Piston

[todaek9]

Hi guys, I wonder is there any diff between the height of the Dome of piston? comparing TODA, JUN, Arias, JE? and how bout their Compression?

Lets say it's for B16 or B18

[iceman91]

as far as i know they have higher compression than standard. each one is a different rating though..if not mistaken toda and jun are quite similar

[tofu R]

the higher the dome the higher the comp..

diff manufacturers have different specs.. also the piston isnt the only thing that governs compression..

[ProECU]

the higher the dome the higher the comp..

diff manufacturers have different specs.. also the piston isnt the only thing that governs compression..

not always.
It depends on the cam profile the vavle reliefs & piston design were made for.

But as a general rule, yes you are correct.

[barefootbonzai]

while we are on the subject of pistons. I was looking at the cp pistons website. I was compaing the B18C vtir and type r. The highest compression they have for the type r is only 11.5 while there one for vtir is 12.x I'm guessing this is due to the different heads pr2 vs pr3.

my question is...... say everything in the engine is the same... a part from the head (same cams and springs etc). would the one with the pr2 head make more power?

question probably isn't really well ask, but i hope you know what i mean

[todaek9]

overall you guys are saying = using the aftermarket piston such as JUN, TODA, Arias or JE with Hi-cams will definately produce a 12.x:1 compression? tell me if i'm mistaken.

[weezer]

Not always. Each company sell different spec pistons. Some may give you 9.xx:1 and some might give you 13.xx:1 Depends on which one you buy.

[ekslut]

Not always. Each company sell different spec pistons. Some may give you 9.xx:1 and some might give you 13.xx:1 Depends on which one you buy.

exactly. They are not all the same and they will give different comp ratios depending on which engine you have, the specs of the engine, the piston dome dispacement, etc..

There are a lot of factors envolved. If you want to work it out check out this:

http://www.c-speedracing.com/howto/compcalc/compcalc.php

Also you can't just say I have JE pistons so my comp will be 13.**:1, coz JE make about 12 different pistons for B16/18 engines. depending on what size and what comp you want to get. Then they also do custom ones too.

[todaek9]

i'm talking bout N/a, not those turbo Piston...aftermarket high Dome Piston will definately bring your compression towards the 12.x:1 rite?...

[barefootbonzai]

depends how your car is set up. Click on the link that ekslut provided and it will show what factors can affect the compression, it's not just pistons.

[todaek9]

omg...i'm getting 12.7:1...is that accurate?????....may i know how do i convert Psi to value of compression (eg. 12.7:1)