Project Polar Bear: 2005 Suburban 2500

[nsogiba]

A while back I installed the LTZ roof rack with multiple Z71 bars. In the back of the truck I carry a piece of plywood so I can throw it up there and have a good observation deck if I'm at the racetrack or planespotting.

Took our first ever camping trip about 2 hours away. Everything worked out great, the truck definitely had to work ******* some of the long grades near the NY/PA line.

Trans stayed nice and cool around 160*F with the TruCool40K. This was a temporary installation...

...Because I'm installing a dedicated external oil cooler. The idea is to increase oil cooling capacity by doing the following:

-Bypassing the oil to water heat exchanger inside the radiator end tank, which will remove some thermal load from the radiator since it only has to cool water rather than water and hot oil
-Making use of the vast surface area available in front of the condenser by installing the biggest air to oil heat exchanger that will fit
-Using an Improved Racing thermostat/distribution block. This will remain shut until the oil reaches 180F, allowing the oil to heat up normally. Once 180F is reached, it begins to open and send oil to the gigantic 30 Row cooler through -10AN lines.

I really need to blow out/hose down the radiator and condenser fins since there is some debris in there. Worst case temps after climbing a long grade were 235F coolant and 240F oil temp, so that's the baseline to improve on. The 40K trans cooler will get relocated slightly lower behind the bumper cutouts.

 

[OBSandaNNBS]

Nice build thread. Nice truck too!

 

[Geotrash]

A while back I installed the LTZ roof rack with multiple Z71 bars. In the back of the truck I carry a piece of plywood so I can throw it up there and have a good observation deck if I'm at the racetrack or planespotting.

View attachment 462042

Took our first ever camping trip about 2 hours away. Everything worked out great, the truck definitely had to work ******* some of the long grades near the NY/PA line.

View attachment 462043

Trans stayed nice and cool around 160*F with the TruCool40K. This was a temporary installation...

View attachment 462044

View attachment 462045


...Because I'm installing a dedicated external oil cooler. The idea is to increase oil cooling capacity by doing the following:

-Bypassing the oil to water heat exchanger inside the radiator end tank, which will remove some thermal load from the radiator since it only has to cool water rather than water and hot oil
-Making use of the vast surface area available in front of the condenser by installing the biggest air to oil heat exchanger that will fit
-Using an Improved Racing thermostat/distribution block. This will remain shut until the oil reaches 180F, allowing the oil to heat up normally. Once 180F is reached, it begins to open and send oil to the gigantic 30 Row cooler through -10AN lines.

View attachment 462046

I really need to blow out/hose down the radiator and condenser fins since there is some debris in there. Worst case temps after climbing a long grade were 235F coolant and 240F oil temp, so that's the baseline to improve on. The 40K trans cooler will get relocated slightly lower behind the bumper cutouts.

I have run this experiment in the past. When you remove the oil-to-water cooler from the circuit, the oil temperature will rise higher than the external air-to-oil cooler can compensate for. I would leave the end tank plumbed into the circuit.

 

[Dantheman1540]

Super cool build! As far as turbo selection goes I see most guys wanting to tow with their turbo LS go with a T6. Trick specifically specs that for anyone wanting to tow with one of his kits to keep gets down.

Anyway super cool truck and you just reminded me I need a bigger trans cooler for my k2500 80E

 

[nsogiba]

I have run this experiment in the past. When you remove the oil-to-water cooler from the circuit, the oil temperature will rise higher than the external air-to-water cooler can compensate for. I would leave the end tank plumbed into the circuit.

Did you mean external oil to air cooler? The air to water cooler would be the radiator itself.

How big was your external cooler, and what were the conditions of your experiment? I ran one that was half this size, with no supplemental oil-to-water cooling, in a C5 Corvette on a road course in 90F and it kept temps in the 240F range. That was with 20 minute sessions.

 

[nsogiba]

Super cool build! As far as turbo selection goes I see most guys wanting to tow with their turbo LS go with a T6. Trick specifically specs that for anyone wanting to tow with one of his kits to keep gets down.

Anyway super cool truck and you just reminded me I need a bigger trans cooler for my k2500 80E

I can't imagine a giant T6 frame turbo being a good selection for a tow rig that needs response under 4K. Most of the time when towing I don't even rev it over 4500rpm. I've been eyeballing the 7675 or similar T4 frame.

Thanks for the compliment!

 

[Dantheman1540]

I can't imagine a giant T6 frame turbo being a good selection for a tow rig that needs response under 4K. Most of the time when towing I don't even rev it over 4500rpm. I've been eyeballing the 7675 or similar T4 frame.

