The stroker was run with a...
The stroker was run with a set of Bassani long-tube headers designed for an '05-up Mustang chassis.
The test motor-at least the short-block portion-came from Coast High Performance. The stock Three-Valve crank, rods, and pistons were ditched to make room for a 3.75-inch stroker crank, forged connecting rods, and forged flat-top pistons which were notched with the necessary valve reliefs. On stock pistons, only an exhaust relief is required, but our stroker motor required both intake and exhaust valve reliefs in anticipation of the larger cam profiles the author neglected to order in time.
This stroker assembly was stuffed into a freshly machined production block and topped off with a set of ported heads. We wanted to make sure the additional lift and engine speed offered by the new cam profiles would not be restricted by the head flow. As indicated, the heads were treated to a competition valve job, a valvespring and retainer upgrade, and even slightly larger intake valves. Rounding out the test motor was a stock intake and throttle body, a set of Bassani ('05-up) long-tube headers, and attending 2½-inch exhaust pipes and mufflers. We liked the sound quality of the Bassani exhaust, and having the mufflers present not only greatly reduced the noise level (compared to open exhaust), but the free-flowing combination offered no power penalty over open pipes (we tested it). What could be better than all the power without the obnoxious noise levels associated with open headers?
The Bassani headers featured...
The Bassani headers featured 2½-inch collectors feeding 2½-inch exhaust pipes. To test whether the collectors and pipes were in any way restrictive to this test motor, we had Bassani whip us up a set of 3-inch collectors and pipes. There was no gain whatsoever from the larger collectors on this test motor.
Running the test was actually quite simple, as even cam changes are a snap on the engine dyno. The new motor was given time to break in using conventional 5W-30 oil from Lucas, but for all of the testing we switched over to the good (synthetic) stuff. During the break-in procedure, we even added some of the break-in lubricant offer by Lucas. Run with the stock cams and tuned using the FAST XFI management system, the 4.6L Three-Valve stroker produced peak numbers of 379 hp at 5,900 rpm and 405 lb-ft of torque at 4,300 rpm. It should be noted that we had no way of controlling or altering the variable cam timing offered by the Three-Valve motor. Retarding the cam timing higher in the rev range would certainly enhance the peak power production, but so too would this be the case for the Comp cams. Having tested this previously on a 4.6L Three-Valve motor on the engine dyno, retarding the cam timing by 8-9 degrees can be worth as much as 12-15 hp. Regardless, we were happy with the power and torque production of the stroker assembly and were anxious to see what the Comp cams had to offer.
Installing a set of Bassani...
Installing a set of Bassani long-tube headers can be worth some serious power. We've seen gains as high as 20 hp over stock exhaust manifolds from a properly designed long-tube header.
After back-up runs produced identical results, we got the wrenches flying and off came the valve covers, front cover, and eventually the cams themselves. It was necessary to bleed down the lifters prior to installation of the new Comp cams. This was performed slowly in the vice, as com-pressing the lifters made installation of the rockers much easier. Like the previous Two- and Four-Valve motors, the timing chains employed on the Three-Valve motors featured copper-colored links to designate the proper position on the cam and crank sprockets. We simply positioned the crank at TDC and adjusted the cams using the marks on the sprockets and chains. This should be done prior to the installation of the rockers, but make sure to install the lifters before installing the new cams. Be sure to reinstall the wheel for the crank position sensor before bolting on the front cover.
With the new Comp cams in place, our Three-Valve stroker was ready for action. After minor changes to the tune-up (to duplicate air/fuel and timing values), we were rewarded with new peak numbers of 397 hp at 6,000 rpm and 412 lb-ft of torque at 4,500 rpm. The mildest of the Xtreme Energy cams offered an extra 18 hp measured peak to peak and as much as 20 hp at 5,300 rpm. Even more impressive was the fact that the sizable gains offered past 4,000 rpm came with no penalty elsewhere in the curve.
In addition to the long-tube...
In addition to the long-tube headers, Bassani also provided a set of 2½-inch exhaust pipes and performance mufflers. We ran the motor with and without mufflers and found that the only change was sound quality. The Bassani mufflers did not reduce the power output of this motor one bit, but they certainly made testing much more enjoyable since we didn't have to run the motor with open exhaust.
All of the programming for...
All of the programming for the motor was provided by the FAST XFI management system, which allowed us to duplicate the timing and fuel curves for each cam combo.
Run on the dyno with the stock...
Run on the dyno with the stock cams, the 5.0L Three-Valve stroker produced 379 hp and 405 lb-ft of torque.