I finally got around to compression testing my JDM H23A DOHC VTEC, and the readings were 215 in all four cylinders. I know that the compression is good, but what is considered perfect?

...and what is even more strange is that I got the engine from Osaka JDM Motors

 

The same number is all 4 cylinders = perfect.

 

I have a JDM H22a 4g Prelude, I got it with 25,000 miles on the clock so it is still pretty new, only got 35k on it now.

When I first got it I did a compression test and got straight 260psi reading across all four.
JDM H22a is 10.6:1 Compression Ratio

yourumbers seem a bit low. 215. How many miles on the engine did they tell you??

 

The engine is practically brand new. What do you think about what 4bidden said?

 

elevation?

 

I am in Illinois by Chicago...I don't know the exact elevation...

 

actually i think 215 is right around where you wanna be for an h23. don't quote me on that, but if i recall correctly you're fine. besides, uniform compression is what you want.

 

My engine builder (at CJ-Motorsports) knows what he's doing, and he told me that I have EXCELLENT compression...what do you guys think?

 

260 is ****** nuts... you must have cranked the engine until the gauge stops going up.

215 was from H23AHybridEG's motor from the standard 4 cranks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by monalisa overdrive &raquo;</TD></TR><TR><TD CLASS="quote">actually i think 215 is right around where you wanna be for an h23. don't quote me on that, but if i recall correctly you're fine. besides, uniform compression is what you want.</TD></TR></TABLE>

I think it's more like 180-185 across the cylinders for an h23

 

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

I think it's more like 180-185 across the cylinders for an h23

</TD></TR></TABLE>

i would assume though that the h23a would come with higher comp pistons than a h23a1, similar to h22 ones

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H23AHybridEG &raquo;</TD></TR><TR><TD CLASS="quote">The engine is practically brand new. What do you think about what 4bidden said?</TD></TR></TABLE>

Thank, it is (and its hella fun ). And 4bidden is right, straight numbers across the board is ideal showing the engine has healthy rings & valves although your compression seems low to say its a H23aVTEC.
I'd assume it would have at least what the JDM H22a has stock. But then again it might just be because your engines done a lot of miles(?) either way you've got a great starting point for a built motor.

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

Below Sea Level/Sea Level the ball is in my court again

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H23AHybridEG &raquo;</TD></TR><TR><TD CLASS="quote">My engine builder (at CJ-Motorsports) knows what he's doing, and he told me that I have EXCELLENT compression...what do you guys think?</TD></TR></TABLE>

I think you should fully build your motor allmotor high compression.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mister2racer &raquo;</TD></TR><TR><TD CLASS="quote">260 is ****** nuts... you must have cranked the engine until the gauge stops going up.

215 was from H23AHybridEG's motor from the standard 4 cranks.</TD></TR></TABLE>

No.
You could crank it forever and all you'd get would be a burnt-out starter and the same pressure reading as you would have got if you did it the proper way (4cranks per cyl).

H23AHybridEG/mister2racer
When you did the test did you hold the throttle wide open as you cranked it?

 

his motor has perfect compression... the dyno graph is amazing and the motor is mint. there is no point to keeping this thread alive.

 

just for referance the helms says usdm 10:1 brand new = 185, 215=~10.5:1, 260= hell of carbon build up

 

my jdm h22 from hmotors is pumping 215 on all 4 also.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fastludeh22 &raquo;</TD></TR><TR><TD CLASS="quote">just for referance the helms says usdm 10:1 brand new = 185, 215=~10.5:1, 260= hell of carbon build up</TD></TR></TABLE>

It's a JDM H23A...not the USDM H23A1. Also, the compression is 10:6:1...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H23AHybridEG &raquo;</TD></TR><TR><TD CLASS="quote">

It's a JDM H23A...not the USDM H23A1. Also, the compression is 10:6:1...</TD></TR></TABLE>

Well there ya go, 10.6:1, 215 across. Looks like you have a healthy motor

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H23AHybridEG &raquo;</TD></TR><TR><TD CLASS="quote">

It's a JDM H23A...not the USDM H23A1. Also, the compression is 10:6:1...</TD></TR></TABLE>

ya i know but the #'s are still the same. i should have worded better, 185=usdm h22a1=10:1, the rest were going by my personal experince

 

An H23a is hondas highest tq producer. and i'm almost sure of the fact that it has a higher compresion than an h22 or f22 for matter

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by leprekhan &raquo;</TD></TR><TR><TD CLASS="quote">An H23a is hondas highest tq producer. and i'm almost sure of the fact that it has a higher compresion than an h22 or f22 for matter
</TD></TR></TABLE>

Actually the compression is 10:6:1

 

those numbers are great for 10.6:1 compression, which I am pretty sure where the H23A vtec is at...

Your engine is fine man ... all the numbers came out the same, beauty

H23 USDM STock DOCH Non Vtec 9:1 compression is happy with ~180 to be considered new ..

My JDM H22 supposedly was 210 accross the board when it compression tested but.. until I put the gauge on it myself .. pfft.