<VV> August 1975 Hot Rod Magazine/Remember Corvair Sand Buggies?

[Andrew Allen]

Greetings,

Bob Helts 'Corvair Secrets' is a pretty cool book in
that it's kind of a display of Mr. Helt's long history
and gathered wisdom regarding the Corvair. I think
it's a nice companion to 'Corvair Basics' and is
essentially a collection of briefs.

One brief entitled 'Building a Hi-Performance Engine'.
In the brief he debates the relative effectiveness
deviating from a stock engine and going whole hog on
modifications in search of more horsepower and/or
torque. Mr. Helt points out that unless you are
equipped with all kinds of diagnostic and testing
capability and, apparently, all the time in the world
you will be hard pressed to beat a basically stock
engine.

The August 1975 issue of Hot Rod Magazine has part two
of a sand buggy article that compares five differently
modified Corvair engines on a dynamometer. This
artilce is metioned in the brief to back up Mr. Helt's
opinion and experience.

The article tests five engines. Engine one is a stock
140 out of a '65 Corsa and is tested three ways. This
engine was provided by Bob Helt.  First with the stock
carbs and linkage and the result is peak horsepower of
120 at 5000 rpm and a broad torque range that peaks a
about 150 ft/lbs between 3000 & 4000 rpm. Additionally
"High speed engine misfire was observed about 5500 rpm
and was attributed to valve float." This same engine
was then tested using the IECO and Edelbrock 4 bbl.
set-ups resulting in a 4% gain in HP and 7% gain in
torque in the same rpm range.

Engine two belonged to the author and was essentiallya
stocker 140 running with four primary carbs and the
Crown carb rotator linkage, signifigant head work,
high lift cam and exhaust headers. The result?
A shift in the torque output and 4% gain in HP.
"Certainly not much of an advantage over a stocker to
justify all the modifications."

Engine three has .60 bored barrels, bored primary
carbs using the Crown linkage, wild cam and individual
zoomie headers. The result? Overall loss of BOTH HP
and torque. "It may be speculated that the
long-duration, high overlap cam used somehow went
beyond the breathing limits of the heads, and the long
individual exhaust pipes provided no scavenging or
extractor effect to further impair breathing. But of
course this is pure conjecture. We are still
scratching our heads on this one."

Engine four had heavily modified heads with welded on
Motive Vair tunnel rams each sporting a Holley 500cfm
2bbl, .60 over, a high lift, long duration Crower cam
and a Vertex magneto set. Yikes! Well...140 HP at 5600
rpm with torque, predictably, down and peaking at
about 145 ft/lbs between 4000 and 5000 rpm.

Engine five was provided by "3 Liters Corvair"  and
was the most modified of all. 3 1/2" barrels for 195
cu. in., milled heads to provide 11:1 compression and
heavily modified intake and exhaust systems. "The
stock intake manifolds were replaced with a custom ram
tube connected directly to each intake port from a
common center mounted log manifold supporting three
two-barrel 210 cfm Holley 1929 carbs."
The exhaust system was really tricked out too. They
had some fuel starvation issues during testing this
engine but recorded 210 ft/lbs torque at 3200 rpm (!)
and predicted it would have showed HP in the range of
200 if they didn't have the fuel starvation problem. 

The conclusion is you have to get totally nuts with
the mods and be REALLY dedicated to beat the stocker
in any meaningful way.

Whew! I'm getting the July issue.

Cheers!

Andy
'66 A/C Corsa









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