2008 Yukon 5.3 Engine Mods

[BPopilek]

Hey all! I currently have a 2008 Yukon with the 5.3l engine, and I am looking to do some mods/upgrades. A couple of my exhaust manifold bolts have broken off in the heads, and in order to get to one of them, I have to remove the head off of the motor. So, since I am going that far, i figured it might be time to do a few upgrades and maintenance to the motor at the same time. I'm looking to try and get some more power and performance out of this beast. I will list out what my buddy and I have priced out so far. My buddy happens to be a GM mechanic, so I have qualified free labor!

Chevrolet Performance Hydraulic Roller Lifters (16)
LS7 Lifter Guides (4)
Chevrolet Performance Camshaft Retainer Plate
Chevrolet Performance Engine Valley Cover
GM Gen IV VVT Cam Phaser Limiter Kit
Comp Cams XFI™ 267PHR14
Chevrolet Performance High Volume Oil Pump
Fel-Pro Head Gasket Set
COMP Cams High Performance Valve Spring Kit
GM LS OE Rocker Arm Trunnion
Cloyes Replacement Timing Chain
Fel-Pro Timing Cover Gasket
Summit Racing® Main Bearings
Clevite H-Series Rod Bearings (8)
Summit Racing® Thermostat
ARP Pro Series Cylinder Head Bolt Kit
Engine Tune
Total Cost (Approx) - $2600

Please let me know if this all makes sense, and if there is anything that you would recommend I change. Anything that I'm not changing or replacing, in my list, that I should be? We're not going for a huge build, just some modest to moderate upgrades. Additionally, when it comes to a tune on this motor, where is the best place to get that done, and approximately how much does that cost? I'm assuming it will be a mandatory thing after changing all of these stock parts out. Thanks for reading!

 

[iamdub]

He's proposing to delete the AFM with a performance cam and replace the bearings in the rotating assembly. So, he's ditching a problematic system (AFM), getting you more power (COMP cam), and refreshing the area of the engine that sees the most stress. Everything else (gaskets, bolts, valvetrain upgrades, oil pump, timing set, etc.) are all necessary/normally replaced parts when digging this deep. I'd recommend a set of thicker pushrods be added to the list. A tune is a must since you're deleting the AFM and because of the performance cam and just because there's improvable areas in the stock tuning. Because of the aftermarket cam, your best bet for a tune would be a custom dyno tune. A mail order type tune can get close, but not optimal. They tend to err a bit too strongly toward the safe side, leaving efficiency and power on the table. You're gonna have to search your area for reputable tuner(s) if your mechanic doesn't know of one. Last I knew of in my area, a dyno tune is around $600 and up depending on extense of mods. So, they cost a little more than the best handheld tuners, but you get optimal results for your setup.

 

[Brian Wilson]

Don't forget to install your long tubes too.

 

[BPopilek]

Thanks for the input guys! As far as removing AFM, is this going to help or hurt anything. I understand how it works, but was curious if I will see a loss of mpg's after removing it.

What kind of thicker rods were you recommending? Any particular brand or model number?

I will consider a pair of long tube headers, but probably later on. Unless I can find a good set for a pretty reasonable price. Do you know of a good decent set? And if I do, do this later, is an updated tune necessary for them?


And lastly, for the dyno tune. I believe there are places south of my house, in the Detroit area, that are able to do this. Will the truck be driveable after the mods, or should I trailer it down? It's about a 30-45min drive down the freeway from my house to Detroit.

 

[NGAneer]

Some have seen an increase in MPG after dropping AFM. I have no proof but it's been said.

 

[iamdub]

I wasn't even thinking about external bolt-ons, but I agree with getting long tubes. Speed engineering has a stainless set with Y-pipe to make it all a bolt-in deal for around $350. Might as well add an Airaid MIT as well (Around $150 unless you find one used). They should be in place before the dyno tune. For pushrods, pretty much anything hardened/chromoly that's thicker-walled than stock will be fine. There are plenty of sellers for them and they average $100/set. Call COMP and give them your cam specs and they can tell you what length and what part number of pushrod from them if you want a set of COMP pushrods.

