the current b20b im running now is the higher compression engine. the stamp on the head reads p75-6 i was wondering if anyone knew the compression with this head first (ive heard 9:2:1 or 9:6:1) Also my main question im sourcing a p8r hear with a PnP wondering if i'd really reap much benifit out of this head swap.. ? also i plan on some light boost soon nothing crazy so i was thinking putting in crowers would be pointless unless they were turbo cams...

I doubt there's a lot to gain as far as HP. So... weigh your options.

As far as I can remember if your B20B has a knock sensor, then it's 9.2:1, if it does not then it has 8.8:1. Is it a B20B or a B20B4?

my engine was hand picked from many shipments from a guy who worked at Noyan motors. but it does have a spot for knock sensor on the back that wasnt used for my obd0 build. To .my understanding the obd2 b20b came in two different ratio's and a mythed 3rd ratio: one was 9:2:1 and the common one i heard was 9:6:1 <could be backwards, and a mythed 9:8:1 ratio motor that people seem unsure whether actually existed..its a B20B

No, they only came in 8.8:1, 9.2:1 and 9.6:1. I dont care if it was hand picked. Does the engine have a knock sensor sticking off the back of the block?

do you feel superoir repeating to me things i already said..? i told you i know all those ratio's and then i said something you dont know that there is a mythed 3rd ratio 9:8:1 ... not "there is" but some believe there was. Also if you would take the time to read i said "it has a knock sensor" which im not using because im using an OBD0 chipped ecu.... i care and so does everyone else who's seen my motor that it was hand picked... as any enthusiast who is not bitter like a child would. Because when we pulled it apart it was so clean that we could only guess it had less than 5-10K on it ... everything was super clean.

Well your mythic 3rd ratio would in fact be a 4th, now wouldn't it? REad what you wrote. What you quoted does not say it HAD a knock sensor, it says there's a spot. I ask did it have a KS when you got the engine? Did it?

Reason I'm asking is my friends B20 had a threaded hole for the knock, but there wasn't on in place.

Provide information and some sort of proof the mythic 9.8:1 exists please. I've just read or heard of a 9.8:1 B20 (Z or B). I've always assumed there were just the 8.8, 9.2, and 9.6 engines.

Apparently your source is more reliable than countless threads and such on the internet (yea, I know the internet how reliable.) but you get my point.

And this was a very nice thread on the B20

http://www.honda-tech.com/zerothread?id=1467903&page=1

ive read all the forums you've read im sure... thats why i said there is no proof of the 9:8:1 only speculation...ok here is the thing you said that makes no damn sense, if there is a knock sensor hole .. then the motor is and OBD2 motor meaning its the higher ratio ruling out the 8:8:1 ratio... yes mine did have an actual sensor in the hole which I DID NOT HOOK UP! because im OBD0 with a chip eliminating knock sensor. only obd0 engine that used a knock was the b16a....

It doesnt rule out the 8.8:1. 96-98 B20B's w/KS were 9.2:1 without they were 8.8:1

From the readings B20Zs were all USDM engines and were 9.6:1. So if your B20B had a knock, it more than likely has P3F pistons and is... 9.2:1. right?

The point he is getting at, is if your engine had a knock sensor (all B20 blocks have the threaded hole for them), then it is a high compression JDM B20, it there was no knock sensor then it is a low compression JDM B20. If you have a P8R head instead of a P75 then you have the 9.2:1 compression JDM B20. The P8R head lowers compression due to the larger 84mm combustion chamber compared to the 81mm P75 head, but the P8R does have larger valves which help it breathe. Regardless of what B20 you have, they are not recommended for boost due to the sleeve design, but it's your engine, do what you want with it.

All JDM B20's were B20b's, the B20z was NA only and signifies the 9.6:1 compression ratio. I've never heard of a 9.8:1 B20.

... damn you people need to read more carefully ... i never said anything in this thread about boosting my b20... and your b/s about the sleeves ... doesnt matter on low boost.. stock internals are fine up to 300hp. over that its pretty much necesary to upgrade the sleeves and internals. But with a GOOD TUNE you can run close to 300 whp daily driven reliably... this is not the first time i've decided to research the b20 blocks or asked about boosting them. also there are different p75 heads ... mine being a p75-6 there are older p75-4's. Also noone has proof of the "4th" ratio of 9:8:1 ... its just a myth.

Sounds like you should be answering questions instead of asking them with your extensive knowledge of the B20 and it's internal workings, good luck!

So based on what ur saying if change my P8R head to a P75 it will yield a higher compression?

More thank likely not. P8R has an 84mm combustion chamber where as the P75s combustion chamber is only 81mm. I've read peoples opinions that 1. its not worth it and 2. you may run into sealing issues. Not only that, but your cylinders will physically overlap the combustion chambers possibly causing hot spots etc. All theory, I dont have any solid evidence.