When we last left our 327 test motor, it was sporting a turbo kit from HP Performance and a carburetor enclosure from Paxton. Equipped with an 825 Speed Demon carburetor, the carbureted 327 belted out 780 hp and nearly 800 lb-ft of torque. Not bad for a "street" turbo kit with a carburetor. You may remember that the 327-stroker Ford was built for such extreme duty. The motor featured an A4 block from Ford Racing stuffed with a SCAT billet 3.2-inch stroker crank, forged Manley connecting rods and Probe Racing pistons.

The short-block was typical of those built to withstand the abuse of forced induction. While a stock 5-liter short-block will take plenty of abuse and come back for more, the thin-wall, two-bolt blocks can become suspect (they crack) when the power is elevated. Since we planned on shooting for four-digit power levels with this motor, we made sure to fortify it with the necessary internal strength. Even with the beefy forged internals, the key to any forced induction motor is tuning. The correct air/fuel and timing curves can literally make or (more importantly) break even the strongest turbo motor.

With our 327 test motor still happy and healthy, we decided it was time to stop messing around with all the street superchargers and turbochargers and step up to some serious power. Not that 600-700 hp isn't impressive for a street Stang, but the difference between 700 and 1,000 hp is significant. Everything changes when you step up to four-digit power levels, the greater the intended power production, and the more critical the tuning.

As power and cylinder pressure go up, the motor becomes less tolerant of errors in air/fuel mixture or excess timing. Truth be known, errors in timing will destroy a motor much quicker than an air/fuel ratio. A serious turbo motor will tolerate a lean air/fuel mixture during a dyno pull, but don't expect it to last long at 13.0:1. By comparison, 3-4 degrees too much timing, and your motor will probably detonate itself to death during one dyno pull. You may never even get past the loading stage if the timing is too far advanced, as you will likely experience a blown head gasket immediately. Obviously the head gasket failure is much preferred over a crushed ring land or holed piston, but the lesson here is to start conservative and work your way up in power and total timing on any forced induction motor.

In previous testing, the 327 stroker was configured with a set of Edelbrock Victor Jr. aluminum cylinder heads, a Comp Xtreme Energy XE266HR cam and either a Performer RPM (when run in carbureted form) or a ported GT-40 (when run injected). While the combination worked well, the hydraulic roller cam limited rpm potential and we felt more power was available from the normally aspirated combination before adding our big Innovative GTB-88 turbo.

While the serious GTB-88 turbo was more than capable of supplying the airflow needs to produce the required 1,000 hp, the more efficient the basic motor, the less boost would be required to reach our goal. Some simple math helps here. Normally aspirated motors actually have atmospheric pressure pushing the air into the cylinders. This pressure (at sea level and at a given temperature) is 14.7 psi or one bar. Doubling the power output of the motor can be as simple as doubling the pressure to the motor. Upping the pressure to two bar (14.7 psi above atmospheric) can double the power output of your motor.

Here is where things start to get tricky. Suppose you have a 300hp normally aspirated motor and want to double the power output. If you install a turbo kit and set the waste gate to 14.7 psi, chances are you will nearly double the power output. Of course, this equation assumes a number of things, the first of which is you have a turbo capable of supplying 600 hp worth of airflow.

The second variable is the 300hp motor can withstand the additional stress applied by the additional power output. Power gains of 50-60 percent are easily handled by stock internals, but doubling the power output can tax the strength of certain components. The stock 5-liter block is a good example. As mentioned earlier, the tuning becomes the critical element in successfully turbocharging a motor. Making power is actually quite easy, doing so in a safe usable manner is a much more difficult proposition.

This pressure-to-power conversion works at elevated power levels as well, which is why we chose to increase the power output of the normally aspirated motor in the first place. If we run 14.7 psi, we essentially double any power gains applied to the normally aspirated motor. An example works well here. Suppose our test motor produced 400 hp normally aspirated. If we applied 14.7 psi to the 400hp motor, we would expect something near 800 hp. If we upped the power output of our normally aspirated motor to 450 (a gain of 50 hp), the same 14.7 psi would give us something closer to 900 hp. If we take this scenario one step further, we can see that a 500hp normally aspirated motor will produce near our magical 1,000 hp at just 14.7 psi. Had we tried to produce 1,000 hp with a 300hp motor, it would take over 34 psi of boost, with a 400hp motor we could lower the boost to 22 psi, while a 500hp motor reduces it to the aforementioned 14.7 psi. Less boost means a lower charge temperature, although we planned on running a rather efficient intercooler regardless of the eventual boost pressure.

