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I have an 86 daytona turbo. The compression is 120 across all cylinders at idle. What is normal for this car. When it is revved up it goes to 150
 

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now i dont know about you guys, but when i take compression measures i normally take all the plugs out, therefore i can't really REV the engine :confused:

sorry to kinda hijack your thread, i have 140-120-120-140 with 100kmls with just cranking it and the plugs out.. comments are welcome :D
 

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to do a proper compression test:

pull all 4 plugs
unplug distributor pickup plug(s) - this shuts off the fuel injectors
bungee or otherwise hold throttle WIDE OPEN
put a battery charger or jumper cables on to prevent battery from draining down during test (which would make readings at end of test lower than tose at beginning)
for each cylinder, let engine turn over for 3-5 seconds or until gauge stops increasing
repeat each cylnder 1 or 2 times to make sure you're getting a good number
add 2 tablespoons oil to each cylinder and repeat ; if (previously) low psi numbers jump up that suggests worn rings in that cylinder

of course even better is to use an actual "leakdown tester" but most of us dont have this tool ; however your friendly neighborhood mechanic prolly does
 

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There should not be more than a 10% difference between your highest and lowest cylinder readings. If one is excessively low- look for ring or piston damage, or a valve train problem. If two adjacent cylinders are excessively low- look for blown head gasket. All cylinders being low- a tired engine that's ready for a rebuild.
 

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^+1 - its more important that they are all close to each other

(janus - sounds like you may have a problem ; repeat the test as described above, including adding oil, and see what happens...)

most "approx sea level" turbo motors (low compression) will be around 130 psi ; I think mine was like 125, 130, 130, 135 w/o oil
 

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now i know that it's not the HG or the pistons because i just swapped that thang lol :bash: might be the rings then? oh well, i think i'm gonna measure again once the alternator is reconnected so the batt doesnt get too low, it's crap xD
this time i will use some oil on another try to see if it makes any difference.. if the oil helps increase comp, this would indicate bad rings, right? do you just add some engine oil like 10w40 or so?
and also, what's that leakdown test if you would be so kind and explain to us :)

sorry glhx for jacking your thread there, but might be some help for you too anyway ;)
 
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