My opinion of AFM is that it is beneficial only to those that live in flat, mostly rural areas where they drive no faster than 55-ish with minimal traffic and accelerations. My opinion is based on my personal experiences with the AFM operation in my Tahoe. I believe the varying reports of the effectiveness of AFM has to do with the vast array of people's driving habits and their locations. In my area, if I drove in the manner necessary to engage AFM for any effective amount of time, I'd be a rolling roadblock and a hazard on even the rural roads around my house. The AFM system is known to contribute to oil consumption in these engines and the lifters are more prone to failure than standard lifters. So, even if it did cost me an MPG or two, I'd take that over my intake manifold and combustion chambers getting cruddy and worrying about the eight "ticking time bomb" AFM lifters. Oh- not to mention having to keep an eye on and adding 1-2 quarts of oil between changes. Synthetic oil is too expensive to be burning and/or storing it uselessly in a catch can.

 

[JZNNJX]

He's proposing to delete the AFM with a performance cam and replace the bearings in the rotating assembly. So, he's ditching a problematic system (AFM), getting you more power (COMP cam), and refreshing the area of the engine that sees the most stress. Everything else (gaskets, bolts, valvetrain upgrades, oil pump, timing set, etc.) are all necessary/normally replaced parts when digging this deep. I'd recommend a set of thicker pushrods be added to the list. A tune is a must since you're deleting the AFM and because of the performance cam and just because there's improvable areas in the stock tuning. Because of the aftermarket cam, your best bet for a tune would be a custom dyno tune. A mail order type tune can get close, but not optimal. They tend to err a bit too strongly toward the safe side, leaving efficiency and power on the table. You're gonna have to search your area for reputable tuner(s) if your mechanic doesn't know of one. Last I knew of in my area, a dyno tune is around $600 and up depending on extense of mods. So, they cost a little more than the best handheld tuners, but you get optimal results for your setup.

Hello I am Brian's Mechanic and larger 7/16" pushrods from a good company is a must I forgot to add than in. as for tuning Dyno is great for a dead on tune but with the modest upgrades I have my good friend in Fla. Chris from CHenrry motorsports can do the tune with HP tuners I am looking into buying a unlimited tune set from HP so sending the base tune to Chris and having him look at a few things not only will it make a better tune but can change trans pressure and shift points. also if Brian decides to add Headers later it wont hurt the tune but can be adjusted at a later date due to working on a budget. any thing I have missed please respond would love to hear the input.

 

[iamdub]

By "mail order tune", I meant a generic "one-time tune based off a stock truck plus a lucky guess for the mods". If he has the ability to have a tune wrote and edited, then a dyno tune isn't so necessary for budget purposes. A good tuner can "blindly" write a base tune to get it running well enough with the cam, but Brian will need a way to datalog so the tuner can adjust as necessary via email until it's dialed in well enough for satisfaction. My thinking was that, sure, the headers can be added later. But, for $350 and since you'll already be in there, why not throw 'em in then? They make such a notable improvement on a stock engine so they're surely to be beneficial if that engine is moving more air from the cam. That additional flow will alter the VE so a retune will be necessary. I feel I'm sorta preaching to the choir, but you can't be too thorough.

The only other thing I can think of at the moment is maybe a slightly looser converter? I'm not the most familiar with that cam, but looking at the specs on COMP's site, maybe the good ol' Trailblazer converter would do?

 

[sumo]

Uhh yeah! Lol flat roads. Staying off the boost

 

[iamdub]

^^^

I've watched mine do that, just not quite those high of numbers. On perfectly flat roads with the cruise on (or just holding the pedal really still), I get the some high V8 mode numbers. As soon as there's any sort of incline, a headwind, a sweeping curve or even a few dips, that number drops like a rock. Does your SC have a bypass when not in the throttle? I'm wondering if, even though you may not be getting positive pressure, it's still not as much vacuum as being NA. I guess technically that'd be "boost", just a very small amount but still enough to increase the TQ at that RPM and throttle angle. Did BlackBear tweak your Lean Cruise table as well?