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Discussion Starter #1 (Edited)
I'm new to the Sky forum, and had to sort through a lot of information to get an idea of what improvements are available. Here I will try to build a short and sweet list of options. The early major lifting is thanks to @Robotech

Here's the Excel sheet

It's a live document I'll be updating as I go.
I'm adding replacement parts too.
Be sure to check each tab.

Please feel free to add in the comments to contribute!

Edit: I'm having a lot of fun doing this... The price disparities between shops is amazing (e.g. $300 price difference between shops for connecting rods).
Edit 2: Summit Racing has so many replacement parts. Redline has a lot of OEM parts pulled from Sky's. ZZ has a great upgrade selection, and has quickly become my favorite LNF supplier. Amazon has a surprising selection of parts. There are so many, I doubt I'll be able to collect them all in the document.
Edit 3: There are an insane number of gaskets. Just Google the gasket you need. Also, it's slim picking for exhausts.
Edit 4: The sheet now has a lot better organization and load of replacement/ exterior/ interior parts. It is far closer to its final form. I'll be updating it a lot less frequently (I've combed through a lot of shop pages in the last 18 hours).

The main vendors for our platform:
DDMWorks - Research. Design. Driven.
Summit Racing
Performance Autowerks (also referred to as PAW)
RPM Motorsports
ZZ Performance
Redline Autoparts
Hahn Racecraft
Amazon

These are some of the options available:
  • Radiator
  • Rear Brace
  • Front Brace
  • Backbone Brace
  • Cold Air Intake
  • Bigger Turbo
  • Intercoolers
  • Charge Pipes
  • High flow cat or catless downpipes
  • Catback Exhausts
  • Coil Overs
  • Sway Bars
  • Front, Rear, Middle chassis and suspension arm braces
  • Limited Slip Diff
  • Clutches and Flywheels
  • Injectors
  • Extra injectors
  • Cams
  • Fuel pumps, both in tank and high pressure
  • Forged Pistons
  • Forged Rods (engine already has forged crank)
  • Intake Manifolds
  • Dash trim
  • Big brake kits
  • Larger brake rotors and better brake pads
  • Larger Valves
  • Heavier Valve Springs
  • Lighter Titanium Valve Retainers
  • ARP hardware for head and timing chain
  • ARP wheel studs
  • Carbon Fiber D-shaped custom steering wheels
  • Headlight and Tail light eyelids
  • Driver's pillar gauge cluster
 

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Great start
1) with the factory tune, no after market parts will add any performance. The factory tune is a torque management tune. It targets 260 ft pounds of torque and adjusts engine performance parameters to achieve that level. (aka learn down over 5-6 key cycles)
2) Of the bolt on hardware mods, charge tubes don't add any power but have shown evidence that they can reduce the roll off of power at higher RPMs due to turbulence in the factory charge tubes, a high flow cat has shown an improvement in power output on the order of 14-16 HP, the existing exhaust (minus the cat) from the factory is not limiting power so replacing it is an appearance or acoustic proposition, the factory air cleaner is very efficient going to a "cold air intake" does not offer performance improvements and greatly increases the intake noise which some like and some don't like, the factory charge air cooler is a good design for OEM and going to an aftermarket design is not "necessary" unless you drive in very hot ambient conditions or race the car and heat soak the factory intercooler, the factory brakes are great for a street car and occasional spirited driving but can be greatly improved by going to a better after market pad like HAWK pads that are sold by Dave and Dave.
3) maintenance quirks include keeping the top lubricated and treated to prevent sun damage. Many hot weather cars (Phoenix) see significant bleed through of the adhesive to the top layer of the canvas. Try to avoid long term parking in direct sunlight. Regularly apply 303 or RaggTopp protectant. Lubricate the folding sides of the top to prevent excessive wear at the hinge points. Keep an eye on the trunk rubber hold down feet as they will separate leaving the plastic mounting points to cut the top when in the trunk. Consider getting a cloth blanket to protect the top when in the trunk. Observe the sides when folded to make sure its not wearing on the side of the trunk. Treat all rubber seals regularly. Some are no longer available or are very expensive. Always carry pucks for lifting. The fenders are fragile and are easily broken by lifting. In fact, make a regular inspection of the bottom of your fenders as they are known to fatigue crack at the mounting point. If not caught in time, the crack will progress from the mounting bold on the bottom of the fender upward until it will require body work to correct. Always lower the windows when latching the top. Always LATCH the top. Some have neglected this and destroyed their top in the wind. Never force the top forward without verifying that the tulip panel flaps are rotating to the open position as they will break if out of time and are very challenging to find. Close the doors before closing an open hood. The hood can come into contact with the door forward edges and strip the paint. Never slam the hood. The corners of the hood can come into contact with the fender and chip the paint off the corners of the hood. Inspect your charge tube clamps. The factory clamps are basically screw type radiator clamps and are known to fail over time. Many of us have replaced them with purpose built higher quality clamps to avoid this potential failure mode. When you check your oil, smell it too. The high pressure fuel pump HPFP is a high failure part - probably right behind the water pump - and one of the more insidious failure modes is it looses the internal seal and starts to drop gasoline into the engine oil. If not diagnosed this can have a catastrophic negative impact on bearing life.
 

