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Compression test

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  • Compression test

    After blowing my 2.3 at the track,I had a 2.5 built with a few mods,284/276 shricks,JE 11.25 pistons etc.
    From day one I had a problem with it using oil and smoking(blue oil smoke)I was told this is normal for a fresh build?
    After 1k miles car went in for a custom remap,great numbers and performance 251bhp+ 196ftlbs,only problem still smoked on hard excelleration and used plenty of oil,was told dont worry it will settle down.
    After a few thousand miles it was just the same and was running very rich,eventually it went back and was remapped and now no smoke at all,great.
    Only thing on the second remap it has lost 5bhp across the board and 10ftlbs of torque.The second session was done on a cool freash winters morning and I would have expected it to be better not worse.
    Did a compression test today;

    Dry Wet

    1. 250 280

    2. 235 275

    3. 240 260

    4. 225 270

    Although the figures are high and within 10% is the difference between the dry and wet settings exceptable,considering it is a new engine?
    Also engine still uses some oil,but was told I should expect this with the JE pistons,this in itself is not a problem,but as this was not a cheap job I wat to make sure its right.
    I have thoughts of it running so rich it was causing bore wash(blue smoke)premature wear on the rings,loss of power,using oil.

    Any thoughts,comments?
    Cheers guys Jon

  • #2
    Cylinders 2 and 4 are more like 20% diff. between dry and wet.
    Running rich causes black smoke,not blue.
    Blue smoke is not good.
    Mel Abrahams
    Abrahams Motorsport
    Direct contact:[email protected]


    • #3
      did you use total seal rings ? They are known to be hard to seat.


      • #4
        Yes total seal rings were used in the build.How hard?A few thousand miles and about 4 trackdays should have sorted it by now?
        I know normally that would be correct,but believe me it smoked blue,but now after adjusting the fueling it dosen`t smoke at all??
        Yes I thought 40%between wet and dry readings was too much on such a freash engine,I wouldn`t have expected it to be much different, maybe 5% max?but then I`m no expert.



        • #5
          I know people who have run total seal rings (gapless) on high performance motors for full race seasons and they saw 2% or under leakdown on all cylinders (non S14) is interesting because some engine builders swear by these while others swear against them. VAC is doing my engine and I am having a 2.5 built w/ Stage 3 head, CP 11:1 compression pistons. They are also boring a 2.3 block and supplying the pistons and I inquired about total seal rings and they were of the "swear against them" club. I'm taking their word for it since they build a ton of S14s and they are building up the block.....I wouldnt expect that much difference in a fresh engine either.
          Charley Terhune
          89 Zinno M3- stock 90k miles
          89 Zinno M3- 2.5 etc. etc.


          • #6
            my rant
            I never got them to seat in my M10 motor. Talking to fellow autocrossers using them in all different engines, they had similiar problems. Buddy had a 3000GT motor that smoked for thousands of miles before he had enough and rebuilt again. I ended up blamming my situation on using the stock pistons with them. Ring landings not the same even though they should of worked no problem. On phone with TS during install to ensure they were faced, filled, positioned correctly. We ended up using stock Deeves rings after the bottom end starved. The machinist that did my block was a 6yr winston cup motor builder. His experience suggested against using total seals in the beginning. You can see how bad my smoke situation was Here
            Those were the days :rolleyes: :rolleyes:
            The following pics show it was a scoring event

            So yes, it's possible yours didn't seat well.


            • #7
              I know it's very hard to judge this by pictures but my block was done in the same machine shop. If you ask me the reason for not sealing properly is the wrong honing finish. Just have a look at the pictures. The first one is the 2.3 bored out, the second is the new EVO3 block I bought after the 2.3 engine was dismantled because it was using 1 Liter of oil on a 120mile trip! (and that was after a rebulid with 2k miles) Piston used where not JE's, but standard EVO3. Jon, this might not help in your case because you don't want to dismantle your engine just to have a look.
              When I decided to pull mine apart, I couldn't believe my eyes when feeling down the liners after the pistons where removed. You could actually feel a step at the bottom where the piston returns direction (ground in from piston ring!!!). The honing pattern below that step was rough like an Grid80 sanding sheet.

              Just keep an eye on the oil consumption. But you don't use the car as daily drive and the mileage needed to proove things wrong will take you well out of the usual warranty period. Can you make an agreement for longer warranty? Should'nt be a problem if the guy's believe in their work.

              that is the piston from the liner in pic1 (you could feel a material build up at the arrows)

              Last edited by UweM3; 01-21-2005, 10:13 PM.

              Goodbye M3, you served me well.


