Supa Troopa

Tried finding a definite answer but no one really seems to come to any conclusion. Will the P30 pistons at 81.25mm fit a GSR block with GSR head with no clearance issues to the head? I read a lot about the CTR pistons and people recommend the P30's but no one says if they still have clearance issues.

Stock Crank, Stock Rods, Stock valves, Stock Cams (if not stock cam then mild cam but lets say stock for now)

Side note, everyone says JDM P30 yet I can still order the P30 through honda parts unlimited. All the compression ratio websites like "c-speedracing" and "zealautoworks" say "USDM PR3 or JDM P30".

Honda Parts Unlimited as this in stock:
13020-P30-G00 PISTON SET (OVER SIZE) (0.25) 1999 CIVIC

Are those incorrect?

Just looking for a definite answer rather then threads ending with no closure. Sorry for asking this, just need a for sure thing before I spend money. It is my first motor build and I want to make sure to purchase the right stuff. Thanks.

lunatics209

iTrader: (1)

No they will not have any problems with clearance. If you're looking at rebuilding the whole bottom end why not look into throwing an 89mm crank in there?

Have you looked into the RS pistons? They don't have p30 but do have pr3 and ITR's at very affordable prices. I couldn't find how much the ones you are looking at cost so can't really say how much difference in cost.

Supa Troopa

Are those P30's the correct ones?

89LSED

Yes, the P30 are the correct ones

What will an 89mm crank do?
what is it out of?

thundernoodle

89mm crank out of an ls, stroke it a bit.

89LSED

I have a few LS cranks... what HP will be gained from putting it in a GSR?

93egSLEEPER

HP is not necissarily gained, longer stroke=more torque. Those pistons on the LS crank vs the GSR crank will be higher in compression. Usually the mix of those 2 makes more HP, but only if used correctly.

89LSED

any LS crank? i have a few A1 Cranks. And a b20 Crank

93egSLEEPER

all the same thing. 89mm stroke

89LSED

hmmmm, Sorry. Not to jack the thread, but what are the downsides to doing this?
if its a simple switch, then im definatly going to put one in!

C_Rock77

Man...before you go tearing into your engine, do some research. If you're asking what the benefit of using an LS crank are, I'm doubting you have the knowledge to be tearing into an engine.

OP....the P30 pistons will fit in a GSR with no clearance issues. It's a good way to boost compression.

The RS Machines are a popular choice, too. You might want to look into those. They've got a good reputation as a good quality cast piston.

93egSLEEPER

Does RS make p30's now? last time I checked it was PR3's and ITR slugs

Supa Troopa

No worries about the crank distraction. My research shows if you do this combination (ls crank with p30 pistons) you compression ratio is super high.

The build I am looking at is going to be about 11.59:1. That is all stock gsr components except the P30 Pistons at .25mm over. With that exact same setup, stock GSR everything with P30 pistons .25mm over, AND LS CRANK, it comes out to be 13.13:1. That is basically asking for race fuel if not then an additive.

From what I have read some people run 93 and some people run race fuel at those ratios. It is all on the tune. Don't take my word for it. I gathered that from researching the piston question I asked. 13.13:1 is a bit high for me as I would still like to drive the car to race events and not feel the need for leaded fuel.

There is also extra work than just throwing in the LS crank, and I believe it relates to the oiling of the crank but do some research because all this information I know is from about 20 minutes of the search button. Clearly I don't know all about the LS crank swap otherwise I would tell you.

Thanks for the input guys, really appreciate it. Ordered the pistons. Thanks.

C_Rock77

Not sure where your info is coming from, Bro. That's DAMN high. Zeal's calculator doesn't put it that high. Are you thinking about PCT (CTR) Pistons?

ruffrhyder

iTrader: (1)

He's probably plugging in the GSR rods, rather than the LS/B20 Pr4 rods which are required to run the LS/B20 crank.

89LSED

Im not tearing my motor apart.
Its being built for me
but yes, i could do a honda OEM just fine if i had time.

So you run LS rods, LS crank, B16 Pistons, GSR block, GSR head, are you saying 13-1 compression?

Supa Troopa

I did, sorry. I didn't say I knew everything about the conversion and theres the proof. I am still going stick with gsr crank though.

blackcracker

I have exactly what your asking about...All stock GSR with JDM p30s...Ill let you know in a week or so,on how it runs.

Supa Troopa

Awesome! I would greatly appreciate it. My pistons are ordered so I am still a way from having the motor complete.

93egSLEEPER

157whp 129tq. Thats my guess

Supa Troopa

Sounds good enough for me, not looking for a bigger numbers motor. I am sure cams will help bring them up some along with intake and a good header but honestly I don't need to much. Tires already break loose in autocross as it is.

2k.civic.si

why not the jdm itr pistons? the jdm itr pistons (p73-00) will give a tiny bit more compression and the side skirts are coated.



the jdm itr pistons have a little less dome but the compression height more than makes up for the compression loss with the smaller dome

thundernoodle

nvm

2k.civic.si

http://cgi.ebay.com/ebaymotors/JDM-I...item3a6012a9f4

DB2-R81

Why pay $260.00 when HMotors Online sells them for $210.00 here:

http://www.hmotorsonline.com/shop/sc...age&item=10016

And a reason for not using them is they are a heavy piston when compared to P30's, 295g+ vs 315g+, the P30 skirts and crowns can always be Tech Line or who ever coated.