Chevy 1.5L Turbo Engine Question
My son has a 2016 Malibu that has a misfire. He ran a compression check and one cylinder is about 110 psi. The other 3 measure about 220 psi. How can a 10:1 engine have 220 psi at cranking speed? Maybe his gauge is faulty. OK guys, start telling me that he should have bought a Ford!
Thanks anyway,
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OK
he should have bought a Ford!
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Theoretically possible. As temperature increases, so does pressure, which increases temperature, which increases pressure.
So, if the volume is 1/10 and the temperature increase is 1.5 (absolute), you could get to 220 psi.
Somewhere in that empty space that was my brain I remember PV=nRT, which describes the relationship.
Folks with a better memory than mine may be able to flush out the details.
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Don McManus: 30444734789659/comments/30444726070427
Theoretically possible. As temperature increases, so does pressure, which increases temperature, which increases pressure.
So, if the volume is 1/10 and the temperature increase is 1.5 (absolute), you could get to 220 psi.
Somewhere in that empty space that was my brain I remember PV=nRT, which describes the relationship.
Folks with a better memory than mine may be able to flush out the details.
The calculation and thought process is correct Don. You could see a temp rise of 1.5 if he is doing a test on a hot engine and it's a cool day, maybe even more. But for a 10:1 engine you should be at about 150 psi. I would do the test with a cool engine and if you're still getting these high numbers I would look at trying a different gauge.
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The 110 cylinder has a bad piston noteable for those engines. Most problems occur from the engine not warming up and the gas getting mixed by blow by into the crankcase oil.
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Weed eater?
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Let's see, a 1.5L car engine?? Must be wound pretty tight just to move a car. Highly fueled, turbo'd engine has low compression in ONE cylinder?? Piston has a hole burned in it. Possibly due to clogged injector not producing a good spray pattern.
Unless the rings are bad, doesn't really make any diff how fast the piston is moving while making compression.
BTW, my UTV has a 1.0L engine and the whole rig weighs only 800#. Why would anyone think it's a good idea to put a lawnmower engine in a car?
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There are alot of successful cars out there with a 1.5 liter motor.
The old Nash Metropolitan, older VW Beetle. More modern; Mazda Miata, Chevy Malibu and Honda Civics, to name a few
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It's not really a 'car' if you have to snug up the laces after getting in.
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Well the head and pan is off. Pistons are out and #1 has a 1/4" hole through it at the middle of the group of ring glands. That may be the reason for low compression. I'm surprised it had any at all! I was surprised that the pistons were $100.00 ea but when I got them they came assembled with rings and rods. Now I'm thinking that the compression numbers were the result of a bad gauge. Take about 100 psi of the original numbers and I can believe it.
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