Cometic supplied a complete gasket set including the necessary multilayer steel headgasket
The Turbo Setup
Following the proper break-in procedure and the normally aspirated test, we fitted the turbo system to our B-series. The turbo configuration consists of a custom turbo manifold from HP Performance feeding a T72 Turbonetics turbo. Since this particular engine is destined for a record-breaking land speed car, the turbo was sized to produce optimum power near peak engine speeds. For street applications, this turbo is just too large, but since we only care about maximum power from roughly 7,500 rpm to 8,500 rpm, the combination produces boost numbers that actually exceed backpressure numbers-needless to say, this is difficult to achieve. The T72 feeds a single-core, air-to-water intercooler, though in the car we rely on a more efficient dual-core system. The injectors were swapped for the larger set and a TiAL wastegate was put in charge for boost control. For this test, we ran city water, not the generally hotter dyno water, through the core since we were running our oil test at a reduced boost level of only 16 psi. The key to successful testing is repeatability. Turbo engines, especially high-horsepower versions, can be temperamental and as such, call for a regimented procedure and precise tuning to achieve the kind of repeatability we require.
The Turbo Test
After fine-tuning the Fast XFI system with the new injectors and race fuel, the turbo engine showed the kind of repeatability we were looking for. The air/fuel and timing curves were perfect, while our start and test procedure all but ensured the same amount of heat energy and therefore boost pressure supplied by the turbo. The circulation through the air-to-water intercooler remained constant as did the cam timing and intake air temperatures. With each variable accounted for, all we had to do was make a few runs with the conventional oil and then again with the synthetic. Lucas suppled the oil required to get the engine up and running properly and allowed us to run a pair of back-to-back tests. Equipped with the conventional 20W-50 oil (again at 190 degrees), the low-boost turbo engine produced 481 hp at 16 psi. After swapping in the 5W-20 synthetic oil, peak power numbers jumped to 492 hp at an identical boost level-of course, air/fuel ratios and timing remained constant. Once again, the Lucas synthetic oil upped the power output of our turbo test engine by as much as 10-plus hp.
The Other Test
Our final test run on the Dynojet chassis dyno involves a 4AGE Toyota engine. The '89 Toyota Corolla GTS is equipped with a high-mileage 1.6L twin-cam 4AGE. The four-valve engine features a custom air intake and cat-back exhaust, but is otherwise completely stock. The oil change was a move to increase the engine's power output in preparation for the endurance race, the 24 Hours of LeMons. The race pits vehicles against not just one another but against the possibility of even finishing in a car that, by the rules, can be worth no more than $500. Running the synthetic oil was one of our tricks to improve the performance of our low-buck race car. Like our turbo engine tests, the 4AGE was run first with conventional oil, making note of the oil, air and water temperatures as well as the air/fuel ratios and timing values, which we data logged for ensured repeatability. We then replaced the conventional oil with a new blend of ultralight race oil offered by Lucas. The conventional oil was a 10W-40 while the synthetic race oil checked in with a water-like 0W-5 weight. Though we were concerned about the viscosity, the oil pressure gauge indicated plenty of pressure, even with the engine at full operating temperature at idle. Run with the conventional oil (at 190 degrees), the 4AGE produced 108 hp. After switching over to the Lucas synthetic oil, peak power jumped to 114 hp with a gain of over 8 hp past 7,000 rpm. Perhaps it's safe to say that Lucas Oil's friction-fighting formula really does work.
Our test regiment includes running the engine with both conventional and synthetic oil in
As with the normally aspirated engine, gains increased with engine speed on the turbo comb
After running the oil test on the normally aspirated engine, we installed the HP Performan
Tested on a Dynojet, the near stock 4AGE Toyota twin-cam engine produced 108 whp running 1
Our final triple-threat test involved replacing the 10W-40 conventional oil with ultraligh
Switching from the 20W-50 conventional oil to the 5W-20 synthetic oil on our turbocharged