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Old 06-27-2013, 07:04 PM   #3
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Join Date: Oct 2005
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Default Continued

...continued from above...

Now we can finally get to the survey categories!
  • Leave it stock ("320hp"+): At this point, you have an Mkiv Supra TT running properly, with all maintenance items taken care of. Like I did, and just as Toyota intended, you need to fun with it bone-stock! This car was under-rated from the factory; a brand-new us-spec 6spd produced almost exactly 320rwhp (376hp at the crank). Even with 100K+ miles on it, as long as your BOV and/or charge-air clamps aren't leaking boost*, you shouldn't be too far off from that number. Consider taking it to a road race track and get some professional driving instruction. Take the time to really learn your Supra's driving characteristics in all conditions with no modifications.
    Note: Replace the oem screw-type hose clamps with T-bolt hose clamps to keep those i/c hoses from popping off.
  • BPU (350rwhp-450rwhp): Bypass the cats with a straight-through 3" downpipe, install a GReddy BCC (to prevent the oem 'fuel cut'), a boost gauge (so you can see how much boost you're running), put a small adjustable clamp on this hose (top right of the photo), fill the tank with unleaded 100+ motor-octane race fuel, and tighten that clamp until you've cranked up the boost to at least 20psi. Be careful! ...when that boost hits you'd better be going perfectly straight, on a dry road with no other cars around. The back end might kick out a bit, so be prepared to counter-steer without overcorrecting.
    • CAUTION: To help maintain traction and control of your car, you may want to go to wider rims&tires at this point. 11.5" wide rear rims and ~9" wide front rims with the correct offsets fit under the oem fenders just fine, and maintain a good balance.
      I know a number of Supra owners that damaged their Supras (not too seriously, thank goodness) because of the change in horsepower to grip ratio. Toyota's engineers did an excellent job balancing the Mkiv Supra bone-stock. Whenever you change anything, you need to reengineer the overall car to reestablish that balance. That includes everything from tires to cooling system upgrades to manage the additional heat generated when you increase the horsepower. Please do not underestimate this responsibility when you start modifying your car.
    • At the higher boost levels, other components will likely need to be 'reengineered'/upgraded to match, like your clutch and blow-off valve.
    • If you find the race fuel thing inconvenient, install a high-flow alcohol injection kit.
    • BPU+++: If you want to squeeze a bit more out of BPU before you go to the next level ("6.", below), upgrade the intercooler, adjustable cam gears, (lightened) flywheel, exhaust system, and fuel controller. About 450rwhp is achievable max, with brand-new oem twin turbos and a brand-new 2jz-gte at BPU++++. Of course, you'll need to spend time on the dyno to tune the fuel controller and adjustable cam gears!
    • Note: An aftermarket exhaust is *not* necessary at 'bpu' level, except for looks. You can wait until BPU+++ or even single turbo level before you upgrade without affecting BPU performance at all.
    • Before any other upgrades, have fun with your Supra and learn it very well at this level. Everything you learn here will apply when you upgrade the horsepower to the next level.
    • If your budget is constrained and you want to optimize your $ invested (including resale value), then don't ever upgrade past BPU. Be sure to use a harness adapter when installing your GReddy BCC.
  • Single Turbo (Small or Mid-Size), Stock Fuel System, Stock ECU, Stock MAF (500rwhp-650rwhp): This next set of upgrades represent a more significant investment than BPU. However, you can get by WITHOUT an aftermarket fuel system or standalone ECU upgrade; the stock MAF (US spec), intake plenum and throttle body are just fine too.
    • To me, this is the level that Toyota *should* have built the Mkiv Supra TT to.
    • You'll need a single turbo kit with relatively small single turbo (67mm inducer or smaller, .80 turbine a/r or less), and a high-flow alcohol injection kit. If you didn't put a fuel controller on in the previous step, you'll need it here. I'd also recommend upgrading your oem fuel pressure regulator to an adjustable aftermarket regulator...and then increase the base fuel pressure by ~10%+.
      Note: Even with that 10% increase in base fuel pressure, your oem fuel system won't handle more than about 525rwhp or so. The alcohol injection kit must make up the difference in fueling requirements for 525rwhp-650rwhp.
    • Now is the time to definitely get yourself a set of the TSRMs (Engine & Chassis at least)
    • You'll benefit from an aftermarket exhaust at this level, if you didn't upgrade it at BPU+++. There's no need to go crazy though - any mandrel-bent 3" exhaust will be just fine.
    • Tuning, tuning, tuning. Spend as much time on the dyno as necessary to tune your air:fuel ratios until they remain perfect throughout the entire rpm+power band.
    • Definitely upgrade your rim widths to handle this horsepower, if you didn't in the previous step.
    • Keep the boost level to about 25psi. Be prepared to supplement your alcohol injection with some race fuel in the tank, to avoid detonation.
    • If you still have your oem clutch, it definitely won't handle this much power. Consider a twin-plate aftermarket clutch.
    • You'll benefit from some aftermarket *shocks* here (note: the Mkiv Supra Turbo has coilover shocks, not struts!). My preference for a cost-effective upgrade is KYB/AGX shocks and possibly some Eibach springs too if you really like that lowered look. You can try a stiffer sway bar on the front, but leave the rear one alone unless you are very well trained in drifting (i.e. your Supra will get *very* 'tail happy' with a stiffer rear sway bar...and not all drivers want or need this, especially (for example) if you daily drive your Supra in the rain).
    • Again, spend time on the track to learn the changes in performance characteristics. Driver training, driver training, driver training. The most important 'nut' to upgrade is the one behind the steering wheel!
    • Don't upgrade past this level if your budget is moderately constrained. You can still more-or-less break even on the whole Mkiv Supra 'deal' at this point. Past this point, you're investing $$$ for pure fun and entertainment with little chance you'll get your $ back. You have to decide if your budget can tolerate the 'hit'.
    • Drive your Supra as OFTEN as possible at this level! You'll have lots of fun here. You'll kick the tail of many other performance street cars at this level, including some 'exotics'.
...continued below...
Phil '94 Supra Turbo, 6spd, 'APU'+
Displacement is no replacement for boost.
Life begins at 30psi.

NB: Please consider posting any help requests in a new thread instead of asking me for help privately. About 99.9+% of the time, private help requests end up covering great information that could be very valuable to other forum members. If you have a good reason for needing the help request to be private, I'll consider it. If not, then why not give everyone else the opportunity to pitch in too, and/or learn from the information? Remember, there's no such thing as a dumb question. We're all here to help within this family of Supra owners.

Last edited by pwpanas; 10-12-2014 at 01:44 PM.
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