vacuum gauge test - Page 4 - Cherokee SRT8 Forum
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post #31 of 40 (permalink) Old 12-01-2012, 05:26 PM Thread Starter
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hahaha ill be the first to admit im ocd when it comes to how she runs.lol. i can imagine illk be putting myself thru changes when i get boosted.. ahhhhhh lol.

2010 silver Jeep SRT8 W/ opts 1 and 2 W/ performance audio and nav

72mm FOGLIGHT TWIN TURBO
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post #32 of 40 (permalink) Old 12-01-2012, 07:46 PM
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Right there with yah man. If I hear anything it drives me nuts lol. "what is that!?!?" hah.

PWR 393, Procharged D-1 @ 6 psi.
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post #33 of 40 (permalink) Old 12-01-2012, 07:56 PM Thread Starter
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Hahaha isn't it the worse?!! Lol


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post #34 of 40 (permalink) Old 12-02-2012, 05:44 AM
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Joe,

Inaccurate checks for bearing wear
A decrease in oil pressure
Engine noise

Fairly accurate check
Engine oil analysis (Blackstone is a very reputable with a quick response time)

http://www.blackstone-labs.com/

I believe we use the particle analysis at work it's about $25, contact them to
verify that's the test that will indicate bearing wear

Most accurate (most expensive)
remove connecting rod and main bearing caps inspect for visual wear and measure
the width of the bearing (a bearing may not have visual wear but can experience
hammering under detonation which makes the bearing wider)

I'd use the oil analysis, at work we use it on $$$$$$ engines.

Hope this helps,
Guy

Last edited by SRT8-DOUGLAS SR; 12-02-2012 at 05:45 AM. Reason: sppelin
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post #35 of 40 (permalink) Old 12-02-2012, 08:03 AM Thread Starter
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Thank u guy! It does help. I appreciate it


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post #36 of 40 (permalink) Old 12-02-2012, 10:39 AM
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If you haven't figured it out by now the vacuum your motor makes isn't rpm dependent, it is load on the motor. Other than idle rpm, which is usually as low as you cam guys can go, the gauge will fluctuate with throttle position and overall engine load.

When you floor it you'll see a drop in vacuum, but you'll realize that rpm climbs the whole time you're wot and that the vac gauge doesn't care if it is 3500 rpm or 5500.

Throw the blower on it and then you'll only be worried about the PSI half of the gauge!
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post #37 of 40 (permalink) Old 12-02-2012, 11:38 AM
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That's interesting Jack. I noticed on mine at idle if I rev it the vac will go to almost 20" from 14 but my cam is pretty mild. Thanks for the info. I didn't realize its from the throttle blade closing when you release the pedal. Starting to understand some of this stuff thanks to the fine folks of this forum

Last edited by Tim H Calgary; 12-02-2012 at 12:14 PM. Reason: Things
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post #38 of 40 (permalink) Old 12-02-2012, 01:22 PM Thread Starter
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Mine sits pretty much at 15 at idle with slight slight movement cause of lope and web I slap open it she dropped to 0 then shot to about 22 or 23 then back down to 15. That's fine correct??


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post #39 of 40 (permalink) Old 12-02-2012, 01:39 PM
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In park if you slowly increase the throttle your vacuum will increase as it should (from the research I've been doing). I think you and I are a bit a like Joe lol. I am always making sure she's running right. To me if you get higher vacuum in park and reving and not under load everything is sealing as it should. I would be far more concerned with low vacuum (not under load). When I get on her at WOT I see a hair over 8 psi on my boost gauge which leads me to believe I am not leaking anywhere. As you are aware not an expert and the stuff I quoted was from the internet lol.

I'd make another video but I have a partially torn belt at the moment.

Last edited by Tim H Calgary; 12-02-2012 at 01:41 PM.
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post #40 of 40 (permalink) Old 12-02-2012, 01:42 PM
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15" vacuum is normal, the flutter probably comes from cam overlap (the portion of the cam lobes that has the intake and exhaust valves open at the same time). I don't know how much overlap your cam has.

Guess I should have included this earlier....

Guy

Last edited by SRT8-DOUGLAS SR; 12-02-2012 at 01:44 PM.
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