Hello to everyone. Iíve searched the forum but havenít been able to get a good explanation. My newly acquired 70 SS 396 has cowl induction. Hood door is open until I start the engine, then closes. It stays closed until such time as the engine vac is almost nonexistent. If my foot is in the throttle sufficiently to actuate the switch next to the gas pedal, the electric pull-down solenoid will open the internal flapper in the hood, and assuming the external door is now open, cool fresh air will go to the carb.
Assuming this adds power to the engine, why do we limit this event to be a WOT function ? My thinking is this feature should be functioning ALL the time (assuming it actually helps).
Remember Iím a newbie to Chevelles. What am I missing ?
Not only are you a newbie, but it is abundantly obvious that you are quite young and have minimal knowledge of the design and development of performance during the "Muscle Car" era----------------of which the 1970 models were the pinnacle of the muscle car development.
automobiles, have an air intake system which ducts cooler, outside air into the fuel intake system. When the engine is cold, during startup and warmup of the engine, this cooler, outside air is closed off and warmer air is taken into the fuel intake system. Once the engine warms up, then the warm air is replaced by cooler outside air. It is------------AND ALWAYS HAS BEEN---------known that cooler, outside air coming into the fuel intake system will produce additional power, as opposed to hot, under hood air. The reason is because the volume of oxygen in cool air is denser than it is in warm (or hot) under hood air.
Back in the earlier days (50s-60s) of automotive performance development, ducting cooler, outside air into the air cleaner/carburetor was "high performance/hotrod" stuff. MOST of the auto manufactures offered some kind of system that ducted cooler outside air to the engine on their ultimate performance options. Only the SERIOUS
hi-perf engine options had some kind of fresh air intake for the air cleaner/carb (ie hood scoop, cowl induction, scoops under the front bumper, etc, etc)
Thus, a 70-72 Chevelle with the Cowl Induction hood made a very bold statement "Hey, I'm bad".
The question is, Did the CI hood provide any added performance? Since the CI hood option on Chevelles was introduced with the 70 model, that has been debated back and forth for many years. Back in the day, one of the automotive publications (HOTROD, Super Chevy, etc) did a comparison between Chevelles with equal engine options, one without the CI hood, onw with the CI hood. The final conclusion was MAYBE, MAYBE, MAYBE, under wide open throttle at higher engine rpm, there MAY HAVE BEEN a 10hp increase in engine performance.
As I mentioned, fresh air ducted to the engine intake system was once hi-perf stuff. Today, it's common on ALLLLLLLLLLL cars.
Soooooooooo, are you missing something? Not really. You're just too young to be familiar with what it was like back in the good ole days of true muscle cars.
, today's cars with performance engines will blow the doors off of yesteryears muscle cars. But NOTHING, NOTHING has the magic of an old time SS454 Chevelle, HEMI Charger, GTO Judge, W30 442, 427 Thunderbolt-------------and several others.
And with that said, the muscle cars of the 60s would also blow the doors off of the flattys-------------but I'd sure love to have a 32-34 roadster or coupe with a 300cube Mercury flatty with finned alum heads and 3 carbs, a LeSalle and a Columbia Butt.
By the way, is there anyone here who knows when/what the very first Chevy was available with ducting that provided cooler, outside air to the fuel intake system?