GXP Sand Car project

**tonka329** · 12-09-2016

Ok guys, need some help... I will be looking at using a running/driving donor GXP for a sand car project (wrecked, salvage title). I thought about using a 3800 supercharged but, I'm really wanting a V8 car. So, with that being said, I will be using both engine and trans in the project. What I want to know is, what "sensors" will I need to have the trans function properly? I'm pretty sure I will need the complete engine harness and maybe the trans harness? Also, what can be "flashed" out of the PCM and cut off the harnesses to make everything work correctly without having a huge bird-nest of wires? Any info would be greatly appreciated!

**Fivefingerdeathpunch** · 12-09-2016

Basically keep everything, it should all be in like 1 large harness for engine and transmission. There will only be a few plug in not used, mainly for the EVAP and rear o2 sensor.

You need to keep the speed sensors and jazz like that. ABS and things like that won't matter.

Disable all the VATS (security), cat tests, evap related codes and stuff like that and it should run and drive fine.

**Scottydoggs** · 12-09-2016

id look for a rwd tranny, the fwd tranny is some what weak really. to use the w body engine tranny combo you just need the pcm and harness. and a load of diagrams to wire this all up right.

**SgtMarshal** · 12-09-2016

can't really use a rwd transmission on a sand car buggy because most of them are rear engine rear drive. what year is the donor car?

**tonka329** · 12-09-2016

Originally Posted by Fivefingerdeathpunch

Basically keep everything, it should all be in like 1 large harness for engine and transmission. There will only be a few plug in not used, mainly for the EVAP and rear o2 sensor.

You need to keep the speed sensors and jazz like that. ABS and things like that won't matter.

Disable all the VATS (security), cat tests, evap related codes and stuff like that and it should run and drive fine.

Sounds good. Will I be able to delete the engine cylinder cutoff mode? Like the fuel mileage stuff?

Originally Posted by Scottydoggs

id look for a rwd tranny, the fwd tranny is some what weak really. to use the w body engine tranny combo you just need the pcm and harness. and a load of diagrams to wire this all up right.

I will need to use the FWD tranny. It is a rear engine car. I have plans on rebuilding the trans with upgraded parts and a 369 sprocket drive and a shift kit. I would really like as much torque as possible. Another thing is, I will be going from about 3,700 pounds down to about 1,800 or 1,900 pounds. However, the sand paddle tires will be about 30" tall...

Originally Posted by SgtMarshal

can't really use a rwd transmission on a sand car buggy because most of them are rear engine rear drive. what year is the donor car?

I don't have a donor car yet. Just tying to get as much info as possible before I pull the trigger on a car. Looking for best years with the strongest trans.

**WarStryker13** · 12-09-2016

05 can be tuned pretty easily with HPT, later years have no tuning support IIRC.

I would say just tune out the DOD, trying to swap the entire valve train ends up to be more hassle than its worth.

For the transmission, look up Triple Edge Performance, send an email to Dave there and he'll get you set on the right path. His built transmissions are the best you can probably ever get... They're worth the price.

**Fivefingerdeathpunch** · 12-09-2016

Yes you can just disable the DoD/AFm with the master enable/disable switch in the PCM, with HP Tuners it's very simple. The only downside is that the parts are still inside the engine, less chance at failure but they are still there.

The transmission is going to be all the same for 05-08 GXP, none is really going to be any stronger than the other.

**Fivefingerdeathpunch** · 12-09-2016

Originally Posted by WarStryker13

05 can be tuned pretty easily with HPT, later years have no tuning support IIRC.

All GXP's are able to be tuned, they run a completely different computer than the V6 engines.

**tonka329** · 12-09-2016

Sounds good guys. I'm just wanting this to work without anything getting messed up. LOL. When I remove the engine and trans harness, will all of the other connections need to come with it? Like the speedo, radio, heater control wires? Or are both engine and trans harness separate from the other stuff?

**tonka329** · 12-09-2016

Originally Posted by WarStryker13

05 can be tuned pretty easily with HPT, later years have no tuning support IIRC.

I would say just tune out the DOD, trying to swap the entire valve train ends up to be more hassle than its worth.

For the transmission, look up Triple Edge Performance, send an email to Dave there and he'll get you set on the right path. His built transmissions are the best you can probably ever get... They're worth the price.

I will shoot the guy an email now. As far as years the '05 models are the easiest to tune? When did the 5.3 GXP start production?

**WarStryker13** · 12-09-2016

Originally Posted by Fivefingerdeathpunch

All GXP's are able to be tuned, they run a completely different computer than the V6 engines.

Well I learned something today then. Lol

**WarStryker13** · 12-09-2016

The GXP Grand Prix started in 05, ended in 08.

**Fivefingerdeathpunch** · 12-09-2016

You won't need the radio, bcm and that sort of stuff. Just the engine/trans harness and computer.

Tuning a 2005 GXP is no different than tuning a 2008, very minor calibration changes happens throughout the years but nothing most would even notice unless they have done a few of them and reviewed the files many times.

**tonka329** · 12-09-2016

Originally Posted by Fivefingerdeathpunch

You won't need the radio, bcm and that sort of stuff. Just the engine/trans harness and computer.

Tuning a 2005 GXP is no different than tuning a 2008, very minor calibration changes happens throughout the years but nothing most would even notice unless they have done a few of them and reviewed the files many times.

Right. I understand that but, is the radio and bcm wiring all inter-twined with the 2 harnesses I need? I don't want to separate wiring harnesses if I don't have to...

**tonka329** · 12-09-2016

Also, are there any interests in a "roller GXP?" I mean, if I strip out the engine, trans. PCM and both harnesses, will anyone get any use out of a "powerless" car? Could I make any money back towards my project? Not sure if I will be stuck with the car...

**Explicit_Spade** · 12-10-2016

Part the rest out. A few things I might be interested in would be:
Floor Mats
HVAC controls
Spoiler
Gauge Cluster
Wheels and Tires

Other people might want:
Radio/ Navigation
Seats
Trim pieces
Compass Module
Heads up Display
Steering wheel buttons

**SgtMarshal** · 12-10-2016

TEP actually advertised a built 4T65E for a dune buggy a while back

**tonka329** · 12-10-2016

Originally Posted by Explicit_Spade

Part the rest out. A few things I might be interested in would be:
Floor Mats
HVAC controls
Spoiler
Gauge Cluster
Wheels and Tires

Other people might want:
Radio/ Navigation
Seats
Trim pieces
Compass Module
Heads up Display
Steering wheel buttons

Ahh yes. I forgot about all those nifty gadgets... However, I may end up using the seats if I can't find a decent set of Race-Trim seats. Not quite sure yet.