Richard Holdener
October 1, 2007
Building a 1,000hp mod motor is as easy as combining a properly prepared Four-Valve long-block with efficient boost and tuning. After upping the boost pressure to the 17-psi mark, we were rewarded with peak numbers of 1,002 hp and 832 lb-ft of torque.

Overkill. If some is good, more is better. But we've learned that in terms of building reliable and useable street power, taking the more conservative route is often better. Once you get past the 500 or 600hp mark, it's hard to keep street tires planted long enough to enjoy the acceleration. Sometimes, though, it's better to go for the ultimate, and this is one of those times.

For this buildup, we wanted more of everything-more cubic inches, more flow, and even more boost. Starting with the 5.4L Lightning, Ford took aim at the performance truck market with both barrels smokin'. It followed the blown Lightning with the 4.6L Terminator motors and, of course, the Ford GT, and now the Shelby GT500. By combining the 5.4L displacement with Four-Valve heads, Ford designed a recipe with all the best aspects of the supercharged Lightning and Cobras to produce one exceptional Mustang.

When you go looking for 1,000 hp, displacement is a welcome part of any buildup. Rather than opt for a typical 4.6L, we stepped things up to a full 5.4 liters of displacement from SHM.

The Shelby GT500 is the cream of the proverbial Mustang crop-that is, until the more-powerful KR version is released next year. We decided, however, it was time to combine displacement with more forced induction and built our own 5.4L. The benefit of the 5.4L over the smaller 4.6L is obviously that the additional cubic inches add power. Given an identical specific output, the 5.4L motor offers an increase of over 17 percent over a similar 4.6L. What makes the larger 5.4L even more appealing is the fact that it doesn't just offer 17 percent more peak power, but 17 percent more power everywhere, from idle to redline.

If there's one area where the normally aspirated modular motors are deficient, it is in low- and midrange torque production. Ford cured this by adding superchargers in various applications, but for the atmospheric reliant engines out there, they can surely use the boost in torque production offered by the increase in displacement. There's nothing more satisfying than sticking your foot in the throttle and being rewarded with some serious grunt.

The SHM 5.4L short-block featured a steel crank, forged rods, and pistons. A beefy bottom end is paramount when looking for four-digit horsepower.

To achieve the desired displacement, we put a call into Sean Hyland Motorsport. The mod motor experts assembled a 5.4L short-block featuring a steel 4.165-inch (stock stroke) crank, forged rods, and pistons. Though the aluminum GT block-suitably modified for wet-sump use-or even the SHM 6.0L block would certainly be high on the wish list, we settled for a good old-fashion iron block. Given that mod motor maniac John Mihovetz exceeded 1,300 hp with a factory iron 5.4L block, we felt confident at our significantly lower power level.

What we needed was a bulletproof (if such a thing actually exists) bottom end that was ready and willing to accept the amount of abuse we had planned. The 5.4L short-block from SHM provided the necessary strength and displacement to help us achieve our goal of 1,000 hp. The improvement in average power production from the large-displacement 5.4L offered another benefit, namely an improvement in the response rate of the turbos from HP Performance. Obviously it takes serious turbos to produce 1,000 hp, and the higher the flow rate of the turbo(s), the less responsive they become. Running a larger motor allows use of larger turbos without paying a penalty in boost response-in this case, bigger really is better.

The 5.4L was topped off with a set of ported Navigator heads. The heads received porting, a precision valve job, and a spring package to provide the necessary valve control.

When it comes to displacement, bigger certainly is better if you maintain efficiency. All the extra cubic inches in the world won't mean a thing if you can't fill the cylinders efficiently. In fact, a poor set of heads or incorrect cam timing will offer even more of a restriction to the larger motor. Mod motor enthusiasts are lucky in that the current crop of Four-Valve heads offered on the Cobra, Ford GT, and GT500s offer exceptional flow even in stock form. Our first choice for topping our 5.4L would naturally be a set of the GT heads (available from Ford Racing Performance Parts), but intake manifold choices are rather limited. The intake port locations and bolt pattern differ on the GT heads (basically a revised version of the original Cobra R), so stock 5.4L intakes are out. Currently the only one available is the Cobra R, but look for something custom to come down the pipeline in short order as more and more GT heads find their way onto Mustang mod motors.

Wanting decent head flow, we selected a set of 5.4L Navigator heads, suitably ported by Sean Hyland Motorsports. These heads feature oversized intake ports, which were further improved by SHM. More than just porting, the heads were also treated to a precision valve job (critical on mod motors), custom valvesprings, and retainers to ensure adequate valve control. Though we would not be winging our long-stroke 5.4L motor to stratospheric rpm levels, we did plan on running some serious boost, so proper valve control was paramount.

