Compression. Technical info needed

S

Shooting Starlet

Member +
Hi everyone, where to start
When i had just started modding i got the compression up to 155-160psi over time this dropped to 130 across due to 4cracked pistons (ARRRHHH)
Now i have gone for wiseco pistons and had 3thou off the head. I want to get compression back up to standard (dont want to spend all this money for a slower car) Basically i want to know what to do to get back up to this psi or really if its going to make much difference by going thinner head gasket and decking the block ?!
I also would like to try and work out the compression ratio does anyone know what the wiseco pistons give ?

Cheers
Paul
 
S

speedvision

Member +
Shooting Starlet said:
Hi everyone, where to start
When i had just started modding i got the compression up to 155-160psi over time this dropped to 130 across due to 4cracked pistons (ARRRHHH)
Now i have gone for wiseco pistons and had 3thou off the head. I want to get compression back up to standard (dont want to spend all this money for a slower car) Basically i want to know what to do to get back up to this psi or really if its going to make much difference by going thinner head gasket and decking the block ?!
I also would like to try and work out the compression ratio does anyone know what the wiseco pistons give ?

Cheers
Paul
Click to expand...

do not touch the head anymore...3 thou is enough what u took off before..dont deck the block either.......to get ur compression up back the easiest is to use a thinner headgasket like a 0.6 or 0.5 trd one....another option is not to use the wiseco low compression pistons...get pistons that are flat top like the standard pistons and ur compression should be back to almost normal...if u still feel a bit concerned then get 75mm pistons and this will even bring the compression up back....

sam
 
G

gorganl2000

Lifer
Shooting Starlet said:
Hi everyone, where to start
When i had just started modding i got the compression up to 155-160psi over time this dropped to 130 across due to 4cracked pistons (ARRRHHH)
Now i have gone for wiseco pistons and had 3thou off the head. I want to get compression back up to standard (dont want to spend all this money for a slower car) Basically i want to know what to do to get back up to this psi or really if its going to make much difference by going thinner head gasket and decking the block ?!
I also would like to try and work out the compression ratio does anyone know what the wiseco pistons give ?

Cheers
Paul
Click to expand...


based on what u wrote here......logic tell me that if u took 3 thou off the head....then simply put in a headgasket which is 3 thoug thivker than the headgasket u have in now
and i must say 3 thou is not a lot.....its about 0.075mm......so if u were running the stock h/gasket....u basically need a h/gasket that is about 1mm thicker

using a thinner h/gasket will raise your compression---as would shaving the head
 
Last edited:
Bullet00th

Bullet00th

Member +
Whilst this thread is up, I did a compression test the other day. I got reading between 130-140 psi. Is this acceptable ?

Matt
 
Ted

Ted

Member +
150 to 160 is normal. you get the odd 'my compression is 170 so my engine is class' but thats up near na compression so could be bull.
 
TurboDave

TurboDave

Member +
Si_Glanza said:
What Does this mean? is this skimming of the head but taking more off to ajust compression?
Click to expand...

It probably needed the 3 thou taking off to make the head flat again.

TBH, If you are keeping the nice CT9 Paul :), idd go for non low compression pistons and stick with the stock HG.

Or if you want to go for more, stick some 75mm low comp pistons in and use a TRD 0.6mm Headgasket to bring the comp back to standard ish.
 
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