Bad Nitrous! and Head Bolt Issue - 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 05-08-2006, 10:15 AM   #1
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Default Bad Nitrous! and Head Bolt Issue

Two disturbing things happened at and on way to Show in Carlisle. First, I got a hair up my rear when a super turbo'd RX7 kicked my *** and rejetted to 125 Hp shot and got a hard predetonation that rattled the pistons like the crank was coming apart....car seems fine though (except for getting 13 MPG on way home, plugs most be toast) It was a ratte that could have punched a hole in a piston and dont recommend a nitrous boost that high. I feel lucky it didnt backfire through the intake.

The second thing was, GM had a custom exibit at the Show (you wont believe what GM did to a Cobalt..... it should be flung by the VW ricer catapault.) A rep of that exibit had an extended chat with me as we went over my car and told me the nitrous was a bad idea, and that ANY mod that increases boost on a '05 and below LD8 was not a good thing.They have a history of poping head bolts with age and/or overheating and its so common GM had to make a kit expressly for them.

The info has slammed my power idea'* into the ground and thinking about if a Truck "80" series Tranny can be morphed with a 4T and allow the old 265-400Ci small block to be ran in the Bonny. Who needs a PCM anyway!


Two positive things to explore is a tranny reprogrammer that increases fluid pressure and delays the traction control and torque management system enough to run a guarter mile (it'* avalable for Caddys and I'm going to contact them about a Pontiac application.)

The other is a "piggy back" signal canceller that cant reprogram our PCM, But can eliminate the rev limiter and do a few more tricks. I'm going to research both as time allows.And not much of as of now.
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Old 05-08-2006, 10:58 AM   #2
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interesting Info about the Trans and the PCM....

It is Very common to Talk to GM people and have them tell you not to mod the car, espically new ones, because they dont want to be responsible when warrenty time comes around, that is prolly why he said about the Nitrous on the N*
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Old 05-08-2006, 11:46 AM   #3
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It'* interesting that when GM redesigned the N* for the 4.4 Liter supercharged application, they decreased the bore size. This was to give more block material for the head bolts so that the extra boost pressure wouldn't loosen the bolts or cause a head gasket failure or warping. So, some of what he is telling you maybe the truth. Otherwise, I think GM could have just thrown a supercharger on the 4.6 N* with a few internal modifications. (I would just love to do that, BTW! )
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Old 05-08-2006, 11:47 AM   #4
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Actually Pat He was very impressed with the Bonny. And I did some "homework " when I got home last nite. the head bolt issue is real and common. Nitrousing puts super high pressures in cylinders and the heat surge is troublesome.

And I'm seriously considering ripping the N* out of mine and selling it, if I can find an alternative. I'm sick of it and want to make real Hp gains to my Bonny.. The N* had little impact on the judging.It'* becoming common place in GM cars

And would love to throw a stroked 350 service duty small block with two chromed Holleys sticking out of hood. That would make some eyes pop out seeing them mounted tranversly. The N* money could go a long way towards buying a stroker......if I can marry it to a FWD tranny .
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Old 05-08-2006, 12:23 PM   #5
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Yep thats why I said I would never put nitous in my car. For the money involved when my engine dies I would rather look for a supercharged N* if it will fit.

Hey you can take out the N* and put in a 3800...*/C.... or who knows

Seriously sorry to hear the negitive news from the Gm rep but your car still looks awesome and I can say you have taken the GXP to a level never before taken and you are just getting started
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Old 05-08-2006, 02:02 PM   #6
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I hear ya shadow but */C boost is similar to nitrous pressures and with headbolts popping out of our blocks, not a good idea either. I realive they are doing them now, but I think something was redesigned to hold them in better. I'm busy unpacking and getting house back together and just checking the forum now and again right now.
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Old 05-08-2006, 07:46 PM   #7
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So did you make the show or no?
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Old 05-08-2006, 08:09 PM   #8
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Where ya been Lake????? I won best in show field and posted pics in lounge.
Show was awesome but Lexi was a no show, but I had some nice consolation girls to present me with the placque and bend over the car.

Shadow, ya it sucks but I'll figure something out. It'* gotta be a v8 and I'm gonna search out a way to marry a 350 to the FWD. So mad ready to frame rail it and put a rear end under.it.
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Old 05-08-2006, 09:07 PM   #9
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She was there, she saw the car, that'* about all I really know. I haven't talked to her a whole lot lately. Trying to get the details as they stream in, only been able to talk to her on another message board lately. Been swampped with work and wanting to beat the snot out of a friends B/F.

I'm above that though, we'll let him make the first move then it'* on like Donkey Kong from there.
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Old 05-08-2006, 09:21 PM   #10
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Quote:
Originally Posted by GXP Venom
Where ya been Lake????? I won best in show field and posted pics in lounge.
Show was awesome but Lexi was a no show, but I had some nice consolation girls to present me with the placque and bend over the car.

Shadow, ya it sucks but I'll figure something out. It'* gotta be a v8 and I'm gonna search out a way to marry a 350 to the FWD. So mad ready to frame rail it and put a rear end under.it.
There was not question in my mind that you would not bring home and award this time and everytime...

Good luck always
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