Steve Turner
Former Editor, 5.0 Mustang & Super Fords
January 2, 2014
Photos By: Courtesy Of Lethal Performance

Horse Sense: It should be no surprise that big blowers make big steam, but in the world of factory-built race cars, Carl Tasca has run as quick as 7.73 at 179 mph in a Cobra Jet topped with a 4.0-liter FRPP/Whipple supercharger. Imagine what it could do with a 4.5-liter Whipple ...

As we have covered numerous times in recent years, the crew at Lethal Performance is not shy about taking a fresh-off-the-dealer-lot Mustang and taking it to the bleeding edge of performance before it's time for the car's first oil change. That kind of modification moxie has earned our undying respect, and a great deal of coverage on these pages.

In the case of the company's '13 Shelby GT500 project car, lovingly named Snow White, this car went from zero to low-9s in the quarter in the blink of an eye. To get there it picked up a built short-block, a 4.0-liter supercharger and all the necessary support hardware. We covered its transformation in detail on these pages, so if you missed it, check out the previous stories on our website.

"The magic question. When do we stop? Is this it for Snow White?" said Jared Rosen of Lethal Performance. "I'm not quite sure I can answer that with assurance. On one hand, we've got one hell of a car. On the other hand, we still have yet to put an automatic transmission in any of our cars. I guess we'll just have to wait and see..."


In the case of the company's '13 Shelby GT500 project car, lovingly named Snow White, this car went from zero to low-9s in the quarter in the blink of an eye.


You might assume that once you get your Mustang to about 1,000 rwhp, you might be able to sit back and enjoy it. Well, the Team Lethal crew is not one to rest on its performance laurels. When the opportunity arose to test one of the first production 4.5-liter Whipple superchargers for the Shelby GT500, it was an easy decision.

"You know I've always been the guinea pig for the vendors we do close business with. So whether it's a new intake, driveshaft, or supercharger that needs some testing done on I'm the first to raise my hand. With that said, we've been waiting on the 4.5-liter Whipple for quite some time. Once the first one was ready, Dustin asked me what color I wanted it and what day," Jared explained. "He really didn't have to twist my arm too hard either.

"For the exhaust, we initially started with the 17⁄8-inch headers from American Racing Headers with a 3-inch collector. On our other cars those seemed to be plenty big and work very well for us. However, with our 2013—since it makes a solid 200 rwhp more than our 2010 did—we believed we would benefit from the larger primaries of their 2x3.5-inch setup."

It was an easy choice for us too. We hopped in the car and headed to South Florida to see what the big hardware would do on a built Trinity 5.8. It was definitely worth the trip, as the results were pretty impressive.

"Happy is an understatement. I'd say impressed is more like it," Jared added. "This thing is ridic. Not only does this car make more power than any of our other project cars, it looks, sounds, and performs better than all of our previous cars as well."

That is saying something. Follow along and see what mods made this kind of improvement.

