What did you do to your NBS GMT800 Tahoe/Yukon Today?

[Sam Harris]

First off- I like the new avatar.



Tighter LSA leads to low-end torque as well as chop.




None of this is really necessary at this level. You're not revving high enough to really benefit from the exotic stuff. Stock valves are fine.




Does PRC build the heads in these packages to suit? I'd recommend getting SCR to ~10.5 or higher. If 87 is a must, maybe at least 9.5-9.75ish? So, whatever chamber size will accomplish this but not put your PTV in danger. If you want thinner head gaskets as part of the equation, I think Fel-Pro has .045" for about the same price as OEM. I saw this long AFTER I ordered $80 Cometics.




That's seems really long. Stock length is 7.385", but most round it to 7.400" for some reason. Performance cams often, if not always have a .050" smaller base circle, requiring a .025" longer rod. Any other changes from stock (heads, gaskets, etc.) will alter the rod length. A 7.400" rod is the general standard for cammed engines to maintain stock lifter preload.

Are those PRC heads made from virgin blanks or are they reworked stock heads?




Will definitely chop and have good low-end and certainly top-end. You're covered with the converter. Gear ratios are a considerable factor- whatcha got?




Can't go wrong with the OEM "HD" LS2 chain. GM uses it in their GMPP line and it's the standard in the Gen4 engine. I believe the part number is 12646386.




If your current pressures are fine, a new OEM pump (which could be Melling) will be fine. If it wouldn't hurt to have a few more PSI, get it from more volume. Look into the Melling M295 or M295HV. I got the HV for mine and I'm pretty sure your Gen3 would take the same.




The RPMSpeed Max Effort kit would be my choice. I'm not totally convinced on the bronze bushing kits. If I were to try them, I'd get CHE.




I'm pretty sure your '03 is a three-bolt TB, yeah? That's a changeover year- is your TB cable-driven or drive-by-wire? Besides the TB, the injector size and plugs are the only other possibly mismatch I can think of.

Thanks brother. It's been a while since I updated it!

Re: LSA: Nice.. I think 112 will be good then..

Stock / Stainless valves are good.. Awesome..

Yes, I can order a number of different options, or build to suit. They do have a handy compression calculator, but it's tough being clueless.. I know I can use a thinner head gasket to bump compression a bit, but I don't know if I can really get all this figured out until some of these things are in place.. Thanks much for the tip on the Fel-pro..!

The heads are new -cast, and this is one of the things I'm trying to decide on. (though they do have a package with customer supplied heads as well) As-cast vs aftermarket casting? Not sure what that means. I think a ported head would be the best option... Here's one that I thought might me a good fit: https://www.texas-speed.com/p-8013-prc-15-degree-220cc-cnc-cathedral-heads-cam-package.aspx however, I also don't know what would be a good choice for cc volume.. 220 all the way up to 247cc..?

Timing chain: I figure between your and Mark's recommendations, I'll probably go with a single roller Cloyes.. Of course that still leaves Z06 or C5R. I guess the Z06 will do fine there.. less expensive..

Melling HV is the plan. I will do this..

Pretty sure the TB is a 3-bolt. I removed it about 18 months ago, but don't remember. lol.. It is a DBW, and since I have Flex, I think I should be good there - hopefully.
Do I need cooler plugs..? If so, I think I'll need to look into a LSA, to justify the plugs..

ETA: Gears are 3.73..

 

[Sam Harris]

Ready for that heat?

I think so... I'm definitely ready for less snow!!.

 

[Sam Harris]

Have we talked valve springs, yet? Need something more stout than the old ls6 for that lift. I just haven't kept up since my f-body days. Lots of companies had challenges with keeping springs from breaking back then. That's part of the reason the Truck Norris appeals to me....plus it kinda sounds like my old hotcam which was relatively low lift, too.

The springs would be upgraded (likely dual), as part of the head upgrade. Trying to get as much as I can in part of a "package"..

