Muscle Mustangs & Fast Fords
1985 Mercury Capri 5.0 Dual Exhaust System Part 3
A Dual Exhaust Uncorks Our Capri, And Some Track Tricks Get This 5.0L Moving More Quickly.
Although the late-model Mustang movement didn't really take off until the fuel-injected 5.0L Mustangs started taking out Brand X cars left and right, Ford's carbureted 5.0L Mustang and Mercury Capris were plenty fast given similar mods. We've so far proven this with our project ercury Capri, and this month we continue to chop at the elapsed-time clock with a dual-exhaust setup, a few changes to our track procedure, and a couple of mechanical modifications.
In the last few issues of MM&FF, we've been modifying this '85 Merc with bolt-on parts, including an intake manifold and carburetor from Summit Racing Equipment, Performance Distributors ignition system, and lightweight Weld Racing wheels with Toyo Proxes slicks. The modifications have allowed us to take this once-sluggish 15.6-second ride to a quick 13.92 at 97 mph. Shaving a second and a half off our elapsed times and adding some 8 mph has been a lot of fun, and this month we aim to improve on our success further.
Since we opened up the intake tract with the Weiand Street Warrior manifold and a more appropriately sized Holley 600-cfm carburetor, it was time to uncork the exhaust system, which up until now was utilizing the factory two-into-one-into-two arrangement. It's amazing to us that the car still had this on it when we picked it up, but it's time for it to go in favor of a true dual exhaust system.
While we could have gone the shorty header route, we decided to optimize the combination by going with long-tube headers. Summit Racing provided us with a pair of Flowtech 15/8-inch headers that wear a nice ceramic coating. The high-temperature ceramic coating will help keep heat inside the header tubes, which helps speed up the exhaust gas' exit, not to mention that it keeps the headers looking nice for years to come. With long-tube headers comes the need for a shorter H- or X-midpipe. Going for the deeper, more muscular sound, we opted for Flowtech's H-pipe sans catalytic converters. It's an aluminized steel piece that features the same three-bolt flanges that the header collectors have.
Looking to keep a cap on excessive noise, we called the folks at Dynomax for the back half of our system. Having used Dynomax's Ultraflo Welded mufflers, flow tubes, and tailpipes on project Stolen Goods a while back, we knew the Dynomax parts would fit well, provide the proper stainless steel tailpipe look we were after, and give our 5.0L a healthy sound without being obnoxious. This time we opted for the Ultraflo stainless steel mufflers, and to be perfectly honest, they sound exactly like the Welded series mufflers. In the staging lanes at the track, the Capri is quite quiet, and even in the burnout box, it's rather docile sounding, but at any rpm, it sounds great and no doubt has improved the exhaust flow. Summit Racing carries the Ultraflo SS exhaust system, and it also provided us with a new double-hump transmission crossmember from Ford Racing Performance Parts.
A couple of late nights in the barn, along with the help of MM&FF subcontractors George Xenos and Brian Bohnsack, had the Capri up and running in time for our track rental at Gainesville Raceway in Gainesville, Florida. We arrived with carburetor jets in hand, and a thirst for quicker elapsed times. Before we took to the track, we had to take care of a leaky freeze plug and used a rubber plug from the local parts store. These things have a bolt that goes through the middle and you can tighten it up in the hole so it doesn't blow out under the pressure. It is a great temporary fix, and we'll be replacing all of the freeze plugs here shortly.