 220.

about the price, i got quoted 800 installed, but im not sure about the machining of the rods, if someone knows FOR SURE. please post

 

A pressed wrist pin is held in the rod's little end. It is a Very tight fit so when the assembly is rotating the pin will not turn in the rod journal. Instead the pin pivots in the piston. A floating wrist pin means that the rod's little end has a very slight gap so that the pin can turn in both the rod journal and the piston. It is loose or floating. But since the pin now floats it can move from side to side (along the crank axis). That is why the Type-s pin is held in place with little clips on either end in the piston unlike the 10:1 pistons. This supposedly allows for a *slight* HP gain because of less friction or something.

The wrist pins for the Type-s and the USDM models are different (see first attached link). The pin on the type-s is .0005" smaller meaning that the pin is not held in place with friction as is the case with pressed pins.

here are some links to other threads that are more indepth/specific particularly the first:

https://honda-tech.com/zerothread?id=307265
https://honda-tech.com/zerothread?id=710814
https://honda-tech.com/zerothread?id=686931

*NOTE* Appearantly the H22A4 has floating wrist pins too.

Anyway back to the point it seems like it is not that cost effective unless you buy aeolus's rods/pistons then if you have your block apart and the pistons are the right size (A vs B vs OS) it is just a bearing change and hone and Boom $80 for about 10hp. Then you can spend another $60 and mill the head .020" and bump compression to 11.6:1 for another 5 hp or so since you already have the head off, but I digress...

the Pirate

 

I'm running a h22a5 (sweden) and I wonder if I have floating wrist pins?

The piston pin is held with small clips. The rod can move easy on the pin and the pin moves easy in the piston.

Might it be that I can just take the old piston and change it with a type-s piston?

 

if you've got the clips on either side of the wrist pin then you can just drop in some type-s pistons. congrats.
the Pirate

 

You must have your pistons bushed for the Type-S pistons. I think they run about $25 per rod.

You'll be going from 10.6:1 to 11:1 compression, which will give you less than 5 horsepower. I would put the money elsewhere.

 

and where's the best place to buy Type-S pistons and cams?

 

jdmhondaparts.com
and yourll get more the 5 more peak hp, AND more hp throughout the powerband, mostly between 4 and 6