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03-21-2016, 10:58 AM
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#1 |
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Registered User
Join Date: Jun 2015
Location: shreveport, la.
Posts: 160
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"Fast" intake flexing
Does anyone have any knowledge/experience with the "Fast" LSXRT Intake flexing at the throat when the throttle is opened? i.e. as engine rpm rises the throat of the intake at the throttle body will push outwards. really freaked me out the first time I saw this. it just doent look right. I called "Fast" but didn't get much help. Thanks Casey
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03-21-2016, 02:12 PM
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#2 |
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meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: "Fast" intake flexing
Like its physically deforming under load? Its a composite intake, but having enough flex to actually deform would throw me for a loop as well.
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING  |
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03-21-2016, 05:37 PM
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#3 |
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Registered User
Join Date: Jun 2015
Location: shreveport, la.
Posts: 160
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Re: "Fast" intake flexing
yes it is actually changing shape. I thought maybe I had a vacuum leak, I checked for that. has to be in the strength of the neck. as engine losses vacuum. however I would think it would pull in instead of pushing toward throttle body... Casey
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03-21-2016, 11:48 PM
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#4 |
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meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: "Fast" intake flexing
Hmmm, we've got the regular non-truck version of the same intake on another car, and I don't recall ever seeing anything similar....now I wanna do stare at it and see if it actually does
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING |
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03-22-2016, 01:21 AM
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#5 |
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Registered User
Join Date: Apr 2013
Location: Nor-Cal
Posts: 632
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Re: "Fast" intake flexing
Video please
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WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered. |
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03-22-2016, 09:47 AM
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#6 |
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Registered User
Join Date: Sep 2005
Location: sc
Posts: 1,203
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Re: "Fast" intake flexing
that should not be happening.
Is it a New intake or a used one? if new, I would be calling Comp/FAST to figure out if they may some idea of what's happening, ie bad batch!?
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71 Cheyenne C10 LWB cam'd 6.0/T56 Swap |
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03-22-2016, 11:28 AM
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#7 | |
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Registered User
Join Date: Jun 2015
Location: shreveport, la.
Posts: 160
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Re: "Fast" intake flexing
Quote:
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03-23-2016, 12:34 PM
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#8 |
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Registered User
Join Date: Jun 2015
Location: shreveport, la.
Posts: 160
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Re: "Fast" intake flexing
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03-23-2016, 05:57 PM
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#9 |
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meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: "Fast" intake flexing
Check that your upper and lower shell pieces are fully seated and bolted together. The upper shell has the TB, and can move on its gasket.
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING |
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03-24-2016, 07:54 AM
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#10 |
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Registered User
Join Date: Apr 2010
Location: Guntersville Alabama
Posts: 1,073
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Re: "Fast" intake flexing
Funny you are having this problem . When I was looking for a performance intake my tuner said stay away from the lsxrt truck intake . Said they flex to much and also is a tuners nightmare . That flex messes with the tune trying to nail down the little quirks . Apparently he has seen a few with the same problem . The intake is so large they just did not build enough support into it . Unless Fast did something to correct this problem it is just the nature of the beast .
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03-30-2016, 11:46 AM
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#11 | |
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Registered User
Join Date: Jun 2015
Location: shreveport, la.
Posts: 160
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Re: "Fast" intake flexing
Quote:
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03-30-2016, 12:32 PM
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#12 |
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Registered User
Join Date: Sep 2013
Location: fairbanks, ak
Posts: 339
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Re: "Fast" intake flexing
this is a fairly good read on ls intakes: http://www.hotrod.com/features/1507-...ifolds-tested/
granted the factory intakes don't quite look as good as the aftermarket.. |
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10-04-2020, 08:31 PM
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#13 |
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Registered User
 
Join Date: Feb 2004
Location: brownfield texas (west texas)
Posts: 1,936
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Re: "Fast" intake flexing
So this is the only thread i can find on this but yea im freeked out to. Just put one on my truck and it does exactly what is stated above. I put a huge filter on and it lessened it some but definitely dances. Any update after 4 years?
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