Single or twin? This is the ultimate crossroads for the power-lusting Supra enthusiast. The choice made here will impact the car's performance and the wallet in a most profound manner. We were checking out UPRD's shop and saw an upgraded twin turbo in for maintenance. What's the difference between the customer's twin and a single turbo Supra? (Too bad the UPRD car was a full race proposition; the differences would affect any comparison too much to be of any value.) UPRD's Matt Hunt offered another possibility; the shop had a good customer with a street-driven single that was outfitted in a manner similar to the twin. He wasn't kidding--both cars were 1997 editions, both had six-speed gearboxes, both had HKS fuel systems featuring 720cc injectors; heck, both were green. What then, is the difference in the boost curves of these two beastly 2JZ-GTEs?
We set boost to (a conservative) 18 psi and let the dogs out. It should be noted that horsepower output was not a concern of this exercise. Our goal was to simply illustrate the boost curve. The assigned boost level was nowhere near the peak efficiency of either system and was far from the max pressure these cars run on the street. Furthermore, low-end and mid-range tuning could play a role in the power output of the engines (which would only cloud the picture in a small "quick tech" style article). However, this exercise has really whet our appetites and we plan to feature both cars in depth and do a no-holds-barred dyno comparison in a future issue.
Dyno Chart
As expected, the twin set-up (red) delivered more boost at lower engine speeds and the single moved more air on the top. But the differences were not as pronounced as we expected. As for peak power? That's an issue we will address in a future, no-holds-barred article. Stay tuned.
Single
Car 1997 Toyota Supra Twin Turbo
Owner Mohammed Binfahad
Engine Internals Built
Transmission 6-Speed
Turbo System GReddy T88
Fuel System HKS, 720cc Injectors
Max Boost 1.8 Bar
Car Color Green
Twin
Car 1997 Toyota Supra Twin Turbo
Owner Yetson Chen
Engine Internals Stock
Transmission 6-Speed
Turbo System HKS GT2835 (2)
Fuel System HKS, 720cc Injectors
Max Boost 1.5 Bar
Car Color Green