street_ride14

<U>Compression question</U>
I used two online calculators based on the H series internal swaps and both show different compression numbers, which one is right ?? Here are the two Compression Ratio calculators used ..
1) http://www.bsperformance.com/compcalc/compcalc.htm
2) http://www.zealautowerks.com/hfseries.html

... My setup will consist of h22a1 block, h23 crank, h23 oem connecting rods, and h23 oem pistons. 87mm bore, 95mm stroke. Cylinder head is stock OEM h22a1.

<U>Redline question</U>
With the above listed setup, can I still tear it up 'till my VTEC 7400-rpm redline or does this change as well when h23 internals are introduced ??

Pman92

just because your changing the block doenst mean that the redline will change on the bottom end.

bb_one

The H23 and H22 blocks are identical. They have the same deck heights so your compression will not differ from an H23a1 if you are using all H23 internals.

You are essentially making an H23 VTEC with the H22 head. This does not change the R/S ratio or strengthen the bottom end by any means for you to rev it up to the stock H22 redline.

In OEM form, many would advise you not to spin the motor any higher than the OEM H23 redline due to poorer R/S ratio than the H22. Unless you planned on balancing the bottom end, blue printing, and strengthening the bottom end, then it MAY be viable, but everyone's mileage varies.

street_ride14

Right now my stock compression ratio is 10:1 .. USDM H22a1 engine .. I want to lower this compression by adding stock h23a1 bottom end internals .. You're saying that my approach is not correct ?

Ludster

You will lower your compression because H23 Rods are shorter than H22 Rods

street_ride14

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ludster &raquo;</TD></TR><TR><TD CLASS="quote">You will lower your compression because H23 Rods are shorter than H22 Rods</TD></TR></TABLE>

I agree, what I'm trying to find out is what will my compression be. I used compression ratio calculators, but those state two different ratios. So my question is this ... What will my compression ratio be considering the following setup ( everything OEM ) ? ... h22a1 cylinder head, h22a1 block housing,, h23a1 rods, pistons, and crankshaft.

mgags7

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by street_ride14 &raquo;</TD></TR><TR><TD CLASS="quote">

I agree, what I'm trying to find out is what will my compression be. I used compression ratio calculators, but those state two different ratios. So my question is this ... What will my compression ratio be considering the following setup ( everything OEM ) ? ... h22a1 cylinder head, h22a1 block housing,, h23a1 rods, pistons, and crankshaft.</TD></TR></TABLE>

You're going to lose a good bit of compression due to the 3.8cc difference in the combustion chamber size. H23 heads are 50cc and h22 heads are 53.8cc. I'd say you'll be somewhere in the low 9s.

That zeal calculator is screwed. If you put a completely factory h23 setup into it, it gives an 11.5:1 CR. lol

You can do what you like, but know that the longer stroke means more wear on the bottom end and more risk of spinning a bearing or throwing a rod. Are you using arp hardware when you rebuild? You doing bearings? (you better be)

zoom14263

i would like to ask you why would u want to do that? i, myself is trying to put together a h23a block with a h22a head. which makes it a h23a dohc vtec engine. but i think i might just a factory h23a dohc vtec form a jdm engine place. but, good luck with your project.

street_ride14

Yup, using ARP hardware, new OEM bearings and piston rings during the rebuild. I'm doing this because I want to lower my compression to around 9:1 so that I could go Turbo. This is supposed to be a budget build, I already have both blocks, h22a1 in my car right now and h23a1 at home. My boost will not be anything out of the ordinary so I'm sticking with OEM parts. I'm predicting that the piston ringlands will crack and/or break within 18 months on boost, but by then I should have a built and sleeved block ready to go in.

Anyone know if I'll be safe reving the motor to 7400-rpm on this setup ?

EFz6er

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bb_one &raquo;</TD></TR><TR><TD CLASS="quote">
You are essentially making an H23 VTEC with the H22 head. This does not change the R/S ratio or strengthen the bottom end by any means for you to rev it up to the stock H22 redline.

In OEM form, many would advise you not to spin the motor any higher than the OEM H23 redline due to poorer R/S ratio than the H22. Unless you planned on balancing the bottom end, blue printing, and strengthening the bottom end, then it MAY be viable, but everyone's mileage varies.
</TD></TR></TABLE>

It sounds like you should stay around the H23 redline.......

If you swap the H22 rods and pistons in the H23 block would that help raise the redline "safely"???????

bb_one

That would not work if you plan on using an H23 crank. H23 crank with H22 rods/pistons will stick outside the block.

H22 stroke = 90.7mm
H23 stroke = 95.0mm

H22 rods = 143mm
H23 Rods = 141.5mm

By sticking an H22 head on an H23 bottom end, you will already be lowering the compression from the OEM C/R of the H23 from combustion cc volume. So to figure out your new C/R, just take the OEM H23 C/R and add 3.8 cc of volume to find your new C/R.


Modified by bb_one at 1:44 AM 7/30/2008

street_ride14

I think the answer is yes, but I just need to know for sure ... will the h23 block bolt directly onto a h22 head ?? .. if so than my compression should be at around 9.3 :: 1

snobordboy

If you look at the h23 vtec threads in the faqs, it will give you all the specifics as to how hard it is to put the h22 head on the h23 bottom end, pretty much you remove a plug in an oil passage, and swap all the h22 timing assembly and water pump/pipe assembly over to the h23 block.

But, if you are building a block for boost, why even take the added time and expense of doing all this, that .7 or so in compression drop is only going to allow you to tune it a bit more aggressively, which will make it tougher for your ringlands anyways, so why not just save the time and cash for the properly built block?

street_ride14

I see what you're saying, and I am aware that that would be the best way to go about boost, .. but money is tight right now. already have both complete blocks, so no extra money spent just my extra time on this rebuild. I'm going to invest into new bearings, rod bolts, and piston rings and that it as far as extra expenses, oh yeah and will purchase the KaizenSpeed balance shaft eliminator kit as well. this block swap is only temperary for about 18 months, then I should have a built block going in anyways. I need to think this through a bit more though. Thanks for your help.