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Ford Mustang Pro Comp Carbureted Turbo Engine
Dig Into This 1,000-Plus-Horsepower, 438-Inch Stroker Carbureted Turbo Torture Test.
At MM&FF, we just love it when a manufacturer hands us parts and tells us to go beat the living snot out of 'em. Not that we're especially abusive here, but we know our readers love nothing more than to see some big, fatty power numbers. In short, this was the perfect opportunity to subject a new block, rotating assembly, and ported cylinder heads offered by ProComp Electronics to the rigors of the dyno. Given the author's affinity for all things forced induction, what better way to demonstrate the strength of the new components than by combining big displacement with boost to create a pressurized power plant?
Rather than take the usual route of supercharging an EFI motor, we decided to combine a turbocharger with carburetion. Though certainly not a low-buck approach, the use of a carburetor and conventional distributor demonstrates an effective alternative to a factory or standalone EFI engine management system. The carbureted combination also allows us to effectively stress test the new block, crank, and even the cylinder heads, as we will settle for nothing less than an honest 1,000 hp!
The first step was to have the new block properly machined. The ProComp block was taken to L&R Automotive. Our 351W block featured a 4.125-inch bore size, which we combined with a 4.10-inch crank to produce a finished displacement of 438 ci. The block was honed and all the critical elements checked prior to assembly. The only oddity during the process was that the main bolts featured metric heads but standard threads. They can easily be replaced with ARP hardware, but we ran them as delivered.
The block was plenty beefy and featured splayed four-bolt main caps, and thick decks and cylinder walls. Basically it was everything the stock 5.0L and 351 Windsor blocks are not. Having split stock blocks in half from excessive power, having a solid foundation is a must when probing the 1,000hp mark.
In addition to the block, ProComp also supplied a 4340 forged steel crank and matching 6.20-inch connecting rods. The long rods were needed to clear the equally lengthy 4.10-inch stroke. To these we added forged (dished) pistons from Probe Racing to complete the 9.2:1 rotating assembly.
Given their extensive lineup of components, ProComp was happy to supply its CNC-ported cylinder heads. We tested a set of these heads previously in MM&FF on a 408 stroker with good success, so we knew they had potential.
When it comes to making big power with a turbo or blower, the key is to start with a powerful normally aspirated combination. Wanting to maximize the power output of the motor prior to the application of boost, we sent the CNC-ported ProComp heads to the flow wizards over at Dr. J's. Dr. J's has extensive experience with the ProComp Ford heads, and took our already-good heads and made them better.
According to Dr. J's, the valve job is a critical upgrade to the ProComp heads. In addition, Dr. J's performed some minor porting and blending to finalize the castings. They can perform the same work to the as-cast heads, but the level of porting is much more extensive to reach the 300-plus-cfm mark.
When all was said and done, the heads flowed 321 cfm on the intake and 247 cfm on the exhaust at 0.800 lift. The ported heads were secured using 1/2-inch ARP head studs and Fel Pro MLS head gaskets designed for our 4.125 bore.
With one of the three major power producers taken care of, we turned our attention to the cam and intake manifold. Given the displacement and intended power level, we chose a single-plane intake. As luck would have it, Dr. J's had an Edelbrock Super Victor that was all ported and matched to the ProComp heads. Since we were running a carburetor, the ported Super Victor seemed like the perfect choice.
Proper cam timing for our boosted stroker was provided by the Ford cam experts at Cam Research Corp. Having had such good success in the past, we were anxious to see the cam specs for our turbo stroker.
Cam Research supplied what we thought was a pretty mild profile, at least in terms of duration. Taking full advantage of our high-flowing heads, the solid roller cam supplied for our 438 checked in with a healthy 0.736/0.727 lift split, a 254/252 duration split, and a boost-friendly 112-degree lobe separation.
Though the 254/252 duration split seemed tame, the results were nothing short of amazing, both normally aspirated and turbocharged. The Cam Research Corp cam was combined with roller lifters, a double-roller timing chain, and hardened pushrods, all from Comp Cams. The final touch of valve train hardware was a set of 1.7-ratio gold roller rockers.