If you are running a 4.5-liter Whipple supercharger on your Shelby GT500, you can definitely say you are running big boost!
Power by the Hour’s Jake Long gets this party started by removing the JLT Super Big Air Cold Air Intake (PN CAISP-GT500-10; $399) from Lethal Performance’s Snow White ’13 Shelby GT500.
Those that have followed the buildup of Lethal’s Shelby on these pages know that the car was already sporting a pretty significant supercharger in the form of Whipple’s 4.0-liter version, which has acquitted itself quite nicely on Ford Racing’s Cobra Jet race cars. Of course, who doesn’t want a bigger blower?
While it doesn’t dwarf the 4.0-liter (right), Whipple’s new 4.5-liter supercharger is noticeably larger than its little brother. Despite its larger proportions, the new blower does clear the firewall and all its connections line up where they should.
Where the factory supercharger uses an O-ring seal, the Whipple adapter plate requires a bead of high-temp RTV around the intercooler flange to form a seal between the blower adapter plate and the lower intake. Of course, before laying down the bead, Jake cleaned both the lower intake and the adapter plate.
It’s a pretty simple swap to install the 4.5 in place of the 4.0. It simply bolts to the lower intake like any other positive-displacement supercharger. Of course, if you aren’t as strong as Jake, you might need an assistant to navigate the big blower into place.
To compensate for the new pulley ratios and keep the blower belt in place at the race track, Jake installed one of Thump Racing’s (www.thump racing.com) billet tensioners (PN PM-1005-GT500; $450) for the GT500. The stock cast tensioners are known to occasionally fail during the rigors of drag racing, where the rpm can rise and fall in an instant. The Thump tensioners are rugged enough to back up a lifetime warranty.
With the Thump tensioner in place and the stock idler pulley reinstalled, Jake was able to use the same belt on the 4.5-liter as he did on the 4.0. When it came time for the dyno, a smaller pulley and shorter belt joined the party.
Jake also swapped over the Whipple 160mm monoblade throttle body (PN WTB-SGT2100; $588) from the 4.0 setup to the new 4.5. It takes this kind of wide-open inlet to eliminate restriction on the front side of these huge twin-screw superchargers.
The JLT Super Big Air features a 6-inch inlet and a 51⁄2-inch opening at the throttle body. Between those points is a 148mm mass air tube. This unit is designed specifically for Mustangs equipped with massive, positive-displacement superchargers.
Almost any modern Mustang can benefit from an oil separator to keep oil mist out of the inlet stream, where it can lower fuel octane causing detonation and even sully interoolers. If a Mustang is going to spend a lot of time at WOT—like any Lethal project—it definitely needs one. Jake installed JLT’s plug and play oil separators on both driver- (PN JLTOSD-GT500-B; $119) and passenger-side (PN JLTOSP-GT500-B; $119) cam covers.
A crucial stage of any Whipple install is installing the lubricant for the supercharger gear drive. These superchargers ship dry, so if you skip this step before running the car there’s a good chance you’ll damage the blower’s gear drive. Whipple supplies the appropriate lube, and you need only fill it until the sightglass on the front of the blower case is at half full. If you go too far, you can always extract some with a turkey baster.
A crucial stage of any Whipple install is installing the lubricant for the supercharger gear drive. These superchargers ship dry, so if you skip this step before running the car there’s a good chance you’ll damage the blower’s gear drive. Whipple supplies the appropriate lube, and you need only fill it until the sightglass on the front of the blower case is at half full. If you go too far, you can always extract some with a turkey baster.
With the 4.5 installed, it doesn’t look that much different than the 4.0 except to discerning viewers. Where the real difference arrives is at the rear tires. If you are wondering, both Whipple and JLT offer custom colors for their products. Obviously, Lethal continued the Snow White theme under the hood.
When you start pushing 28 pounds of boost through a Trinity 5.8-liter, it’s going to tax the exhaust system. The Lethal Shelby was already wearing 17⁄8-inch long-tubes from American Racing Headers. To make the most of the 4.5-liter blower, Jared Rosen at Lethal opted to upgrade the exhaust system with ARH’s long-tubes with whopping 2-inch primaries and 3-inch merge collectors (PN SH072NC; $1,614) and a matching 3-inch midpipe.
After removing the existing headers, Power by the Hour’s Jesse Guajardo installs the new big-tube ARHs.
With the headers bolted on, Jesse mates them up to the matching ARH 3-inch X-shaped crossover pipe.

On the Dyno

In our last installment ("White Feat," July '13, p. 54), Snow White put down 1,107 rwhp with a built Trinity 5.8 and a 4.0-liter Whipple supercharger. Anything above four digits is going to impress almost any gearhead. However, if more is better, then a lot more must be great.

It should come as no surprise that augmenting Snow White with a massive supercharger and bigger exhaust would result in huge power at the rear tires. In the case of the Whipple 4.5 and ARH 2-inch headers, they pumped up Lethal's Snow White Shelby GT500 to the tune of 1,236 rwhp on the Dynojet at Power by the Hour in Boynton Beach, Florida—and that's with a bit of boost lost to a slipping belt. Of course, these gains didn't just appear from the hard parts. They needed the assistance of Ken Bjonnes of Lund Racing to work his keyboard magic and tune-up the new combo.

