FS: 1984 Grand National Turbo 6.0 LS Swap 7875 4L80E


New Member
Jan 26, 2016
I don't know if this should go here or in For Sale, but it is located in Carlsbad, CA. My name is Chip if you PM me on here I'll give you my phone number.
The price is $20k, obo.

For you real sensitive guys who get offended by the swap, make sure to tell me all about it.

Video of car driving

Hello! This is my car, I did all the work on it, and I can answer any questions. I am a semi-professional EFI tuner (my main job is developing manufacturing software). Please read everything below. I tried to document everything and take lots of pictures with labels. I set this car up to be a basic 9 psi, pump gas, low maintenance, fun hot rod, and it is just that.

This car is not emissions-compliant in California (or states that enforce the same standards on cars this old).


  • Real 84 Grand National - 99.9% rust free west coast car with all common G body problem areas photographed
  • Very straight, very clean, beautiful 37 year old car, compliments everywhere
  • Clean title no known accidents
  • Odometer shows 169k miles
  • Only known rust spots are front corner of driver door - door jamb was repaired at some point. There is a small pit above passenger door that has not advanced in last 7 years
  • Some light paint fading on roof
  • Last owner spent $7000 painting car 6 months before I bought it
  • All original sheet metal, never removed from frame
  • Original 84-85 15x7 aluminum wheels, 2 extra 15x8.5 replicas included
  • New spoolfool bumper fillers
  • No T Tops
  • Original 84-85 hydraulic brake booster with no problems unlike 86-87 electric brakes


  • Full dynamat on floor and roof
  • Original 84-only Lear Siegler double lumbar seats rebuilt with new padding - power driver seat, leg support extends, passenger seat is manual
  • Factory console with 4th gen F body shifter with correct detents for 4L80E
  • Sale includes original Buick radio, extra mint grill, new set of weather stripping, other small GN parts
  • Electric windows work, vent works, rear defrost works
  • No heat or A/C (heat could be easily hooked up and A/C is not removed from car)
  • Fuel gauge works, speedo does not work with 4l80E - Holley EFI has speedo
  • Bluetooth stereo, new recent 6x9 rear speakers
  • E brake works
  • Remote driver mirror works
  • Black carpet, black headliner, OE driver black door panel, some panels painted black


  • Holley Terminator X Max EFI mounted in passenger footwell
  • Controls LS engine, 4L80e transmission, engine fans, trans cooler
  • Can control boost and E85 if future owner wants to add


  • 6.0 LQ4 with "Gen IV" floating rods and .030" over OE-type pistons
  • Originally purchased through LKQ, refreshed by Machine Tech in Oceanside, CA at time of conversion
  • Holley 302-2 swap pan, engine side mounts, transmission crossmember
  • LS9 head gaskets, stock head bolts
  • Stock 317 heads with .660" lift dual valve springs, locks retainers, rocker trunnion upgrade
  • Elgin "Sloppy Stage 2" camshaft 228/230 @ .050, .585/.585 lift, 112 LSA
  • Idles at 825 RPM in gear - 12 inches manifold vacuum (not required for hydraulic brakes)
  • Stock LQ4 truck intake, fuel rail, regulator, throttle body
  • Real siemens deka 80 lb injectors


  • Hooker turbo LS driver manifold, fabricated crossover pipe, passenger log manifold
  • On3 7875 turbo
  • -4 AN oil feed with restrictor
  • -10 AN oil drain to timing cover
  • Turbosmart 50mm wastegate
  • No BOV
  • 3" aluminum piping into intercooler
  • 31x12x4 front mount intercooler
  • 3.5" pipe out of intercooler
  • 3" downpipe into 3.5" single exhaust with catalytic convert and bullet muffler


  • G Body 305 "tow package" El Camino radiator from Auto Zone
  • Ford Windstar electric fans - about twice the CFM of LS1 4th gen f body fans
  • Can be driven in 100+ degree stop-and-go summer cruise nights without overheating

