What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[Charlie207]

Just did an oil change - Mobil 5w-30 synthetic, with Mobile 1 filter. 190,068 miles on odometer, but 10,000 miles on the 6.0 engine.

The old oil, Valvoline Restore & Protect, came out pretty dark, so I'm assuming it's cleaning?

Also realized while I was laying on my back how strangled the 5.3 exhaust is after the 3rd (passive) catalytic converter. It goes from 3.5" to 2.75", and is annoying to think about how the oenny-pinchers ruin the fun for everyone.

 

[LSCALADE]

In the next steps of making this thing a bit more offroad themed I got some Avalanche flares and installed them. They fit pretty good but the rear bumper does not align the flare lines but it is what it is, they are sturdy as can be. Mounted them using 5-6 M6 bolts and riv nuts on the factory holes in the fenders.

 

[PG01]

In the next steps of making this thing a bit more offroad themed I got some Avalanche flares and installed them. They fit pretty good but the rear bumper does not align the flare lines but it is what it is, they are sturdy as can be. Mounted them using 5-6 M6 bolts and riv nuts on the factory holes in the fenders.

View attachment 460412

View attachment 460413

I feel like there is a diff rear bumper for some reason or another….one has a harder body line towards the wheel well than the other… not sure if this would line up better for you… not that you’re swapping rear bumpers but ya know….

 

[kbuskill]

Not today but the other night...

My oldest son went and had a custom set of real deal old school neons made for the Burb, for Father's day, last year. Life has been busy but we finally got them put on the other night.

These run a 7.5K volt transformer.

We had installed LED Underglow a while back but evidently the manufacturers idea of "waterproof" and my idea of waterproof aren't the same. They were ok for a while but eventually they started giving me issues.

LEDs are very directional in the way the shine light, whereas these neon tubes shine a nice glow in every direction.

I think they turned out pretty well.

The first and last pic were taken with some kind of "night" setting on my son's phone. The middle one is just a regular pic and no fancy settings.

 

[Runfor5]

Officially all disassembled! Plan to start install of new parts this week. Ended up dropping off the heads at a machine shop to hot tank clean + remove the pre-existing 2 broken exhaust manifold bolts stuck in em.

Any thoughts on if a tune is 100% needed just to start the car and check for leaks (like not drive down the road)?

Stock cam:
195/201-115 (?)

Cam Motion “stage 1” cam:

206/216-117+4​

 

[kbuskill]

Officially all disassembled! Plan to start install of new parts this week. Ended up dropping off the heads at a machine shop to hot tank clean + remove the pre-existing 2 broken exhaust manifold bolts stuck in em.

Any thoughts on if a tune is 100% needed just to start the car and check for leaks (like not drive down the road)?

Stock cam:
195/201-115 (?)

Cam Motion “stage 1” cam:

206/216-117+4​

Sorry, I don't know the details of your truck or what you are accomplishing with this work, but...

If this truck had AFM before and you are doing a delete then the truck will start but run very poorly, if the VLOM is unplugged, until you turn it off in the tune.

 

[Grady_Wilson]

Cleaning out garage cabinets, packing stuff for my move.
Come across this air filter but all the numbers show it to be an oil filter.
WTF?
It's obviously an air filter.

 

[SpareParts]

Today i replaced these.

With these.

I think they look a lot better personally. The controller will not be here for a couple more days, so probably will not be able to get the wiring done till next week.

 

[Runfor5]

Sorry, I don't know the details of your truck or what you are accomplishing with this work, but...

If this truck had AFM before and you are doing a delete then the truck will start but run very poorly, if the VLOM is unplugged, until you turn it off in the tune.

Yes that part makes sense and I am able to do via HP Tuners from a buddy. I’m doing a DOD and VVT delete. I’m more curious given the not-stock-cam.

 

[Scrappycrow]

Also realized while I was laying on my back how strangled the 5.3 exhaust is after the 3rd (passive) catalytic converter. It goes from 3.5" to 2.75", and is annoying to think about how the oenny-pinchers ruin the fun for everyone.

