Twins with Twins, Anyone?

[Chevy1925]

Yeah i basically tried to follow the stock layout. But to date still can't tell ya which direction factory fluid flowed..

Does it flow from bypass tube thru turbo to that upper rad hose with thermostat, or does it flow out of that inline thermostat and get sucked back to waterpump??

We used a freeze plug for a Saab I believe. Would have just welded off that bypass port but bridge was already powder coated..

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when the bypass is open on the factory setup, water just circulates the block. Nothing makes it through the turbo. basically, the pump is drawing water through the bypass to then feed back to the oil cooler. Now im not real sure when the turbo thermostat opens but when it does, the water pump can draw or push water through the turbo depending on normal thermostat operation as the turbo is fed off a little nipple from the bypass tube.

now that i think about it, running my heater hoses like i did really didnt do much for bypassing and if i put a freeze plug in the bypass, its going to cause issues as the water wont have anywhere to go in the block. hmmmm guess ill be changing that!

EDIT: yup, im gunna need to swap heat hoses so that one end attaches to the upper rad hose and the other feeds off the factory port to the side of the thermostats. then block off the lower rad hose line that use to go to the heater core. that should keep water flowing through the rad even when the bypass is blocked. my reasonings are different than yours though. im trying to keep some water flowing through the radiator when thermostats are closed to keep the trans heat exchanger cooler for the long grade braking i do. apparently 315+psi line pressure and grade braking at 4k rpm likes to get things hot lol

 

[2004LB7]

I'm not sure but 130 something degrees comes to mind for the turbo thermostat. Maybe 132*

 

[NC-smokinlmm]

The resivoir on 2000hp cats isn't really that big, the raw water pumps are more important, volume of flow will need to be determined to keep them in optimal range. Are you going electric or parisitic off engines?

 

[kidturbo]

Angle of this thermostat port tends to lean towards flowing from rad side to engine doesn't it? No temp rating on outside.

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[Chevy1925]

Angle of this thermostat port tends to lean towards flowing from rad side to engine doesn't it? No temp rating on outside.

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The more i think on it, the more i think so. It will flow from the upper rad hose, to turbo, back to bypass tube at all times regardless of thermostat position.

 

[kidturbo]

The resivoir on 2000hp cats isn't really that big, the raw water pumps are more important, volume of flow will need to be determined to keep them in optimal range. Are you going electric or parisitic off engines?

The sewater pumps are thru hull fed 20AN 1-1/2 inlets. Then splits into a 1.5 and a 1.25 outlet. The 1.5 feeds charge cooler and then main heat exchanger. So that supply should be about 95gpm at 3800R.

The 1.25 feeds 40gpm into oil, transmission, and drive coolers then exit to exhaust manifolds.

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[kidturbo]

This one shouldn't slow things down much. But I will check in/out temps on water side at wide open to calculate efficiency of the main cooler and electric engine circ pump configuration.

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[NC-smokinlmm]

How are you drawing in raw water?

 

[kidturbo]

Pickup in transom, with adjustable height. Then a pressure relief valve in the sea strainer. So inlet hose to pump is pressurized at speed.

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[THEFERMANATOR]

The factory coolant path to the turbo works pretty screwy. The turbo only gets cooling after the bypass has fully closed at 212 degrees, and the turbo stat is designed to hold the turbo coolant around 225 degrees iirc. If you look at the system, it actually pulls coolant from the upper radiator hose back through the turbo t-stat, turbo, and then back to the bypass tube. Once the t-stat bypass closes, the water pump creates a vacuum on the bypass to do this. When the stats are closed you get a tiny amount of coolant flow through the turbo and back out the upper radiator hose, but it isn't but an air bleed flowing it.

 

[kidturbo]

Thanks for that breakdown. I knew the design sucked, but now we know it's literal..

If I recall, they didn't add that thermostat to the top hose till LBZ? So just guessing, but maybe GM is trying to bring turbo temps up to stop the VNT blades from sticking. Obviously some reason they wanted it running hotter, and ya don't hear much about gummed up turbos after the LLY.

I'll try and shoot some temps off those cooling lines once both thermostats are opened, and see if it's still flowing good. Since I stacked my adapter plate under the factory thermostat housing, I have room to hog out the flow area a bit. My only concern is once the back thermostat opens, it might stop the flow through the turbo lines. I can always dump it directly into the reservoir tank, once I iron out the size and placement.

 

[THEFERMANATOR]

They all got it at least through the lmm. But it's a really screwy design how it flows one way when the stats are not fully open and the bypass is flowing, then reverses flow once the bypass closes.

 

[kidturbo]

Time to play name that sensor.

I first attempted to tap an oil Galley plug but didn't work out.

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[2004LB7]

Looks like a liquid (coolant) temperature sensor to me

Using it to monitor oil temps?

 

[kidturbo]

Hint..

It's oem Dmax, has an oring seal, but scaling is not same as ect sensor. So to match ecm tables I chose the factory unit. I've yet to find another sensor with same resistance values and tapered thread. Had to do a little recess in the oil filter housing.

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[2004LB7]

Ahh, the fuel temp sensor

 

[kidturbo]

Ahh, the fuel temp sensor

WINNER!!

You can defuel based on fuel temp, and with 300gal tank, I doubt it's ever gonna be an issue. And I have liquid/liquid fuel coolers on return side. So now I can tune to defuel if Oil Temp reaches xxx.

Plus fuel temp is in canbus data, so now it gets handed off to the dash gauges.

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[2004LB7]

I really like that idea. While high fuel temps can be a minor annoyance, oil brakedown can be catastrophic

 

[kidturbo]

I've done that mod for couple other customers in the past. Always wondered why they never included one from factory.

Watched my machinist buddy do a trick last night I'm still trying to grasp.. Needed a wedge to set this turbo straight, and we did one for the other engine on his milling machine. But this time he cut one perfectly using a lathe..

Clamped it up at an angle and started spinning, while I stood there in amazement saying no way that's gonna be right.

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[2004LB7]

I can imagine. When you put something in a lathe offset like that and you see it "wobbling" it doesn't look like it is going to work but sure enough it can