              • #8
                Originally posted by UweM3
                If you ask me the reason for not sealing properly is the wrong honing finish. When I decided to pull mine apart, I couldn't believe my eyes when feeling down the liners after the pistons where removed. You could actually feel a step at the bottom where the piston returns direction (ground in from piston ring!!!). The honing pattern below that step was rough like an Grid80 sanding sheet.
                Agreed, but in my case the machinist used the correct finish which is more of a smooth mirror finish. He knew what he was doing, but it still went wrong for us. The walls were so screwed up, we had to go oversize to correct it. The machinist gave insight to using them in the winston cup days. He said they tried them in varying combonations in all different builds. Some cases actually lost hp. I'm not suprised to find more builders steering clear of them. My situation wasn't pretty, but the car still made it 20miles home. Even on that scored, piston slapping mess. "just say no total seals"[done]


                • #9
                  Uwe, you know I suspected the same as you,as the build date between yours and mine is only a matter of weeks,and it`s a fact they went to the same machine shop for boring.
                  The way I see it is,it has lost power in the space of months,so it can`t be the rings not bedding in as surely it would have got better over time,but is in fact getting worse.
                  As it no longer smokes excessively and the only thing that was adjusted was fuel,I was thinking that perhaps it was over fueling so much that it was washing the oil from the bores.(hence the blue smoke)and this has caused wear to the rings and bores??Is this possible or am I way off?
                  As Uwe said time is moving on,and at the moment I can still back it if it`s not right.
                  What do you think guys?Haven`t approached them yet as want to be sure that I have a problem.

                  Cheers Jon


                  • #10
                    If you have the option of backing out, I say do it.

                    If I saw those compression numbers after a fresh rebuild I paid high dollar for, you can bet I would hit the reset button. It should be closer across the board than that to me.


                    • #11
                      shame I haven't got the video where mine was on the rollers with the smoking engine. Mine was smoking heavily at lift off, not so much under acceleration like yours. I think yours was a mix of overfueliing and oil. Get someone to drive behind you and give it some welly. I didn't see mine smoking, someon behind me noticed it. Even if you come to an agreement to open the engine.
                      Who is the judge???? Who will be the person to give thumbs up or down? This will decide who's paying the damage in the end.
                      With the EVO3 block mine is consuming almost no oil. If driven normal I don't need to top up between oilchanges at all. It just goes from max to min, then I change anyway.

                      Goodbye M3, you served me well.


                      • #12

                        When we were up at brunts the other day, I can`t say I noticed the smoke anymore, compared to the day at Brands where I needed oxygen when following you..

                        My engine also went to the same machine shop, but nobody has said my car is burning off oil and giving off smoke, even when asking, and as you know the car is only used on track days so it has not done a lot of milage since the rebuild. I`m using JE`s with total seal rings, and not noticing any problems. It may be an idea to do a compression test on my engine and see what figs we get, using the same tester you used. The only difference is I built my own engine and took my time getting the ring gaps setup. It could be an intresting excercise.

                        Did you do your compression tests on a cold engine??? Have you done them again once the engine has been up to operating temp, to see if there is a difference.

                        Jon, bottom line as Uwe has said, Its going to be a difficult one to call, cause the engine is running well, blue smoke stopped, now that it has been remapped although power is down from the orginal mapping. There is nothing indicating a problem except for the doubt that you have. The fact the car is used on track days, if I was the vendor I would not extend the gaurentee period as there are to many variables. I`m not sticking up for anyone but just looking from the outside.

                        Let me know if you want to do a comparrison compression leak down test. Just give me a call.


                        E30 M3 for the Road
                        & one for the Track &
                        a S14 2002 for fun


                        • #13
                          hi Dave,Uwe

                          Yes,engine was at normal operating temp and readings were taken WOT.
                          I agree the engine is going well and seems to have stopped smoking after the remap? why?where was the oil going? I think the blue smoke was a clue.
                          So if the oil was being washed from the bores and out the exhaust,what was lubricating the rings etc.for those 4000 miles when I kept imforming them that it smoked badly,only to be told not to worry?

                          Anyway we are getting ahead of the game.
                          The question was is a 40lbs difference between a wet and dry reading exceptable on such a fresh engine??

                          Cheers guy`s Jon

                          ps dave I might take you up on that offer,a leak down should tell all


                          • #14

                            I would repeat the test a few times to confirm the accruacy of my readings, And maybe start with a different bore each time. It may be worth jumpering another battery, to ensure all are getting the same cranking pressure.

                            Your low ones could also be down to how well your Valves are sealing. ?????????? Another can of worms opened.

                            Give me a call if you want to do a comparrision test.


                            E30 M3 for the Road
                            & one for the Track &
                            a S14 2002 for fun


                            • #15
                              Yeah, what happened to the head? New valve seats cut?

                              Goodbye M3, you served me well.