Our low-compression (8.4:1) 327 was previously run with Edelbrock Victor Jr. aluminum heads, a Performer (or GT-40) intake and a Comp Xtreme Energy XE266HR hydraulic roller cam. In carbureted configuration, the motor produced 392 hp and 386 lb-ft of torque. In an effort to improve the normally aspirated power, we made a few changes to the motor. The idea was to both improve the power output as well as increase the rev range of the motor. We knew that by shifting the torque curve higher in the rev range, we could increase the power output. Using the formula Hp = Tq/rpm ----------- 5252

we see that making 1,000 hp at 6,000 rpm will take 875 lb-ft of torque. If we produce the same 1,000 hp at 7,000 rpm, it will only take 750 lb-ft of torque. The benefit is it may take less boost pressure to produce 750 lb-ft of torque at 6,000 than at 7,000 rpm. Obviously you need to have a short-block designed to run effectively at 7,000 rpm. Our forged test motor certainly satisfied the criteria.

In order to increase the airflow and rpm potential, the 327 was stripped down to the bare short-block. The first component to be changed was the camshaft. Out came the XE266HR (.544/.555 lift, 224/232 duration, 112 lobe sep) and in went an XR286R Xtreme Energy Street Roller. The street roller allowed use of the hardened distributor drive gear without switching to a bronze gear normally run with billet cams. The street roller offered slightly milder ramp rates than a full-race roller, but still offered plenty of power potential.

The solid roller profile ensured we had plenty of rpm potential, as we planed to buzz the turbo motor to 7,000 rpm. The XR286R cam featured a .614/.621 lift split, a 248/254 duration split (at .050) and a 110-degree lobe separation angle. The street roller cam was actually installed as our backup cam after discovering that our initial choice (.675 lift, .245 duration and wider 114 lobe sep) resulted in a piston-to-valve clearance problem. We liked the custom cam spec'd by Comp Cams for our turbo motor, as we felt the motor would benefit from the additional lift and wider lobe separation angle. We did not have time to notch the pistons for the bigger cam before running the test, so in went the XR286R grind.

Heads Up
The next change came in the form of a set of Air Flow Research 205 cylinder heads. Unlike our Edelbrock Victor Jr. heads, the AFRs featured full CNC porting and even some additional work on the exhaust to further improve the flow rate. The AFR 205 featured 2.08 stainless steel intake valves, 1.60-inch exhaust valves and a spring package suitable for our roller cam. The springs offered 200 pounds of seat pressure and 500-plus pounds of open pressure. The AFR 205 also had a number of other desirable qualities, including .125 raised exhaust ports for maximum exhaust flow, a 1/2-inch thick deck surface to minimize the distortion associated with elevated power levels and an excellent intake-to-exhaust flow relationship. The heads came fully CNC ported, assembled and ready to install. All we did after installation was to adjust the guide plates to properly position the Comp Pro Magnum roller rockers on the valve tips.

Since we planned on an effective operating range of 4,000 to 7,000 rpm, we selected a suitable intake manifold. We planned on making a few preliminary runs in carbureted form before installing the fuel injection, so we selected an intake that allowed us to do both with a minimum of fuss. Our intake of choice was the Coast High Performance Spyder intake. The CHP Spyder is an Edelbrock Victor Jr. converted for EFI use. The conversion consisted of welding injector bungs and the installation of a 90-degree elbow to mount a throttle body.

We elected to forgo the throttle body casting, as our turbo motor incorporated a Vortech Mondo air-to-water intercooler, which mounted right onto the carburetor pad of the Spyder intake. The Spyder allowed us to run the motor in carbureted and injected form with the same intake. All we had to do was plug the injector bosses when running the carb. The Spyder also allowed the motor to run effectively in our chosen rpm range. Remember, it is important to match the effective operating range of the cam and intake. It does no good to choke off an 8,000-rpm cam with a 5,500-rpm intake.

After completing the 327 with an MSD billet distributor, a set of 1 5/8-inch Hooker headers and a 750 Speed Demon carburetor, we ran the normally aspirated motor to see how much power we had gained. Remember, any power gained normally aspirated would be doubled at 14.7 psi. Running the motor from 4,500 to 7,000 rpm resulted in some impressive numbers. The 8.4:1 compression 327 was now producing 470 hp, along with nearly 400 lb-ft of torque. The CHP Spyder intake, AFR 205 heads and XR286R cam added nearly 80 hp while upping the power peak from 6,000 rpm to our self-imposed redline of 7,000 rpm. We had successfully completed our first mission of adding a significant chunk of normally aspirated power while simultaneously increasing the effective operating range.

Note that the peak torque was not so much increased as it was shifted. The shift resulted in a gain in peak horsepower. I made the unfortunate mistake of uttering the famous words of the now-defunct A-Team, "I love it when a plan comes together." This would be the last time the phrase was heard during the two-day dyno thrash.

