Well the #7 went bye bye...

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May 7, 2007 | 03:58 PM

#11

andrewb70

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Quote:

Originally Posted by Bill Reid

I have seen this too many times as well... in vette's... and apparantly trucks are not immune either. Results definitely show the #7 is being hammered to destruction due to detonation. However, we are talking about 2 completely different intake manifolds. Unless someone can post hard data (such as flow characteristics of each intake / port) I still think some other sinister thing is happening... or perhaps the combination of 2 completely different perhaps poorly designed intake manifolds coupled with coolant flow issues. One thing is for certain... the coolant flow between a truck engine and a vette engine is the same... including the fact that the back 2 coolant vent ports are blocked off. Earlier vette's (97-00) had a common "manifold" that tied all 4 vent ports together. I don't recall earlier year (99-03 timeframe) trucks ever having this from the factory. As for vette's I speculate GM cut off the back 2 ports when the (LS1/LS6) redesigned intake manifold, with its lower floor, hit the streets in 01. How this effects coolant flow around #7 i don't know... but I think coolant flow or lack thereof is a possible culprit or contributor...

... just speculating here...

(edit) Hmm... just thought of something... I have one of those older vette style 4 vent port "manifolds"... may have to see if it fits under the truck intake manifold

Bill

Bill,

Your coolant crossover tube theory is right on the money. I too suspect that this is the real cause of #7 and #8 cylinders going into detonation. Hot spots form around the combustion chamber as a result of air pockets. This causes detonation to occur. Adding a crossover tube in the rear will help as will running NPG from Evans cooling.

Andrew

May 7, 2007 | 04:03 PM

#12

logan214

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From: New Freedom, PA

Damn man sorry to hear that, I was really pullin for you to have something simple wrong. Good luck with the rebuild. As Brain had said before " cough, cough, piston."

May 7, 2007 | 04:42 PM

#13

Slowhawk

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#7 and #8 go first because the most boost pressure hit's them by design with FI. As a tuner you have to tune off of #7 + #8 to make it live.

Last edited by XLR8NSS; May 7, 2007 at 06:35 PM.

May 7, 2007 | 04:43 PM

#14

Allgonoshow

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this thread is not finished but read what boostfan from wheeltowheel has to say

https://www.performancetrucks.net/fo...d.php?t=385867

May 7, 2007 | 05:32 PM

#15

Bill Reid

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Quote:

Originally Posted by Allgonoshow

this thread is not finished but read what boostfan from wheeltowheel has to say

https://www.performancetrucks.net/fo...d.php?t=385867

ok... so coolant flow around #7 cylinder is/may not be optimal. This makes since... as if it was head design related would we not see a proportionate amount of complaints/failures on cylinder#2?

I agree this thread is not finished... but for the sake of argument... lets assume #7 cylinder coolant flow is a problem. couple questions on that assumption...

1. Is this GENIII block design related only? Are we seeing any similar problems on the GENIV platform? LS2/LS7, etc...

2. Would something simple as a lower temp t-stat be an effective solution?

3. Would something like Evans coolant be an effective solution.

4. Would tying all 4 coolant vents together help? Another informed opinion says lack of coolant flow through the rear vents is not the problem as apparantly its been determined... I assume due to a proportionate number of early LS1 failures that actually had all 4 vents tied together at the factory...

Again, I don't want to steer this thread off course with an assumption... just want to discuss options as well as try to get additional real world feedback from folks that have had this expensive failure... as well as tuners like Slowhawk that see/deal with this problem regularly...

FWIW, I started a thread over on Corvette Forum C5 Forced Induction inquiring about some feedback there too...

Bill

May 7, 2007 | 05:34 PM

#16

1slow01Z71

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From: Austin, TX

Call West Coast Cylinder Head they can get you set up with a nice motor or just the parts whatever you want. Best customer service in the business.

May 7, 2007 | 05:46 PM

#17

GMChasLS1

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Quote:

Originally Posted by andrewb70

So what would it take to do this? I think I could drill and tap the fittings to add some cooling hose. Where would be the proper place to attach this to the cooling system? How much flow is needed or is it simply steam that needs to be evacuated from the heads?

May 7, 2007 | 05:47 PM

#18

Slowhawk

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It's not coolant flow.We've tested it years ago. It's a tuning/timing/fuel problem mixed with a bad intake.

Last edited by XLR8NSS; May 7, 2007 at 06:34 PM.

May 7, 2007 | 06:17 PM

#19

Bill Reid

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From: Chandler, AZ

Quote:

Originally Posted by Slowhawk

It's not coolant flow.We've tested it years ago. It's a tuning/timing/fuel problem mixed with a bad intake.

So, if you know the intake manifold is an issue would you agree then that GM got it wrong on every GENIII intake manifold up to at least the LS2 and LS7 motors? Or would you include the GENIV motors too? I am just trying to understand how #7 can die... on 2 completely different intake manifolds - truck and low profile LSx intakes... including any iterations like the older LS1 and newer LS1/LS6.

Bill