quote:Originally posted by ItalFord:
... The Maserati Bora we have owned since 1977 has never given us any problems what so ever. The car runs smooth and never changes its tune with the wind. I wonder if this is a function of the build / system quality? Don't know. Why would'nt the pantera system be so unreliable ...
Every single cylinder internal combustion engine ever built has been equipped with independent runner induction. (single cylinder street motorcycles, dirt bikes, lawnmowers, power edgers, garden tillers, chain saws, leaf blowers, portable generators, cement mixers, construction air compressors, portable arc welders, motor boat engines, the list goes on and on). Multi-cylinder engines found on a lot of sporting equipment like "sport bikes" and several sports cars have also been equipped with carbureted IR systems. Ferraris, Maseratis, Lamborghinis, Porsches, Alfas, Lotus, Jaguars, Aston Martins ... even a European Ford Escort was equipped with IDF Webers.
There is an overwheling amount of evidence that an IR system can be a reliable and drivable induction system for a street automobile. It is a combination of carburetor set-up and camshaft design that will most influence the success. The things in a camshaft's design that will hurt an IR system are too much overlap, overlap that is not centered on TDC, or a late closing intake valve.
Modern camshaft design with narrow lobe separation, lots of overlap, a steep and narrow torque curve, a lopey idle, and a tire frying low rpm powerband is not a good match for an IR induction system. This is why Inglese Systems sells camshafts to compliment their induction systems; all of their camshafts have 115 degree lobe separation angles. My camshaft spec that I call the Cobra Jet cam would make a good cam for an IR system too. The 351C 4V cylinder head imbues a motor with a wide flat torque curve and therefore a wide flat powerband, with a strong mid-range rush. My camshaft spec was set-up to compliment that type of powerband. This type of torque curve and powerband is an ideal characterisitic for an IR induction system too, IR induction is very good at operating over a wide powerband with a strong mid-range rush. I am convinced the 351C 4V cylinder head was designed with IR induction in mind.
One problem I have encountered is that some people are not willing to give up their narrow LSA "hot rod camshaft" when they install an IR system; in being stubborn like that they've already destined their street motor project to difficulty or doom, in my opinion.
-G