LLY: my custom big twins build

LarryJewell

LarryJewell

Back with his honey :)
Jan 21, 2007
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where do you plumb the boost gauges to see what individual turbo is putting out, I have one boost gauge in the driver side boost tube near where it hooks to the turbo, the second gauge is in the inter cooler pipe near the Y bridge, both pretty much have the same readings :confused:
 
TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
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LarryJewell said:
where do you plumb the boost gauges to see what individual turbo is putting out, I have one boost gauge in the driver side boost tube near where it hooks to the turbo, the second gauge is in the inter cooler pipe near the Y bridge, both pretty much have the same readings :confused:
Click to expand...

You should have a gage in the charge pipe between the 2 turbo's larry , its the only way to know what boost the 2nd turbo is putting out and is nec for tunning the turbo's . in short you should have 1 gage reading total boost , then a gage reading the boost from the secound turb , you want to see the secound turbo put out 1/2 the amount of total boost , so if boost is 50 psi the the sceound turbo should bne putting out 25 psi
 
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LarryJewell

LarryJewell

Back with his honey :)
Jan 21, 2007
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TrentNell said:
You should have a gage in the charge pipe between the 2 turbo's larry , its the only way to know what boost the 2nd turbo is putting out and is nec for tunning the turbo's . in short you should have 1 gage reading total boost , then a gage reading the boost from the secound turb , you want to see the secound turbo put out 1/2 the amount of total boost , so if boost is 50 psi the the sceound turbo should bne putting out 25 psi
Click to expand...

Ok, looks like i'll be moving the gauge then :D
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
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2500HeavyDuty said:
ben, heres phil's 05 lly's stock ecm tune. his table goes up to 1024.
Click to expand...

ya thats nm... ;)

I want to know what simon was talking about, he said it can be set higher than 756 ft lbs. Or maybe hes been looking at newton meters the whole time too..........................
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
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ripmf666 said:
I only have one it mounted were the big turbo feeds the stocker is that the right place.
Click to expand...

yes that is correct


mine is mounted in the mouthpiece that feeds into the stock turbo. Is there anyway that airflow disruption from the blades of the stock turbo could be giving me bad readings???
 
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Subman

Subman

Old Geezer
Jun 27, 2008
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paint94979 said:
sorry Ben you are unhappy with your twins... my 4094 is really loud and the turbo whistle is ear piercing. It seems when you use the stock VVT/big primary they are REALLY! quiet i remember watching DPC when Rob was sledpulling with his LBZ sounded really quiet too me.
Click to expand...
What is your other turbo Paint?
 
sweetdiesel

sweetdiesel

That's better
Aug 6, 2006
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duratothemax said:
now how am I supposed to set it higher than 756 ft lbs. As far as the TCM, I understand it simon.
Click to expand...

duratothemax said:
D5196 is maxed out in my 2001 TCM OS.
Click to expand...
The whole table?Or WOT? Maxed to what 756 ft lbs?

duratothemax said:
ya thats nm... ;)

I want to know what simon was talking about, he said it can be set higher than 756 ft lbs. Or maybe hes been looking at newton meters the whole time too..........................
Click to expand...

View it as Nm or ft lbs its your choice.;)

Open the TCM tune that is in your truck right open table D5196
The name of that table is torque limit.


Now tell me what the EFI limit is on that table?
Mine says 1500 Nm and when I convert that to ft/lbs it = 1106 ft lbs:confused:

Now if you compare this with ECM tq tables it seems to me that they have this table set lower by approx 10% in the TCM table.....Things that make me go HMM.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
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just an update.

they are running very well. Spool up is VERY quick, thanks to that "stupid" VVT that simon was giving me shit about. The turbo exhaust braking using the VVT is very nice when towing as well. :cool:

I havent measured drive pressure, but EGT's never get above 1200* with a 2400us tune. (now simon before you snicker at 'baahaha you think 2400us is big', remember that I have big injectors)

Pressures between the two turbos are split basically 50/50. When im at 55psi, the big turbo is doing about 27psi, and on my stock tune (well stock, plus injectors) it will make 40psi overall, and the big turbo is going 20psi. If I drive it nicely on the highway at 68-70mph I can get 20mpg. But I never drive that slowly, so I usually get about 17.7-18 hand calculated.

The VVT also makes it very easy to control overall boost without having the need for an external wastegate.

My intercooler pipe broke at the weld a couple weeks ago so I need to redo that pipe. Now wait a second before someone comments on that. The weld/pipe that broke was the ONE weld that I didnt do. It was on the aluminum intercooler pipe; I dont have a tig so I had a local welding shop do it. But the pipe was a modified stock LLY pipe so it was tricky to get clean; I cant really blame the guy for it breaking. Im re-doing it with a regular mild steel intercooler pipe.

I also found out that 60psi is NOT the limit of what autometer Nexus gauges will read/register/record.....they will read up to the limit of the sensor (100psi I think?) and the gauge will register as such. I did a run with a pretty decent size tune and when I played back the run on the gauges and recalled my peaks I found I had hit 70psi. :eek:

I wont be doing that again...man I miss having a built motor...its ok though, the stock LBZ short block is stronger than my old built motor so Im not too worried.

This week I should have my new pipe done, its been too nice outside this weekend to be inside messing with the truck. Now off to do some water skiing! :joker:

ben
 

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Ridin'GMC

Ridin'GMC

I like red
May 20, 2010
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Awesome twin setup. I hope to build one of mine in the future.... Except I need to figure out if the turbos through my work is the right setup for the big charger (might use a turbo off the CAT 793D since they are designed to spool quickly but not sure if the vanes are the correct pitch to use as the big turbo). I love the VVT turbos and will continue to use the VVT with a twin setup.

Where did you get the flange to make the exhaust pipe from the stock turbo to the S480? I would like to know where to get the supplies for the flanges, I know where to get the piping though.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
Ridin'GMC said:
Awesome twin setup. I hope to build one of mine in the future.... Except I need to figure out if the turbos through my work is the right setup for the big charger (might use a turbo off the CAT 793D since they are designed to spool quickly but not sure if the vanes are the correct pitch to use as the big turbo). I love the VVT turbos and will continue to use the VVT with a twin setup.

Where did you get the flange to make the exhaust pipe from the stock turbo to the S480? I would like to know where to get the supplies for the flanges, I know where to get the piping though.
Click to expand...

Custom made it. Its just a regular T6 square flange that we flared/blended/welded a piece of round 3" 90* piping to.
 
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