We needed a vacuum source...
We needed a vacuum source to operate the power brakes and PCV valve. Neither the Race Demon nor the M1 intake had a provision for vacuum. RBRE drilled and tapped a vacuum port in the M1. The 493 has 11 inches of vacuum at its 1,200-rpm idle, just enough for our power brakes. We used the original valve covers as a reminder of our factory stock-appearing days-instead of using a racy-looking crankcase evacuation system, which could have given even more power.
Wheeling The Rollers
A conversation at Pocono Raceway with Ed Hamberger's-Hamberger is the legendary Mopar small-block racer of the '70s, founder of Hamberger's oil pans and Street Legal Performance (SLP)-son Dave, led to the mention of a new chassis dyno at the SLP facility in Toms River, New Jersey. This new chassis dyno is the latest, most accurate dual Eddy-current-type that can withstand torque levels of up to 1,000 hp. SLP is welcoming owners of different makes of musclecars to make an appointment for dyno testing. All vehicles will see some horsepower losses through the drivetrain between the flywheel and tires. Automatic cars will typically see a 70-120hp loss and stick cars about 50-75hp.
We made an appointment with Brian Reese (chief engineer at SLP) for our dyno session. On the half-hour ride to SLP, the R/T easily wasted an M3 Beemer. Upon arrival of the R/T, a freshly modified Z06 Corvette pulled out to let the '60s Mopar muscle machine onto the rollers.
Our RBRE motor would remain in the same state of tune as it was on Barton's dyno. We expected horsepower losses from the belt-driven accessories, air cleaner, and exhaust system. We also considered drivetrain losses through the heavy 727, although it is rollerized. The R/T also sports a lightweight 4-inch aluminum driveshaft. Chassis dynos measure power in direct 1:1 drive ratio. Would 500 hp make it to the rear tires of the R/T?
With E-Town closed for the...
With E-Town closed for the winter, we drove to nearby SLP Performance Parts for additional dyno testing. Before testing, a bung for an O2 sensor was installed. The O2 sensor monitored the air/fuel mixture ratio while idling, cruising, and WOT on the dyno. Also observed on each dyno pass were the mph, engine rpm, air inlet temperature, manifold vacuum, and water temperature. SLP's new chassis dyno is accurate (it estimated flywheel horsepower within 2 hp of Barton's new engine dyno) and can withstand extremely high torque levels of up to 1,000 hp. Some of the older-style dynos can't hold a high-powered car without tire slippage. We were able to coax 7 more horsepower and 12 lb-ft of torque through simple squirter swapping. We are anxious to see how 621-flywheel horsepower and 524 rear-wheel horsepower will relate to e.t.'s in our 4,000-pound B-Body. Maybe high 10s or low 11s. What's your guess?
With the R/T safely strapped down, the moment of truth came when Brian put the pedal down. The numbers read 515 hp at 5,431 rpm. Brian announced the R/T was the new dyno king on their two-month-old dyno! With that, more SLP employees came to see the car's power. Another spin of the rollers showed us 517 hp at 5,420 rpm.
Before the dyno testing began, SLP installed an O2 sensor to monitor the idle, cruise rpm, and WOT air/fuel mixture. The Superflow computer showed us we had an ideal 12.6 to 12.7 A/F mixture at WOT and 14.7 at idle and steady cruising speeds. With the proper A/F mixture, our jetting was on target, and the jets could stay in the box. At the strip, bigger-than-stock squirters always meant lower e.t.'s. We reached into our squirter box and grabbed a 37 and a 35 to replace the stock 31s. The larger squirters proved themselves worthy on the chassis dyno, picking it up to 520 hp at 5,462 rpm.
With the old 440 and the 950 Holley, a pair of 40 squirters worked for us at the track. We thought, shouldn't a pair of 42s be beneficial with more cubes (493) and the larger 1,000 Demon? Once again, it was proven bigger squirters equate to more power. Now the rear wheels were running to 524 hp at 5,476 rpm. The torque was up 12 lb-ft from the baseline made with the 31 squirters. With that, we called it a day.
Dyno tuning performed on Barton's engine dyno and SLP's chassis dyno enabled us to gain 38 hp and 84 lb-ft of torque at peak. The average 3,500-6,000-rpm improvement on Barton's dyno was 44 hp and 50 lb-ft of torque. On SLP's dyno, we picked up 14 hp and 19 lb-ft of torque using a 5,000-6,000-rpm average. We can't wait to get our dyno-tuned Barton engine to the track. We'll keep you posted-we're hoping for high 10s.
Working with Ray Barton and the gang, we could have built a motor with over 1,000 hp. But, that's not what we were looking for. We can't express how happy we are to have a real pump-gas (94 octane) street motor. The old 440 needed a half-race and half-pump-gas mixture to survive. Ray and his crew have put many R&D hours into these B&B "Krate" motors. So far, we've enjoyed over 300 miles with our Barton Bruiser. This motor delivers much more drivability and knockout power than the old 440, which was a strong runner.