h22 h22a h22a4 - Honda Prelude Forum

mrmumbels · 10-11-2002, 08:11 PM

h22 h22a h22a4? what's the difference?

LegoMahEggroll · 10-11-2002, 08:51 PM

uhh i think h22a is jdm.......h22a4 is usdm

axion68 · 10-11-2002, 09:00 PM

I though the a4 was for OBDII?

I don't really have any idea though

ZDVS1 · 10-11-2002, 09:10 PM

Off the top of my head...

never herd of just H22..

H22a is JDM, could be any from 92-01 either closed or open deck.
H22a1 USDM 92-96 closed deck
H22a4 USDM 97-01 open deck

if I remember correctly. This has been covered many times.

mrmumbels · 10-11-2002, 10:18 PM

usdm means? open close deck?

vipastyle · 10-11-2002, 10:38 PM

usdm - united states domestic market

open deck -

closed deck -

Do you see around the cylinder? In the S2000 motor, it is opened deck which means there is a gap around the cylinder. This makes it prone to flexing and can cause breakage. I don't know too much on it, but I know it isn't as strong

In the WRX motor (bottom) it is closed, so it seems more "solid".

98TypeSH · 10-11-2002, 11:45 PM

H22a1
Bore x stroke 87.0 x 90.7 mm (3.43 x 3.57 in)
Displacement 2157cc (132 cu. in.)
Compression ratio 10.0:1
Hp 190 hp @ 6800 rpm
Torque 158 lb-ft @ 5500 rpm
Deck Type close

H22a4
Bore x stroke 87.0 x 90.7 mm (3.43 x 3.57 in)
Displacement 2157cc (132 cu. in.)
Compression ratio 10.0:1
Hp 195 @ 7,000
Torque 156 @ 5,250
Deck Type open

The H22A4 engine is the open-deck aluminum cylinder block with cast-in iron linersâ€“a change from the previous closed-deck design H22a1. The open-deck design is less prone to casting reject, and helps to fix the overhearing issues caused by the closed-deck design of the H22a1. The H22a4 features a three-layer, two-bead welded head gasket compensates for reduced rigidity of the block, and has a full-floating crankpin which contributes to quieter engine operation by allowing a closer fit between the pin and the piston, thereby reducing any clatter when the engine is cold. The H22a4 is great for n/a because the open-deck design allows for better cooling, where the H22a1 is better for FI because the closed-deck design is more solid than the H22a4 and can safely take higher levels of boost.

This is a close up view of an open-deck block

BTW the open-deck cools better than the closed-deck because with the open-deck design oil circulates through the area between the cylinder and block thus cooling down the cylinder.

winterlude · 10-12-2002, 12:03 AM

Quote:

Originally posted by 98TypeSH
H22a1
The H22a4 is great for n/a because the open-deck design allows for better cooling, where the H22a1 is better for FI because the closed-deck design is more solid than the H22a4 and can safely take higher levels of boost.

Which one would be better for nitrous?

98TypeSH · 10-12-2002, 12:24 AM

Quote:

Originally posted by winterlude

Which one would be better for nitrous?

Not real sure if you think about it puts a lot of pressure on you engine so the closed-deck should be safer. But nitrous also creates a lot of heat in you engine so the open-deck would cool it better. I cant think of any members off my the top of my head who have blown their engines running a reasonable shot (50-75) of nitrous oxide on a stock (by stock I mean not built up cylinders, rods, ect) H22a4 engine. Can any one with nitrous oxide shed light on this topic?

ZDVS1 · 10-12-2002, 10:28 AM

Quote:

Originally posted by 98TypeSH
BTW the open-deck cools better than the closed-deck because with the open-deck design oil circulates through the area between the cylinder and block thus cooling down the cylinder.

I coulda swore it was coolant/antifreeze, not oil flowing through that part....

PreludeBrad · 10-12-2002, 10:48 AM

so all the 5gens sold in america are h22a4? and thats the only option?

jnkoh · 10-12-2002, 06:54 PM

i'm pretty sure that the pressure increase from nitrous is neglible compared to boost pressure. Open deck should be fine. I just started spraying a 75 shot, no problems so far.

98TypeSH · 10-12-2002, 11:19 PM

Quote:

Originally posted by ZDVS1
I coulda swore it was coolant/antifreeze, not oil flowing through that part....

I think you right it may be coolant.

Quote:

Originally posted by PreludeBrad
so all the 5gens sold in america are h22a4? and thats the only option?

Yea all USDM 5Gens came with the H22a4 but there are 2 different types (both engines have the same specs). Due to the ATTS on the Type SH the H22a4 in the Type SH has a different shaped block to allow for the ATTS to fit. I think the Typed SH has a longer header and a shorter exhaust pipe and the drain plug of the oil is in a different place (there are some more differences but canâ€™t remember them). The H22a4 for the Type SH only is offered in Manual transmissions where the base model is offered in Auto and Manual transmissions. Also you canâ€™t swap such things as transmissions from the base to the Type SH because of the different block and bolt pattern.