Forced Induction Superchargers | Turbochargers | Intercoolers

#7 Always Broken

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Old Sep 15, 2010 | 11:37 AM
  #21  
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Wouldnt having EGTs on #7 and #8 help to make sure the combustion process is not getting too hot? If you base your tune off #7 and #8 there shouldnt be an issue with detonation, given the rest of the cylinder will be progressively more lean/rich but you will have a much smaller chance for detonation.

Does that makes sense?
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Old Sep 15, 2010 | 12:01 PM
  #22  
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Originally Posted by XtremeDime
Wouldnt having EGTs on #7 and #8 help to make sure the combustion process is not getting too hot? If you base your tune off #7 and #8 there shouldnt be an issue with detonation, given the rest of the cylinder will be progressively more lean/rich but you will have a much smaller chance for detonation.

Does that makes sense?
Food for thought here. If 7 gets the same AFR as all the others, EGT should be the same.

On the other hand, I dont think it can be detected with EGT since a hot spot in the cylinder head triggers early detonation. How does a hot spot alter EGT, I dont know, but my guess is it probably doesnt.

However if we didnt have taper seat plugs, we could have used a CHTG to look for a change.

Cheers
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Old Sep 15, 2010 | 12:02 PM
  #23  
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#7 and #8 will not be getting the same AFR as the other cylinders. It gets leaner the further you go back, lean = hot. Hot = detonation.
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Old Sep 15, 2010 | 12:04 PM
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Originally Posted by XtremeDime
#7 and #8 will not be getting the same AFR as the other cylinders. It gets leaner the further you go back, lean = hot. Hot = detonation.
How does 7 and 8 get leaner?


Cheers
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Old Sep 15, 2010 | 12:11 PM
  #25  
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Originally Posted by LS4_DeltaV
How does 7 and 8 get leaner?


Cheers
If any thing they would get richer. as some of the air gets consumed before the 7/9

but I dont think that is a issue because the flow of the throttle body should be greater than the runner flow at any given time
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Old Sep 15, 2010 | 12:19 PM
  #26  
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In early testing I put 4 wide bands in each header, flipped the intake around and could never find any tuning issue with #7 that varied from cyl to cyl. Coolant problems seemed the culprit as the LS6 transfer tube change is when the problems started coming around. The steam vent tubes need very little flow as they really just clear air that can be trapped in the head causing hot spots in the rear combustion chambers.
The LS series of engines has many coolant issues that can cause problems in higher hp engines or long duration run type engines. Everybody that is working with these engines has different approaches to fix these problems, all of which probably have merit. The basic flow path in the engine is not very good for sustained high power, or short burst extreme power engines.

Kurt
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Old Sep 15, 2010 | 12:24 PM
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Originally Posted by LS4_DeltaV
How does 7 and 8 get leaner?


Cheers
Lol, no idea. Sounded good in my head, but ya, they would be richer.
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Old Sep 15, 2010 | 12:26 PM
  #28  
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I woudnt think the crossover tube has any cooling affect....its just a vent.

And cleaning out my stock intake last night (off the engine) I blew it out with an air hose... through the throttle body the majority of the air went out the back ports. The back ports are going to run leaner because of air flow characteristics of the manifold. It wasnt designed to have air pushed into it.... it was designed to have air pulled into it. .....2 totally different flow concepts.
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Old Sep 15, 2010 | 12:57 PM
  #29  
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Originally Posted by 427
In early testing I put 4 wide bands in each header, flipped the intake around and could never find any tuning issue with #7 that varied from cyl to cyl. Coolant problems seemed the culprit as the LS6 transfer tube change is when the problems started coming around. The steam vent tubes need very little flow as they really just clear air that can be trapped in the head causing hot spots in the rear combustion chambers.
The LS series of engines has many coolant issues that can cause problems in higher hp engines or long duration run type engines. Everybody that is working with these engines has different approaches to fix these problems, all of which probably have merit. The basic flow path in the engine is not very good for sustained high power, or short burst extreme power engines.

