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Fast intakes causing # 7 cylinder failure ??

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Old Sep 23, 2009 | 08:50 PM
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Default Fast intakes causing # 7 cylinder failure ??

I have heard from more than just 1 or 2 that when they switche dto a fast intake (90/92) that they had the #7 cylinder fail...How true is this, i know of one having a H/C for a while then put the intake on and # 7 failed with only 30,000 miles on the car......Seems that we really dont have too many other choices other than the vic jr. and im not cutting up my hood or cowl for it to fit.....Is there any truth to this or is it bullshit ??
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Old Sep 23, 2009 | 08:55 PM
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my motor blew number 7 bone stock no mods besides exhuast at 37k with the ls1 intake
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Old Sep 23, 2009 | 09:00 PM
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#7 and #8 run lean from the factory.. Your jsut adding more air.. maybe you need more fuel.... Try upgrading your injectors
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Old Sep 23, 2009 | 09:28 PM
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It is a cooling issue - everything you hear about air flow and fuel is false. You can switch the intake around and would assume #2 would fail if it was airflow - but 7 still fails.
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Old Sep 23, 2009 | 09:33 PM
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the fast intake will not make it fail. the only thing i see it making it fail is not tunning properly for the extra air. its not even related, its like saying u got a flat tire because u ran out of gas.
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Old Sep 23, 2009 | 10:52 PM
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Originally Posted by 98Aggie
It is a cooling issue - everything you hear about air flow and fuel is false. You can switch the intake around and would assume #2 would fail if it was airflow - but 7 still fails.
Care to expand? I've never heard this, but it does interest. me.
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Old Sep 24, 2009 | 12:02 AM
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^^u have to go to the different cooling tubes switching it the ls1 cooling tubes work better but its still not good enough
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Old Sep 24, 2009 | 12:07 AM
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Right, several are going back to the LS1 vent tubes - this helps the back of the block circulate water. A couple of vendors have tested this and verified also.
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Old Sep 24, 2009 | 09:07 PM
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Well, ill just make sure to get my car retuned when i do the heads and fast intake......I am considering getting Nick Williams to do it, always heard that his tuning while the car is being driven is the way to go and can be more accurate
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Old Sep 24, 2009 | 10:05 PM
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So its bad to block off the cooling tubes?
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Old Sep 24, 2009 | 10:16 PM
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Originally Posted by 383lt1impala
So its bad to block off the cooling tubes?
not bad, just not the best thing for cooling. thats why when i did my ls6 i left my stock lines and trimmed the bottom of the intake. i heard about the cylinder #7 failure due to poor cooling.
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Old Sep 24, 2009 | 10:39 PM
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Originally Posted by twitchtwice
not bad, just not the best thing for cooling. thats why when i did my ls6 i left my stock lines and trimmed the bottom of the intake. i heard about the cylinder #7 failure due to poor cooling.
What exactly did you trim on the intake to get it to fit?
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Old Sep 25, 2009 | 10:41 AM
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Originally Posted by Greenbird97
What exactly did you trim on the intake to get it to fit?
I`m pretty sure there are ribs on the bottom of it that need trimming.
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Old Sep 25, 2009 | 11:58 AM
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Originally Posted by Spd-Kilz
I`m pretty sure there are ribs on the bottom of it that need trimming.
Yep I removed my fins with a chisel and hammer in about 10 min....
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Old Sep 25, 2009 | 02:05 PM
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hmmm hopefully it doesnt cause a problem. i aint gonna dd my impala. only on the track.
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Old Sep 25, 2009 | 02:50 PM
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Rail-end injector positions do take "hind tit" for fuel
even when proper, and they also tend to accumulate
the most silt and lose delivery first. Challenge that
with a lot more air, and there you go.

I rigged my rails to Y-feed from the rear, so maybe my
#1/#2 are the doomed ones now.
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Old Sep 25, 2009 | 03:46 PM
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Originally Posted by twitchtwice
not bad, just not the best thing for cooling. thats why when i did my ls6 i left my stock lines and trimmed the bottom of the intake. i heard about the cylinder #7 failure due to poor cooling.
You guys arent talking about the egr air block off plates that you use on the air tubes coming off the headers are u? Im not sure what tubes your talking about....
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Old Sep 25, 2009 | 03:54 PM
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Originally Posted by 1nastyss
You guys arent talking about the egr air block off plates that you use on the air tubes coming off the headers are u? Im not sure what tubes your talking about....

There are coolant tubes on a ls1 run underneath the intake, from the back of the cylinder heads to the front. When switching to an LS6 intake alot of people block off the back holes with plugs
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Old Sep 25, 2009 | 05:19 PM
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Originally Posted by 1sick'98WS6
There are coolant tubes on a ls1 run underneath the intake, from the back of the cylinder heads to the front. When switching to an LS6 intake alot of people block off the back holes with plugs
Yep. Using the LS6 coolant bypass makes the rear cyls run hotter. (7 & 8) Someone in a post a year ago did a lot of testing on this & found installing a heater hose to each corner of the heads equalized the cyl temps.

Add to this the fueling issue that jimmy talks about above ^ and you end up with hotter, leaner cylinders. Viola, you get detonation & the pistons break.

Running a Vic Jr is supposed to help. But I would think bigger fuel rails & dual walbros would be a better option. I have all of that & my corner plugs are darker than the 4 in the middle. But then I have an ATI F1 & made sure I had a rich mixture....

I've never tried it, but I understand there is a way to tweak each inj with HPTuners. Jimmy probably knows that answer.
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Old Sep 25, 2009 | 05:21 PM
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PS I still use the LS1 coolant tube because of this issue.
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