ThunderV12, LLC

Re-Birth of the GMC 702 ci V12 Engine

Sales Page

Sales are backed up and we are not currently taking orders.  Check back here for updates to finished inventory. Below pricing may change when when the order book opens again.

Stock Long block $15,000

Rebuilt block, fresh bores, fitted pistons, fresh heads, balanced rotating assembly. Stock cam with new bearings, new rings, seals, re-ground lifters, stock oil pan and a SAE #2 bell. No induction, ignition, water pump, alternator, valve covers, flywheel or starter.

Turn Key stock engine $18,590

Stock long block finished out with stock intakes, points distributor, plain valve covers, 14" flywheel, old style starter, internal oil pump, factory oil filter, new holley style 4 bbl. carbs, water pump, plug wires and new 100-amp one wire alternator. Wired up and running on stand with 3 gallons of Brad Penn 30wt break-in oil and 50/50 antifreeze to control corrosion.

HP Long block $17,400

Same as stock long block but with HP "Hot-Rod" cam, upgraded valve train, higher compression and ARP custom rod bolts.

The ThunderV12. Turn Key HP Engine $24,900

Our signature engine. A true ThunderV12! The HP long block plus HP oil system, Dual carbs, distributor less ignition system,3hp modern style starter, GM bell housing adapter, 100-amp alternator, water pump and laser cut exhaust flanges. This engine comes on a stand and has been tuned using the settings we gathered on the dyno abusing our in-house dyno mule. We run the engine prior to delivery to set the chokes and check systems. This is a running engine! Simply the highest power crate engine you can buy between 2,000 and 3,000 rpm that is naturally aspirated and runs on 87 octanes. And it is an ultra-rare V-12 to boot. Yes, it should cost more.

Example of recent full build

Engine with 5sp overdrive trans and dual disk clutch.

The engine is a rare low time unit that ThunderV12, LLC has stuffed full of our signature parts. The core engine was easily a top 10% core. In other words, if you attempt to build such an engine yourself, you will need to buy 10 engines to get one this good.

Strength comes from the custom ARP fasteners. Power comes from the custom Hot-rod Cam and twin Holley style carbs. Reliability comes from the custom high flow oiling system based around the Peterson Fluid System hi-volume dual feed pump. Upgraded valve train components assure years of trouble-free performance.

The flywheel and clutch are from McCleod. Here we have a twin disk unit that optimizes 800lb-ft of holding power with low pedal pressure. Twin disk units are commonly only found on supercars. The bell housing is a Chevy style unit from Lakewood.

The transmission is a 5-speed overdrive TKO 600 from Tremec Transmissions. These transmissions have proven themselves both on the drag strips and the road courses around the world and should provide faithful service to a hot-rod for many years. We would not recommend this transmission for vehicles of excessive weight or for pulling heavy trailers. Our personal experience with a TKO behind a 700hp, 660lb-ft BBF with slicks has been flawless for over 70,000 miles of track and street use. The .64 OD ratio is simply wonderful on the street.

The engine ships with a chrome 100amp one wire alternator and (4) precut 1/4" exhaust flanges to aid in fabrication of your custom exhaust.

This engine is runnable on the shipping stand prior to sale.

Reserving Engines

Engine production is currently sold out. Check back often for updates.


We prefer engines be picked up in person at ThunderV12 LLC's dock in Evansville, IN. The engine can be run for the customer prior to loading. Engines are on shipping frames that easily fit in a pickup truck. We load all engines via fork truck.

With that said, ThunderV12, LLC has working relations with several freight companies and can ship engines anywhere in the US. If truck lines are used to ship your engine, ThunderV12, LLC will only charge our actual freight cost to your location.

There are two packaging options for engines shipped via common carrier (LTL).

  • We can ship the engines on the frames as-is for no additional packaging fee but we transfer all liability for shipping damages or theft to the buyer.
  • Option two is an additional $500 packaging fee and ThunderV12 will package your engine and accept liability for any freightliner damages or theft.

We can only accept liability for freight damages if engines are shipped pre-paid by us. Customers arranging their own shipping assume all liabilities of shipping.


ThunderV12, LLC will not release any engine that has not been paid for and cleared by our bank. Checks will have to wait for clearing. Wire transfers can be set up at the buyer's bank and executed quickly when the time comes to ship.

Sales Tax

All engines to Indiana customers or shipped to Indiana addresses, or picked up by the customer at ThunderV12 place of business will be charged 7% Indiana sales tax.

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