1987 GN 600+ RWHP


VIN: 1G4GJ1173HP461480

My nicely modified GN has sat in the garage this summer (with the car cover). I have not driven it hardly at all in the last 3 years. I don’t have much time to drive it and have lost interest. I could use the garage space so it is time to sell. My asking price is $28,000. Please no low-balls. You know what it takes to duplicate this car. The car is located near Romeo, MICHIGAN. I am not looking for trades. Please send me a private message with your phone number or I can provide my number through the private message here on the forum. I can provide many pictures as needed but the best way is to see the car in person. I purchased car in August 2009 when it had approximately 77,000 miles. The previous owner had the car painted Fall of 2008. There is absolutely no rust on the vehicle. Vehicle has over 620 RWHP at 24# of boost and tuned by Cal Hartline. Yes, it runs a 10 sec 1/4 at 131 mph. Probably go 9 sec by turning up boost but that is too fast for me. Current mileage on body is about 81,000 and about 3,700 on engine. Engine was built in 2011. I have Carfax from time of purchase documenting miles. AC has been converted to R134A and blows cold. GN was purchased with front and rear aluminum bumper cores and bumper supports. Weigh ticket from previous owner shows vehicle weight at 3320 lbs.

T-tops; Power Windows; power locks; power driver’s seat; power trunk opener; concert sound II (radio changed to early 90s Delco radio w/ CD/equalizer/modified to play mp3/ipods; cruise control; Rear window defroster; power antenna (changed to fixed antenna)


• Engine built by DPR Custom Services (TurboDave231 on TB.com) Fall 2011:
o Displacement: 249 CID 4.1L
o Bore: 3.820 Stroke 3.625
o Compression Ratio: 8.9:1
o Cam Specs: DLS custom grind hydraulic Roller 218/218 duration @ .050
o Pistons: Diamond Pistons 3.820
o Connecting Rods: K1 5.950
o Crankshaft: GN1 forged steel 3.625 stroke narrow rod journal
o BHJ Balancer with internal balance
o Block: “109” with Billet Steel Main caps in #2 & #3 position
o Rocker arms: T&D Machine 1.65 (used)
o Modified front cover
o Complete build sheet and pictures available
• GN1 Aluminum Heads with spring upgrade; Cometic head gaskets
• Precision DBB 6765 H cover turbo and RJC 4” intake pipe
• TR Custom Super Extreme front mount intercooler
• Kenne Bell 70mm throttle body and plenum (came w/ purchase of vehicle)
• Champion 1” spacer with vacuum lines plumbed eliminating stock vacuum block
• Evac electric pump plumbed to custom made oil catch can
• AlkyControl progressive methanol kit with single nozzle and 3 bar MAP sensor
• Big Mouth Cold Air kit
• Alradco aluminum radiator with oil and trans coolers
• Precision oil saver (used)
• RJC 20-bolt deep oil pan with custom made oil pick up
• AC Delco AC compressor from Highway Stars
• Derale dual fans generating 4000 CFM
• FAST XFI 2.05 with Internal Data Logger installed under passenger seat with EDash

Transmission and driveline
• 2004R rebuilt by DPR (TurboDave231)with billet parts from CK Performance Transmissions
• PTC Converter #PTC-9-5-700-27-17 SBP (spec’d by Dusty Bradford)
• Art Carr Deep Trans Pan with trans temp sensor
• B&M Trans cooler 11 x 7.5 installed in serial with radiator trans cooler
• DTS 3-inch steel driveshaft with 1350 forged steel slip yoke
• DTS Chromoly Billet 1350 pinion yoke
• Metco driveshaft loop
• TA rear diff cover with studs

Fuel System
• Racetronix dual in tank pump hanger with wiring harness
• Hanger fitted with -8AN outlet and -6AN return (connected to stock fuel lines)
• Dual Aeromotive 340LPH pumps
• DEKA 80lb high Z fuel injectors
• Billet adjustable fuel pressure gage
• Racetronix fuel injector harness (Part #G77)

Brake System
• Hydratech Hydro-Boost brake booster
• Wilwood Master Cylinder
• Wilwood proportioning valve
• Rebuilt power steering pump
• S10 rear brake cylinders and with Kirban soft long shoes
• Stainless Steel front brake lines
• Hawk brake pads on front brakes
• Brake speed bleeders for front and back

Front Suspension
• F-Body 34mm front sway bar with new end-link set
• Frame braces (2) purchased used
• Grand Prix brace (used) to form triangle – installed toward front of frame
• QA1 single adjustable front shocks
• Savitske front upper control arms – Stage 1 with greaseable bushings and NASCAR ball joints

Rear Suspension
• Strange single adjustable rear shocks
• UMI Rear Shock tower brace
• Dual airbags with independent air valves(on vehicle when purchased)
• GNX body bushings
• Brace tying rear frame together – 1” rectangular steel
• HR Parts anti-sway bar
• HR Parts lower control arms
• Metco adjustable upper control arms (used)

