We Wrap Up Our Summit Racing/MCE Engines 331 Stealth Stroker, Then Put It On The Dyno For A Little Truth-Telling
Last month, we began our two-part series on how to get 400 hp and 400 lb-ft of torque from a 331ci stroker small-block fitted with factory Ford iron cylinder heads, and we learned something remarkable during the attempt. You can achieve 400 hp and 400 lb-ft of torque from 331ci and iron cylinder heads without selling the farm.
This month, we wrap up our Summit Racing/MCE Engines 331 Stealth build and show you why we fell a pinch short of 400/400. What's more, we're going to show you how to hit pay dirt and make 500 hp and 500 lb-ft of torque with a few easy modifications and these same iron Ford heads. Think we're just bench racing? Read on ...
Let's begin with the events of a steamy, hot Southern California summer day. We arrived early at Westech Performance to get our 331 Stealth small-block engine on the dyno. Right away, two things necessary to make the projected power weren't available at Westech on the day of our test. Without a velocity stack for the carburetor and the appropriate-sized 1-3/4-inch Hooker Super Comp headers, our numbers fell below 400/400. Despite these shortcomings, we did remarkably well on the dyno, turning in the broadest torque curve we've ever seen from a low-cube small-block Ford.
When Marvin McAfee of MCE Engines was planning our 331 Stealth small-block, he predicted numbers between 350-400 hp and 350-400 lb-ft of torque through the mufflers, which we essentially made. Marvin's goal was a streetable small-block powerhouse that would:
Have a single four-barrel carburetor; Have a cam profile that would provide enough intake-manifold vacuum to operate power brakes and run other accessories; Operate on pump gas; Be able to run an automatic or manual transmission in a matter of hours, swapping a flexplate for a flywheel; Have the minimal upgrades required to make at least 100 more horsepower from the same short-block and iron heads.Under ideal circumstances, we should have achieved 410 hp and 404 lb-ft of torque with our engine package. Ideal conditions include:
A velocity stack on the carburetor with cold-air induction; Ambient temperatures in the 60s with humidity in the 40-60-percent range; A match-balanced flywheel. Westech didn't have a dyno-coupling package that would work with our match-balanced Milodon flexplate; Hooker Super Competition headers with 1-3/4-inch primary tubes; Open headers or a verifiable set of low-restriction mufflers.