Red Rocket – Daily Driven 460 HP 944 Turbo
In 1988 when the Porsche 944 Turbo S was first sold, there were only three other production cars in the U.S. with higher top speeds – the Porsche 911 Turbo, 928 and Ferrari Testarossa. With a rear transaxle, the 944’s balance was excellent, and won praise as having the power and running gear to now go along with the praise as perhaps the best-handling sports car in the world.
This story is about one of those 944’s, purchased new and still maintained by its original owner, Robert Hemphill, who’s driven it daily for nearly 240,000 miles. Like other sports car fans in the 80’s, Robert fell in love with the 944 style and affordability, and when the Turbo S was available, he upgraded from a beautiful silver 944 NA to a “car with some real beans” and never looked back.
Eventually some tough decisions had to be made. An engine rebuild was needed, and the inevitable choices about whether it would be worth it to invest in a car with over 190,000 miles. The process began rather simply, but, of course, inertia took over and much more went into the process. The first rebuild wasn’t pretty, nor reliable. Well, actually, it looked good on the outside, but one mistake was to try to work with a fixed bid at a low price, to keep things reasonable. The result was a car with upgraded power, poor drivability, and a failed engine in under 25,000 miles.
With significant upgrades to the engine, turbo, intake, exhaust and electronics, the power has jumped from 250 hp to 460 hp @ 5989 rpm and from 248 to over 504 ft/lbs of torque @ 3832 rpm, a massive change in power running at 1.175 bar (17 psi) of boost, on 93 Octane.
The idea was to have a great improvement, with only minor changes to appearance reflecting the changes for performance and style, without changing the base nature of the car’s lines. Robert decided it would be a waste to try to hold all that power on the road with the tires that once seemed to have plenty of grip, but would not stand up to the new power. The new wheels are 18” in diameter; interestingly, sixteen inch wheels were considered large in 1988, but time marches on. The rears are 10” wide, and 9.5” in the front, at 22 pound weight, with no spacers needed. Single piece, forged 6061-T6 aluminum, by CCW (Complete Custom Wheels) of Florida, were literally CNC engineered to HMR’s specs for the correct fit and offset.
With only some of the performance upgrades in place, Red was breaking loose with fat Michelin Pilot Sport PS2 tires, so the next change was to try Michelin Sport Cup tires (street legal track/competition DOT tires). Now as long as the tires are warm, Red doesn’t break out in third gear on a straight acceleration runs! The tires are much lower aspect ratio in order to keep within a reasonable rolling radius; the fronts are big, fat 265 x 35 and the rears are 295 x 30.
The 944 Turbo S had great brakes, but with all the power and grip, an upgrade was in order. New “Big Red” 4-piston calipers originally used on newer Porsche 993 twin turbos were installed, with 12.7” diameter, cross-drilled rotors.
The engine block was fully blue-printed on HMR’s in-house CNC engine machining center. For longevity, HMR modified the oil galley to flow more oil volume on a wet sump engine. In order to eliminate all possible debris, all the factory freeze plugs were removed, and CNC threaded plugs installed. Crankshaft oil galley plugs were removed, cleaned, and a CNC tap was done with a threaded plug installed.
HMR Superalloy main studs (260Kpsi tensile) were installed, and main journals were line bored on HMR’s unique vertical line-bore machine. Jason explains that keeping the crankshaft from whipping and moving at high rpm is critical for engine’s longevity. HMR also included their custom engineered, very large head studs, made from an Austenitic Superalloy that have never experienced a head gasket clamp failure.
HMR worked with JME (Jon Milledge Engineering) to test and develop unique cam profiles for 944 turbos. A new cam, HMR.498.16L2 was made for Red, using a chill-cast German blank, with a much better acceleration ram angle and harmonic characteristics, to reduce valve float.
With all the extra torque, the car has gone through two sets of factory motor mounts in 15,000 miles. HMR had a solution – a new motor mount design that can vary from solid mount to a semi-solid version with damper shims for a streetable durability.
Special 8:1 CR Mahle racing pistons were used against Porsche’s Alusil bore, with HMR’s custom oil jet to shoot oil at the bottom of the piston, cooling the piston, and better oiling the piston pin. The 2.5L cylinder head was fitted with HMR lightweight Inconel racing valves, HMR titanium valve spring retainers (stronger than Ti6AL/4V), HMR racing valve springs, and CNC machine head porting.
Both the intake and exhaust valves were enlarged significantly to feed the need for more air flow, with the internal runners tweaked with extrude honing and hand polishing. The original exhaust headers had cracked, again, and were replaced with Billy Boat racing headers.
A much larger, HMR ball-bearing turbocharger was installed, with HMR custom caste hot-housing. Turbo boost is kept in control with Motec controlled Tial wastegate and blow-off valves. The old airbox was removed and a custom cold air intake installed. A HMR custom mandrel-bent hard pipe feeds the intercooler. Did we mention they look really cool? The turbo boost is now controlled by a custom programmed Motec M400ECU, with available settings from 8 to 17 psi boost thru a Motec 11 position switch, which accesses a different location of the Motec Map specifically tuned for that boost setting, with correct fuel, ignition and boost trim.
Electronics, Dash, Speedometer
All engine electronics, controls and wiring were replaced and upgraded to Motec gear, removing the Motronic ECU and boost controller. Known around tuner circles as a premium brand for racecars, it takes a certified tech to be licensed to custom program the Motec ECU, and Jason at HMR is one of those guys. Tuning and testing in his clean facility was greatly helped by being able to hook up Red’s rear axles directly to HMR’s advanced Dynapack dynamometer for calibrated results.
Driving, Not Parking
The Red Rocket has been driven a lot over the last twenty-two years. Yes, it’s parked in a garage at night, and hasn’t been subject to much snow, but it’s not babied that much. Ten years ago it was repainted after a front nose fender bender, but the guards red paint still looks pretty dang good for a driver.
Photos: 9 Magazine