Since the 440 D.U.I. will not fit a Wedge engine with Indy heads, we felt that maybe the Hemi D.U.I. would be tall enough to fit one. Good friend Vic Palombo graciously lent us his '66 Charger with an Indy-headed RB, and our buddies at SLP welcomed the Charger for a flogging on their chassis dyno. This time the Hemi D.U.I. would be up against the MSD Pro Billet distributor with a more street-like MSD 6AL ignition box and MSD Blaster coil. For our baseline pull, the rwhp was 457 at 6,200 rpm, and the air/fuel (A/F) mixture ratio was a good-looking 12.8 at WOT (wide open throttle). Timing was at 39 degrees total-right where this Indy-headed Wedge makes its most power. We made three more pulls to confirm there was consistent power production.
At Vic's home garage, all the MSD ignition components and wiring were removed. This really cleaned up the engine compartment (see pics). We used the stock 12-volt wire that originally juiced the positive side of the coil to power the D.U.I. distributor. The original ballast resistor was bypassed. With the Hemi D.U.I. dropped in place, the stroked Wedge fired right up. We immediately noticed that it was running smoother and with better throttle response.
Now back at SLP, we made certain the timing was set at the same 39 degrees. With the Charger securely strapped down, the moment of truth came when SLP's Hank Denieki (Chief Engineer) punched the pedal down. We were very pleased to learn we picked up 5 rwhp. With the A/F at the same 12.8 we didn't need to reach into our boxes of Holley tuning supplies. Again, we made three more pulls to check consistency.
As an added bonus to our testing of the Hemi D.U.I., we wanted to see if Performance Distributors' Mini VIP (18-volt step-up regulator) would step up the power. The Mini VIP was plugged into the D.U.I. and another spin of the roller showed us 5 more horsepower to the wheels. That's enough of a power increase to be worth a tenth at the track. The additional spark output changed the combustion burn to a lean and mean 13.0 A/F. This was on an exceptionally warm and humid December day (72 degrees, 77 percent humidity). If it was cool and dry we would have richened it up for a few more hp but we left well enough alone.
Testing ignitions and seeing and hearing the new Street Hemi make 650 hp was amazing, considering we did no special tuning (using only an 830 Holley HP with 30 degrees timing, and unported heads and intake) on the mild-mill. Most enthusiasts with a Hemi or Indy-headed Wedge will see more power using the Hemi D.U.I.-if it will fit under the hood!