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Discussion Starter #3
Great start
1) with the factory tune, no after market parts will add any performance. The factory tune is a torque management tune. It targets 260 ft pounds of torque and adjusts engine performance parameters to achieve that level. (aka learn down over 5-6 key cycles)
2) Of the bolt on hardware mods, charge tubes don't add any power but have shown evidence that they can reduce the roll off of power at higher RPMs due to turbulence in the factory charge tubes, a high flow cat has shown an improvement in power output on the order of 14-16 HP, the existing exhaust (minus the cat) from the factory is not limiting power so replacing it is an appearance or acoustic proposition, the factory air cleaner is very efficient going to a "cold air intake" does not offer performance improvements and greatly increases the intake noise which some like and some don't like, the factory charge air cooler is a good design for OEM and going to an aftermarket design is not "necessary" unless you drive in very hot ambient conditions or race the car and heat soak the factory intercooler, the factory brakes are great for a street car and occasional spirited driving but can be greatly improved by going to a better after market pad like HAWK pads that are sold by Dave and Dave.
3) maintenance quirks include keeping the top lubricated and treated to prevent sun damage. Many hot weather cars (Phoenix) see significant bleed through of the adhesive to the top layer of the canvas. Try to avoid long term parking in direct sunlight. Regularly apply 303 or RaggTopp protectant. Lubricate the folding sides of the top to prevent excessive wear at the hinge points. Keep an eye on the trunk rubber hold down feet as they will separate leaving the plastic mounting points to cut the top when in the trunk. Consider getting a cloth blanket to protect the top when in the trunk. Observe the sides when folded to make sure its not wearing on the side of the trunk. Treat all rubber seals regularly. Some are no longer available or are very expensive. Always carry pucks for lifting. The fenders are fragile and are easily broken by lifting. In fact, make a regular inspection of the bottom of your fenders as they are known to fatigue crack at the mounting point. If not caught in time, the crack will progress from the mounting bold on the bottom of the fender upward until it will require body work to correct. Always lower the windows when latching the top. Always LATCH the top. Some have neglected this and destroyed their top in the wind. Never force the top forward without verifying that the tulip panel flaps are rotating to the open position as they will break if out of time and are very challenging to find. Close the doors before closing an open hood. The hood can come into contact with the door forward edges and strip the paint. Never slam the hood. The corners of the hood can come into contact with the fender and chip the paint off the corners of the hood. Inspect your charge tube clamps. The factory clamps are basically screw type radiator clamps and are known to fail over time. Many of us have replaced them with purpose built higher quality clamps to avoid this potential failure mode. When you check your oil, smell it too. The high pressure fuel pump HPFP is a high failure part - probably right behind the water pump - and one of the more insidious failure modes is it looses the internal seal and starts to drop gasoline into the engine oil. If not diagnosed this can have a catastrophic negative impact on bearing life.
That's a great list! I live in a very hot climate, so much of that will help. Thank you!
 

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There is a lot of information out there but it can be a challenge to find

Here is a link to Flash's owner review of the first installed GM tune. He was/is a GM engineer who personally knew the powertrain engineers for the Kappa platform and took advantage of that to ask them questions.

He has several very informative threads that are worth knowing.

