Should I install a Turbo Timer?
Absolutely. Unless you don't mind sitting in your car while it idles down every single time you need to turn the car off. A Turbo timer keeps the engine running for a preset time once you turn off the ignition. So you can remove your keys, and lock up the car and not have to worry about it, it will shut off on it's own. This is important for the life of the turbos. If the turbos are not given time to cool down, it can overheat the oil and cause coking which will block oil flow to the turbos and damage bearings and cook seals.

How long should the car idle before shutting it off?
Anything over 3 minutes for daily driving is just excessive. I recommend 1-1/2 minutes for normal (i.e., calm) driving, and 3 minutes for "enthusiastic" driving, and after a race, it is recommended that you drive the car for a few minutes to let air flow through the radiator and cool things down before parking. Then I would follow that up with a 4-5 minute cool down. Here is what the Toyota manual recommends:

Normal city driving: Idling time- not necessary

High-speed driving, About 80 km/h (50mph): Idling time- About 20 seconds

High-speed driving, About 100 km/h (63mph): Idling time- About 1 minute

Steep mountain slopes or continued driving above 100 km/h (63mph): Idling time- About 2 minutes

How much is the Supra's power output affected by changes in ambient temperatures?
Very noticeably. Just as with most turbo cars, the Supra Twin Turbo can be very temperature sensitive. Especially with the stock turbos and intercooler. On a BPU™ car, I would not be surprised to see a 10 percent reduction between mild 50-60deg temperatures, and 90deg plus temperatures

Why is pulling the TRAC fuse beneficial over just turning it off with the switch on the center console?
Just pushing the "Trac Off" button only partially disables the Trac system. It disables the Trac throttle body, but not the Trac system's ignition timing retard function. Unplugging the Trac fuse eliminates both functions, as well as the 155mph speed limiter, which works through the trac system. The fuse can be found in the main fuse box on the driver’s side of the engine compartment. It must be noted that removing the fuse will cause the TRAC light to stay on, but you'll get used to it.

Will the TRAC system improve the cars performance?
NO. The Trac system was calibrated to improve traction in slippery conditions. It was not calibrated with performance in mind. When the Trac system senses a loss of traction, it comes on hard, cutting power drastically; this will do nothing but hurt performance. I also would not rely on the Trac system for providing stability at high speeds, if you were to loose control, it would be too slow and clumsy, and would more than likely hamper your efforts to regain control.

How can I remove the factory 155mph speed limiter?
Remove the fuse for the Trac system. The speed limiter works through the Trac throttle body.

What is the Supra TT's top speed with the Trac fuse removed?
There is some debate on this subject. There are rumors that 180mph can be achieved. But by going with the numbers, 168-172mph in stock form seems possible.

What is the Supra TT's maximum theoretical top speed? Can it exceed 200mph with enough power?
Lets find out.
The Supra TT with the 6-speed has a stock engine redline of 6800rpm, and a 6th gear ratio of .79:1, with a rear axle ratio of 3.13:1. Now we multiply our 6th gear ratio times our rear axle ratio, and we find out our final gear ratio is 2.472:1. Now we divide 6800rpm by our total gear reduction of 2.472:1 and we find out our rear axles, and therefore wheels are spinning at 2751rpm at 6800 engine rpms.

Now we need to calculate our tire circumference. The rear tires section width it 255mm, and the sidewall's aspect ratio is .40, so our sidewalls are 102mm. Now, to convert this to inches, we divide this by 25.4, which equal’s 4.015 inches. Now multiply this by two, since we have two sidewalls making up the total diameter, and add the wheel diameter of 17", and we see a total diameter of 25.031 inches. Now to find out our circumference, we multiply that number times pi (3.14), and we find out the circumference is 78.59 inches, now divide that by 12 to convert to feet. And we get 6.549 feet total circumference.

Now multiply our tire's revolving speed, by the tire's outside circumference, and we find that the tire is covering 18,016 feet per minute, divide that by the 5280 feet in a mile, and we find we are covering 3.412 miles per minute, now multiply that by the 60 minutes in an hour, and we find we are traveling 204.7miles per hour @ 6800rpm in 6th gear. If the engines redline is increased to 7500rpm, which it often is, because of a higher flowing turbo. Then our maximum speed would be 225.8mph, given enough power of course.