SHM also stepped things up with a set of Stage 2 cams, offering 0.475-lift and 235 degrees of duration on the intake side and 0.452-lift and 225 degrees of duration on the exhaust.

Speaking of valve control, we went with a set of hot cams for this monster. SHM supplied a set of its reground Stage 2 cams, which offered 0.475-lift and 235 degrees of duration on the intake side and 0.452-lift and 225 degrees of duration on the exhaust side. Naturally, this was a significant step up from the factory Navigator or Cobra cams. Just like the ported Navigator cylinder heads, the cam profiles were employed to enhance the efficiency of the motor. A powerful turbo motor always starts with a healthy normally aspirated motor. Building up the power of the normally aspirated combination makes reaching our 1,000hp goal not only easier, but allows us to do so at a reduced boost level.

Where a stock Navigator motor might require 30 psi or so to reach the 1,000hp mark, improving the power output of the normally aspirated combination enables us to do so at nearly half that boost level. Though our combination employed an efficient intercooler, every effort should be made to keep boost pressure as low as possible while still achieving the desired power goal. Reducing the boost pressure decreases the chance of harmful detonation. By combining the added displacement of the 5.4L with the ported heads and Stage 2 cam profiles, we were able to greatly enhance the power output of the normally aspirated 5.4L.

On the dyno, the normally aspirated 5.4L produced 441 hp and 387 lb-ft of torque.

The final touch on the 5.4L was the induction system. Though the motor was run in normally aspirated trim with a set of Hooker headers, the crowning touch on this combination was a Sullivan 5.4L intake manifold. Naturally, a stock Navigator intake was not going to get things done, so we stepped up to the Sullivan piece to further improve the breathing potential. In addition to the additional airflow offered by the Sullivan intake, the short-runner design (compared to most production intakes) enhanced power production higher in the rev range. While we had no intention of running this motor to 8,000 rpm, or even 7,000 rpm, we knew peak power would occur somewhere north of 6,000. Since we were looking for a four-digit peak power number, the short-runner Sullivan unit was just what the doctor ordered. To ensure adequate breathing throughout, we installed a 90-degree elbow from Coast High Performance, along with a 90mm throttle body from Accufab. The combination offered impressive breathing potential, especially once under boost. The final touch was the Sullivan fuel rails feeding the 65-pound injectors from Holley. As it turned out, even the 65-pound Holley injectors were insufficient to feed this thirsty mod motor once we installed the turbos.

The HP kit included a set of 67mm turbos capable of supporting over 1,200 hp, more than enough flow to meet our needs.

With the naturally aspirated combo finalized, it was time to talk turbos. We went right to the experts at HP Performance in Roswell, New Mexico. We suspect alien technology from the Roswell landing in the '50s, but whatever the reason, those guys know how to make boosted power. We relied on a twin-turbo kit designed for the 4.6L Cobra. HP is currently working on an upgrade kit for the Shelby motor, but our testing came before completion of that project. Besides, our 5.4L wasn't exactly a GT500 motor anyway. The twin-turbo kit featured a pair of 67mm turbos, complete with 0.70 A/R compressor housings and Stage 5 turbine housings with 0.63 A/R ratios. The combination offered an exceptional response rate and ultimate power potential. In fact, we suspect the 1,000hp mark was obtainable even with smaller 57mm turbos, but it's always nice to have more than you need, right? The kit also featured a front-mounted air-to-air intercooler, which we employed on the dyno using a dedicated cooling fan. The only change to what would be in the car was shorten-ing the tubing running from the exhaust manifolds to the turbos and to run the motor with a FAST management system.

The first step toward big power was to break in the new 5.4L combination. The normally aspirated motor was run with Lucas conventional oil and lightly loaded for 25-30 minutes before attempting any full-throttle runs. After the break-in procedure, the motor was tuned by Big Ernie Mena at Westech, and run in anger to the tune of 441 hp and 387 lb-ft of torque. Torque production from the 5.4L exceeded 375 lb-ft from 4,300 rpm to 6,100 rpm, making for one impressive powerband. After break-in, we installed the HP twin-turbo kit. The turbo system was run with pump gas up to 9 psi. At this point, we filled the tank with Rockett Brand race fuel just to be on the safe side. Given the boost and timing level required to reach our goal of 1,000 hp, we'd like to revisit the motor with larger injectors and pump gas. After tuning the different boost levels (in 2-psi increments), we finally reached 17 psi.

It was at this boost level that the 65-pound Holley injectors went static (at 6,000 rpm), but a fuel-pressure adjustment gave us just enough fuel for the twin turbo 5.4L to produce 1,002 hp at 6,500 rpm and 832 lb-ft at 5,500 rpm. With over 800 lb-ft available from 4,600 rpm to 6,500 rpm, this is truly a mod motor maxout.