Our Project Supra has seen several upgrades that kicked its performance level up several notches. Although it's fast and very entertaining to drive, I'm sure you know we didn't start a 2JZ-GTE-powered project to stop at 400 whp. The time has come to get into the next dimension of performance for this street machine. Time for asphalt-thrashing power!
Since day one of this project it was a given Project Supra would be sporting a single-turbo setup with more than enough power for the street and occasional time-trial. It took a while to decide on which turbo system to use but we eventually decided on Sound Performance's SP71-GTQ turbo kit.
Initially, we were going to test it on the stock engine but a compression test revealing a leak in cylinder four from either a burned up exhaust valve or bad ring threw a wrench in our plans. Since a repair would call for decapitation of the engine we decided to have it rebuilt from scratch altogether.
Our shop of choice, although a newcomer to this project series, is well known throughout the Supra community, Speed Force Racing. The Santee, Calif. shop has performed big jobs on cars ranging from BMWs, Porsches and Toyota Supras to Nissan 350Zs and Skyline GTRs. Armed with a plethora of fabrication, welding and machining devices, SFR technicians are fully capable when it comes to fab work. The shop's in-house fabricated intake and exhaust manifolds, as well as its turbo kits speak for themselves. But its experience with turbocharged vehicles and attention to detail made it especially easy to leave Project Supra in SFR's hands.
Over the next few months we'll go into detail over the parts and processes we chose to make this 2JZ-GTE engine extremely durable. This month we'll start with the short block.
Building a block capable of comfortably withstanding the pressures this 71 mm turbo will put out relies on several key components. This is not to say a stock 2JZ-GTE motor can't handle the horsepower from the turbo-featured on our March, 2004 cover, a Sound Performance-tuned car dynoed 980 whp on the stock block! Regardless, we're over-building this motor which could probably handle over twice the power we'll put to it just for peace of mind.
JE Pistons were our pistons of choice. Also seen on Editor Griffey's Project Scerious 2JZ-GTE-powered SC 300, JE Pistons have an undisputed tradition of winning. Using state-of-the-art CNC and FEA (finite element analysis) computer processes, these forged pistons withstand the tremendous pressures of race cars seen in NHRA, IHRA, NASCAR and IDRA. At just 335 grams per piston, the light weight reduces damaging tensile loads-the load realized when the piston is changing direction, or inertia load-on each connecting rod. Since Project Supra's pistons are 0.50 mm over bore, SFR had to machine the cylinder walls accordingly for a precise piston-to-wall clearance.
The pistons were sent out to Swain Technology for its Thermal Barrier Coating (TBC) on the piston dome and tungsten-molybdenum disulfide polymer matrix (PC-9) coating on the skirts. TBC is a 0.002-inch ceramic coating that protects the piston by preventing heat transfer through the piston and holding the heat inside the combustion chamber. Additionally, the rods, crankshaft and bearings stay cooler. Since the entire dome surface is coated, flame travel is improved for a better burn as well as helping to prevent hot spots, which can lead to pre-detonation.
Swain Tech's PC-9 coating on the piston side skirt is 0.0007-inches thick and has an extremely low coefficient of friction. The durable coating partially transfers to the walls during piston movement, reducing scuffing and friction.
Pauter Machine billet connecting rods will be responsible for keeping our reciprocating mass together under the high horsepower conditions. Each rod is CNC machined from E-4340 vacuum-melt chrome-moly forging, heat treated, full-coverage shot-peened, balanced in sets. Pauter includes MSP220 steel bolts rated at 220,000 psi tensile strength with each set of rods. Although Pauter generally builds rods to custom specifications it does keep a few rod sets for popular engine applications on the shelf, the 2JZ-GTE happens to be one of them.
The crankshaft was left stock for maximum strength. We also decided against knife-edging for easier around-town driving and to keep the load at a maximum between each wide-open-throttle shift. Knife-edging the crank is a widely practiced process because it helps the crank rotate through engine oil more effectively and reduces the overall reciprocating mass enabling higher rpm capabilities. It's really a matter of choice for turbocharged street cars.
Factory Toyota rod and main bearings were chosen since they are popular among high-powered Supra owners and are known for their durability. Champion Toyota in Houston, Texas is a large Toyota dealer and TRD parts distributor. Its knowledgeable staff helped us get the correct main and rod bearings for our specific block and crankshaft. To order the correct parts, you'll need the reference numbers off the components to cross-reference them with the Toyota factory manual.
Another important aspect of keeping a motor together under high cylinder pressure/high rpm situations is to prevent the crankshaft from moving out of position-"crank walk" as it's sometimes referred to-by keeping it bolted in place effectively. Pro-Gram's heavy-duty billet main caps are an awesome replacement option for the factory units. The billet units are much beefier, giving us peace of mind that makes them worth every penny. The block will have to be properly line-bored and honed to accommodate them.
The main caps were supplied with main bolts but we decided to use ARP studs instead. ARP offers replacement main fasteners for the 2JZ-GTE, an even more effective way of securing the main caps rather than using stock hardware. We are also using ARP stock replacement cylinder head studs to keep the cylinder head bolted to the block more securely. Each ARP stud is shot-peened and then thread-rolled after heat treatment for maximum thread strength. ARP uses SDF (guaranteed seamless and defect free) and CHQ (cold head quality) materials, which are much higher grades than aircraft quality.
As if we didn't have a strong enough bottom end already, we decided to cryogenically treat the block. The "Ice Guys" of Cryo Science in Oceanside, Calif., offer a free pick-up and drop-off service for orders over $300 in the San Diego, Orange and Riverside counties, as well as parts of L.A. county. Cryo Science treated Project Supra's crankshaft, engine bearings, connecting rods and piston rings.
According to the company, it has seen an increase in durability of over 100 percent, as reported by several of its racing team customers. That's right-twice as long for an engine rebuild or brake rotor replacement. Cryo treating turns Austenite-the weak carbon particles formed through manufacturing in atmospheric temperature conditions-into Martinsite, resulting in an extremely strong and durable metal without any drawbacks. Cryo-treated metal dissipates heat better, meaning treated engines, transmissions, differentials and other metal components can run significantly cooler.
After treatment, the parts were returned to SFR. Having made the mistake of not file-fitting the piston rings before cryo-treating, SFR's Tim Richards' amusingly colorful comments on the hardness of the treated piston rings, and how much longer it was taking him to file-fit them, speaks volumes about the effectiveness of the process.
If you have a motor already apart and are concerned with strength and durability, you may want to consider cryo-treating. First, make sure to get the necessary work done on the motor beforehand. "Only after having gone through several drill bits have our customers learned to do the drill work on their engine blocks before cryo-treating," said Cryo Science Vice President, Travis Young. The company reports it can do an entire six-cylinder engine assembly for about $500, which can turn into tremendous savings over time.
Next month we'll tackle the details of Project Supra's trick cylinder head. Stay tuned.