I'm in the process of rebuilding a H23 I think its out of a 92-95 Prelude. Can I run .25 over factory pistons with the stock sleeves? Will boring it out and removing the nikasil (sp) coating hurt anything? If so what are my options?

Thanks

 

Yes, you can run the OS pistons, but you may have to hone the cylinders a bit to make them fit within spec. You will not remove the FRM by just goin .25 over.

 

I had it bored yesterday and the coating is totally gone. At least it cannot be seen. It looks like its all aluminum at least and a magnite won't stick to it. Is it still useable?

 

Well you shouldn't have bored it, only honed it to spec.

I think I remember the .25 OS pistons aren't the normal .25 like in chevy's, but like .25 mm. You would have made the surface of the cyilnders very shiny, but I think it'd be hard to tell if the FRM was actually gone.

 

the boring / honing process for the h23/h22 is no light matter. according to the helms it is quite involved, and you need special tools and stones to do it. how much did the shop take off, are they a reputable shop?

maybe some pics of the block?

 

The cylinder walls are deff shiny. Each cylinder was bored to the piston and put .001 in the hole.

 

so did they bore .25mm over?

if you read the helms manual, this is a complex process for honing the frm, it looks like they did a 60 degree cross hatch with a normal stone.

do you have a helms, if not ill post what it says

 

No I don't this is the first Prelude motor I have played with.

 

up

 

frm sleeves...must sleeve to run forged

 

oh nm factor piston

 

So is it OK to run a factory honda .25 over piston on stock sleeves. It appears the cylinders are aluminum and the coating is gone from being bored out.

 

up

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid901 &raquo;</TD></TR><TR><TD CLASS="quote">So is it OK to run a factory honda .25 over piston on stock sleeves. It appears the cylinders are aluminum and the coating is gone from being bored out. </TD></TR></TABLE>

If you had it HONED properly and the specs are correct, then yes.

 

Just curious what your plans are for the engine? Is it just to get a little more power out of it??

 

The block had slight scaring so we needed to go .25 over on the rebuild.

 

The H23 has FRM sleeves, which are non-magnetic. If you have oversize Honda pistons and the block has been bored/honed to match them with a .001" piston to bore clearance, then you should be fine.

 

up ,, im curious whats going on with this motor

 

We just started it and ran it for 15min. We will start driving it tomorrow.

 

bump up, want to see whats happening with factory pisotns on what looks like aluminum

 

The car had about 5500 miles on it and is running fine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid901 &raquo;</TD></TR><TR><TD CLASS="quote">The car had about 5500 miles on it and is running fine.</TD></TR></TABLE>

nice! no oil consumption

whats the complete build, pistons? and bore size?

 

Stock h23 pistons .25 over. No oil consumption.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid901 &raquo;</TD></TR><TR><TD CLASS="quote">Stock h23 pistons .25 over. No oil consumption.</TD></TR></TABLE>

when you did the .25 over bore what stone did they use, and what kind of hone is it? 60 degree cross hatch?,

cuz rules of the helms manaul dictates that boring the frm is no easy task

are you using stock oversized rings as well?

 

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

when you did the .25 over bore what stone did they use, and what kind of hone is it? 60 degree cross hatch?,

cuz rules of the helms manaul dictates that boring the frm is no easy task

are you using stock oversized rings as well?</TD></TR></TABLE>