Wheels & Tires
• Mickey Thompson ET Drag Wheels 15x8; weight – 12 lbs each
• Front: BFG T/A radials 225/60/15 Rear: MT Drag Radials 275/60/15

• Reproduction GNX dash with Auto-meter Phantom gages
• Kenwood rear deck 4x10 speakers
• GNS 3-gage holder with Auto-meter Phantom fuel press, trans temp, and coolant temp gages
• Black and gray console riser with cup holders
• LED lighting throughout interior
• Highway Stars Exclusive front and back seat covers
• Highway Stars Exclusive door panels – Front and Back
• Black billet shifter handle from TR Customs
• Ashtray 5 switch panel
• Alky control panel in dash on left side by head light switch
• Kirban T-top shades
• Steering wheel wrapped with new leather

• Alradco HID low and high beam headlamps 4300K
• Window motors – Driver and passenger sides
• New GM door seals
• GNS LED taillights and 3rd brake light
• LED front driving lamps and turn signals
• Trunk carper Kit

• ATR Stainless Steel Headers ceramic coated (came w/ purchase of vehicle)
• ATR Stainless Steel downpipe (came w/ purchase of vehicle)
• Electric cut-out (used) with QTP turn down
• ATR 2.5” Stainless Steel Exhaust
• ATR Pitbull Mufflers

Ignition and electrical System
• TR6 Ignition
• Extension harness to mount box on Driver’s side inner fender well
• Custom made Moroso Ultra 40 wires made for TR6
• New Autocraft Gold battery May 2015
• Rebuilt Delco CS144 alternator with 240 amp upgrade
• Positive and negative battery cables from Caspers Electronics

• Window Sticker (reproduction)
• Dealer invoice
• Build sheet
• 1987 Buick Owner’s Manual and other documents
• Car fax from when I purchased

• Braided line for turbo oil drain from TR customs
• New AC Delco water pump and radiator hoses
• Angle Boss
• Vibrant Performance vacuum manifold mounted on firewall
• Stainless steel hard coolant lines w/o TB coolant line nipples from GBody Parts
• Smoked taillights w/ GNS LED lights
• Smoked side marker turning lights w/ LED bulbs
• Clear bumper marker lights w/ LED bulbs
• Interior LED lights for each fuel pump (2nd pump on at 15lbs) and Evac pump (on at 4lbs)
• Stainless steel header bolts
• Stainless steel bolts for water pump
• RJC aluminum pulleys purchased used
• IAT extension to relocate sensor in back of intake
• Comes with 1987 Buick Grand National Manual and documentation
• T-top bags
• Remote keyless module installed – one key fob for car
• Upgraded rearview mirror with compass and garage door opener

It does have a rear main seal oil leak and the power steering pump will whine a little due to the hydroboost. Paint does have shrinkage (orange peel) in spots. I can send serious buyer plenty of pictures.


  • IMG_1255.JPG
    674.1 KB · Views: 861
  • IMG_2997.JPG
    726.5 KB · Views: 744
  • IMG_2993.JPG
    688.5 KB · Views: 730
  • IMG_2983.JPG
    1,006.5 KB · Views: 796
  • IMG_2986.JPG
    964.8 KB · Views: 782
  • IMG_3003.JPG
    1.1 MB · Views: 829
  • IMG_3005.JPG
    1.1 MB · Views: 813
  • IMG_2998.JPG
    777.7 KB · Views: 750
  • IMG_2991.JPG
    590.4 KB · Views: 727
  • IMG_1235.JPG
    1.2 MB · Views: 713
Last edited:
More pictures


  • IMG_2989.JPG
    881 KB · Views: 421
  • IMG_2994.JPG
    959.2 KB · Views: 434
  • Dyno.JPG
    105.4 KB · Views: 423
  • IMG_2702.JPG
    234.5 KB · Views: 430
  • IMG_2984.JPG
    917.9 KB · Views: 421
  • IMG_2991.JPG
    590.4 KB · Views: 397
  • IMG_3001.JPG
    795.6 KB · Views: 402
  • Trunk Label codes.JPG
    Trunk Label codes.JPG
    520.7 KB · Views: 389
  • IMG_3006.JPG
    1 MB · Views: 428
  • IMG_3010.JPG
    1.1 MB · Views: 413
Some more pics of interior and the engine build.


  • interior.JPG
    704.3 KB · Views: 282
  • interior1.JPG
    687.8 KB · Views: 286
  • interior2.JPG
    712.8 KB · Views: 291
  • Eng.JPG
    78.6 KB · Views: 306
  • Eng1.JPG
    74.5 KB · Views: 299
  • Eng2.JPG
    82 KB · Views: 295
Few more pics of LED lights, dash and trunk label.


  • IMG_3028.JPG
    864.1 KB · Views: 213
  • IMG_3031.JPG
    723.9 KB · Views: 223
  • Trunk Label codes.JPG
    Trunk Label codes.JPG
    520.7 KB · Views: 190