Be sure to check out Part 1 and Part 2 of our 426 Hemi install!
Excitement prevailed as we loaded up the Hemi for the trip to the dyno. We had to update the strain gauge on Mopar Engine West’s dyno, as it was limited to 1,000 lb-ft, and we predicted at least 1,200 lb-ft, from our engine. That wasn’t the hardest part of connecting our Hemi to the dyno. I also had to provide all the harnesses for the electronics, as this isn’t your typical Hemi. Once the engine is in the dragster, I will use an electric pump to prime fuel, because the engine has to be running before the mechanical fuel pump can produce pressure. But, on the dyno, we have to start the engine the old fashion way--spray raw fuel into the hat from a squeeze bottle. There’s something really nostalgic about doing it that way.
The Hemi fired right up, and while doing some manual loading to the engine so that we could build some heat and seat the rings, it became quickly obvious that we should not be using any blower over drive. We found that boost would scoot off the scale quicker than you can say, “Oh crap”! So, we kept changing pulleys until we ended up at a 1:1 drive ratio. The oil pressure looked good, and we had no leaks--yet. Dyno operator Dave Timmons noted that we would probably have to start the pull at 5,000 rpm, because the Dyno’s absorber couldn’t hold the torque at a lower rpm. It was a short pull, but our first pull was from 5,250 to 7,000 rpm.
I also realized that the dragster might start doing wheel stands, so I’ll launch on the throttle stop during testing, until I feel comfortable.
What we learned was, so much for our 1,300 to 1,400 horsepower target at 10 pounds of boost. With this short pull, we had 1,426 horsepower with only 8 pounds of boost. With a little more rpm, we’d definitely hit 1,500 horsepower pretty quick. And as you can tell from the screen shot who knows what the maximum torque could be. The computer estimated that 10 pounds of boost would yield 1,550 horsepower. Unfortunately, we developed a serious oil leak from the front of the engine, so we had to abort the session.
When this engine was in its normally aspirated state, I had been having oil-leak problems. The camshaft seal-retainer was popping out of the timing cover. This time, the crankshaft seal-retainer fell out of the cover. I was using the Jesel to make it easy to imbed the magnet for the cam sensor, since the cam gear is external to the cover. Dave and Angie at Mopar Engines West said, “Blown Hemis run a gear drive. Why don’t you?” So, we ordered a Keith Black gear drive set up for the dual drift key crankshaft.
The Keith Black gear drive is hardened, and impossible to drill. But, I had to imbed the magnet for the cam sensor, so I replaced the seven 12-point screws that hold the cam gear on the hub with seven socket head screws. It turns out that the socket heads are almost a perfect receiver for the MSD magnet that is part of the MSD 2346 cam sensor kit. All we needed was a little JB Weld, space the gear cover slightly to clear the taller socket heads, drill and tap the cover for the sensor, and we have a cam sensor. Sure, the gear drive will make some noise, but I doubt anyone will hear it.
We didn’t have a chance to go back on the dyno, but the computer’s prediction about what the volumetric efficiency of the engine would be at wide open throttle was very close, so the fuel correction was within two percent. During the manual loading and ring seat period, I did notice that the cylinder to cylinder EGTs were inconsistent. Fortunately, the FAST software allowed me to add and remove fuel on an individual-cylinder basis until the EGTs matched. I was able to get all the EGTs within 50 degrees before that first pull.
The chassis that we will be putting this Hemi into is a 185 inch Landshark dragster chassis. After all, we are competing in the Top Dragster class. Inside the transmission, we would need a seriously stout torque converter. The new Coan converter was much larger than what I normally used, but that’s what Coan said I needed for the higher horsepower level we were at. The decision was made to also change the rear gear. It’s rpm that kills engines, so I try to keep the trap rpm under 7,500. For this combination, I installed a 3.70 gear. I know that I’m giving up e.t. using this gear, but, since Top Dragster is basically a fast bracket class, as long as I can qualify, I’m willing to give up some e.t in return for some reliability.