I will relate a little story of how I made a poor mans cowl induction for my RX7 GT3 car. I was having trouble with the Hondas that race in our series, it seemed they had at least 20km/hr on me at the end a long 1/4 mile straight away. Being the resourceful type I figured that the rules against rotary engines were so restrictive that there was no way to beat them unless I cheated and I was not about to do that.
So I bent the rules a little, the fresh air pickup for the interior heating system draws air right in front of the windshield through a grille--a nice high pressure area at speed. I cut a hole in the firewall and put a real cheesy looking aluminum dryer duct and a plastic adapter with flap right from the hardware store. The rules said no ram air systems but nothing about cowl induction and stated that as long as the system was not sealed it would be acceptable.
So here I was in tech inspection and the inspector has a look at my contraption and says "what the hell is that!". I explain that according to the rule book it is not a sealed system and proceeded to dump a pail of water down the grille, it ran out all over the ground with no restriction. He was happy but wasn't sure if the competition would be, so he called them all over to have a look. Needless to say there was lots of laughter and giggles because it looked so cheesy. It passed.
Now rotary engines are restricted severely by intake and exhaust. Any muffler will cost you 20HP and even Holley carbs are a restriction as changing to Dellorto carbs generally get you 15 free HP. I was running a Holley 750 DP. Out on the track it was immediately obvious there was more power especially at high speed, I sand bagged a bit so it wasn't too obvious. But during practice my speeds went up 30Km/hr on the straight and I could grab the next gear before braking for the hairpin-Yahoooo! Made a hell of a nice sound inside the car too!
During the next race I not only could keep them bastards from passing me on the straight but now it was a race to see who could get the inside line before the hairpin at 130 MPH. As the race progressed my fuel load lightened and it gave me even more of an advantage (rotary's are gas pigs!). I won that first 10 lap race. Ha Ha Ha!
I often thought about doing the same to a street car but with a nice carb bonnet and some nice 6" silicone hose, sure worked like a charm for me and is completely invisible from the outside. Filtering can be done with round K@N cone filters pointing into the hoses so it is possible.
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Outlawed tunes from outlawed pipes
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