GMC V-12

Cranked up the GMC 702 V-12 that will be going in my '50 COE soon. It is stock except for the Jet 500 cfm two barrels I adapted to it.

Category:

Autos & Vehicles

Tags:

• GMC
• V12
• V-12
• 702
• Twin
• Six

[jrkepler]

This isn't really that impressive of an engine. It was huge, heavy with really quite modest horsepower for its size. It was rated at 250 HP despite its massive displacement. This really was about the last effort, the diesels were just so much better for trucks that standard petrol engines just couldn't compete, really a treat to see one of these rare pieces in working order.

[LocomotiveBreth]

@jrkepler You are slightly off on your HP numbers. The 7.5 to 1 compression truck engines were rated at 275 HP and 630 ft. lbs. of torque from 1600 to 1900. This engine has the 9.0 to 1 natural gas pistons, and bigger carburetors, it's probably around 300 HP and 650+ ft. lbs. of torque. A modern naturally aspirated diesel of the same displacement would be similar. Add boost to either engine and the numbers go way up. The rising price of gasoline and poor economy is what killed the big gas engs.

[cedartowndawg]

Is that a legit v12 or just two v6s ran cam to cam?

[LocomotiveBreth]

@cedartowndawg Its a real V12, one piece block, crank, cam, just uses heads, manifolds, valve covers off the V6 version.

[paulmerz]

Needs a half dozen Weber DCOE..would sound much better!

And, of course, look better.

[scott93257]

@LocomotiveBreth

Your engine is a thing of beauty. It's too bad what the economy has done to these things...

[ztwntyn8]

realy effin responsive breath

[rewind48]

imagine..... dohc, efi, electronic ignition, and dual stage quad turbochargers feeding into one intake manifold.......

[28yogy4todd]

I've got the little brother engine in my 59 gmc, the 305 ci V-6

[TheVooDooReverend]

This is called the GMC Twin-Six

[cedartowndawg]

@LocomotiveBreth Ahh, alright. Makes sense in terms of cost and availability.