That drop in diameter is quite drastic, but consider that the pipe after the 3rd cat is close in cross-sectional area to dual 2" pipes (if you consider 0.063" wall thickness, a single 2.75" has 5.41 sq in and dual 2.0" have 5.52 sq in), but with slightly less internal surface area (again, with 0.063" wall area, a single 2.75" has a 5.25" internal circumference and dual 2.0" have 5.80").

Dual 2.0" on a hi-po 327 from the '60s would be an equivalent (remembering that HP ratings were gross back then and net today).

So, there's definitely something being left on the table, but probably not as strangled as it initially seems.

 

[kbuskill]

That drop in diameter is quite drastic, but consider that the pipe after the 3rd cat is close in cross-sectional area to dual 2" pipes (if you consider 0.063" wall thickness, a single 2.75" has 5.41 sq in and dual 2.0" have 5.52 sq in), but with slightly less internal surface area (again, with 0.063" wall area, a single 2.75" has a 5.25" internal circumference and dual 2.0" have 5.80").

Dual 2.0" on a hi-po 327 from the '60s would be an equivalent (remembering that HP ratings were gross back then and net today).

So, there's definitely something being left on the table, but probably not as strangled as it initially seems.

I think most people over estimate how much pipe diameter is needed when naturally aspirated.

This isn't directed at anyone in particular, just a general observation.

 

[Charlie207]

That drop in diameter is quite drastic, but consider that the pipe after the 3rd cat is close in cross-sectional area to dual 2" pipes (if you consider 0.063" wall thickness, a single 2.75" has 5.41 sq in and dual 2.0" have 5.52 sq in), but with slightly less internal surface area (again, with 0.063" wall area, a single 2.75" has a 5.25" internal circumference and dual 2.0" have 5.80").

Dual 2.0" on a hi-po 327 from the '60s would be an equivalent (remembering that HP ratings were gross back then and net today).

So, there's definitely something being left on the table, but probably not as strangled as it initially seems.

Two things: You're not wrong about one large pipe vs. two smaller pipers, which is why I think twice pipes are dumb, 99% of the time, due to the extra weight you're carrying to achieve the same fluid flow.

In my case, I think there is certainly something left on the table for a cammed/tuned 6.0 blowing through that little coupler. I'm forever looking at LT headers and how to add cats. to the Speed Engineering Y-Pipe, but will definitely go full Denali-sized 3.5" catback with some more muffler experimenting.

I'm genuinely surprised and impressed with this muffler. It's almost too loud, but there's no drone, and has a great tone. I've been watching a bunch of "exhaust tuning/fabricating" videos to absorb some of the concepts, and if/when I fill out a 3.5" system, I'd probably try to get the longer 4" version installed.

 

[Tonyrodz]

Two things: You're not wrong about one large pipe vs. two smaller pipers, which is why I think twice pipes are dumb, 99% of the time, due to the extra weight you're carrying to achieve the same fluid flow.

In my case, I think there is certainly something left on the table for a cammed/tuned 6.0 blowing through that little coupler. I'm forever looking at LT headers and how to add cats. to the Speed Engineering Y-Pipe, but will definitely go full Denali-sized 3.5" catback with some more muffler experimenting.

I'm genuinely surprised and impressed with this muffler. It's almost too loud, but there's no drone, and has a great tone. I've been watching a bunch of "exhaust tuning/fabricating" videos to absorb some of the concepts, and if/when I fill out a 3.5" system, I'd probably try to get the longer 4" version installed.

Just a little expensive.

 

[Charlie207]

Just a little expensive. View attachment 460475

Yeah... tariffs and supply from the Jade Kingdom. I had emailed the vendor about getting a long 3" version, but they had no timeline for US shipments. I probably got the last short 3" muffler.

 

[the_tool_man]

Just a little expensive.

It's nice to see exhaust manufacturers adding quarter-wave attenuators to exhaust. I used to have a Mustang with Flowmaster mufflers that had a serious drone. I installed attenuators and was amazed at the difference.

 

[Charlie207]

It's nice to see exhaust manufacturers adding quarter-wave attenuators to exhaust. I used to have a Mustang with Flowmaster mufflers that had a serious drone. I installed attenuators and was amazed at the difference.

