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Discussion Starter #1
I purchased my GXP last April and have been reading post on these forums for a while. One thing I noticed is that I haven't seen a complete build posted on here. I wasn't sure where to post since I will be covering a mods that spread across multiple tech forums so here I am.

So far what I have done:
GMPP
Footwell LEDs (controled by the auto light circuit)

Plans: These may change as this build will take awhile
Phase 1 (powertrain goal 400whp)
HP Tuners custom tune done by myself
Intercooler with pipes
3" downpipe and exhaust
Big Turbo (possible Werks WR-3, they took the rest of their turbo kits off their website today)
forged pistons to handle the extra heat
any thing else to help me hit my target such as higher flowing manifolds, headwork, etc

Phase 2 handling
probeams
backbone brace
coilovers
big brake kit
light wheels w/ good rubber

Phase 3 exterior
need to repaint and fix a the front bumper


Please feel free to comment, make suggestions or just leave your opinions.
 

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I don't mean to hijack your thread. since I basically would want a goal of 400hp but would anyone know if anything else would have to be changed other than pistons/rods/valve springs? my plans are to be fully bolted and tuned, then swapping out the pistons/rods/valves for the turbo swap....lookin at it, my wish list is sort of like yours, I would just like to know if I can call it a day and safely run 400hp with that kinda set up? or if theres any other internals I would have to change out? good luck with your build!
 

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Discussion Starter #4
Thanks, from what I have read there are a few running at 400whp with stock internals. It seems that the pistons are the weak point. By upgrading the pistons you can run higher cylinder temps/pressures which will make it easier to get more out of the engine during tuning.
 

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LNF's start to run out of fuel above 400 hp.

The stock pistons can take it but I wouldn't recommend pushing your luck.

The springs and valves can take the hp just fine, you only need to start worrying about them when you increase the rev limit.
 

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Discussion Starter #6

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Discussion Starter #7
I haven't updated here in a while but about a month ago i got my HPtuners in the mail. The first thing I did was remove most of the torque management and WOW what a difference. The unfortunate thing is that I was boosting the stock turbo wayyy too much, 29 psi with about 4 degrees of knock retard at all of the areas of high boost.

I tuned the boost back down to 20 psi now so I can start dialing in the spark advance. I will then creep boost back up to 24 psi.

Wish me luck!
 

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auto or manual? In either case you're planning to stay stock at this point of your build and perhaps wait and see? It won't give you more power, but there is a 6 speed manual option now that will provide strength and driveability.
 

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Discussion Starter #9
Its an manual. I do see DDMworks has the conversion kit. It is a possibility down the road.

Right now I have to track down what appears to be a boost leak. I was doing a 4th gear pull and boost spiked to 29 psi, then dropped to 5 psi. Does any one know the common places for leaks so I can begin there?
 

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I don't know how you'd check for a leak here, but as I understand, with more boost (a tune for instance), you should upgrade the stock hose clamps after the turbo to the DDM T clamps. This is a cheap way to ensure no leak here, and you'll need them in the future anyway. 6 will come to you.
 

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Its an manual. I do see DDMworks has the conversion kit. It is a possibility down the road.

Right now I have to track down what appears to be a boost leak. I was doing a 4th gear pull and boost spiked to 29 psi, then dropped to 5 psi. Does any one know the common places for leaks so I can begin there?
The symptoms, as you have described them: Appear to be a case of "over-boost" and the ECM throwing you into "Limp Mode Light" to protect the engine.

"Limp Mode Light" disables electronic boost command, but leaves throttle command, A/F, and spark advance normal. (Mechanical boost command is still working and will typically run up to about 5 PSI) The ECM will deploy this safety protocol when it has detected a parameter out of spec that it considers somewhat dangerous to the engine. It may leave you in "Limp Mode Light" for a couple-three key cycles then return to normal operation to see if the problem is detected again.

If the ECM detects a worse problem, one that it considers potentially catastrophic: Then it will throw the car into "Full Limp Mode"; electronic boost command and mechanical boost command are disabled-the car will produce NO boost (the Waste Gate is locked open). Throttle command will be reduced to about 25-30% of normal. A/F will be set pig rich, and spark advance will be severely retarded. You will literally be limping around. :lol:

Potential Causes of "Over-Boost"

1. Waste Gate adjustment has come loose and spun itself to the tight side.
2. Electronic Waste Gate actuator has failed and is not responding correctly to command.
3. Programming Error that is commanding to much boost.

Personally, I am voting for #3; since you have been playing around with HP tuners.

Be aware that the GMPP tune retains a couple safety protocols. It does remove the peak torque management limitations that holds the stock flash to 260 lbs of peak torque. But it does retain some torque management in lower gears. I am suspicious that since you state you "removed" torque management completely, that you have created an issue.

The GMPP tune also retains "Turbo over speed protection": The program runs a clever algorithm that estimates turbo RPM from various parameters sensed. If the ECM detects that the Turbo is spinning to fast, it will slightly open the WG to reduce the Turbo RPMs. This can create a "High Altitude Condition". For example: I have the GMPP tune and no other mods. I live at 5000 feet above sea level. On a hot summer day, in 4th gear and doing a WOT pull: The ambient air pressure may be so low, that I start to pull upwards of 27 PSI (equivalent of 23ish as sea level). If the air happens to be thin enough that day to start getting above 27, into 28-29 territory: The ECM will determine a "Turbo over speed condition" and slightly open the WG. As the driver, I will feel a slight power drop off when this happens. Completely normal operation, and no codes are thrown or CELs are thrown. This is just a little protection protocol run by the ECM and makes perfect sense because the stock Turbo runs out of it's efficiency curve past 23 PSI at sea level (which is about 27 PSI at my altitude).

And the GMPP tune retains a "Max Manifold Pressure protection". This is a situation where if the ECM detects manifold pressure exceeding a preset max limit, it will reduce boost to protect the engine. To the best of my knowledge, no one has ever reached this point on the stock turbo; regardless of tuning changes.
 

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You are on a dangerous road. :). The turbo over speed and boost limits are there for a reason. Several threads have begun in similar manner and ended with the news that the engine was fried. One member is on his fourth motor.

Have fun and take lots off pictures

It's also possible you have cracked your IC
 

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Discussion Starter #13
GS Stage 1, I agree with all that you are saying. I reviewed the data again last night. I incorrectly described the 29 psi boost spike as my 4th gear pull. The spike was in 3rd and I didn't see a difference until I tried the 4th gear pull. It looks like I hit the Pressure Boost Limit on my 3rd gear pull which could have put me in to limp mode light. I really hope that is it because I don't want to waste all weekend chasing down a boost leak.

Rob, I also agree with what you are saying. That is why I haven't removed those limits.
 
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