compression test - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

mifesto · 04-15-2008, 06:40 PM

"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* · 04-15-2008, 06:44 PM

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 · 04-15-2008, 09:30 PM

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 · 04-15-2008, 09:43 PM

whats the price

jspaeth · 04-15-2008, 09:48 PM

Quote:

Originally Posted by 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

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

mifesto · 04-15-2008, 09:48 PM

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

SoguRacing · 04-15-2008, 09:52 PM

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 · 04-15-2008, 09:53 PM

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 · 04-15-2008, 10:00 PM

Quote:

Originally Posted by 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.

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..

I would also add to that a Vacuum test.

Rnz520 · 04-15-2008, 10:13 PM

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 · 04-15-2008, 10:36 PM

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 · 04-15-2008, 10:41 PM

Quote:

Originally Posted by 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

Wow! That was one long sentence.

mifesto · 04-16-2008, 09:26 AM

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 · 04-16-2008, 10:35 AM

Quote:

Originally Posted by 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

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

AllMotorS13 · 04-16-2008, 03:16 PM

Quote:

Originally Posted by gotta240

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 · 04-16-2008, 03:20 PM

Quote:

Originally Posted by gotta240

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 · 04-16-2008, 03:24 PM

Quote:

Originally Posted by steve shadows

yeah he needs to open his throttle body

...or he just had low compression.

mifesto · 04-27-2008, 08:19 PM

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 · 04-28-2008, 10:20 AM

Quote:

Originally Posted by AllMotorS13

...or he just had low compression.

IT wouldnt "Run like a champ" then.

*wangan_cruiser* · 04-28-2008, 11:58 AM

15k. build your own sr dude.

jspaeth · 04-28-2008, 03:14 PM

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 · 04-29-2008, 09:49 PM

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

04-15-2008, 06:40 PM	#1
mifesto Zilvia Member Join Date: Jul 2007 Location: NJ Posts: 209 Trader Rating: (2) Feedback Score: 2 reviews	compression test "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?

04-15-2008, 06:44 PM	#2
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	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. __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

04-15-2008, 09:43 PM	#4
jskateborders Zilvia FREAK! Join Date: Apr 2007 Location: Tucson AZ Age: 32 Posts: 1,258 Trader Rating: (5) Feedback Score: 5 reviews	whats the price __________________ "I am Norwegian, and are not familiar with your urban words :P"

04-15-2008, 09:52 PM	#7
SoguRacing Post Whore! Join Date: Nov 2007 Location: (714) Age: 35 Posts: 2,967 Trader Rating: (23) Rides Gallery: SoguRacing Feedback Score: 23 reviews	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. __________________ Pre Tune Checkup! Compression,LeakDown,Vacuum Test $80. Cams Install: $180

04-15-2008, 10:13 PM	#10
Rnz520 Zilvia Junkie Join Date: Oct 2007 Location: Culpeper Age: 32 Posts: 388 Trader Rating: (0) Feedback Score: 0 reviews	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 __________________ *93 240sx:KA-T, FLTA-2s, MR TR, Greddy F&R bars, Greddy gauges, Cusco brace, etc

04-15-2008, 09:30 PM	#3
mifesto Zilvia Member Join Date: Jul 2007 Location: NJ Posts: 209 Trader Rating: (2) Feedback Score: 2 reviews	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

04-15-2008, 09:48 PM	#6
mifesto Zilvia Member Join Date: Jul 2007 Location: NJ Posts: 209 Trader Rating: (2) Feedback Score: 2 reviews	15k... cars done extremely well and drives nicely too... this sucks. maybe i should get a second compression test done somewhere else.

04-15-2008, 09:53 PM	#8
gotta240 Post Whore! Join Date: Dec 2005 Location: so cal Posts: 3,496 Trader Rating: (21) Feedback Score: 21 reviews	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.

04-15-2008, 10:36 PM	#11
blownmotor Zilvia Junkie Join Date: May 2006 Location: land of the sideshows Posts: 402 Trader Rating: (0) Feedback Score: 0 reviews	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

04-16-2008, 09:26 AM	#13
mifesto Zilvia Member Join Date: Jul 2007 Location: NJ Posts: 209 Trader Rating: (2) Feedback Score: 2 reviews	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.

04-27-2008, 08:19 PM	#18
mifesto Zilvia Member Join Date: Jul 2007 Location: NJ Posts: 209 Trader Rating: (2) Feedback Score: 2 reviews	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.

04-28-2008, 11:58 AM	#20
wangan_cruiser kouki man Join Date: Apr 2006 Location: downtown oakland,ca Age: 36 Posts: 3,535 Trader Rating: (36) Feedback Score: 36 reviews	15k. build your own sr dude.

04-28-2008, 03:14 PM	#21
jspaeth Nissanaholic! Join Date: Mar 2006 Location: Philadelphia suburbs Age: 37 Posts: 2,347 Trader Rating: (7) Rides Gallery: jspaeth Feedback Score: 7 reviews	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. __________________ Daily driven

04-29-2008, 09:49 PM	#22
AutoKA24DE Zilvia Member Join Date: Nov 2005 Location: 818 California Posts: 176 Trader Rating: (0) Feedback Score: 0 reviews	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

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