 

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And from another thread in 2013
Here is what I think I know about the factory tune:
There is a very lengthy post on this subject. Westers did a write up on the GMPP tune and what it does and does not do to the car.
The way the code is written in the ECM, the 2.0 is torque managed. The factory tune manages the engine parameters to produce 260 ft pounds of torque. The horse power is a result of achieving that torque value.
If you add hardware that is capable of producing torque values (and resultant HP) above the 260 ft pounds target, the ECM will "learn down" to achieve 260 ft pounds.
Basically, there are a set of data tables that are fixed. And there is memory that is controlled by the ECM. The fixed parameters cover all the possible variables, timing, fuel, air, boost, cam timing etc. It’s more complicated than that but conceptually you get the idea.
The ECM is constantly looking at all the sensors it has available. It is constantly "learning up and learning down" the various parameters it can control to maintain what it believes to be the settings that produce 260 ft pounds of torque.
It’s not strictly learning down because the ECM is constantly varying in real time the engine parameters it controls. What is really happening is the ECM is choosing specific settings from the pre-programmed tables for timing, fuel, air, boost, cam timing etc. based on near real time calculations. The calculations include throttle pedal setting, ambient temperature, air flow rates, O2 sensor readings etc.
The ECM "remembers" where it is at in each of the data tables. It "learns" where it is in each of the tables as it changes its mind on where to pull the settings from the tables based on current sensor readings. It does not create data per se, it uses the data it has in the tables but changes where it pulls the data in the tables based on a set of rules programmed into the ECM operating system.
Since the ECM can react faster than the mechanical systems it is managing, there is a built in time constraint on how much it can change its entry points into each of the data tables. The time constraint is a real time - mille seconds for some setting changes and key cycles for others.
Typically when you are running an unmodified car, when you start the car it "remembers" where it was when it was shut down and begins with that location as the current setting. It looks at the MAF to update air density and watches the O2 sensors to make sure it’s managing the settings. But it does not make any big changes when you start the car. It is making small "make play" environmental changes to optimize the startup and initial running experience. It may make small changes during that run cycle but is constrained to making small changes per run cycle.
If you bolt on a piece of hardware that can produce 10+ hp, the ECM makes small adjustments per its constraints, but it will experience an increase in torque measured because of the hardware update. It will adjust the engine parameters to avoid damage - that is crank up the fuel to avoid lean runs and vary the timing to avoid knock. So you may see the 10 hp increase for that cycle.

When you shut the car off and restart it - executing one key cycle - the ECM will recognize that it is producing MORE than the target of 260 ft. pounds and will crank down the parameters it controls as much as it can in that key cycle. Over the course of 5-6 key cycles, the ECM will be incrementally adjusting the engine parameters to get back to the ideal 260 ft pounds. After 5-6 key cycles, with each cycle resulting in the maximum "learn down" allowed, the car will be producing 260 ft pounds of torque. Again the HP is a product of producing the value that results from the ECM setting parameters.
 

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And
Here is what I think I know about the GMPP tune:
The GMPP tune loads a new set of FIXED data tables. The ECM operating system still operates in fundamentally the same manner, but when it enters a particular data table it pulls out data that is different. The new data tables are designed to produce 340 ft pounds of torque with the stock hardware. The resultant horsepower is said to be 290 HP but it’s again just a product of the new data tables.
The biggest change in the new ECM software is that it NO LONGER is constrained to the fixed torque rating of 340 ft pounds. It can go higher than the level because the data in the tables allows it to go higher.
There really is NOT a learn down feature.
There are constraints on the allowable settings in the factory tune and the GMPP tune. In the factory tune, the constraints result in the ECM always modifying its entry points into the tables to produce 260 ft pounds. In the GMPP tune, the constraints are higher because there is "room" in the tables for the ECM to "learn up" to a higher torque (and resultant HP) value. If you hit the edge of one of the data tables, then you are through "learning up". So it’s not really a learning constraint, it’s the combination of the data tables are fixed and constrained to max values, and the ECM has built in code that predicts what the turbo will do in the near future and will not allow any combination of settings that is predicted to over speed, over heat or over boost the turbo.
So there is not any real learning going on as I understand the system.
 

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And from wspon in 2009
Oct 27, 2009 (Edited)

This post is just to sum up the results of some interesting discussions about the LNF engines in the GXP and to perhaps act as a primer for newer owners wondering about some of these issues, and how they relate to the claims of advertisers trying to sell them products to enhance performance.

