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Compression Test - high lift cams with overlap & vitaras
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Author:  db [ Tue Nov 15, 2016 8:28 pm ]
Post subject:  Compression Test - high lift cams with overlap & vitaras

Has anyone performed a compression test with vitara pistons and high lift cams in the G13B? I've started seeing smoke from my catch can, when I plug the catch can outlet with my finger, I get a lot of smoke in the exhaust. There seems to be pressure getting up into the valve cover, most likely through a valve guide. I ran a compression test after warming up the motor and got 90psi on all 4. It still runs strong at 15 psi boost, so I was expecting higher compression numbers. I have 3tech cams which are a higher lift with some overlap and thought that might be what's causing the lower numbers. I haven't ran a "wet" compression test yet.

I'll be pulling the valve cover to take a look at things and most likely pulling the head sometime this winter.

Curious what you guys think about the low numbers.

Thanks, Dave

Author:  suprf1y [ Tue Nov 15, 2016 9:04 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

Blow by and low compression, sounds like rings to me

Author:  db [ Tue Nov 15, 2016 10:50 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

Would bad rings allow pressure up into the top side of the head though? This engine has maybe 3000 miles since the rebuild.

Author:  suprf1y [ Wed Nov 16, 2016 6:55 am ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

Likely cylinder pressure leaking past the rings to the crank case and up into the head via the drain ports. Very common in the G10

Author:  db [ Fri Nov 18, 2016 9:00 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

Good point, I agree. Looks like a teardown is in order this winter.

Author:  db [ Sun Feb 19, 2017 3:36 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

Well, I lucked out.. Didn't see anything obvious after the tear-down, but i was taking a a closer look at the #1 piston and saw a very thin crack in between the top two rings. Picked at it and the entire chunk came right out. No damage to the cylinder wall and i'm thankful the piece didn't let loose and wreak havok while it was still running. Guess it's time for a Wiseco upgrade.

Image Image Image

Author:  91 ragtop [ Mon Feb 20, 2017 10:50 am ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

What kind of fuel management are you running that you can run 15# of boost without detonation ?

Ken...........

Author:  suprf1y [ Mon Feb 20, 2017 2:30 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

98-01 G13 pistons are an excellent budget choice.

Author:  db [ Mon Feb 20, 2017 10:14 pm ]
Post subject:  Re: Compression Test - high lift cams with overlap & vitaras

These are OE replacement 75mm Vitaras, the initial build was done on a tight budget. I'm actually surprised they lasted this long. I'm currently using an Adaptronic E420C ECU. It's controlling fuel, timing and boost. I absolutely love it and highly recommend it.

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