h22 against h22a2

ludeswamp · Post by **ludeswamp** » Fri Jun 22, 2012 8:38 pm

so im prolly bringing an old topic back to life but ive always wondered what it is between the JDM and UKDM that is different in the engine or ancilleries to produce the better compression etc giving the h22a 15bhp extra and is it possible to make a UKDM power like a JDM????

Just for information really always wondered and could be an interesting set of Mods in order to achieve UKDM insurance prices whilst getting the benefits of the JDM power

bristol_bb4 · Post by **bristol_bb4** » Fri Jun 22, 2012 8:47 pm

different ecu, h22a is closed deck, a4 is open, different compression ratio's and i THINK the h22 has different cams aswell

Post by **4thgenphil** » Fri Jun 22, 2012 8:48 pm

pistons really and a different map makes the power, also i think the manifold is a bit larger on a jdm one along with a smaller cat.

other bits are a knock sensor on the h22a
ukdm has an extra bit on the manifold, no real power gains there by deleting it

Post by **4thgenphil** » Fri Jun 22, 2012 8:49 pm

bristol_bb4 wrote:different ecu, h22a is closed deck, a4 is open, different compression ratio's and i THINK the h22 has different cams aswell

a4? usdm lump

the a5 (ukdm) has open deck and 10-1 comp pistons like the h22a2 although the a2 is closed deck. open or closed deck makes no real difference in power i believe

bristol_bb4 · Post by **bristol_bb4** » Fri Jun 22, 2012 8:52 pm

ahh my bad

ive got the best 4g engine so im not uber spec'd up on lesser versions

Post by **4thgenphil** » Fri Jun 22, 2012 8:54 pm

bristol_bb4 wrote:ahh my bad ive got the best 4g engine so im not uber spec'd up on lesser versions

Only one

loser!

Post by **RattyMcClelland** » Fri Jun 22, 2012 8:54 pm

a2 is twice the number so its twice as better.

Post by **Merlin** » Fri Jun 22, 2012 8:54 pm

Engine wise its just compression ratio, the head and cams are the same. My JDM BB4 has had an H22a2 put into it at some point. With a JDM Spoon ECU and exhuast mods I get 200bhp or there abouts depending on the dyno.

Performance Autoworks wrote:The heads are the same between JDM H22a and H22a2...as are the cams, valves, springs and retainers for that matter
H22a has higher comp than the H22a2 10.6:1 vs 10:1 this is achieved with a higher comp piston in the JDM engines - This is not hearsay BTW it is fact.

Exhaust manifold (inc 2-1 section) is larger bore especially at the collector
Cat is more free flowing and is shorter.

Knock sensor is screwed into the block between cyl 1&2 just below the intake manifold. Knock sensor can be fitted to ANY H22 series engines as the threaded hole is present in them all.

http://preludeuk.forumup.com/viewtopic. ... =preludeuk

littlefeller · Post by **littlefeller** » Fri Jun 22, 2012 10:48 pm

compresion ratio is where the extra oooph comes from (its simple chemistry, to raise pressure in order to adjust the rate of a reaction) your also condensing the reactants into a smaller volume. however this gives rise to the need of a knock sensor or boooom, but then the knock sensor needs an ecu it can send its signal too, hence the different ecu (different map). raising the compression ratio also gives you more for cam options, but i dont know if the jdms are different, i would not have thought so as the rev limit is the same