Modified Mustangs & Fords
385-Series Ford Big-Block Build - Monster Mash, Part 3 - The Finale
Our Ford Racing 598CI T-Rex Fat-Block Wraps Up And Goes To The Dyno For Number Crunching
Our Ford Racing/MCE Engines big-block buildup hasn't been the easiest engine project to undertake due to its limited production nature. We have a block and heads you don't encounter every day, which makes it tricky to find compatible components. Because the C460 isn't a mainstream off-the-shelf cylinder head, finding just the right headers exhausted most of our resources. When we contacted Custom Performance Racing in Gardena, California, it was glad to accommodate us and knew exactly what we needed to make the most of our T-Rex 598. McAfee wanted a custom equal-length step header with 2 1/8-inch primary tubes that opened into 2 1/4-inch pipes and dumped into 4 1/2-inch collectors. We had to go with a 4-inch collector because necessary raw materials (4 1/2-inch pipe) weren't in stock at the time. The upside of going with 4-inch collectors is improved backpressure along with velocity for good scavenging depending upon valve overlap. Custom Performance Racing was able to fabricate a set of long-tube, equal-length step headers just in time for our T-Rex 598 dyno session.
We did run into fitment issues with our headers, however, as JGM Performance Engineering in Valencia, California, had a scattershield that was not compatible with our custom headers. There just wasn't enough space for the step headers and equal-length tubes to fit around the dyno bellhousing. Jeff Lattimer of JGM went above and beyond the call of duty when he modified the bellhousing to fit the headers. Unfortunately, this cost us a lot of valuable time that could have been spent dyno tuning. You'll want to talk it over with your dyno operator beforehand regarding the headers you'll be using. Many dyno operators keep a number of headers on hand to fit the dynamometer machinery, but some don't.
We went to the dyno expecting 800-850 hp and a comparable amount of torque. Some may consider this conservative, considering engines of this caliber can make 1,000 hp and more than 900 lb-ft of torque without breaking a sweat. McAfee takes a more conservative approach to maintain durability. He wants an engine that will stay together, while delivering planet-rocking power. You can't go rounds or make it to the winner's circle if you're picking your rods up off the ground.
We were pleasantly surprised that we well-exceeded our power number aspirations with this build. Our horsepower and torque numbers prove Ford Racing has one heck of a casting in its C460 race head considering the flow numbers shown above. Depending upon your budget, the ported Jon Kasse C460 head and a change to a larger carburetor would likely take the combination even further. Make no mistake, though-915 hp is enough to propel your modified Ford well into the 8-second range at the dragstrip. Check out how it went down.
Dyno Pull 1Holley 1,150-cfm Dominator
Ignition Timing: 32 Degrees BTDC at 3,500 rpm
Step pull in 500-rpm increments beginning at 4,000 rpm