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Assuming your 1987-1992 Supra Turbo with its 7M-GTE engine is in good overall condition and has had ALL needed maintenance (headgasket, radiator, belts/hoses/timing belt, couplers, fluids, filters etc all replaced)

This is the tried and true formula for 'a little more' on the stock ECU without major changes, set up in easy stages:

First upgrades: (210-240whp)
  • Air filter/intake upgrade of choice - Apex'i still makes a nice air filter kit that suits our cars.
  • Divorced WG or bellmouth downpipe - this is the exhaust piping that goes from the turbo to the main cat. If you buy one part and only one part to upgrade your car, this is the part to buy. The restrictive factory pre-cat is eliminated as is the very restrictive turbo elbow. Avoid the HKS downpipe or similar copies that do not replace the cast iron elbow off the back of the turbo.
  • Catback exhaust system - HKS and Tanabe still offer quality catback systems for the MKIII that are compatible with virtually any engine or engine swap and fit, sound, and look great.
If you need a bit more (240-260whp)
  • Intercooler upgrade w/hardpipes - Driftmotion offers a nice affordable kit complete with IC piping to suit the 7M-GTE. This offers a much better intercooler and much less piping restriction in the IC piping. It also usually includes an upgraded blow off valve (BOV)
  • Boost Controller - buy once cry once, a quality electronic boost controller will always be worthwhile. This will allow you to turn the boost up to approximately 12 psi. Boost cut/fuel cut occurs shortly after that, it's a safety measure to save the engine.

If you still need more: (270-300whp)
  • Upgraded fuel pump (Walbro 255, 416 or 450, or a Denso Supra Twin Turbo fuel pump)
  • 550cc import pattern (11mm) top feed low impedance injectors (set of 6). RC Engineering, Fuel Injector Clinic, and Driftmotion all offer good options for this. Depending on the specific injector chosen, you may need to replace the injector clips (plugs) on the wiring harness.
  • Lexus Air Flow Meter (AFM) housing from a 1990-1994 LS400 or SC400. This accepts the factory 7M-GTE AFM sensor but the larger housing allows for approximately 25% more airflow to roughly match the larger 550cc injectors.
  • Apex'i S-AFC or S-AFCII that supports a Karmann-Vortex AFM like the 7M-GTE's. You will want to install this to adjust the AFM signal during wide-open-throttle (WOT) to the ECU as needed to reach approximately 11.5:1 Air:Fuel ratio. Using the S-AFC to reduce AFM signal to the ECU will effectively raise your boost cut/fuel cut ceiling. On almost all cars this combo will allow you to max out the stock turbo's effective boost levels at approximately 14-15psi. If you live in a high elevation region (e.g. Colorado) it's recommended to avoid going higher than 12-13psi on the stock turbo unless you want it to look like the grenaded CT-26 in my avatar. The thinner air at higher elevation requires the turbo to physically spin faster to make the same amount of boost pressure, and 14-15psi on a stock CT-26 will spin the turbo faster than it can physically handle at 5000ft+ Density Altitude (DA).
  • Wideband O2 sensor w/gauge readout. This should be installed in the downpipe and many modern options exist. This is the single most important safety measure for your car at this stage.
"All of it" for what the stock ECU can safely support: (340-375whp) Beyond this a standalone ECU with proper cam and crank sensors is STRONGLY recommended.
  • 57 Trim or similar CT-26 based stock turbo upgrade - this is a rebuilt stock turbo that has a larger compressor wheel. The most proven and reliable option has long been the 57 trim but some newer billet options exist. Larger wheels have been done up to even 62-63mm, but the stock exhaust housing and turbine are too great of a restriction at this stage. Driftmotion, BNRSupercars, and a few other vendors offer CT-26 upgrades on a core exchange basis. These upgraded larger compressor wheels can safely be ran to 17-18psi on 91+ octane premium fuel, and when properly tuned with an SAFC/Lexus AFM/550cc injector combo you should not hit fuel cut.
  • Test pipe/cat delete - this is a controversial upgrade and is generally not street legal in the USA. This can be applied at any upgrade level, but the stock cat is a 3in passthrough and is generally not a significant restriction below 300whp if it's in good condition aka not plugged.
Optional at any one of these steps, but always VERY good ideas:
  • New radiator, radiator fan, and fan clutch
  • Silicone hose upgrades for cooling system, and silicone/new 'accordion pipe' that goes from the AFM to the Turbo inlet.
  • 7M-GE oil filter union bolt w/oil filter relocation kit and full flow oil cooler with a thermostatic housing, use original oil cooler as a power steering fluid cooler
  • Modern decent quality (Tein, Megan, etc) coilovers or at least good quality shocks/lowering springs.
  • Refreshed brakes w/quality pads or a Big Brake Kit (BBK)
  • Wider wheels w/modern performance tires. 17-18in wheels in 8.5-10in widths work best, +35 to +45ish offsets are ideal.

