General Northstar Info and Help (was More HP for GXP) - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Bonneville GXP/ Northstar Powered Cars Discuss your Bonneville GXP and/or any other Northstar powered Olds or Cadillac... Including the 3.5L Twin Cam V6 (Short Star ) 4.0L and 4.6L Northstar V8's. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-28-2005, 11:50 AM   #1
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Default General Northstar Info and Help (was More HP for GXP)

Does anyone know how far(what specs) the throttlebody can be bored to before it causes problems with the computer in the GXP'*?
Scott


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Old 07-29-2005, 02:18 AM   #2
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any change at all will screw up the computer, since it is figuring a TB cross sectional area of 70.1(example number) and instead its getting 71.3. Mod the airbox first.
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Old 07-29-2005, 09:41 AM   #3
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When I had my '02 T/A with an LS1, anytime the TB was modified or replaced with a bigger one, a MAF translator was needed. The MAF translator modified the signal coming from the TB to compensate for the additional air flow. Without the MAF translator, special PCM programming was needed.
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Old 07-29-2005, 01:32 PM   #4
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Thanks for the info, but that is what I figured. My GXP responded so well to the gutted air filter box, I thought I would go a bit further. I guess I'll just have to wait for more tech tips and products from our "specialists"!
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Old 07-30-2005, 03:54 AM   #5
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change your signature so we know what you are driving and what you have done to it.
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Old 07-31-2005, 08:24 PM   #6
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I don't mean to sound stupid, but I cannot figure out how to get my signature changed to show a picture of my car and a descrition of my upgrades? Any help would be appreciated!
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Old 08-01-2005, 01:14 AM   #7
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scroll to the top of the page and click on the little red "profile". Then scroll down to the signature box. To add an image you need to open a reply to any old post, use the img buttons at the top of the page around the link to the pic. Then you copy and paste this into your sig box. If this is confusing send me a PM.
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Old 04-12-2006, 05:32 PM   #8
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How much more power will gutting the air intake result in. I already have have a K&N filter. Also is there any advantage in fuel ecomony???
Does anyone know?
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Old 04-13-2006, 02:18 PM   #9
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GXP Venom: If you have all that invested in your GXP, can you share what you have done with the rest of us? No one else seems to have any "mods" that work with our cars. I am contemplating NOS, but would rather have the increased HP on demand without having to arm/disarm a power adder. Thanks for your advise!
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Old 04-13-2006, 03:35 PM   #10
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I have to admit most of my war chest in in body mods. The few and I mean few things you can do is...Switch out your air filter, Bore the TB, and nitrous injection. I spent months now up long nites scouring web sites and forums, and have had a couple in depth discussions with a local service mananger who is a leader in dirt tracking around here. One item I havent done that might be worthy is to locate unworn, undamaged STS heads, that would add the 25Hp lost in the STS trade.

The PCM cant be reflashed. I mentioned somebody will eventually crack the codes to the service manager and he said aint gonna happen. I forgot the term he used for our PCM, I'll ask him again whenever my dam wire harness for fog lamps gets here( I think their making the things one at a time )

The flow is already tuned well for OEM and I wouldnt put steel headers against these aluminum heads(especially with the added heat of nitrous) the block and heads are cast using a "squeeze process" that left them unexpectedly porous and I have read more than one account that the average of a half a quart of oil missing each oil change may be seeping into the block.(god knows what that will do over time.)

The Valves can NOT be altered. The valve seats and guides are power coated at Northstar and cant be redone. The valve drain depends on tolerances set for this powder coating. They are throwaway heads and if you damage one one valve, the only fix is replacement. This is true of the bottom end also where thin steel sleeves are used in the cast process of block and cant be rebored. Getting depressing isnt it.

Nitrous IS on demand, if your fittings are all tight and you check them well for leaks you can leave bottle on without worrying about leaking. I leave mine on all the time.;when car is running. yhere is a arm switch with Zex but the valves work when you WOT and close as you let up on throttle. Zex chip knows exact throttle posiition by means of a wire that ties into TPS switch. The other info is in the Nitrous threadhttp://www.bonnevilleclub.com/forum/viewtopic.php?t=52111
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