compression test

[mifesto]

"S14 SR20DET jdm motor VVT ball bearing with about 50k miles and gt28 turbo"

looking to buy this ride, had a compression test. From the radiator and forward, it returned 145, 145, 135, 135. Its within nissan spec, opinions?

[fliprayzin240sx]

OEM says acceptable up to 125 psi. Personally, I wouldnt touch it, 135 is too low for me. If it was sitting around 145-150, its okay in my book.

[mifesto]

also the difference is within specs too ..... hmmm. what really annoys me is the numbers they got that day may not be 100% concrete. maybe the block wasnt warmed up enough. maybe it wasnt at 100% wot... i dont know :P

[jskateborders]

whats the price

[jspaeth]

also the difference is within specs too ..... hmmm. what really annoys me is the numbers they got that day may not be 100% concrete. maybe the block wasnt warmed up enough. maybe it wasnt at 100% wot... i dont know :P


Extremely correct statement. I wouldn't believe any numbers I didn't see myself.

[mifesto]

15k... cars done extremely well and drives nicely too... this sucks. maybe i should get a second compression test done somewhere else.

[SoguRacing]

Or just do it yourself. if somebody is confident selling the car they should let you do a compression test. Its very simple and you would be using your tools which you know work correctly and you know what's being done and how it's being done.

[gotta240]

You NEED to do a leakdown test. Although a compression test is a START, a leakdown test tells you MUCH more. If i were to spend 15 grand i would

1. Do another compression test MYSELF and properly
2. Do a LEAKDOWN test

The varience of 135-145 isn't an issue at all. Thats much less than 10 percent which is acceptable. I would be slightly concerned with the 135 numbers as i've heard of many 145-150 motors.

[SoguRacing]

You NEED to do a leakdown test. Although a compression test is a START, a leakdown test tells you MUCH more. If i were to spend 15 grand i would

1. Do another compression test MYSELF and properly
2. Do a LEAKDOWN test

The varience of 135-145 isn't an issue at all. Thats much less than 10 percent which is acceptable. I would be slightly concerned with the 135 numbers as i've heard of many 145-150 motors.

I agree, There's nothing worse than spending 15 grand then finding out you need to put 5 grand more into making it run properly..:x: I would also add to that a Vacuum test.

[Rnz520]

haha my ka24 is 120, 115, 110, 110 from radiator back. It runs like a champ tho, it just crossed 164000 on a 75 shot :)

[blownmotor]

150 to 155 psi is ideal those numbers are too low that means the rings are kinda worn my old engine got 160 across the board so if you're gonna spend that much money on a car i'd say move on and find something healthier

[SoguRacing]

150 to 155 psi is ideal those numbers are too low that means the rings are kinda worn my old engine got 160 across the board so if you're gonna spend that much money on a car i'd say move on and find something healthier

Wow! That was one long sentence.

[mifesto]

i appreciate your support guys, i will ask for another compression test. i've seen alot of guys posting a big variations in compression test results simply from doing it on different days and/or different tools. the variance in the 4 cylinders i think its fine. i will give it one more try then maybe ask him for a discount to offset a rebuild later on if the second compression test shows low numbers again.

[gotta240]

haha my ka24 is 120, 115, 110, 110 from radiator back. It runs like a champ tho, it just crossed 164000 on a 75 shot :)


If your motor really is "running like a champ", i think you did the test wrong.

[AllMotorS13]

If your motor really is "running like a champ", i think you did the test wrong.

hah, my old sr was 135 135 75 130. ran fine. just had a TON of blow by and boost dropped off. ringlands were shattered on #3. ran perfect though. make sure to use a good gauge too, i've seen differences in gauges up to 20psi. especially these cheap autozone sets.

[steve shadows]

If your motor really is "running like a champ", i think you did the test wrong.

yeah he needs to open his throttle body

[AllMotorS13]

yeah he needs to open his throttle body

...or he just had low compression.

[mifesto]

i got another compression test done but this time i was present. shop was busy this saturday so we dropped the car off and went to grab some mcdonalds breakfast. by the time the car was ready to be tested, it was semi cold. mechanic said he rather do it colder. anyhow the numbers were alot better this time. roughly...

140 150 145 145 about 7-8 cranks but saw it could have crept up slightly more if we gave it one more crank. basically i was alot happier with these results on a cold test result. its not super motor but my worries are gone. thanks for everyones input.

[steve shadows]

...or he just had low compression.

IT wouldnt "Run like a champ" then.

[wangan_cruiser]

15k. build your own sr dude.

[jspaeth]

Yeah keeping the throttle open is a must.

My last compression test, I was spaced out and forgot to open it, and my shit came out 145s across the board....I remembered afterward why they were like 155-160 last time.

[AutoKA24DE]

just pull all the plugs out, because even with the wide open throttle body, the other cylinders still have to fight the compression when the valves are closed