 

[Rocket Man]

I definitely want the trunnion upgrade. Can't those be used with either the factory rockers, or aftermarket? Or would I need to get a kit that has both to use on aftermarket rockers? Sorry, I'm pretty clueless.

Afaik the trunion upgrade is for OEM rockers, they have needle bearings that can fail and you end up with little roller gearing’s in your engine. I’m sure somebody with more knowledge like @iamdub has more info. The last I heard, the Jones Bros upgrade with bronze bushings was a preferred go-to but I see he has other recommendations. If you want to spend some money, you can buy something like shaft-mounted full roller rockers like the Yella Terra’s I’m running. Roger Vinci told me they’re good for 15 hp with my setup. They’re $800-900 though.

LS1

 

[Sam Harris]

Afaik the trunion upgrade is for OEM rockers, they have needle bearings that can fail and you end up with little roller gearing’s in your engine. I’m sure somebody with more knowledge like @iamdub has more info. The last I heard, the Jones Bros upgrade with bronze bushings was a preferred go-to but I see he has other recommendations. If you want to spend some money, you can buy something like shaft-mounted full roller rockers like the Yella Terra’s I’m running. Roger Vinci told me they’re good for 15 hp with my setup. They’re $800-900 though.

LS1

I mean… if they’re recommended for stability.. sure I can do that.. but if they’re only needed for higher HP, as in… a whipple.. I probably don’t need to do that yet at least..

 

[Rocket Man]

I mean… if they’re recommended for stability.. sure I can do that.. but if they’re only needed for higher HP, as in… a whipple.. I probably don’t need to do that yet at least..

Well I mean they’re extremely stable and I doubt either of us NEED them but they sure are cool. The added benefit is freed up HP.

 

[iamdub]

Yes, I can order a number of different options, or build to suit. They do have a handy compression calculator, but it's tough being clueless.. I know I can use a thinner head gasket to bump compression a bit, but I don't know if I can really get all this figured out until some of these things are in place.. Thanks much for the tip on the Fel-pro..!

Raised compression, yes, but the real benefit to thinner gaskets is tighter quench. This promotes a fuller burn of the fuel mixture and helps to stave off detonation. Between this, the stronger power band at cruising speeds/RPM, etc., I'm able to meet or exceed my stock fuel economy, but with 80-90, maybe even 100 extra horses.

The heads are new -cast, and this is one of the things I'm trying to decide on. (though they do have a package with customer supplied heads as well) As-cast vs aftermarket casting? Not sure what that means. I think a ported head would be the best option... Here's one that I thought might me a good fit: https://www.texas-speed.com/p-8013-prc-15-degree-220cc-cnc-cathedral-heads-cam-package.aspx however, I also don't know what would be a good choice for cc volume.. 220 all the way up to 247cc..?

Those heads look to be modeled after or are modified 243/799. I'm assuming this based on the chamber volume of 64cc. Your stock heads (706/862, right?) have 61.5cc chambers. So, you could order the heads with whatever chamber size works with any other planned mods (thinner gaskets, shaved, etc.). Your stock heads are advertised as having a 197cc port volume on the intake side and 69cc on the exhaust. There's a whole deep science to port volumes in relation to cams. I'd let them recommend a port volume based on your setup. It's not a bigger is better thing. Bigger ports flow more air, but you lose velocity. This can fight the cam, reducing efficiency and causing a loss of potential power. Everything must be complementary.

Pretty sure the TB is a 3-bolt. I removed it about 18 months ago, but don't remember. lol.. It is a DBW, and since I have Flex, I think I should be good there - hopefully.

I'm thinking that, best case, you'll just need the TB adapter and injector plug adapters or to splice the correct plugs onto your existing injector harness.

Do I need cooler plugs..? If so, I think I'll need to look into a LSA, to justify the plugs..

Ummm. Yaaas.

Gears are 3.73..

Good.