Thanks for the compliment!

I’ve always thought the same thing as far as response goes. I’m super interested to see how it goes. I’ve considered a turbo on my Tahoe for a long time. That 76/75 has a good track record.

 

[Geotrash]

Did you mean external oil to air cooler? The air to water cooler would be the radiator itself.

How big was your external cooler, and what were the conditions of your experiment? I ran one that was half this size, with no supplemental oil-to-water cooling, in a C5 Corvette on a road course in 90F and it kept temps in the 240F range. That was with 20 minute sessions.

Oh it was big.

Yes, oil-to-air, sorry. Fixed.

It was actually transmission fluid, which of course has greater cooling needs than engine oil - especially in my intended use, which was towing. But it still proves the theory, though perhaps the difference in thermal dissipation needs for engine oil renders the point moot.

Anyway, the cooler was/is a Derale 13960 mounted below the lower grille on my 2012 XL Denali, through which I had drilled holes for the cooler to get good airflow. The experiment was towing our 7500 lb camper over the Blue Ridge on route 33 between Stanardsville and Elkton, VA. It's a long, steep pull and I was having trouble keeping my transmission temps below 240ºF on hot summer days by the time I got to the top. So I installed the Derale, which has its own fan and a much greater cooling capacity than the factory external cooler, and took the oil-to-water cooler in the radiator end tank out of the loop in hopes of improving engine cooling too. Boom - right up to 265ºF on the same grade. Plumbed the end tank back into the circuit, and it holds 230ºF on a hot day now, with no noticeable impact on engine cooling.

 

[nsogiba]

240F-265F?! Holy moly, that's wild. The trans in my truck has never seen above 175F using the radiator end tank cooler in series with the Trucool 40K, but then again my towing profile on gradients is much easier than yours.

I'm not saying your experiment is invalid, but in the interest of comparing apples to apples I don't think we should make the same conclusion for the thermal demands of the engine oil.

There is no question that water, having over 4x as much specific heat capacity is a better cooling medium than air, but it's only effective if the water doing the cooling is at a lower temperature than the oil being cooled by it.

Regardless, my hope is that the engine oil stays between 180-200F, with the thermostat doing the regulating. I also left a fairly sizeable air gap behind the engine oil cooler to prevent hot air from stagnating behind the core - cool air can't get in if the hot air behind it can't get out. I wonder if that was part of the problem you had - the Derale has a big ole shroud on it with a fan, and unless the fan is running there will be very little airflow. Curious to see how your experiment would turn out if you replaced the tiny factory external trans cooler with a bigger 40K but maintained the same design - no shroud, some air gap, etc. Then try it again with/without end tank plumbed.

Good conversation!

 

[Geotrash]

240F-265F?! Holy moly, that's wild. The trans in my truck has never seen above 175F using the radiator end tank cooler in series with the Trucool 40K, but then again my towing profile on gradients is much easier than yours.

I'm not saying your experiment is invalid, but in the interest of comparing apples to apples I don't think we should make the same conclusion for the thermal demands of the engine oil.

There is no question that water, having over 4x as much specific heat capacity is a better cooling medium than air, but it's only effective if the water doing the cooling is at a lower temperature than the oil being cooled by it.

Regardless, my hope is that the engine oil stays between 180-200F, with the thermostat doing the regulating. I also left a fairly sizeable air gap behind the engine oil cooler to prevent hot air from stagnating behind the core - cool air can't get in if the hot air behind it can't get out. I wonder if that was part of the problem you had - the Derale has a big ole shroud on it with a fan, and unless the fan is running there will be very little airflow. Curious to see how your experiment would turn out if you replaced the tiny factory external trans cooler with a bigger 40K but maintained the same design - no shroud, some air gap, etc. Then try it again with/without end tank plumbed.

Good conversation!

Agreed. And it's worth noting that part of the role of the end tank engine oil cooler is to help warm the oil more quickly in cold climates, but if you don't live where it gets really cold, then it's probably not much benefit to you in that respect.

For what it's worth, I ran a Tru-Cool 40K on the same Denali and then started having trouble keeping coolant temps down when towing pretty much anywhere - but especially in the mountains in the summer. That's why I went to the Derale and located it below the bumper where it wouldn't block airflow through the radiator. Since I did that, I've had no more trouble with coolant or transmission fluid temps. I don't have an engine oil temp gauge installed.

 

[nsogiba]

Got back from a weekend camping trip, about 120 miles round trip on mostly flat ground with some hills here and there. The terrain didn't really push the drivetrain the way I would have liked, but the oil temp didn't get above 205F on the few hills we encountered.

