Long term update on the Race Ready 7MGTE Supra: I've been driving the Supra’s new set-up, lightened Fidanza flywheel, new Action clutch kit, new poly bushings for the motor and transmission mounts, and all the suspension bits, for the past four months (Oct, Nov, Dec, Jan) through the wet, dry and the cold. As reported earlier, the Supra on stock rims w/ sticky 245/45/16 on all corners, are no match for the new set-up, as the torque overcomes the rear contact patch. I can now spin the wheels in gears 1-2-3 at will! Obviously, a much wider contact patch is required.
This version of the Supra, is an evolutionary development. As a reminder, the new engine is running 9.4:1 compression ratio, has a modified head, with the purpose of getting better flow. To that end the stock head was subjected to a port and polish to open up the exhaust side by removing the offending phospher-bronze valve guide right down to the port surface and the intake port dividers were reduced by 20% to increase flow into the head. Additionally, a slight change to the combustion chamber squish area by 20%, valve seats are fully radiused and valves back cut for the seat and 100Lbs springs added to the valve train, to reflect that this engine was going to spend most of its existence above 3000 RPMs. All this was done by the great team at M&B Cylinder Head. The finished head was then sent off to get ceramic coatings to the valve face, and cylinder head combustion chamber to help control the heat this engine was going to generate. Baked on moly coatings to the cam seats and caps to aid their durability, all done by the team at RM Engineering.
To get that power out effectively, we put in lighter and stronger, short skirt, forged pistons, lighter forged rods, and lightened, reshaped and hardened 6M crank. Additionally, the piston faces were also ceramic coated, baked on moly coating on the skirts and oil shedding ceramic coating to the under side. To help control the inherent vibrations of reciprocating parts, the pieces are balanced to within 1 gram of each other. The rotating assembly (included the crank, flywheel, pressure plate and clutch disc), was then zero balanced at 750RPM on a Sunnen computerized balancer, at M&B, to allow the top RPM of 7500 RPM. The block was milled down to give us the 9.4:1 compression ratio and both the oil and coolant passages dressed up to improve flow. M&B then put an RA on the milled surface that was down around 5 or 6. At RM Engineering, we modified the block with an oil shedding ceramic coating to speed up the return of oil to the sump on the inside, and a heat dispersing ceramic coating on the outside. There has been a lot of time and thought that went into the improvements on this engine. The oil pump was modified to give more pressure at idle, but very little more than 45 psi at WOT. A crank scraper was added to get more of the oil off the crank for less parasitic drag and back into the sump more readily. Oil capacity in the sump was increased from 5 to 7 quarts, added baffles, gates and a temperature activated oil cooler, to keep those oil molecules happy.
Next the Supra was sent to be tuned at VIP Performance. We are using a Gready SBC II to control the turbo waist gate, adj cam gears, adj FP regulator on a JDM ECU (no EGR), Lexus MAF(w/ extended set screw), for fine tuning. The engine is tuned to stay in a safe range for this engine using a stock CT26 with modified ports and the stock exhaust manifold. Both were ceramic coated inside and out, with exhaust going out a full three inch piping and muffler, with a ceramic coated down pipe. This resulted in 316/328 bhp/tq, on a stock clutch kit. The result was a significant improvement over the 7MGTE’s 232/248 bhp/tq. I hazard to say it is the next generation of M engines, an 8MGTE.
As to the chassis, the suspension set-up which includes uprated RSR racing springs (700Lbs front/400Lbs rear), poly bushings all around, Tanabe Sustec light weight chrome-moly anti-sway bars front and rear, and a poly transmission and engine support help to transfer the power more effectively, w/o too much noise getting into the cabin. Handling is much improved over the previous generation’s rubber bushings.
Next, the Supra went on a diet to lose weight and increase the Supra’s handling in corners. Steering has been modified from stock to delete the power steering pump for the purpose of increasing control and reducing weight and power loss. We added a recirculation hose across the high pressure feeds on the steering box, so any fluid in the box re-circulates through the hose. The result is noticeably increased control and road feel through the steering wheel. A smaller alternator, a larger, lighter radiator of aluminum, is added. Aluminum ATI Super damper replaces the heavy steel version. The back plate which the transmission bolts to at the back of the engine, is replaced with a hardened aluminum version. Other plates on the engine are replaced with lighter versions as well. As mentioned earlier, a 9.6 Lbs flywheel replaces the stock steel version. An aluminum drive shaft replaces the stock steel version. The front steel bumper was cut out to reduce the weight, but not lose integrity. The plan is to replace both front and rear with fabricated aluminum versions to hang the bumper covers on. The interior also went on a diet; stock seats are replaced with Kirkey aluminum, intermediate road race versions that weigh in at fifteen pounds each. Radio and Air-conditioning controls are removed, in their place a gauge cluster to monitor the engine oil, transmission and differential temps. Radio speakers are removed.
To lower the center of gravity, we bolted the seats as low as we could get them using a floor bracket. We achieved a 4.5 inch reduction in the driving height over stock. The RSR racing springs lowered the overall height of the car by a little over one inch in the front and a little less than one inch in the rear. This necessitated a realignment to get the set-up as close to spec and reduce bump steer.
It’s not all good news; first, we added the Supra Sport traction bars, but I can still get wheel hop under very hard launches, so that needs resolving. Due to the heavy bumpers; the car tends to pitch too much. Due to the Supra being top heavy, it tends to roll too much. After all is said and done, it now is a better GT car then it was from the factory, as the fun to drive quotient is almost off the scale.
The acceleration is exhilarating; press the go pedal carefully and the Supra nails you to the seat from 2,500 – 6000 RPMs. Over exuberant use will cause it to spin the rubber. Driving around town your reminded of the power under the hood, from the nice exhaust note. Snap the throttle, and the new engine willingly revs, then falls quickly back to idle. The new lightened flywheel needs some getting used to, as the lack of mass can cause the engine to die when engaging the clutch from a stop in my usual way. Also, the reduced mass will cause the engine to lose inertia more quickly, causing more engine braking effect than usual, so I’m guessing here; that the stock clutch disc won’t last as long…five years?
The weight reduction from 3535 to 3325 Lbs, works well for the new Supra, as it is more predictable in corners w/o under steer and has been a joy to throw it into corners, and let it go into a four wheel drift. In auto-cross, it's fun to be able to tap the brake to get the front under control and thread the needle or tap the gas to get power over steer when needed, the car can do all of that. What is un-nerving is the rate of deceleration, when I lift off the go pedal, due in large part to the lightened flywheel, the car just loses momentum. Gas mileage is likely improved, but as I’ve been driving the new Supra aggressively, I haven’t seen any savings at the pump.
I’ll plan on a track day at PIR, so I can know how well this set-up works on the track.
Van