With the success of our baseline behind us, we installed the new HP turbo kit. We say new kit because HP sent us one of their race kits. The race kit consisted of larger diameter primary tubing along with repositioning of the turbo to the driver's side. The merge from the cross over tube to the turbo flange featured a true Y connection, something that aides exhaust flow to the turbo. The new street kits also employ a similar Y connection, but the turbo is still positioned on the passenger's side. Installation of the HP portion of the turbo kit was pretty simple, not unlike bolting on a set of headers. What took some time was fabricating the inlet tube running from the discharge side of the turbo to the inlet of the Paxton carburetor enclosure. The fabrication required utilization of a V-band clamp to secure the inlet tube to the turbo. It was also necessary to connect the 5-inch (that's right) exhaust tubing to the turbine housing, a situation cured in haste by tack-welding it to the turbine housing. Not ideal, but it would hold for the dyno sessions.

After running the oil feed and drain lines, we mounted the 750 Speed Demon (an 825 was also tried) in the Paxton carb enclosure and went to work. The HP turbo kit came with one Turbonetics Delta Gate, something that would prove to be too small to adequately control our 1,000-plus hp Innovative turbo. After getting everything situated, we tried loading the carbureted turbo motor with limited success. Leave it to the author to miss two plugs in the carb bonnet and two oxygen sensors bungs in the exhaust. We wondered why the motor only made 2-3 psi of boost!

After plugging the four holes, the motor was much more responsive. The boost gauge indicated 5.6 psi at 4,000 rpm upon initial loading, so we were ready to run a few sweeps. The first sweep indicated the waste gate was having a hard time controlling the boost pressure. Under ideal circumstances, the boost pressure rises to the preset level and then the waste gate keeps the pressure consistent to the end of the run. Our boost gauge showed that the boost increased from 5.6 psi at 4,000 rpm to 9.8 psi at just 5,600 rpm. Obviously the waste gate was somewhat under sized for this application.

While we recognized that the boost was creeping, we ventured off and performed a few tests anyway. The motor was run from 4,000 to 5,600 rpm and eventually to 5,900 rpm before the fuel system would call it quits. With the waste gate set to open at 7.5 psi, the carbureted turbo stroker was run from 4,000 to 5,600 rpm. The lambda meter indicated the motor was leaning out near the end of the run and the boost gauge showed that the boost began at 5.6 psi and ended at 9.8 psi. The Innovative turbo was obviously on the job, as the motor produced 714 hp at 5,600 rpm and 669 lb-ft at the same rpm. The fact the horsepower and torque peaks occurred at the same rpm was an indication we had not revved the motor high enough to find the power peak. As we would find out, we had not revved the motor high enough to find the torque peak yet--this motor was going to make some serious power.

After running the motor to 5,600 rpm, we decided to try a bit more engine speed. The motor was run from 4,000 to 5,900 rpm, where the mixture was becoming excessively lean. Running to 5,900 rpm brought more boost pressure and more power along with it. The motor now produced 805 hp at 11.6 psi and 717 lb-ft of torque. On a subsequent run, the carbureted motor would peak at 859 hp, but only because of the lack of fuel. The lean mixture increased the heat energy to the turbo, which increased the airflow, which leaned out the motor even further. The boost pressure hit 16.8 psi before we yanked back the throttle.

We tried a larger carburetor, but even with the boost-referenced regulator, the fuel pressure was not rising. The culprit turned out to be the fuel pump. Apparently it was internally regulated to bypass (or dump) fuel at 16 psi. With 8 psi of static pressure, once we reached 8 psi of boost pressure, the pump would sign off fuel supply to the carb bowls. The motor would exhaust the supply of fuel in the bowls and then lean out. Our day with the carbureted turbo motor was done.

While we were never able to rev the carbureted motor to 7,000 rpm, we were not disappointed about the results of the testing. Even given the limited engine speed, the motor reached 800 hp at 11.6 psi at 5,900 rpm, no less. Had we been able to keep fuel to the carburetor and stabilize the boost pressure, the motor would have been well on its way to making serious power. We yanked the Paxton carb bonnet and installed the Vortech Mondo air-to-water intercooler. The Vortech intercooler was configured to install onto the CHP Spyder intake. Vortech offers a number of different bottoms to mate to the more popular EFI and carbureted intakes.

Setting up the EFI system was not without its problems, as a new discharge tube was necessary, as was a reducer to allow the C&L meter to be used on the 5-inch turbo inlet. The MSD distributor cap interfered with the Vortech Aftercooler, which necessitated a Wilson carb spacer. The use of the carb spacer required sourcing longer mounting bolts, as the Vortech Aftercooler could not be mounted using traditional carb studs. The dyno fuel system required a pump upgrade to allow us to reach 1,000 hp at 65-70 psi. The situation was solved by Aeromotive, which supplied an EFI pump reported to be capable of 1,500 hp.

