'72 LT1 Factory Supercharged Car

[Gordon A.]

I am trying to verify the possiblity that the factory authorized a Paxton supercharged LT1 to be built. The story is that the car went directly from the factory to Paxton.

Following is the information I have: Vin#1Z37L2S500783, Engine Block Cast #3970010, Engine Pad V0914CKY(Flint MI plant, Sept. 14, 1971 Assemb. date,350/355 HP solid lifters,4 Speed close ratio trans, ) Secondary # on pad is 12S00783, which matches VIN#. EXHAUST manifolds 3932461RH, Intake appears to be 3972110 LT-1 Holley carb, Polished, rear axle code AB M 181 E1-3:30:1.
Paint and trim codes, Paint 972, trim 400, A23(assem date of Aug 23, 1971
The car does have a tank sticker with it and it shows a CHY 2VLT-1 20 SPECIAL TURBO FIRE ENGINE option.

This is something I am completely unaware of and would like anyone's help in determining whether this is a real car. Thanks.

[William C.]

Re: '72 LT1 Factory Supercharged Car

Others may correct me, but by '72, it's my understanding that a GM "factory" sale would have required emissions certification, not a viable deal for a one-off. Paxton could have modified the car for sale under an exemption for low volume vehicle builds, but that should mean the title would read "paxton" as the manufacturer.

[Clem Z.]

did not zora have some supercharged vettes

built with his name on them????

[Duke W.]

Re: '72 LT1 Factory Supercharged Car

Agree with Bill on the emissions issue, and the business case for certifying what would be a low volume engine would have been weak as GM had its hands full even getting one or two optional engines certified. Also, the engine would have had to go through and meet all of GM's durability requirements.

The other issue was the GM management mandate that all GM engines operate on unleaded fuel, which was only available in 87 PON form back then. There were NO exceptions, and very little boost would be possible on 87 PON, or the CR would have had to be dropped so low that normal driving fuel economy would have made a big block look good.

Also, the LT-1 cam is a poor candidate for boost - too much overlap. Valve timing for a boosted engine should have very little overlap. Otherwise too much fresh charge leaks out the exhaust during the overlap period. An otherwise LT-1 except for substitution of the base engine cam would be a good candidate for boost as it has the added durability features of forged pistons and generally stronger bottom end components.

Paxton built "bolt-on" supercharger kits for various cars/engines going back to the sixties, and this would be a more likely explanation. Most of these kits had very modest boost level - about 5 psi.

Though it is technically illegal under federal low for anyone to modify a car without recertifying emissions, there is effectly no enforcement at the individual level other than state emission testing, which was not in place back then. Thus a company could get away with selling parts to individuals as long as that company didn't install them.

Several dealers/modifiers were served with "cease and desist" orders back then when EPA got wind that they were modifying new cars and selling them to the public without recertifying emissions. They had to either shut down or face possible civil and criminal action.

They all chose the former.

Duke

[William C.]

Re: did not zora have some supercharged vettes

Pre emissions era possible, or after retirement under one of the "low volume Manufacturer" exemptions that existed at the time.

[John H.]

Re: did not zora have some supercharged vettes

Clem -

Yes, but they were aftermarket conversions, and were turbocharged.

[Michael W.]

Re: '72 LT1 Factory Supercharged Car

I think all LT-1 cars showed 'special turbofire engine' on the tank sheet.

Our local chapter looked at a paxton equipped '56 last year. The owner was convinced that it was a factory installation.

[William C.]

Re: '72 LT1 Factory Supercharged Car

"Paxton" did not arrive on the scene until the 60's I believe when Granatelli either bought or sold McCullough, the manufacturer of the blowers used by Ford and Studebaker in the 50's.

[Loren L.]

It won't help Gordon in his quest, but

it's interesting that the last Engineering work order concerning the Cunningham 1960 LeMans engines was the purchase of pistons from Thompson Products in 1961. Under the SUBJECT heading on the WO:

"283 Cu. In. Engine For Supercharger Tests"

Perhaps the fact that there are no further #'s under that work order tells us what the results were.......

[Michael W.]

Re: '72 LT1 Factory Supercharged Car

That's right. Out of respect for the owner of this '56, we did not pursue the matter.

[Dick W.]

Re: '72 LT1 Factory Supercharged Car

Bill, I saw a Paxton on a '55 Vett in 1958 or 59. Five carbs. Was on the '55 engineering car that Bob McDorman has today. At that time the car was being campainged as a drag car, Church's Little Angel. Joe Wolf in Reading PA built the engines.