NMAC BTWN 2 SMA SEL ACFT IN UNCTLED TFC PATTERN.

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I WAS R SEAT PLT (PIC) TRAINING FOR MY CFI TICKET. THE INSTRUCTOR AND I HAD JUST MADE SIMULATED ENG OUT LNDG ON RWY 24R AT ENW. WE HAD BEEN MONITORING AND ANNOUNCING ON 122.7 CTAF/UNICOM ENTIRE FLT. AFTER LNDG WE CLRED RWY 24R AND TAXIED TO RWY 24R FOR DEP. AFTER A C172 EXECUTED A TOUCH-AND-GO ON RWY 24R I TOLD THE INSTRUCTOR TO CLR VISUALLY FOR TFC AND MAKE THE DEP ANNOUNCEMENT ON UNICOM. WE SAW NO TFC ON FINAL; PATTERN OR OPPOSING (ON ILS RWY 6L) SO THE CFI ANNOUNCED THE DEP AND WE ROLLED ON RWY 24R. (THE SCENARIO WAS I WAS TEACHING A PVT PLT FOR HIGH PERFORMANCE ACFT CHKOUT SO THE CFI WAS FLYING L SEAT.) AT APPROX 500 FT AGL I WAS MONITORING THE CFI'S PWR REDUCTION TO CLB SETTING (AT THROTTLE/PWR QUADRANT FOR APPROX 3-4 SECONDS) AND LOOKED UP TO SEE A RED/WHITE SKYHAWK ON A HEAD-ON COLLISION WITH US. AT THAT TIME I EXCLAIMED TO THE CFI FLYING TO 'BREAK R; BREAK R IMMEDIATELY!' HOWEVER; HE HAD WHAT I CONSIDER TO BE A NATURAL 'HUMAN' DELAY AS HE HAD NOT YET SEEN THE THREAT ACFT. AT THAT TIME I TOOK THE CTLS AND ENTERED A 45-50 DEG CLBING R TURN; AS THE THREAT PASSED OUR 7 O'CLOCK POS I GAVE THE ACFT CTL BACK TO THE CFI. WE DISCUSSED THE EVENT AND CONCLUDED THE OTHER ACFT HAD TO BE ON THE ILS OR NDB RWY 6L APCH AND THEY DEFINITELY HAD NOT BEEN ANNOUNCING ON CTAF. ENW HAS NUMEROUS TRAINING OPS (UNBELIEVABLY BUSY) AND HAS A TWR OPENING OCTOBER/XX/94 WHICH IS LONG OVERDUE BUT SHOULD RECTIFY THE PROB AT ENW AT LEAST DURING OPERATIONAL HRS. HOWEVER; I DO BELIEVE THAT WE HAVE REACHED THE POINT IN TIME WHERE COMMON SENSE AND THE AVIATION COMMUNITY AND THE FAA SHOULD REQUIRE RADIOS AND THEIR USE (ON CTAF) AT UNCTLED ARPTS.