Engine accessories:​

  • Engine oil cooler mounted in front
  • Factory silverado crank pulley with ARP bolt
  • Silverado power steering pump with cooler
  • small case "car" LS alternator for hood clearance
  • silverado water pump
  • Stock truck coils
  • NGK TR6 spark plugs
  • Ebay "nascar" spark plug wires with great heat shielding


  • GM Goodwrench 4L80E that was new in crate 7 years ago
  • Transgo shift kit
  • Circle D triple disk billet converter they built to provided specs
  • Transmission has been 100% awesome
  • Stock 6.0 flexplate
  • Stock 2500 Silverado 4L80E locking dipstick
Fuel system:
  • OE grand national fuel tank and hanger with Walbro 525lph "Hellcat" fuel pump
  • 10 GA wire and 40A relay to rear, run by Holley EFI
  • 3/8 feed and 5/16 return Dorman OE-style vinyl fuel lines
  • Uses fuel filter from ~2013 660hp GT500 (3/8 quick disconnect on both sides available at any Auto Zone)


  • Original 8.5" 3.42 posi 10 bolt "Grand National rear end"
  • Passenger axle replaced with aftermarket after wheel stud broke


  • Wilwood 12" 4 piston front disc brakes - much better, safer, and lighter than factory discs on original spindles
  • Factory rear drums
  • Rear upper and lower tubular control arms with RUBBER bushings for smooth street driving
  • Front upper and lower factory control arms rebuilt with new rubber
  • OE-style shocks all the way around
  • Factory G Body Monte Carlo SS 305 "handling package" coil springs that sit very nice with the weight of the LS/4L80E
  • Car rides very comfortably "like a Buick"
  • New front sway bar bushings
  • Car drives nice and straight but could use front tie rods eventually (I believe original)
  • Original steering box with no noise

Common Questions:​

Question 1: Do you have the V6?

No. The 4L80e is run by Holley EFI, and COULD be used with the v6 with an adapter. Holley EFI can also run the v6 if someone wants to convert it back. No permanent changes were done. The LS is installed using OE 5.0 regal mounts.

Question 2: Is it a real Grand National?

It is a real "hot air" Grand National, not a T Type, not a Regal, not a clone.

Question 3: How much power does it make?

I do not know.
Never dynoed. Tuned by me on the street. Research sloppy mechanics "dont bs me" combo for similar 7875 turbo LS numbers.

Question 4: What does it run in the 1/4 mile?

I do not know.
I have only used this car to drive my kids to cruise nights. I have not raced it. It does not have a driveshaft loop or some of the other items required to run NHRA. If you want to race it you will have to check with your local track what they would require. The closest regularly operating 1/4 mile drag strip is 6 hours from me.

Question 5: How fast is it/how powerful is it?

It will fry the tires from 30mph until you lift. Fastest car I have owned/been in - you may think differently.

Question 6:
What kind of gas does it use?

I use pump 91 octane. No methanol/water.

Question 7: How reliable is it?

I have been semi-daily driving it for 7+ years. It has been on a few 1000 mile trips to other states. The engine and transmission seem to be about as reliable as if they were still in a silverado.


Purchased car in Chehalis, WA. Originally sold in CA. Owned back-and-forth by same family (traded between brother-in-laws) since new. Car was all original when I purchased.Original 3.8 wiped camshaft on way to California. Car included two more 3.8s - both had cracked blocks. Made the decision to swap to turbo LS combination for greater power and reliability on pump gas. Originally used LS 411 PCM and HpTuners, switched to Holley EFI TerminatorX when it became available.


New Member
Jan 26, 2016



You can't knock them up with spit.
Dec 9, 2002
Lot's of info but no price? Looks decent, good job on it.


New Member
Jan 26, 2016
Thanks for the PMs and questions everyone. The car is now over $20k on ebay with three days to go so I believe I will wait to see how that pans out before pursuing other options.


May 19, 2006
I was unable to find the car there, did it wind up selling? Very cool, but all the pics here are gone too :(