To see video of Chenoweth's dyno run click here.
The annual Amsoil/Mopar Muscle Engine Challenge is a favorite subject here at Mopar Muscle because it gives us a chance to share so much great information with our readers. Since this year's contest featured a 440 spec motor, all of the builders had to use the same Indy SR cylinder heads, and their 440s were limited to a maximum .060 inch overbore and stock stroke. Additionally, all the engines had to run on the same Rockett Brand 93 octane pump fuel while on Comp's dyno, limiting the compression of most engines to around eleven to one. With rules such as these, our top finishers had to find incremental ways to optimize their engines' power and were forced to get pretty creative. This month, we'll go inside Chenoweth Speed and Machine's engine and show you just how they achieved their 695.8 hp and 567.3 lb/ft of torque for a combined score of 1263.1 and a third place finish in the Amsoil/Mopar Muscle Engine Challenge.
Known for their expert machine shop service, and for products such as their big-block main stud girdle and block-in-a-bag service, Chenoweth was expected to perform well during our competition. Engine builders Dale and Mike Chenoweth stated that they treated this engine like any other leaving their shop, using all new top quality parts and precise machining techniques, and didn't cut any corners simply because it was a dyno contest engine. They also didn't choose to bore their engine to the maximum size allowed by the rules. Since their block cleaned up at .030 inch oversize, they decided to stop there rather than boring to .060 inch over just to net a few additional cubic inches. This will allow the block to be taken to the next oversize if necessary during a future rebuild.
So how did Chenoweth Speed and Machine achieve nearly 700 hp from their pump gas 440? Starting with a factory block with a casting date of April 1977, they treated their block to Chenoweth's full "block-in-a-bag" machining service which includes completely cleaning the block, boring and honing the block with plates, decking and squaring all surfaces, bushing the lifter bores, and line boring the main journals. Once the machining was complete, a 440 Source 3.75 stroke forged crank and H-beam connecting rods were matched with a set of Diamond forged flat-top pistons, and the entire rotating assembly was precision balanced. Diamond moly piston rings were utilized and the Chenoweths used Clevite bearings throughout their engine. To keep the crank solidly in place and to prevent the main caps from "walking" during high-rpm operation, the Chenoweths bolted on one of their CRE Main Stud Girdle kits with a dipstick and pickup provision. We've used the main stud girdle kit before and have found it's a great way to tie the main caps to the oil pan rail, giving the mains an additional plane of support in high-horsepower applications.