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Forum namePerformance/Engine
Topic subjectCyl. psi low, but even...
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i5&topic_id=109542
109542, Cyl. psi low, but even...
Posted by justins71, Jul-31-08 01:50 PM
So I'm pretty sure I know the answer to this, but don't want to admit it to myself so I want someone else to say it.
My car's been running hot lately, but mainly only with a/c on in the day time (granted in ~105* temps), but it'd rise a bit above the norm halfway position on occasion. So just to be on the safe side I did a compression test, pulled all plugs, open the TB, d/c fuel pump, and got 140, 140, 145, 142. All nice and close, but low to me. Put a tablespoon or so of oil in #1, and got 210. I'm runnin stock head/valves, stock bore, 8.8:1 with Total seal rings (total seal my ass). I clocked the rings correctly, but yeah.
109547, RE: Cyl. psi low, but even...
Posted by 740 turbo brick, Jul-31-08 07:55 PM
Sounds like normal engine wear for a high milage engine. Thing is, I dont know how many miles are on your engine, and with your mods Im assuming it was rebuilt recently.
109549, RE: Cyl. psi low, but even...
Posted by Star Turbo Talon, Aug-01-08 01:31 AM
Engien hot or cold when you did the test?
109552, RE: Cyl. psi low, but even...
Posted by justins71, Aug-01-08 07:56 AM
engine warmed up, then about 15-20 min cool off before pulling plugs. It does have maybe 30k on it. I remember doin the test shortly after I built it (maybe after 3k or so) and it was only around 150. I just thought the low numbers were my rings still seating, but after 3k they should be well set. This was my first low comp build; I'm used to ~210 psi norm, with 180 being on the lowest side. Thing is if I run it hard day-to-day, it'll go through a quart of oil a week or so. Babying it, I can go 4 months or so before i'd need to add anything. I've rebuild the turbo once already just as pm, and it wasn't leaking before or currently, so the oil's not going through there.
109553, RE: Cyl. psi low, but even...
Posted by RoninEclipse2G, Aug-01-08 08:01 AM
I would pull compression without a cooldown time. double glove it to prevent burns and get crackin right after warming up.
109555, RE: Cyl. psi low, but even...
Posted by Star Turbo Talon, Aug-01-08 08:29 AM
I get 150 across cold. I am sure its not that much better warmed up. Block has 10k at the most.
109559, RE: Cyl. psi low, but even...
Posted by RoninEclipse2G, Aug-01-08 10:10 AM
just noticed, you are running low compression pistons, that sounds about right