Installation of the Vortech Aftercooler also required two supply pumps for feeding water through the intercooler cores. Since we were running on the dyno, we took water from the cool side of the dyno supply and drained it back to the hot side. Basically, our air-to-water intercooler had an endless supply of ambient water. We planned to run some ice, but the situation never presented itself. We mounted a 90mm billet AccuFab throttle body on the Vortech Aftercooler.

Steve Ridout from PowerTrain Dynamics was on hand to burn chips for our custom application, and his fabrication talents were called on to build the discharge tube to connect the turbo to the repositioned throttle body inlet. Steve also configured an inlet system to connect the 96mm C&L meter to the 5-inch compressor housing. The C&L meter was used in conjunction with electronics from a 90mm Lightning meter and a set of 150 lb-hr injectors. Is it any wonder we needed Steve's help in calibrating the turbo motor?

Actually the injected motor fired up right off the bat. Steve had previously run the 150-pound injectors in a stock 5-liter at his shop in Huntington Beach, California. The program was used to burn a baseline chip for our turbo application. That the motor fired to life immediately is a testament to his ability. The guy understands the programming as well as the motor's needs, not many people are so fluent at both ends of the spectrum. After some minor tuning, the injected motor was run up in rpm. With the chip delivering 25 degrees of total ignition timing, the motor produced 655 hp at 6.3 psi. While that may not sound like much, it correlates nearly perfectly with our boost vs. power calculation. If we take our 470hp motor and multiply it by the boost percentage (6.3/14.7), we get 671 hp. Given the rich mixture and conservative timing, we will take the difference of 16 horsepower. Everything looked like it was cooperating, and the fuel injection seemed to provide the needed fuel flow at high rpm. It looked like we were going to reach 1,000 hp yet!

With the tuning optimized for 6.3 psi, we did what any turbo owner would do, cranked up the boost. It should be noted before running the EFI turbo setup, Tom Habrzyk from Westech welded on a second waste gate from InnovativeTurbo. This allowed us much better control over the boost. Unlike previous attempts with the carburetor, the peak boost during the latest EFI run only reached 6.3 psi. Our second waste gate was performing well. Using our handy-dandy Turbo XS manual waste gate controller, we upped the boost pressure to a peak of 9 psi. The power jumped to 783 hp, while the torque was up to 624 lb-ft. The mixture was a tad too rich, resulting in a slow spool up. Even with the soft spool up, we were happy with the peak-power number. According to our boost/power calculations, we were actually ahead of the game slightly. Our 783 hp exceeded the calculated 758 hp shown at 9 psi. The formula to calculate this is (9/14.7 +1) x 470, where 9 is the boost pressure and 470 is the power output of the original normally aspirated motor.

Lucky for us, John Pizzuto from JS Electronics was on hand during the testing. John came equipped with one of his sophisticated knock sensors to monitor for any trace of detonation. We had obviously made every effort to eliminate detonation. Our efforts included 118-octane Pro Stock Race fuel courtesy of Union 76, a rich 11.5:1 air/fuel mixture and a conservative amount of total timing. Steve from PowerTrain had the programming set to provide just 25 degrees of total timing. Tossing on a big turbo like our Innovative GTB-88 (with taking the aforementioned steps) and hoping for the best is a sure-fire recipe for disaster. John from J&S indicated there was some trace detonation present during our last run, so Steve pulled 2 degrees of timing from the program and richened the mixture further. The air/fuel was reaching 12.0:1 up near 6,000 rpm, so we decided to put it back in the safe zone. We also upped the boost pressure to 11.4 psi. So equipped, the 327 produced 803 hp at 6,700 rpm, but the motor was pig rich. The drop in timing negatively affected the turbo response and overall performance. Combined with the additional fuel, the result was an air/fuel ratio of 10.5:1. Did the air/fuel and timing changes hurt power? The torque production was down by nearly 100 lb-ft from the previous run. It was time for some more tuning.

Steve from PowerTrain made a few adjustments to the chip and we tried to start the motor. Unfortunately, this is where things went awry. The motor did not want to start. We noticed the C&L meter had become dislodged from its mounting to the turbo, so we quickly made the necessary repairs and clamped it back in place. Again the motor would not start. Here is where the head scratching began. At first we suspected the 6-ohm, 150-pound injectors burned out the injector drivers in the computer. According to Steve at PowerTrain, not all Ford EEC-IV computers are compatible with the mid-ohm injectors. We swapped computers, but no luck. There seemed to be no (pulsed) signal to the injectors, though there was 12 volts present at the harness. We tried a new thick film ignition module, a set of new injectors, tracing all the dyno wiring and checking for voltage, but nothing seemed to be out of the ordinary. In the end, (around 10 p.m.), we decided to call it quits. The 1,000hp number would have to wait for another day.