During the install process you'll want to eliminate the 'J tube' from the fuel return line as well. An adjustable fuel pressure regulator (AFPR) can help curve overall fuelling up or down as needed, if needed, but is generally not a requirement for this combo.

You'll need to schedule a dyno appointment and tune the SAFC or other chosen piggyback to achieve around 11.5:1 A/F ratios on the wideband when in boost. Having a tuner experienced with these older piggybacks is highly advised. Also ensure your base timing at the Cam Position Sensor is set to 10* BTDC per the Toyota repair manual specs.

Overall this combination will typically make 340whp-375whp depending on the dyno and atmospheric conditions on pump premium. Keep the oil changed, be very mindful of oil level in the pan, and allow the car to fully warm up before beating on it (engine oil does need to be at operating temp for best performance, hence the thermostatic switch being strongly recommended in any oil cooler setup) and you'll enjoy a generally reliable(ish) high 12 second 1/4 mile capable MK3 Supra.


NOTE: All of the wheel horsepower (whp) numbers given are approximate, and can vary significantly depending on the dyno type and your particular car. If you start upgrading and doing power checks on a dyno, return to that same dyno for consistent, accurate data regarding your upgrades and what you actually gained. Dynojets are my personal preference based on overall very high consistency between different Dynojets across the country on a given correction factor. Other dynos such as Mustang Dynos can be calibrated to operator preferences and it is very easy to manipulate numbers. So I strongly recommend picking a local dyno and sticking to that local dyno for all power checks on your build to ensure consistent 'real' numbers that accurately reflect your upgrades.

ALSO NOTE: The 7M-GTE has been around a LONG time and there have been a lot of other upgrades, particularly piggyback electronic upgrades, that were once common. These either did not survive the test of time (e.g. early MAP ECU's, MAF-T's etc) or are simply too old and rare and unsupported to be practical (e.g. the HKS VPC). Some folks went well beyond the rated power numbers with much larger injectors and much larger turbos in years past, but these cars were rarely reliable or long-running at that power level.
This is largely due to the inconsistency of ignition timing caused by the factory TCCS ECU running both cam and crank sensor position off of only the Cam Position Sensor (CPS). The rubber timing belt flexes even when properly tensioned, which means the crank position is not accurately known by the ECU, but instead is approximate to within around 6-10* depending on who you ask. At high boost levels, your ignition timing being 6-10* off what is mapped is routinely disastrous, and causes significant detonation aka pre-ignition inside the cylinder.
The two most common major failures from this detonation are the headgasket and the piston ring lands. In extreme cases, the exhaust valves and rod bearings can also fail. Because of that risk and unreliability that is now known, and can be avoided with modern crank position sensor kits and various CPS upgrades, it's strongly recommended to make the investment in modern, effective engine management at any upgrade level beyond what's discussed in this sticky.

Cheers and happy boosting 馃嵑
 

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I would be careful on the air filter as it is outweighed by the hot post radiator air being ingested unlike the OEM which actually pulls air from under the headlight.
 

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Discussion Starter · #4 ·
I would be careful on the air filter as it is outweighed by the hot post radiator air being ingested unlike the OEM which actually pulls air from under the headlight.
This is a significant issue if the fan shroud is missing or damaged on that side. With an intact fan shroud I never had any noticeable intake air temp issues, especially with the oldschool SOGI trick of using some cheap NASCAR surplus air duct hose to make a 'ram air' tube from the bumper inlet up under the headlight and through the stock airbox 'snorkel' passage to point at the air filter.

Is there an effective upgraded/high flow air filter that fits our stock airboxes?
 

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This is a significant issue if the fan shroud is missing or damaged on that side. With an intact fan shroud I never had any noticeable intake air temp issues, especially with the oldschool SOGI trick of using some cheap NASCAR surplus air duct hose to make a 'ram air' tube from the bumper inlet up under the headlight and through the stock airbox 'snorkel' passage to point at the air filter.

Is there an effective upgraded/high flow air filter that fits our stock airboxes?
Im doing the ram air ducting right next to my left fog, snaked through the driftmotion intercooler kit piping, into and through the factory cutout. It鈥檚 a tiny run of ducting and idk if it does anything but 馃し馃徏鈥嶁檪锔

Also the heat shield made of the old license plate and bolted to the ps resevoir

It still gets nuclear meltdown hot as far as I鈥檓 concerned. I think I鈥檓 just going to drive around without the hood.

No cat, divorced downpipe
DM intercooler kit
Shimmed wastegate
Stock turbo, fuel, AFM (its a pita stretching that accordion hose)
 

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Thanks Wreckless! Couple questions:

I've seen you recommend getting a new crank pulley as well in other threads, like the ATI super damper. I had it on my future list. Would you consider that high enough to make it to your "Optional but very good ideas" list here as well?

For the divorced down pipe recommendation, the one that always comes to my mind is the BIC one. Any other options you've seen out there?
 

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Thanks Wreckless! Couple questions:

I've seen you recommend getting a new crank pulley as well in other threads, like the ATI super damper. I had it on my future list. Would you consider that high enough to make it to your "Optional but very good ideas" list here as well?

