Can you really run a carburetor...
Can you really run a carburetor on a turbo stroker motor? Despite the turbo kit from HP Performance being designed for a 5.0L fuelie motor, it worked perfectly with the modified Holley carb from CSU.
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!
Given the power potential,...
Given the power potential, we needed something stronger than the production block. ProComp supplied a new heavy-duty Windsor block for this build. The block was precision-machined by L&R Automotive and features all the usual strengthening tricks, including splayed fou-bolt main caps. The ProComp block is stuffed with a 4340 forged-steel, 4.1-inch stroker crank, and matching 4340 forged rods, also from ProComp.
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.
Naturally, our turbocharged...
Naturally, our turbocharged stroker required forged pistons. Probe Racing supplied dished pistons (4.125-bore) for our turbo motor. When combined with the 70cc combustion chambers on our ported heads, the static compression checked in at a boost-friendly 9.2:1. Note also the use of Fel-Pro MLS head gaskets and 1/2-inch ARP head studs-a must for boosted applications.
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.
A portion of the success (both...
A portion of the success (both normally aspirated and turbocharged) goes to our cam profile. Cam Research Corp supplied the hot roller cam for our stroker motor. The aggressive profile featured a 0.736/0.727 lift split, a 254/252 duration split, and a (turbo-friendly) 112-degree lobe separation angle.
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.
The Cam Research Corp roller...
The Cam Research Corp roller cam required solid roller lifters from Comp Cams (PN 836) along with a set of Magnum pushrods. The ProComp block can be drilled to accept the factory hydraulic lifter assembly, or a link-bar setup can be used (similar to our roller lifters).
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.
Since we were using a ProComp...
Since we were using a ProComp four-bolt block, we decided to complete the motor with a set of CNC-ported ProComp aluminum Ford heads. We were looking for some serious power, so we shipped the ProComp heads to Dr. J's for further massaging. Dr. J's has done extensive work with the ProComp castings and has taken an already good head (we tested a set of MM&FF on a 408 with positive results) and made it exceptional.
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.
The extra porting performed...
The extra porting performed by Dr. J's produced impressive flow numbers, both peak and the all-important low-lift numbers. The work included a custom valve job and additional hand-porting to finish up the already CNC-ported heads from ProComp. Dr. J's can also work its magic on a set of as-cast heads, but the work is much more extensive. Once completed, the heads flowed 321 cfm on the intake and 247 cfm on the exhaust at 0.800 lift.
The guys at Cam Research Corp...
The guys at Cam Research Corp specified a set of 1.7-ratio rockers for use with the roller cam, so we installed a set of Crane Gold rockers. Comp cams supplied the valvesprings and retainers for our roller cam application.
Since they already ported...
Since they already ported the ProComp heads, we enlisted Dr. J's to work some magic on the intake manifold. The Edelbrock Super Victor was fully ported and (like the heads) matched to the Fel Pro 1262R intake gaskets.