"We're more than happy with the results from this car," Jared enthused. "It's by far my favorite Mustang we've ever owned. Everything about the 2013—just how it came from Ford—was awesome. We just made it bigger, stronger and faster." Indeed.

To stave off the sticky South Florida heat on the outdoor dyno, Lund Racing’s Ken Bjonnes puts ice into Snow White’s spare-tire-well intercooler reservoir, just like Team Lethal does at the racetrack.
Here we learn what a bigger blower and a bigger exhaust will do for an already powerful Shelby GT500—on the Dynojet at Power by the Hour in Boynton Beach, Florida.
It turns out that 0.5 liters of supercharger displacement and a full 2 inches of primary tube diameter mixed with a custom tune can really make a big difference on an already powerful Shelby GT500.

Built 5.8 w/ 4.0-liter
4.5-liter w/ Headers
Difference
RPM Power Torque Power Torque Power Torque
3,900 667.25 898.58 682.40 918.98 15.15 20.40
4,000 690.99 907.29 722.12 948.16 31.13 40.87
4,100 704.97 903.07 764.23 978.95 59.26 75.88
4,200 727.96 910.31 808.38 1,010.87 80.42 100.56
4,300 743.13 907.68 855.43 1,044.83 112.30 137.15
4,400 767.70 916.36 884.54 1,055.84 116.84 139.48
4,500 792.99 925.52 899.69 1,050.06 106.70 124.54
4,600 824.47 941.35 922.95 1,053.79 98.48 112.44
4,700 839.93 938.59 957.87 1,070.38 117.94 131.79
4,800 864.53 945.96 1,005.39 1,100.08 140.86 154.12
4,900 875.48 938.39 1,022.91 1,096.42 147.43 158.03
5,000 896.07 941.24 1,023.54 1,075.15 127.47 133.91
5,100 917.94 945.32 1,034.71 1,065.57 116.77 120.25
5,200 935.58 944.96 1,057.04 1,067.63 121.46 122.67
5,300 949.72 941.13 1,091.09 1,081.23 141.37 140.10
5,400 972.00 945.38 1,110.13 1,079.73 138.13 134.35
5,500 990.64 945.99 1,103.26 1,053.55 112.62 107.56
5,600 990.49 928.96 1,105.06 1,036.42 114.57 107.46
5,700 1,008.74 929.48 1,116.19 1,028.48 107.45 99.00
5,800 1,022.31 925.74 1,148.99 1,040.45 126.68 114.71
5,900 1,039.24 925.12 1,174.12 1,045.19 134.88 120.07
6,000 1,040.44 910.75 1,180.40 1,033.26 139.96 122.51
6,100 1,054.66 908.07 1,178.06 1,014.32 123.40 106.25
6,200 1,061.89 899.54 1,199.51 1,016.12 137.62 116.58
6,300 1,070.89 892.77 1,212.89 1,011.15 142.00 118.38
6,400 1,080.10 886.38 1,209.07 992.22 128.97 105.84
6,500 1,077.61 870.73 1,195.72 966.17 118.11 95.44
6,600 1,086.32 864.46 1,197.89 953.25 111.57 88.79
6,700 1,094.93 858.31 1,208.68 947.48 113.75 89.17
6,800 1,086.79 839.41 1,223.41 944.93 136.62 105.52
6,900 1,102.07 838.87 1,227.35 934.23 125.28 95.36
7,000 1,105.10 829.16 1,222.56 917.29 117.46 88.13
7,100 1,095.30 810.23 1,225.74 906.72 130.44 96.49
7,200 1,106.15 806.89 1,235.37 901.16 129.22 94.27
7,300 1,078.83 776.19 1,220.40 878.05 141.57 101.86