I have been searching and doing a lot of reading on max bore sizes for the H22A. The general rule of thumb for motors that are not strictly race seems to be:
87 = stock
89 = max for turbo apps

I was thinking about going .40 over (88mm) to split the difference. I figure I might as well bump up the bore a little bit since I have to sleeve anyway, but I would also like some rebuild room down the line.

I have also been reading about compression ratios. I think I would like to drop the compression to around 10:1 or maybe even a bit lower. 9.5:1 would be ok too...but I want to stay away from the 8.x:1 stuff.

My problem is piston selection. I don't really want to run custom pistons (price, wait time) but H22A's dont seem to have too many choices.

CP Pistons = 9:1, 10:1, or 11.5:1 but stock bore only
JE Pistons = 9:1, 10:1, or 11.5:1 but stock bore only
Ross Pistons = B Series only?
Endyn = 87mm or 90mm only

Arias seems to be the closest match with 87.5mm and 9.7 compression.

So my question is, are there any pistons I am missing? Should I just give up on going with the 88mm bore and stick with 87? It seems like free displacement but if I have to pay for custom pistons it sure isn't going to be free.

If I do stick with standard 87mm I would have plenty of choices...who would be the best bang for the buck?

Thanks.

 

i believe you can get cp pistons in an 88mm bore 9.0:1
not sure if you can get them 88mm-9.5:1 though

 

What compression ratio you want is dependant on what you plan to do with the built motor and what altitude you're driving at......the higher the compression, the better your turbo will spool but the less max boost you'll be able to run without being "at risk"......

Typically 9:1 is a good all around C/R. Still spools decently and you can run 30+ psi if you want. I'd say if your power goals are 550-600+ whp go with a 9:1 compression stock bore (JE or endyn)

If you're aiming for lower #'s but want better drivability, go with 10:1 stock bore. You can run a smaller turbo because you need less pressure and flow to make power, and it'll spool quicker.....I'm not saying that a 10:1 motor can't run 30+ psi either, because it can, I'm just saying that 10:1 and 30+ psi is putting you "at risk"....

An extra 1mm bore isn't going to make much of a difference, especially when you can just turn up the boost
B

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SKDRCR &raquo;</TD></TR><TR><TD CLASS="quote">i believe you can get cp pistons in an 88mm bore 9.0:1
not sure if you can get them 88mm-9.5:1 though </TD></TR></TABLE>

They arent in their .pdf catalog on their website...but I could check around. Thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Firedrake &raquo;</TD></TR><TR><TD CLASS="quote">What compression ratio you want is dependant on what you plan to do with the built motor and what altitude you're driving at......the higher the compression, the better your turbo will spool but the less max boost you'll be able to run without being "at risk"......

Typically 9:1 is a good all around C/R. Still spools decently and you can run 30+ psi if you want. I'd say if your power goals are 550-600+ whp go with a 9:1 compression stock bore (JE or endyn)

If you're aiming for lower #'s but want better drivability, go with 10:1 stock bore. You can run a smaller turbo because you need less pressure and flow to make power, and it'll spool quicker.....I'm not saying that a 10:1 motor can't run 30+ psi either, because it can, I'm just saying that 10:1 and 30+ psi is putting you "at risk"....

An extra 1mm bore isn't going to make much of a difference, especially when you can just turn up the boost
B</TD></TR></TABLE>

Well I have a SC61 and will be running 94 octane most of the time. Like everyone else, I want to do a street/strip setup where I can run higher octane at the track and lower on the street (via my AEM EMS).

I was thinking 10:1 would be the highest compression I would go for sure. 9.5ish seems good.

I suppose stock bore wouldnt be bad (lots more piston choices) but again, it just seems like since I am sleeving the block anyway it would be easy to bore it.

Maybe I am just looking at the glass 'half empty'?

 

That SC61 is going to spool slooooooooo........we did a car here (B-series) running 10.x:1 compression and an SC61, and the stupid thing didn't spool till like 5K. Funny too, since it seems honda-tech has adopted that turbo as the best thing since sliced bread.....I'd take a t3/t04e 50 trim any day of the week......

What is your elevation? I'd say go 9:1 and run 35 psi, you should make ~630 whp and use the AEM to do progressive boost settings (so the turbo doesn't just finally spool and bust the tires loose)
B

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Firedrake &raquo;</TD></TR><TR><TD CLASS="quote">That SC61 is going to spool slooooooooo........we did a car here (B-series) running 10.x:1 compression and an SC61, and the stupid thing didn't spool till like 5K.</TD></TR></TABLE>

Too bad mine (<u>t4</u>) kicks in hard as **** at 4k

And by the way, a 50 trim is not going to be efficient at 35psi of boost. Well, unless you are running a pt72.

Compressor maps own j00.

 

Well we will see. The only experience I have with it is on H series. The guy was getting spool around 4k (equal length) so that seems bearable.

I got a pretty good deal on it and if it doesn't work out the used market seems pretty favorable...but I am hopeful it will work out for me.

 

Oh yea I forgot your question.

Elevation is like 100 feet. Downtown is right at 20-40? I think...my side of town is a bit higher (100ish).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">

Too bad mine (<u>t4</u>) kicks in hard as **** at 4k

And by the way, a 50 trim is not going to be efficient at 35psi of boost. Well, unless you are running a pt72.

Compressor maps own j00.</TD></TR></TABLE>

Just to clear things up, I'm not saying a 50trim will even make 35 psi (we had trouble making 28 on a 9:1 B16)......I'm also not sayin it'll make 630 whp (50trim is only good for low-mid 500's).......I'm saying it's a better choice for a street driven car, as you'll never ever ever be able to use more than 5xx whp on the street in an FWD anyways. Hell, our teg was baking tires all the way down the track didn't matter if they were drag radials or slicks.

I'm posting a vid with that run (teg on drag radials) among other things, I'll post in the prelude vids section (even though my prelude only makes a cameo appearance)....as long as it's coo with the modz
B

 

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

Just to clear things up, I'm not saying a 50trim will even make 35 psi (we had trouble making 28 on a 9:1 B16)......I'm also not sayin it'll make 630 whp (50trim is only good for low-mid 500's).......I'm saying it's a better choice for a street driven car, as you'll never ever ever be able to use more than 5xx whp on the street in an FWD anyways. Hell, our teg was baking tires all the way down the track didn't matter if they were drag radials or slicks.

I'm posting a vid with that run (teg on drag radials) among other things, I'll post in the prelude vids section (even though my prelude only makes a cameo appearance)....as long as it's coo with the modz
B</TD></TR></TABLE>

FWIW, I actually have an EK hatch...not even a Prelude owner (doh).

How much does elevation change things?

 

I agree. I could throw on a large trim turbo and hit an easy 600whp on my car, but that power doesn't do **** for me on the street when I don't spool till 6k and redline is 7200. Cranking up the boost on smaller trim turbo's is great to do, but as I stated before you must look at the compressor maps and see the turbo's efficiency range. Everyone thinks boost equals power, well when a turbo is out of its efficiency range you will do nothing but blow hot air and lose power.

In my opinion, the sc61 is better then sliced bread... and an H series can spool it with no problem as long as you are not going with an S trim and a .68 t4 housing. Then yes, you might have added lag.

Post up the video y0!