In contrast, VarioRam can vary the length of the intake tracts at the ECU’s bidding, enabling the engine to make more torque throughout the powerband. Below 5000 rpm, the system utilizes six long intake runners to increase torque. Between 5000 and 5800 rpm, a second configuration with shorter runners and a resonance plenum with a single crossover tube works in conjunction with the long runners. Past 5800 rpm, a second crossover opens to maximize peak horsepower. While the plenum is somewhat bulky and perhaps not as sexy as a pair of Webers or period-correct mechanical fuel injection, Vario-Ram delivers seamless torque and power from just off idle all the way to redline.
Hooked on the VarioRam concept, Jeff Smith wanted more than a stock 3.6-liter 993 Carrera engine could give. He called on Gordon Ledbetter to help him assemble a big-bore 3.8-liter flat six based on a 1997 3.6-liter core motor. Ledbetter and Smith backdated the crankcase to allow the installation of an on-engine oil cooler as per all 911 engines prior to 3.6 liters. This modification required removing the engine-mounted oil filter and moving it to the traditional 1973 location on the dry-sump system tank. That required modifications to the engine sheetmetal and oil cooler ducting, as well.
Instead of simply changing the intake to accept a conical filter like those found in most 3.6-liter transplants, Smith carefully modified the 993’s original airbox so it would fit in the confines of the early engine compartment. While all this external work was carried out, Ledbetter converted the engine to 3.8 liters of displacement by replacing the stock pistons and cylinders with Mahle slip-in cylinders and pistons. The latter feature deeper valve pockets and short skirts for light weight and reduced friction.
The stock 3.6-liter crankshaft and connecting rods were retained, but the original cams were traded for hydraulic 3.8 RS Sport cams. A set of 3.8 RS/RSR cylinder heads, with 51.5-mm intake and 43.5-mm exhaust valves, were fitted next. Minor tweaks to the Motronic engine management, the addition of a pair of headers from European Racing, and a unique Flowmaster muffler system fabricated by Smith completed the modifications.
An afternoon spent testing the engine and setting it up on the dyno at Rothsport Road & Race in Tualatin, Oregon proved all of the effort worthwhile. Smith claims the 3.8-liter flat six made 324.6 peak hp at 6200 rpm and 289 lb-ft of torque at 5500 rpm — and that the motor demonstrated an impressively flat torque curve. He says it made more than 250 lb-ft from 3300 rpm all the way to 6500 rpm.
That kind of twist dictated upgrades to the rest of the drivetrain. A lightweight flywheel from Patrick Motorsports and a Sachs Sport Clutch were added to the flat six before it was mated to an aluminum 915 transaxle. Ledbetter and Smith used an 8:31 ring-and-pinion along with “mildly close-ratio” gears. A factory limited-slip differential — set at 80-percent lock-up on the over-run — was installed along with a rare factory RSR oil pump, cooler, and spray bar. The latter directs oil onto third, fourth, and fifth gears as well as the ring-and-pinion gears — helping to cool and protect the valuable cogs during sustained high-speed runs.
Smith and his fellow horsepower junkies in the Portland area like to refer to their 3.6- and 3.8-liter hot rod 911s as “big-block” cars. And they’re all about driving them. If this 911 appears to be a pristine garage queen in these photos, that’s only because it was essentially a new car when the photos were taken. Seen in person, there were already a few rock chips earned by Smith on his trip from Oregon to R Gruppe’s 2006 Treffen in Santa Rosa, California — seeing much of the Pacific Coast along the way.
Smith plans to add some more chips. In addition to continued use on the street, he plans to use the car for Porsche Club of America driving schools and other track events. So if you’re ever on road or track in the Pacific Northwest, make sure to keep a regular eye your mirrors — because Jeff Smith’s 911 will be out there, ready to pick you off with 3.8 liters of 993 power stuffed under its unassuming red rump.