ALSO: My thoughts are that the Stage 3 might be a touch on the excessive side, especially if you tow and or just wanna minimize low-end loss. The converter, tight LSA and bumped compression are all to make up for the cam's sacrifice in low-end power. Ever watch any Richard Holdener vids? He actually compared the various Stages of cams in a Gen3 5.3 and 6.0. But, it's all in what you want. It might have plenty of low-end for you and you would enjoy and actually use maximizing the top-end power.

 

[iamdub]

Afaik the trunion upgrade is for OEM rockers, they have needle bearings that can fail and you end up with little roller gearing’s in your engine. I’m sure somebody with more knowledge like @iamdub has more info. The last I heard, the Jones Bros upgrade with bronze bushings was a preferred go-to but I see he has other recommendations. If you want to spend some money, you can buy something like shaft-mounted full roller rockers like the Yella Terra’s I’m running. Roger Vinci told me they’re good for 15 hp with my setup. They’re $800-900 though.

LS1

I mean… if they’re recommended for stability.. sure I can do that.. but if they’re only needed for higher HP, as in… a whipple.. I probably don’t need to do that yet at least..

The trunnion kits replace the guts of the stock rockers. Unless you've had an oiling issue or water intrusion or really high mileage, the stock rockers are hardly a wear item. You can get new rocker bodies, though. Or, buy rockers with the upgraded trunnion kit already installed so they're just a direct, bolt-on replacement for the stock ones. The stock rockers are actually really good. But, after certain points, they quickly become questionable. The needle bearings are retained by a pressed-in cap. At it's breaking point, that cap can pop out, causing all kinds of misalignment hell as well as spewing tiny needle bearings all through the engine. It seems that the consensus is anything over .570" lift should be upgraded. Stability really isn't much of a concern with the cam and the RPM you're looking at with your truck. A good trunnion setup on stock rockers would be plenty sturdy enough. I would recommend chromo 5/16" (or 3/8" if they'll fit) push rods, though.

 

[ivin74]

Got tired of looking at the axle
not been center after the drop. Replaced the oem panhard bar with the adjustable one. I tried the DJM links and did not like how close they got to the shock air bags so I put 1" spacer on the sway bar to have more clearance between the panhard bracket and the sway bar.

 

[Walchit]

I need help.. I spoke with Performabuilt regarding my transmission upgrade.. I’ll be ordering the level 3, and a 2800 stall TC.. that part was easy..

Next, I want a cam and heads. I’d also like to do the intake, and already have the NNBS intake in storage.

I want a fairly good chop in the cam, so expect that’s pretty easy to accomplish with the correct lsa around 112 or so, but I also want the best low end torque I can get with the stock 5.3. Not necessarily the best top end.

Looking at the TSP PRC head and cam packages, I think this would be a good way to go, and take some of the guesswork out of it. However, even looking at the packages, there are a lot of options..

stainless valves / hollow stem valves / inconel.?

Chamber size? 68cc is standard and I expect I want to stick with this, to avoid and milling, rather than sending brand new heads off to the machine shop.

Pushrod length: defaults to 7.475 I’m assuming that’s factory length. No idea if I’d need a different size until cam is in and heads are on.

Cam: looking at Stage 3 truck 216/220, .600”/.600” (112 lsa)

Timing chain: I think this is wise to replace, but I have no idea what to go with for the replacement. Lot of options..

Oil pump: I think this is also wise to replace, and don’t think there’s any need for higher pressure, but higher volume may be desirable.. so thinking the Melling HV pump.

Rocker arm trunnion upgrade: I definitely want to upgrade these but TSP kits are back ordered..

Any advice is very much appreciated

I also need to determine what is involved and part list what I need to swap the existing intake, for the NNBS intake. Money is less of an object at the moment, than time.

ETA: Any other supporting mods that I haven't listed here will certainly be appreciated, and entertained..

I ordered the Truck Norris cam from BTR
I think it's 212/22x .552/.552 107.5 lsa
Haven't seen a bad review yet. I'm contemplating a small stall, but I really don't want to have it too radical for the wife to drive.