I really would like a little more power, so up next is:

245/75/16 highway tires to change overall gear ratio. The current 265/75/16s look cool but are heavier and taller than the factory size, and even with the 4.10s I'd like more grunt.

Tune the PCM to enable power enrichment, optimize timing, and shift points

E-fan conversion to remove parasitic loss.

 

[nsogiba]

Deleted the radiator end tank oil cooler, added the external air to oil cooler, and installed e-fans on the 2500. Had the PCM tuned by PCMofNC for the fans as well as a general performance 93 tune to wake it up. Slapped on some stock size 245 tires to replace the 265 A/Ts in an attempt to give it some gearing edge and reduce tire weight. The combination of changes really woke the thing up!

More room to work on things in the engine bay is nice too.

We spent all summer running around the western half of NY pulling the 27' Jayco. First year camping, half a dozen trips and we had a blast. Can't wait for next year. Between the half dozen camping trips and 3 trips down to Watkins Glen, I put on about 1800 miles towing around 7K lbs this year.

Exploring the outskirts of the track at the Glen after HPDE lapping ended

Makes for a very comfortable and secure hotel room, too.

Oh and I am bringing home another car tomorrow. Shocker, has a V8. I think I might have a cigar this weekend to celebrate.

 

[nsogiba]

 

[Tonyrodz]

That went incredibly easy for you. Nice. Me and @89Suburban had a helluva hard time getting ours off. We both needed to use an air chisel. We are in the rust belt.
Also--does anyone know if the 2500 brakes--rotors and calipers--are bigger and or beefier then the 1500s? The regular gmt800s.

 

[89Suburban]

That went incredibly easy for you. Nice. Me and @89Suburban had a helluva hard time getting ours off. We both needed to use an air chisel. We are in the rust belt.
Also--does anyone know if the 2500 brakes--rotors and calipers--are bigger and or beefier then the 1500s? The regular gmt800s.

My sister got me this for my birthday last summer. I have not had a chance to try it out yet.

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www.amazon.com

 

[Tonyrodz]

My sister got me this for my birthday last summer. I have not had a chance to try it out yet.

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www.amazon.com

Gotta let us know how it works out when you eventually use it.

 

[nsogiba]

That went incredibly easy for you. Nice. Me and @89Suburban had a helluva hard time getting ours off. We both needed to use an air chisel. We are in the rust belt.
Also--does anyone know if the 2500 brakes--rotors and calipers--are bigger and or beefier then the 1500s? The regular gmt800s.

I have to admit, I cheated a bit - those wheel bearings were actually replaced last year. Branded as Timkens, but came in a Made in China box, so I have a feeling they were knockoffs as they didn't last a year. At least everything was antiseized well. Helps that it's a rust free truck too.

 

[strutaeng]

That went incredibly easy for you. Nice. Me and @89Suburban had a helluva hard time getting ours off. We both needed to use an air chisel. We are in the rust belt.
Also--does anyone know if the 2500 brakes--rotors and calipers--are bigger and or beefier then the 1500s? The regular gmt800s.

Yes, the 2500 brakes/rotors/calipers are much beefier than 1500 series. For comparison, as large as the 2019+ Silverado front brakes i swapped into my 99 Silverado GMT800 are, the calipers are even larger and heavier on my 06 Suburban 2500.

The 2500 Suburban brake setup are actually the same setup as the 2500HD trucks with gvwr 9200 lbs AFAIK. GMT800, at least.

@nsogiba I also installed those Timken bearings on my 06 Suburban a few months ago. Unfortunately, after a few weeks I got an ABS code (completely my fault). Turns out I left the ABS wire over the dustshield and it rubbed through. I replaced the speed sensor with a GM Genuine one, and a Carquest from my local AAP, but can't get rid of the code...so I just ordered another new Timken bearing. Should be here later this week.

Great progress on your rig BTW!

 

[nsogiba]

Thanks! I'm trying to document everything as well as I can mostly for my own records and to get some traction on my youtube channel. I just picked up another project that was sitting for years, 2001 BMW 740iL. Much longer video on that one coming out soon.

 

[Tonyrodz]

Thanks! I'm trying to document everything as well as I can mostly for my own records and to get some traction on my youtube channel. I just picked up another project that was sitting for years, 2001 BMW 740iL. Much longer video on that one coming out soon.

Good luck with the 7 series. I've heard they always wind up with a ton of issues. I've heard nothing but horror stories. Lots of motor and transmission issues.