If You Can’t Buy It, Build It!
By Ed Hohenberg
photos by the author and John Garner
Did you ever have someone tell you something “couldn’t be done”? And did that just motivate you further to prove them wrong? Well, John Garner is just such an individual. He found personal motivation in other people’s pessimism.
John wanted to build a 800+ HP Mustang that could still be street driven. Every day. With decent street manners, good gas mileage, functional A/C, and a back seat you could still use. When he shared his plan with some experts in the 5L Mustang field, he was told it “couldn’t be done”, without some major compromises. To John, the word compromise is defined as "an arrangement where nobody gets what they really want”, so he set out to build the car to his original goals, without giving anything up. The car would ultimately end up being a “Super Stang”: mild mannered during the day, but able to leap small dynos in a single bound.
The car was acquired a few years ago from a good friend of John’s, who maintained the car in absolute original condition, right down the factory air silencer. When John started with the car, it was the usual initial mods at first, like a K&N, and Flowmasters. Then he stepped up to a supercharger, and things just kept rolling from there. For John, who bounces between his home in Seattle and work base in Minnesota as the Chief Technology Officer for WhereToLive.com, the car became a therapeutic distraction from his hectic job.
The Powerdyne originally started with the 6 lb pulley. Soon after a 9 lb pulley was added, then 11 lb, then he found someone who sold a 13 lb pulley. Along the way, he added the necessary larger fuel pump, bigger injectors and a bypass valve. At that point, he felt the car would be better off with a beefed up automatic trans, rather than risk the disposable T-5 with all that compressed power.
Sticking with the Super Stang goal, the auto trans selected needed to have an overdrive to maintain the mild (street) manners. It was therefore decided to stick with an AOD, but add the necessary Lentech components to give the desired performance, and necessary strength. It took a few iterations to get the strength and performance, yet still maintain reasonable shift firmness, without jarring teeth out on the daily drives to work. One of the early iterations resulted in shifts so harsh that John’s wife, who raises horses, refused to drive the car, and commented to John, “I teach my horses not to kick, you need to train yours better.” Unfortunately, even when the shift firmness problems were ironed out, the reputation still remained, hence the custom license plate, “ITLKICK”.
Being a convertible, and with all that supercharged power, a roll bar soon became a requirement. But a true Super Stang would still have a back seat that could be used by people other than contortionists and professional limbo artists, with the roll bar installed. This led John to design and build his own innovative roll bar that would not only conform to the necessary sanctioning body rules, but also allow access to the rear seat. By using a forward facing support strut in the middle, John was able to construct the necessary rear cross bar from the drivers’ side hoop to the new middle strut, thus opening up the access to the rear seat from the passengers’ side.
Okay, so now John and the transmission were safe, but the same couldn’t be said for the stock 8.8. So in went a 3.73 geared, 31 spline 9" setup, along with some 4 piston rear disk brakes for added stoppage power.
We that was fun for a while, but now the stock 5 L engine looked like the weak link in the chain. More cubes seemed like a good way to make more power, without risking the low speed mild manners, so John went after a 347 crate engine shortblock, build by Probe Industries with all forged internals. Up top, new aluminum heads and a Trick Flow intake were added.
But it turned out the power brakes didn’t get along with the initial cam selected for the new engine. Since that compromised the mild street manners, a cam change was necessitated. Within minutes after the cam change, John unfortunately learned the true value of a small screw. Normally worth only a few cents, this particular screw managed to increase its value by several orders of magnitude, by taking a trip through John’s new engine. Somehow, this small screw found its way into the intake during the cam swap, and the resulting engine damaged coined the label of the “$2000 screw”.
A lesser man may have given up at this point, but John forged ahead, and now a second, stronger R302 block 347 resides in the Super Stang. Intending to make use of the added strength of the new R302 block, John also decided a new Vortech YS-Trim Renegade supercharger would be a good addition at that point.
At the18 psi of boost the new setup was now making, some sort of charge cooling was definitely required. John shopped around, but in the end he didn’t like the compromises made in the commercially available systems. For example, the air-to-air intercooler systems really compromised cooling system efficiency, while also making A/C impossible. The air-to-water systems available were either physically too big to fit under a street hood, or thermally too small for extended street use. So the Super Stang would need a new system, and John set out to design and build his own high capacity, street friendly air-to-water aftercooling system.
Starting with three 3" thick Spearco heat exchanger cores welded together into one larger unit, John custom built a new 2 piece aftercooling upper intake that would bolt right up to his existing Track Heat lower, and still maintain the factory throttle body location, vacuum ports, etc. The lower plenum was fabricated and welded from aluminium bar and plate to minimize any air flow restrictions. The upper plenum was similarly fabricated, but also included the mounting and bulkhead plumbing connections for the heat exchanger, and the mounting of the 90 mm throttle body. Hood clearance required only a 2" cowl to package the new charge cooling intake. John figures a smaller 2" thick Spearco core would have allowed packaging under a stock hood. How cool would that be?
The water tank to support the aftercooler is another example of John’s clear thinking. Instead of mounting a small tank up front in the engine compartment, John decided the spare tire well in the truck could hold much more water (thermal capacity) and not be subjected to hot under hood temperatures, while also giving a much better weight distribution to the car. So more aluminium was cut and welded to fab up the custom tank. A 7 gallon/minute pump ensures sufficient flow to the aftercooler, and a grill mounted Setrab heat exchanger ensures consistent water temperatures on extended runs. For short hauls (i.e. drag races, or dyno pulls) the tank can be filled with ice water for “super” charge cooling.
With the killer Aeromotive 2 gallon per minute fuel pump needed to support the horses up front, the total capacity of the fuel tank (14 gallons) only needs 7 minutes for a complete round trip back to the tank. As a result of the extended street driving excursions, all the fuel in the tank could quickly heat up. The solution for John was a custom fuel cooler, sharing the aftercooler cold water supply. The logic used here was: return fuel flow volume would be highest during the lowest boost conditions, and vice versa. One tank, 2 benefits.
One of the really cool things on the Super Stang is the exhaust cut-outs. Previously, John needed to crawl under the car to uncork the exhaust the old fashioned way. Now he has installed an innovative system that uses electric solenoids to bypass the mufflers. No phone booth is required to change identities from a quiet, mild mannered street car to a Super Stang, just a simple flick of the switch from the driver’s seat.
So what are the results of all this effort? Well John’s job has been keeping him busy so he still hasn’t made it to the race track yet, but that hasn’t stopped him from finding a few spare minutes here and there to torture some chassis dynos with the car. The car dyno’d well over 500 RWHP on 2 separate occasions, once with a problem injector in the #7 hole, and the other time with a slipping blower belt. Even still, the Super Stang produced the most RWHP of any small block powered car the 2002 Car Craft Nationals Dyno Challenge. Since then a cog belt has been added to cure the belt slip, and squeeze out some more ponies, but John has yet to redyno with the cog at press time. For John, the goal is 650 rwhp, which assuming 80% driveline efficiency translates to over 810 HP at the flywheel. This computes to twice the HP of a new Z06 ‘Vette, in a single Mustang. In a single Super Stang, that is.
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