Silvia Club of NSW

hey all,

I was just wondering if anyone knows what the stock compression should be on a red-top SR20DET from a 180sx ??

_________________
Do Unto Others, Before They Do Unto You
- Hobzta

I believe its the same as the blacktop SR20DET found in 180sx:

in which case:
150

_________________
I souport publik edukashun

if i remember corectly it is 156 exactly.

All 4 of mine got about 150-152

i thought it was 150 exactly

all 4 of mine got 150 (+/- 0.5) exactly, and i got told it was suppose to be 150 before i did the test and i was very impressed with the result..

_________________
I souport publik edukashun

sr20det and ca18det have same compression ratio, then why is the stock ca18det compression 171psi & sr20det 150 ?

171 sounds a bit high, who said they have same compression?

And 171 is almost NA compression

_________________
I souport publik edukashun

171psi is waht the service manual states factory compression for a ca18det is.

Actually, after speaking to a mechanic i was told it should be around 170 and higher. When people do compression tests (like myself and my mates) they leave out a few factors.

1 -> how old is the battery? If it is new the engine will crank over well and read a good figure. If it is old then it wont crank as hard.

2 -> If you dont leave the throtle wide open then the butterfly (opening to the plenum, i believe) stays shut and there for the engine can not suck the air into it.

Look more at if all 4 cylinders are reading the same. If all are at 150 then it is ok. If 3 are at 150 and one is at 120-130 then there is a problem.

sounds like I have problems...we did a test on my car a few months ago and it came out at an avg of 125

any ideas on what could be wrong ??

_________________
Do Unto Others, Before They Do Unto You
- Hobzta

If all are at 125 then at this stage i would not worry.

Try it again with WOT and maybe if you can a fairly new battery.

When i did mine, the car was fresh off the boat, so a new battery was needed.

i did mine with an okay (not brand new) battery and not WOT and it read fine.

rings on pistons could be stuffed/worn, therefore not sealing properly to get proper compression
but as said before usually as long as they are equal then it shouldnt be too much of a problem

yeah they are pretty even,

Dry test was 135, 125, 125, 115
Wet was 140, 135, 135, 125

_________________
Do Unto Others, Before They Do Unto You
- Hobzta

what about if there is work done to the enigine such as bolt on turbo injectors maybe cams???? or is 150 compressoin for any sort of stock internal engine???

Dry test was 135, 125, 125, 115 <- Rings are going, wouldnt be boosting this car too much from now on

_________________
http://home.iprimus.com.au/xris5/rebuil ... ection.htm