How come the Supra TT was never on Car & Drivers Top Ten list, but the RX7 and 300ZX were?
Car and Driver has a price limit for the Top Ten list. And when the Supra TT was introduced in 1993 it was over that limit, but the 300ZX TT and RX7 TT were not. Even though the Supra TT received a HUGE pricing drop (about a $10,000 drop) in 1996, it could not be put on the list. That is because the only cars that can be nominated to the list, are ones that have been significantly updated or redesigned, or that were winners from the previous year. The Supra TT was not significantly redesigned that year, nor was it a previous year's winner, so it could not be nominated. So the Supra never made it to the Ten Best list, even though it beat the 300ZX TT and RX7 TT in every major magazine comparison test.

Is the Supra TT practical as a daily driver?
DEFINITELY! It has PLENTY of room for 2 people, as well as sufficient storage room. It has a decently smooth ride. The interior is very Lexus like, all the amenities, very comfortable; everything placed logically, and good fit and finish. Interior noise levels are very low, even with most aftermarket exhausts. The motor is very smooth, and has great low-end torque. In typical Toyota fashion, it is very reliable and dependable. You have good visibility, even with that big wing. 

Do some Twin Turbo models not have a "Turbo" badge on the hatch?
Correct, not all Twin Turbos came with a Turbo badge. It appears to be a dealer-installed feature, and there is more that one style of Turbo badge.

Do all Twin Turbo models have the rear wing?
No, the rear wing was an option on earlier models. Most Twin Turbos had the rear wing though. Also, not all Supras with wings are turbos. Many naturally aspirated Supras came with them as an option, and it became standard in the later years.

Does the Supra TT's rear wing actually provide a purpose, or is it just supposed to look pretty?
Unlike most spoilers, the Supra's rear wing actually provides down force. It provides 66lbs. of down force at 90mph.

Are all Twin Turbo models equipped with Sport Roofs (Targa Tops)?
No, the Sport Roof was an option on earlier models. Most Twin Turbos that were sold were Sport Roofs though. But the hard tops may be more desirable because of their rarity, added chassis strength and reduced weight. The Sport Roof became standard on later models.

Were any Twin Turbo models more powerful than the rest?
No, even though performance test results varied slightly, the stand out being the TT featured in the 1993 Car and Driver, there were no changes in power output between the years, and there were no special high-output models.

What are the sizes of the factory stereo's speakers?
The dash-mounted tweeters are 1" in diameter. The door speakers are 4" and are mounted in ported enclosures. The rear speakers are over-sized 6.5". And the Subwoofer is a 5x7".

What is the box under the passenger seat?
That is the factory stereo's amplifier.

Do all Supra TTs have key-less entry?
No, it was an option. 

How does Bar translate to P.S.I., and is kg/cm2 the same thing as Bar?
Atmospheres, Bars, and kg/cm2, are always assumed to be the same value, but each of them is slightly different.
1 Atmosphere Equals 14.69psi
1 Bar Equals 14.50psi
1 kg/cm2 Equals 14.22psi

You more than likely only need to worry yourself with "kg/cm2". That is the common metric measurement for pressure and what is used on almost all of our automotive "metric" gauges and meters. Below is a chart that converts kg/cm2 to psi.

Kg/cm2 value = equivalent in psi
0.50 kg/cm2 = 7.11psi
0.55 kg/cm2 = 7.82psi
0.60 kg/cm2 = 8.53psi
0.65 kg/cm2 = 9.25psi
0.70 kg/cm2 = 9.96psi
0.75 kg/cm2 = 10.67psi
0.80 kg/cm2 = 11.38psi
0.85 kg/cm2 = 12.09psi
0.90 kg/cm2 = 12.80psi
0.95 kg/cm2 = 13.51psi
1.00 kg/cm2 = 14.22psi
1.05 kg/cm2 = 14.93psi
1.10 kg/cm2 = 15.65psi
1.15 kg/cm2 = 16.36psi
1.20 kg/cm2 = 17.07psi
1.25 kg/cm2 = 17.78psi
1.30 kg/cm2 = 18.49psi
1.35 kg/cm2 = 19.20psi
1.40 kg/cm2 = 19.91psi
1.45 kg/cm2 = 20.62psi
1.50 kg/cm2 = 21.33psi
1.55 kg/cm2 = 22.05psi
1.60 kg/cm2 = 22.76psi
1.65 kg/cm2 = 23.47psi
1.70 kg/cm2 = 24.18psi
1.75 kg/cm2 = 24.89psi
1.80 kg/cm2 = 25.60psi
1.85 kg/cm2 = 26.31psi
1.90 kg/cm2 = 27.02psi
1.95 kg/cm2 = 27.74psi
2.00 kg/cm2 = 28.45psi

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