S2000 Under The Hood S2000 Technical and Mechanical discussions.

Low compression. Gauge at fault?

Thread Tools
 
Old Aug 24, 2017 | 10:23 PM
  #11  
HarryD's Avatar
15 Year Member
Liked
Loved
Community Favorite
 
Joined: Oct 2008
Posts: 1,113
Likes: 51
From: San Francisco
Default

Originally Posted by Charper732
I don't get where this mythical "consistency is key" came from. That is literally one of the dumbest things I see get constantly repeated on the forum. I've tested a legit 185psi with snap-on comp gauge across the board and the leakdown showed 45% leak at the rings. Along with other similar results on other engines. Consistency means NOTHING if the comp is actually low.

That being said. HF comp gauges are horrible. I've seen two guys use them and they both topped out at 180ish psi. Get a quality gauge or do a leakdown if you really want to know the health of your motor
So what was wrong with ALL your cylinders that they were ALL the same consistently low PSI at the same time?

Shop manual says there's a max variation of 28 PSI -- that's where we get the "consistency across all cylinders" parameter.

If that's the dumbest thing you've seen on s2ki, you need to spend more time here.
Reply
Old Aug 24, 2017 | 10:24 PM
  #12  
miloking's Avatar
Registered User
 
Joined: Nov 2011
Posts: 435
Likes: 16
Default

Originally Posted by Charper732
I don't get where this mythical "consistency is key" came from. That is literally one of the dumbest things I see get constantly repeated on the forum. I've tested a legit 185psi with snap-on comp gauge across the board and the leakdown showed 45% leak at the rings. Along with other similar results on other engines. Consistency means NOTHING if the comp is actually low.

That being said. HF comp gauges are horrible. I've seen two guys use them and they both topped out at 180ish psi. Get a quality gauge or do a leakdown if you really want to know the health of your motor
Yea you are right so dumb its much better to have one cylinder with way lower reading... who needs same compression across whole engine.
Reply
Old Aug 25, 2017 | 06:26 AM
  #13  
Car Analogy's Avatar
10 Year Member
Photogenic
Photoriffic
 
Joined: Aug 2012
Posts: 8,759
Likes: 1,861
Default

Consistency isn't an S2k thing, its an industry wide accepted concept.

Engines rarely wear completely evenly. When engine wear gets bad enough that it starts to effect power significantly or makes it run bad, there will be unevenness of its compression.

If all the cylinders are the same, engine probably doesn't have much wear. If there is significant variance, there is wear or damage. Period.

Can an engine wear evenly, such that the cylinders are all still close, but worn so badly that engine runs bad and is way down on power? Yes. Its not as common, but possible. This is why there is also a minimum compression spec.
Reply
Old Aug 25, 2017 | 08:04 AM
  #14  
tama05's Avatar
10 Year Member
Photogenic
Photoriffic
 
Joined: May 2011
Posts: 829
Likes: 24
Default

^Correct, and there may be nothing wrong with the engine at all, which is why I suggested using a better quality gauge, because I have seen the difference first hand. I understand consistency isn't everything, but if the cylinders are within certain psi of each other, the gauge itself may be at fault for low readings. There's a ton of people on here who have witnessed the same which led me to getting a new compression tester myself. Just giving OP some ideas of what can be done if they question the results.
Reply
Old Aug 25, 2017 | 11:03 AM
  #15  
Charper732's Avatar
5 Year Member
Photogenic
Liked
Loved
 
Joined: Aug 2016
Posts: 1,154
Likes: 183
From: US129 Maryville, TN
Default

Originally Posted by Car Analogy
Engines rarely wear completely evenly. When engine wear gets bad enough that it starts to effect power significantly or makes it run bad, there will be unevenness of its compression.

If all the cylinders are the same, engine doesn't have much wear. If there is significant variance, there is wear or damage. Period.
You see, that is where you are wrong. I don't know what your experience is, but in general 180 psi is a lot when compared to a lot of engines out there. The F20s Ive seen with low comp across the board still ran fine, albiet maybe down on power if you are use to driving a s2k. You would never know they had low comp. But yet they leaked 40-45% at the rings. "if all the cylinders are the same, the engine doesn't have much wear" well I just proved to you that is wrong soooo.....
Reply
Old Aug 25, 2017 | 04:25 PM
  #16  
Car Analogy's Avatar
10 Year Member
Photogenic
Photoriffic
 
Joined: Aug 2012
Posts: 8,759
Likes: 1,861
Default

Yes, I should have said 'probably' doesn't have much wear. Like I said after, its possible, but less likely, to have even wear down to min spec. So I obviously didn't mean even compression is a guarantee of engine being ok.

Bit again, this isn't an S forum thing, its an industry thing. So your argument is with the automotive industry in its entirety...
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Rostyslav_18
S2000 Engine Management
7
Mar 11, 2018 07:32 AM
papa Fittig
S2000 Under The Hood
4
Dec 25, 2014 08:10 PM
Competitor9
S2000 Forced Induction
4
Jun 18, 2010 10:13 AM
lownslowneon
S2000 Under The Hood
13
Oct 25, 2009 12:58 PM
revhi
S2000 Under The Hood
7
Oct 16, 2006 09:46 PM




All times are GMT -8. The time now is 10:47 AM.