I'm trying to calculate my compression on my h23 vtec and need some help. I have h23 crank crower h23 rods and type s pistons. after doing some math this is what i came up with.

Crank shaft off put+rod length+piston compression height

Crank 95mm=3.7402inches 3.7402/2=1.8701

1.8701+5.580+1.221=8.671inches

8.671in=220.24....mm

I found the in the chilton manual the deck height of a h22 is 219.52.
219.52-220.24 = -0.72mm

So does this mean my pistons are going to stick out .72mm out of the deck?
so if I go to c-speedracing.com for there compression calculator I have:

Block
Bore mm is 87
stroke in mm is 95
Head
combustion chamber 53.8 cc
piston dome displacement 3.9cc
headgasket thickness .026in
Piston-to-Deck Height -.0283in (or the -.72mm)
and came up with
12.3968/1cr and 2259.1917cc for displacement

does this make sense? The compression sounds right, but the displacement didn't really change over the h22. also isn't -.72 out of the hole a lot? I know to clay the motor when I have the block and head done, but it just doesn't seem like it would really work. Thanks a lot and PLEASE HELP ME OUT

 

The H22 pistons are .020" taller than the H23's. H23Vtec will have H22 pistons sticking out of the deck ~.020" It will work just be sure to clay the engine and be very careful of milling the head.

Pirate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred &raquo;</TD></TR><TR><TD CLASS="quote"> be very careful of milling the head.</TD></TR></TABLE>

Is that just because of piston/valve clearances or is there more to it than that?

 

BUT he's using H23 rods and crank, so that should make up the difference, correct? the rod lengths are different, and so is the crankshaft throw. the JDM H23 VTECs come with JDM 10.6:1 pistons stock.

 

yea you are right they will stick out just a smidge. check your clearances and or get a thicker head gasket.

 

I was already planing on claying the motor so I would know how many degrees I could turn my cams. I don't want to mill the head unless it isn't flat. The .02" is about .72mm, almost a 1mm. Is that just the dome of the piston sticking out? What type/brand of head gasket would work best with this? I will figure out the thickness as long as all my math is right.

 

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

Is that just because of piston/valve clearances or is there more to it than that?</TD></TR></TABLE>
I'm just about positive that is the piston to valve clearance, with the h23 vtec they are really close. I know you can only change your came degree so much


Speaking of cams, I have skunk2 stage 2. I know I will have enough compression, but when I bought them I wasn't planning on doing the h23 vtec. I'm only planing on reeving the engine to like 7800rpms, will the camps make that great of power up to there? I know I should search, but what is a cam that make good mid range power over the band?

 

12.12 Compression ratio
2259.20 cc displacement

Since you asked this on my site, the math is done there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point6 &raquo;</TD></TR><TR><TD CLASS="quote">12.12 Compression ratio
2259.20 cc displacement

Since you asked this on my site, the math is done there.</TD></TR></TABLE>

thanks for the help

 

the actual surface area of the piston will stick out a little. the dome will as well. you may wanna contact comectic about a custom head gasket, i think a .56 is what i ordered and its almost two times as thick as the stock headgasket. just check your clearances.