vega

Unfortunately 1975 was the first year of catalytic converters at GM and they
were very restrictive, so power was ridiculously low then, and gradually
improved as catalysts got better.
Now that my Cosworth restoration is completed and is now being entered into
area (Dallas/Ft. Worth) car shows, I have made some display signage. I have
come across some interesting statistics and comparisons between the Cosworth
and three other 1975 Chevys.

The advertised Cosworth's 110-111 horsepower at 5,600 rpm doesn't sound
impressive at face value today with V6 Camaros rated at 304 hp (SAE Adj.)
and base LS3 Corvette engines rated at 430/436 hp (SAE Adj.). All my
performance figures will be in the GM standard used in 1975, SAE Net, the
numbers used for advertising, unless noted otherwise. I know Duke will keep
me honest.

So, I began researching the specs of various 1975 Chevys and what I found
was surprising and at the same time, enlightening. You already know that
1975 GM cars were the first models to have HEI (high energy ignition) and
catalytic convertors. The 1975 sales brochures touted these improvements as
those that would allow the engines to be tuned for more responsiveness and
"performance" . Wow, the performance part was misleading. 1975 Chevys had the
lowest performance figures (hp/liter displacement) of any '70s Chevrolet.
That is, EXCEPT for the Cosworth Vega engine! Only in the very late 1980's
did GM's engines begin to gain substantial performance figures.

I took three other popular '75 Chevys, the Vega, the Corvette, and the V8
Camaro. I then compared them to the Cosworth Vega. The Vega body was the
lightest of the three, weighing at about 2480#. The Corvette weighed about
3660# and the V8 Camaro weighed about 3532#. So, you can already see that
the Vega body was at least 1,000 lbs. lighter than the Corvette and Camaro.
That low weight is why we saw loads of V8 Vega drag cars in the 1970s and
80s.

Now, let's reference the engine statistics. The Corvette and the Camaro both
had the 350 cubic inch (5.7 liter) iron engine with a four barrel
carburetor. The base Corvette engine (L48) was rated at 165hp @ 3800rpm. The
base V8 Camaro had its engine rated at 145hp @ 3800rpm. The standard Vega's
base engine was the 140 cubic inch (2.3 liter) SOHC engine with a one barrel
carburetor, rated at 78 hp @ 4200rpm. All this is meaningless unless you
compare horsepower per liter displacement and the power to weight ratios.

The Corvette's OHV base engine had 29 hp per liter
The V8 Camaro's OHV base engine had 25 hp per liter
The Vega's SOHC base engine had 34 hp per liter
The Cosworth DOHC engine had 56 hp per liter
Higher numbers are better, just as in bowling. The Cosworth engine was very
impressive for the day! The only other cars sold new in America with a
similar engine (DOHC-16 valve I-4) were Loti (plural for Lotus?) and the
Jensen-Healey that had a Lotus engine. The Cosworth was the ONLY one with
EFI (electronic fuel injection).

Above is about engine output. Let's compare the real issue, power to weight
ratios or how did they REALLY perform?
The Corvette does pretty well with 22.18 lbs. per horsepower
The V8 Camaro had 24.36 lbs. per horsepower
The Vega had 32.1 lbs. horsepower
Lower numbers here are better. And...Ta Dah...the Cosworth has 22.34 lbs.
per horsepower, pretty much comparable to the Corvette.

So, why was the Cosworth so darned expensive, over $2000 more than a V8
Camaro and only $600 less than a Corvette? Well, the all-aluminum engine was
very costly for Chevrolet/GM to produce and the loss on EVERY CAR was
initially written off as an "engineering exercise". But, when Vega sales,
totalling a million by the end of the '74 model, fell precipitously in early
'75 due to the press coverage about blown-up Vega engines, the Cosworth
quickly lost all its support. The '75 Corvette convertible list price was
$6,550 in 1975. The '75 Cosworth Vega list price was $5,916, so if you think
that the Cosworth Vega wasn't a "good value", it certainly gave you a decent
power to weight ratio for the times.

The Cosworth Vega is a part of American automotive history. Take better care
of your car, for it is the rarest of the rare.