I have a b20 vtec build that I am about to assemble...

i had wanted 12.5 compression yet wiseco sent me this piston part number k594m845. The box itself reads 13.0 and higher....


Yet when i check around on different sites etc...this part number is given for a 12.5 compression piston. Im a bit confused. I know that the decking and milling and the vtec head itself will play a role in compression yet i would like to know if anyone can clarify from EXPERIENCE what compression this pistons is.


I am using a b16 head....and a 3 layer oem head gasket.

Again...the part number is k594m845 and its for a 84.5mm bore b20.


Thanks

 

no help? opinions...experience?

 

i would recommend calling the manufacturer.

and then cc'ing the parts.

m.

 

i called wiseco...im probably ganna get about 13.2 the guy from wiseco said.

At the moment i think im going to use a bit thicker head gasket....been thinking about a .051" thick cometic gasket.


If anybody knows how much this will actually lower my compression I would appreciate the input. I was told a few different things from different store owners.

On average they said the .051" thick head gasket will lower it about 1/2 a point...


please anyone with experience or knowledge please chime in!

 

....?

 

Assuming u are using a stock gasket .027 and its putting u at 13.2. Than a .051 gasket would put you around 12.2-12.4 range.

 

i dont thionk that thicker gasket of .051 will lower it by almost a full point...from what ive read and been told by a few people is that the rule of thumb is every .010 lowers it by .2 of a point.

not sure how true it may be but a few ppl seem to agree.

again...will 13.2 really be that different than 12.7 or so...

 

after messing around with the online compression calculators...im not sure if im even getting the correct numbers...

with my pistons being 8.25 dome
head is a b16 head 42.7cc
block is b20 overbores to 84.5mm

then putting in the piston to deck height with im not too sure about neway..

im gettin in the 12's..

i have no clue...

somebody with experience please help!

 

what cams are you going to be using?

those pistons are tough to use with pump gas. You will be ~13:1 with a stock headgasket.

A thick head gasket will lower the compression, but it wont make it any easier on pump gas due to increased piston-head clearance.

if you use a cam with a big primary lobe it will work fine though.

 

im using pro1s...they have a good sized primary lobe...


i just am stuck between leaving it with the stock 3 layer gasket...or just getting a thicker cometic to lower it a bit...

i will be degreeing the motor and checking all clearances and also i will be tuning with water injection...

what do you think about the cams...and also the compression...

 

use pro2's and skip the water and use a stock gasket.

 

i had a b18c....with b16 head....im using the b16 head which already had pro1s...

so thats what im going to be using....

do you not think the pro1s will help a bit?

 

pro2's will make a TON more power on that setup and run alot better

 

i no wat ur sayin....i just alredy have the pro1s in my head and thats what ill be using...im sure it will help bleed off some of the compression


with the pro1s....what do you think about the head gasket choice..

i have the option of getting a 0.051" cometic head gasket...i think it will lower it about .4 of a point.

just not sure cus if im going to be using water...maybe the more compression will be better...i just dont no man

 

dont use a thicker headgasket. the pro1's will work fine, its just pro2's will work better!

 

yea i no what u meen..i drive the car as a semi daily driver...basivcally at nites...and on weekends at the track...

im ganna stick with the stock HG...see how it goes