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View Full Version : RB25DET COMPRESSION NUMBERS!!any good?


Busted_daily
06-24-2015, 10:22 PM
I picked up a rb25det s2 swap all stock compression numbers were

#1-150
#2-175
#3-150
#4-150
#5-175
#6-150

ive read alot and alot of people are saying 150 is fine no problem i just want to double check that these numbers are good and not bad since this is my first time owning a Rb25 but everytime i read someones answer on a thread always differs from another just want someone with better knowledge to check this out and let me know thank you guys .

Mitsubayati
06-24-2015, 10:27 PM
There's more than a 10% variance in compression between cylinders. Regardless of the nominal compression number, that is already a sign that something is wrong. 175 is where your compression should be around. If it's lower then you should contemplate a rebuild. Do a leakdown test to verify percentage of leakage and where the leak may be coming from but it's most likely your rings.

Busted_daily
06-24-2015, 10:35 PM
=( i dont want to rebuild lol and ill call them see what we can do

Ilya
06-24-2015, 11:00 PM
Seems like the resolution of the tool you were using was in 25psi per mark. So it was either 150 or 175 and nothing in between. Try again with a different tool

Busted_daily
06-24-2015, 11:09 PM
alright you think that would change it?

Ilya
06-27-2015, 12:18 PM
I think with a different tool instead of getting either a 150 or 175, you would get a better resolution number.

Resolution - n. The smallest interval measurable by a scientific (especially optical) instrument; the resolving power.

Kingtal0n
06-28-2015, 04:25 PM
I think with a different tool instead of getting either a 150 or 175, you would get a better resolution number.

Resolution - n. The smallest interval measurable by a scientific (especially optical) instrument; the resolving power.

this.

Your numbers should be plus or minus 2 or 3, not plus or minus 25.

Right off the bat I would say its just been sitting.

Busted_daily
06-29-2015, 01:28 PM
Im going to try with a new tester i bought a compression tester from harbor freight i have been busy sorry have not responded back to you guys but i will for sure try it as soon as i get the chance and i just hope the motor doesn't need rebuild and yea i got the motor from a importer in FL so im hopeing its just from sitting and nothing major

Kingtal0n
06-29-2015, 02:10 PM
for example, you want to see this

125
123
124
125
126
123


then, you want to add a cap-ful of oil, and see this:

127
126
125
127
129
124

Busted_daily
06-30-2015, 08:00 PM
well i bought i about month and a half ago it could of been sitting at the importer but if numbers do not change is it a chance of the rings just sticking from sitting and once i crank it in car it would change ? if that makes any sense