There were a few older posts here that a member shared the formulas, or website that had the formulas, for how to properly size the attenuator pipe for your engine, but I don't have a welder. The longer muffler version of what I have has the longer attenuator, but.... OOS.

 

[Scrappycrow]

Two things: You're not wrong about one large pipe vs. two smaller pipers, which is why I think twice pipes are dumb, 99% of the time, due to the extra weight you're carrying to achieve the same fluid flow.

In my case, I think there is certainly something left on the table for a cammed/tuned 6.0 blowing through that little coupler. I'm forever looking at LT headers and how to add cats. to the Speed Engineering Y-Pipe, but will definitely go full Denali-sized 3.5" catback with some more muffler experimenting.

Ah, I missed that yours was not a stock 5.3. I can certainly see your interest in larger piping, then.

I'd be interested in headers, except for: 1) dealing with integrating cats, and 2) the available diameters are for hp, not torque. You used to be able to get (maybe still, haven't checked) 1.5" truck headers for small-block Chevys, which were great for torque gains.

FWIW, when I designed a custom exhaust for my BMW E28 535i with dual 1.75" stock, I didn't go to dual 2" or the 524td single 3" (both of which are IMO way too big for a normally-aspirated 3.5L), I went with a single 2.5", which provided about 12% more area and was much easier to package.

 

[Runfor5]

Cam is in fellas! Loosely have the chain and damper on for now, need to get some ARP lube for the 3 cam bolts.

Cam retainer plate torqued 18-ft lbs.

Went w a new GM OEM chain damper here (part #12588670) as: 1) all reviews of the “Trick Flow” VVT delete kit I bought from Summit say it’s provided damper bolts are too long, and 2) it’s a random aftermarket plastic damper (which I don’t trust given the amt of work I’m doing here).

 

[Charlie207]

Ah, I missed that yours was not a stock 5.3. I can certainly see your interest in larger piping, then.

I'd be interested in headers, except for: 1) dealing with integrating cats, and 2) the available diameters are for hp, not torque. You used to be able to get (maybe still, haven't checked) 1.5" truck headers for small-block Chevys, which were great for torque gains.

FWIW, when I designed a custom exhaust for my BMW E28 535i with dual 1.75" stock, I didn't go to dual 2" or the 524td single 3" (both of which are IMO way too big for a normally-aspirated 3.5L), I went with a single 2.5", which provided about 12% more area and was much easier to package.

I'm sure a 3" system would be fine for my engine, even with LT headers. I've seen some ebay kits that include a y-pipe that seem to have enough usable length after the collector to fit a short-as-possible 3" cat. on the driver's side and still have room to bend 90* to run along the transmission cross-member/under the AT pan. But.... chinesium.

I know Speed Engineering is also imported, but at least their stuff looks really good for the budget. Stainless Works sells a system that includes cats in their header-design, but its well over $2k, and that's too rich for my blood. I feel like there is a viable DIY solution that can work with a little cutting and someone else's welder.


(I'm also an old euro-car buff... have owned a lot of old turbo Saabs, E46s, and E39s)

 

[kbuskill]

Ah, I missed that yours was not a stock 5.3. I can certainly see your interest in larger piping, then.

I'd be interested in headers, except for: 1) dealing with integrating cats, and 2) the available diameters are for hp, not torque. You used to be able to get (maybe still, haven't checked) 1.5" truck headers for small-block Chevys, which were great for torque gains.

FWIW, when I designed a custom exhaust for my BMW E28 535i with dual 1.75" stock, I didn't go to dual 2" or the 524td single 3" (both of which are IMO way too big for a normally-aspirated 3.5L), I went with a single 2.5", which provided about 12% more area and was much easier to package.

I installed the JBA "cat forward" shorty headers on my 5.3l. I believe the Gibson shorties are basically the same. Either way I found these had really good torque improvement with independent dyno testing. I am always skeptical of in house dyno numbers because they are trying to sell a product.

They are 1 5/8" primary tube and they make good torque, which is what I was after. It is very noticeable while cruising the interstate and going to pass someone, you have to be careful because you will blink and you are running 90+.

@Doubeleive just laughed and thought to himself 90? That is residential neighborhood territory... lol