The GM programming is based on torque limiting. There is a table in the program that sets desired power, and the ECM adjusts boost, cam timing, throttle position and ignition timing to hit the targets. It doesn’t matter what you do to the engine in the way of ‘power improvers’, the ECM will always adjust down to the preset power (actually torque) targets. You get 260 BHP and 260 ft-lbs. no matter what you do to the engine.

The programming does not react instantly to changes, but rather learns new inputs over several start/run cycles, so that when you first add a power mod, you may indeed see an increase in output if you put the car on a dyno immediately, but that power will go away as the ECM learns back down to the preset level.

GM offers a second tune, the GMPP upgrade, often called (but not by the factory) the stage 2 tune. This does not eliminate torque management, as that is fundamental to the program. It bumps power and torque significantly to 290 BHP and 340 ft-lbs. This may not be felt the first time you fire up the car, but the learning sequence will take place over several key cycles.

On this tune I defer to Bill Duncan, a GM employee, who explains it thus:

There is a calculated torque model that uses all the inputs pressure, temperature, rpm, throttle position, spark advance, cam timing...etc. If it sees that you have an under performing engine, maybe due to the CR being at the low limit then the program will add power until the original power level is acheived. That is the learn up portion. There is also a learn down portion that if the torque model see there is too much torque, usually due to an add on, it will learn out the torque until the original power is restored.

The GMPP Turbo upgrade kit turns off the learn down portion of the torque managing program. Therefore it will not learn out add-ons such as CAI or Exhaust systems.

What most people are mistaking as learning out/Learn Down, are the safetys that are still in the software and still active. These are there to help guarentee the system is durable for the 100,000 mile warranty and parts are not damaged. There is still an overboost protection, there is still a program that is calculating what the turbine speed is and will limit boost if you approach the maximum allowable speeds.

So as an example if you change the turbo and are getting much higher boost you will engage the overboost protection.
Click to expand...
Advertisers do not generally lie about this situation, but they do mislead by advertising the temporary improvements they no doubt record by dyno after installing their product – they just forget to tell you that this improvement is temporary and will go away after awhile. Any mods you buy for the basic factory GM tuned LNF should therefore be done for aesthetic not power considerations. If you like the sound of a free flow exhaust better, that’s great, but don’t be fooled into thinking you are gaining any (permanent) power from doing it. The GMPP tune OTOH would give additional benefits with mods.

To get any improvement in power that would violate factory safety values requires a non-factory tune for the ECM. The disadvantage of this is that it can be used to deny warranty coverage if something goes wrong with the engine – and high output 4 valve VVT engines can be VERY expensive to rebuild, so this is a serious consideration.

After market programming comes in many different flavours, some requiring that you unplug the ECM (be careful, very delicate contacts not intended to be plugged and unplugged often and if you bend/break one a $400 bill), or buy a special tuning unit and software for installation. Some offer a so called ‘stealth’ feature where GM is apparently unable to detect the new program when they plug into your car for service, while others require that you temporarily unload the after market tuning files and restore the GM program if you need to take it in for service.

The feature of all of these after market tunes is that you can at last get some benefit from mods done to the engine. They can’t eliminate the torque management, which is fundamental to the operation of the GM system, but they can ‘fool’ it by replacing the stock values with much higher values such that the system no longer limits torque to any figure realistically attainable by tuning.

With these tunes, and with teh GMPP tune, you can take advantage of mods and actually get some of the power promised by the manufacturers of the parts.
 

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Flash also did some basic data collection on atmospheric conditions and we figured out that the boost can range from 18 pounds at sea level with the GMPP to 22 pounds of boost above 5000 feet.
 

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Here is a thread on Trifecta also from 2009

 

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Discussion Starter #11 (Edited)
The sheet now has a lot better organization and a load of replacement/ exterior/ interior parts. It is far closer to its final form. I'll be updating it a lot less frequently (I've combed through a lot of shop pages in the last 18 hours).
 

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Discussion Starter #12
I struck GOOOOOOOOLD. I found front and rear control arm bushings!! They are graphite impregnated polyurethane bushings made by PST. $104 for each set. I have added them to the sheet under the suspension tab.

113323
 

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Discussion Starter #13 (Edited)
The parts list has been updated with a TON from Rock Auto. Lots of relays, major components, and more.
Good luck and god speed~!

 
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