Kurt

Did you detect any success in adding the additional coolant crossover?

Thanks for the input.

Cheers
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Old Sep 15, 2010 | 02:57 PM
  #30  
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Yes the rear bleeds are very helpful, they keep air pockets from insulating the head around the rear cylinder.

Kurt
Originally Posted by LS4_DeltaV
Did you detect any success in adding the additional coolant crossover?

Thanks for the input.

Cheers
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Old Sep 15, 2010 | 06:20 PM
  #31  
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http://www.kurturbanperformance.com/...or-system.html
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Old Sep 15, 2010 | 06:45 PM
  #32  
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Default Also address the cause

Great info and research so far on keeping the rear tubes.

Another approach also aimed at the cause in a boosted engine is to maximize cooling and lower intake charge temps.

I personally have a 74 camaro I am installing my LQ4, turbo 400, 3.73 gears, 75mm turbo, air to air intercooler and meth injection. For now using stock 317 heads. This will be a street/strip car with a lot of strip use (mostly 1/8th mile).

So for a car that also sees street time I would go air to air intercooler and meth injection. A strip only car I would go air to water intercooler as we know it is 14 times more efficient than an air to air intercooler. For strip only use I would even go air to water intercooler and meth injection.

Also use the biggest radiator that is practical for either use.

My strategy is to maximize cooling in all these areas at the same time to not only address the symptoms, but also more of the cause. I personally will be running the rear tubes, air to air intercooler, meth injection, and a huge radiator. This is instead of just running an air to air intercooler and calling it a day like a lot of guys do. My .02 cents.

Hpbob1
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Old Sep 15, 2010 | 07:14 PM
  #33  
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Originally Posted by Beaflag VonRathburg
Id rather just buy 4 block off plates, and tap them. It would be about 50$ total with lines. $200 is a bit steep.
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Old Sep 15, 2010 | 08:27 PM
  #34  
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where is the BEST place to tie the top port to your cooling system? thanks
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Old Sep 15, 2010 | 09:09 PM
  #35  
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Originally Posted by eviltwin_1987
where is the BEST place to tie the top port to your cooling system? thanks
you can tap into your water pump or you lower radiator hose housing. make sure it is the lower one which sucks.
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Old Sep 15, 2010 | 09:59 PM
  #36  
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Originally Posted by edge04
you can tap into your water pump or you lower radiator hose housing. make sure it is the lower one which sucks.
What's the difference. I have only seen people tap the flat spot over the upper hose outlet which seems like it would be the same as tapping the upper hose. I guess I am just asking, which one is BEST. I don't care what's easier or faster
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Old Sep 15, 2010 | 10:25 PM
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Originally Posted by eviltwin_1987
What's the difference. I have only seen people tap the flat spot over the upper hose outlet which seems like it would be the same as tapping the upper hose. I guess I am just asking, which one is BEST. I don't care what's easier or faster
are you referring to where the blue fitting is on the wp in this pic? if so yes that is a good spot but that is not in the upper hose. the spot where it is would be sucking so pulling the coolant from the vent tubes. With my electric wp I had to tap into the lower housing because there wasn't room above and plus I didn't have to tap the wp itself. I'm no expert so someone correct me if I am wrong.

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Old Sep 15, 2010 | 10:51 PM
  #38  
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Exclamation reverse flow?

what about converting the ls1 heads for reverse flow a la lt1? Would this eliminate the cooling problems seen in higher hp and boosted applications?

seems like it might work better than having your tubes tied
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Old Sep 16, 2010 | 04:55 AM
  #39  
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why not run 1 heat range cooler plugs in cyl 7 and 8?
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Old Sep 16, 2010 | 11:11 AM
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Originally Posted by CarolinaCamaro
what about converting the ls1 heads for reverse flow a la lt1? Would this eliminate the cooling problems seen in higher hp and boosted applications?
I thought LSx motors were reverse flow?

I thought the coolant entered the head, travelled down to the end of the head, them dropped down to the jackets and back out.

Can anyone confirm this?


Cheers
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