Hi all, longtime member, I used to have a fun little toy that I posted about here, 2002 RCSB 2WD 4.8 I called "Project Stepslide". Fun truck, but parted ways with it in 2019. Done a few other LS builds over the years too...LQ4 E39 BMW, L92 C5 Vette, LQ4 turbo Crown Vic, and my current LQ4 turbo Jaguar "XJ6.0".

I'm brainstorming on towing with a turbo LS. I have a 2016 BMW X5 with the turbo 6, probably makes a bit north of 300 whp with a tune. Most I have towed with it is my E92 M3 on a Uhaul trailer, probably close to 6500lbs all loaded up with tools and tires, but being physically smaller and with a short wheelbase, I am looking to get something a little more secure. Since we are planning on buying a travel trailer this year (6-7K lbs) the X5 doesn't seem fit for the job. Got my eye set on finding a rust free '01-'06 Suburban/Yukon XL 2500 from down south (stock 6.0 and 80E). I thought about getting a 1500 Burb since they are easier to find but only 5.3/60E, wimpier frame/brakes, etc...

My thought is 6.0 with stock cam for good response down low, upgrade valvesprings to handle boost
1.25A/R 7875, 2.25" hotside using truck manifolds, ebay cast log
Stock exhaust with 3" boost activated cutout (I love these things)
93 pump with some E85 splashed in for good measure, bigger pump and injectors naturally
3" A2A, 8-10 lbs boost
Freshened up 80E, add HD2 kit.
Converter - have had good luck with Circle D's 3200 - it has no issue spooling the 7875 in my Jag despite 2.88 gears. My understanding is that too high of a stall, while helping spool, will heat the trans quickly.

Regarding trans cooling - any reason one couldn't run a couple of stacked Trucool 40k coolers behind the grille as long as there's space? Combine that with the end tank cooler to keep it from overcooling?

How does the IFS on the GMT800 stand up to boost when towing a lot?

 

I have a 2001 Silverado 1500HD with 7875 .96AR turbo that I use for towing and commuting a good number of days. I would absolutely dump the stock cam if you are upgrading valve springs. I started with a 212/218 cam and now have the Texas Speed stage 1 208/214 cam with 1.8 roller rockers (which gives ~.582" of valve lift). It pulls hard down low with a ton of mid range power. I would absolutely NOT get the 7875 1.25AR and use stock exhaust. That turbo has the larger 3.5" outlet and your going to choke it down with stock exhaust? Since I have the .96AR with 3" outlet, I went 3" all the way out the back and two big Magnaflow mufflers. It's super quite. I wish I had gone the 1.25AR with bigger exhaust, but I'm very happy with my setup. I have Circle D's 265mm 2A triple disk convertor, I think they advertise that as a 2800-3000 rpm convertor. Plenty good, my truck spins the rear tires unloaded with 5.5 lbs of boost in first gear. As far as cooling, I have a trans cooler twice the size of stock (will have to look up the number/not near the size of a 40K cooler) and never have issues. Just lock the convertor in 3rd and 4th and you will be fine. Honestly on the long 6% grades in PA, the engine temp starts to climb if I stay in boost too long. Why would you have concerns about the IFS?

 

Planning a similar build on a 03 Suburban.
5.3 stock bottom, with TSP 208/214 .550" Low-Lift cam
going to decap the stock 25# injectors, 340LPH in tank.
Trying to decide between several Turbo choices:
VSR 70/70
Precision 6766 HP
AGP Z2 6868
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. Goal is reliable 4WD family wagon/ daily driver with stock 3.73 gears, 33 inch tire diameter, and will tune for maximum 90 octane around 12 pounds manifold pressure.
Key for my purposes is A- RELIABILITY, B- good low end response and driveability, C- economy, intend to run stock quiet exhaust, with a boost actuated cutout set to open around 4-5 PSI.
Seeking recommendations on turbo.

 

The only thing I can comment on is the Trucool 40K cooler.
I have two Suburbans with them and think that not only will two of them not fit without a lot of hacking, it would be a waste of money.

 

Plenty of people will disagree with me and have done it, but I would never put a turbo on one of these trucks for towing performance and expect reliability. I have had plenty of turbos and superchargers and superchargers (specifically a roots or screw) are a much better idea for towing and responsiveness. Much easy to maintain, easier install, much less heat, and more responsive.

 

Rick @TrickTurbo talked to me a couple years ago about a turbo build for towing and his big suggestion was T6 vs T4

Just tossing that out there

 

I'd suggest starting with one cooler first and see how it does. I think if you lived in death valley and see 100*+ everyday it might be a consideration on needing something bigger. All the results I've seen over the years is the one does a great job.

 

.
. Well, Huron Speed talked me into trying the VSR7875 Billet NextGen.96
Pushing 12 pounds manifold pressure, at the LIMIT of stock, factory GMT800 fuel pump.
So far I've only taken it up to
4000 RPM, 60% Injector duty cycle, 9 degrees spark, and AFR holding10.5
Yeah, can and WILL lean it out 8% or so.... But, before I go cell by cell into VE table, I need to replace the FUEL pump, and free up some exhaust flow. I am right about the limit of the STOCK Suburban muffler.
3 Inch Boost activated cutout and a Y-Pipe should help everthing spool up easier.

 

Tried my damndest to retain the stock in tank FUEL bucket.
Dicked around for a couple hours.... Just no way to DUAL feed the AEM340 (50-1200 ) pump.
Solution: hacksaw, cut the bottom 2 inches OFF the plastic bucket. Safety wired the AEM fuel pump to top of bucket, 3" x 15" Holley HydroMat plugged onto bottom of pump, measuring tape indicates that it should be pushed down to tank bottom. Stock factory wires at this point, looks like the nearest metric equivalent to 16 gauge.
Makes fuel pressure, no leaks. AEM pump draws 13 amps.( edit ) Stock GMT800 truck return fuel regulator handles flow, no problem.
......... 58 PSI static, Fuel pressure jumps up quick to 70 psi with boost...( edit)
.
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Anyone using the Holley Hydromat ?
How long do they last ?
How low can you run the tank ?
I Just put 28.5 gallons in, drove to gas station no problem with probably less than one inch of fuel depth. .

 

Hydromats work pretty well. So you did 2 pumps or just 1?