For the divorced down pipe recommendation, the one that always comes to my mind is the BIC one. Any other options you've seen out there?
Personally I would regardless of power level. If the OEM where still available and being produced, that would be the way but this is the closest.

This is a significant issue if the fan shroud is missing or damaged on that side. With an intact fan shroud I never had any noticeable intake air temp issues, especially with the oldschool SOGI trick of using some cheap NASCAR surplus air duct hose to make a 'ram air' tube from the bumper inlet up under the headlight and through the stock airbox 'snorkel' passage to point at the air filter.

Is there an effective upgraded/high flow air filter that fits our stock airboxes?
The OEM air filter is massive. Its like 8 inches no? Maybe K&N has a drop in OEM filter for that but as always, it goes back to if there are any other cars using something like that.
 

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Discussion Starter · #9 ·
Thanks Wreckless! Couple questions:

I've seen you recommend getting a new crank pulley as well in other threads, like the ATI super damper. I had it on my future list. Would you consider that high enough to make it to your "Optional but very good ideas" list here as well?

For the divorced down pipe recommendation, the one that always comes to my mind is the BIC one. Any other options you've seen out there?
Unlike the 2JZ, the 7M's don't have crank pulley separation failures often, if ever.
The biggest issue with the 7M crank pulley is usually caused by insufficient torque on the crank pulley bolt, which leads to it backing off and generally destroys the woodruff key, the keyway for the woodruff key, and in extreme cases can cause the crank pulley to walk off. Usually things are noisy and obviously problematic way before that point.

That said, an ATi crank pulley is always a fantastic reliability upgrade, and helps pave the way for a proper crank position sensor/trigger wheel setup like the Sound Performance 7M crank trigger kit.
For the purposes of this thread, I'd consider it a purely optional upgrade if you're staying on the stock ECU.

Unfortunately I haven't seen a good, current production option for a divorced downpipe, but 3in downpipe with elbow offered by Driftmotion will work great on virtually any CT26 based setup. With the factory CT26's turbine housing largely limiting most setups to ~400hp or so, I'm not sure there's a lot to gain from a divorced DP aside from an open WG sound if you choose to vent it to atmosphere.

For the purposes of this thread, I'd recommend the Driftmotion DP to keep things simple. If anyone knows of any other reliable shops offering a CT26 downpipe for the 7M-GTE MK3, I'd love to know about it. Basically everything seems to be discontinued :(

I'd love to see a comparison between stock, HKS style with the stock elbow, a bellmouth 3in elbow replacement like the Driftmotion DP, and a BIC style divorced downpipe on a stock CT26 car and also on a 57 trim or other upgraded CT26 car, but that'd be testing two cars with four different configurations each and a lot of dyno time to make happen, which isn't likely these days.
 
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I've hooked a vacuum gauge behind the stock filter in the accordion hose.
Never measured anything negative, but a manometer would be the way to go to see an effect between stock and something aftermarket.

3P I vote you do it before I do.
My car is down for awhile :)
 

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Great info Wreckless. Agreed, the Driftmotion downpipe can be used for simplicity. Also, if you already have something like the HKS downpipe or similar, cx racing has a 3 inch elbow that you鈥檙e able to use with the down pipe.
 

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Nice thread Jeff. I'm guessing that oil control isn't much of a necessity on a stock ECU? I ask because I've seen what happens to a 7m when you do a rather massive burnout and accidentally starve a couple rod bearings... that's what led me down my path of overkill ridiculousness. For what it's worth, I always ran mine with 6 quarts of oil, if I recall.

Also, to this list, I'll add that it doesn't matter how good your heat exchangers are if your ducting isn't functional. ;)
 

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Also, to this list, I'll add that it doesn't matter how good your heat exchangers are if your ducting isn't functional. ;)
Key bit here IMO. Especially on turbo cars, where the factory intercooler acts almost as a deflector of incoming air if you don't have anything channeling air through the exchanger stack, and let's be fair, after over 30 years none of our cars retain the factory undertray.
 

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Nice thread Jeff. I'm guessing that oil control isn't much of a necessity on a stock ECU? I ask because I've seen what happens to a 7m when you do a rather massive burnout and accidentally starve a couple rod bearings... that's what led me down my path of overkill ridiculousness. For what it's worth, I always ran mine with 6 quarts of oil, if I recall.

Also, to this list, I'll add that it doesn't matter how good your heat exchangers are if your ducting isn't functional. ;)
Brad - my 'good idea' list does include the 7M-GE union bolt and eliminating the factory bypass oil cooler. That combined with a good thermostatic sandwich plate/oil filter relocation and a good full-flow oil cooler do wonders for oil flow and distribution even in a tired 7M-GTE. For the purposes of this thread, that's the only pragmatic upgrade as everything else (upgraded oil pump feed line from AZ Performance, shimmed oil pump, etc) requires dropping the oil pan.

I considered getting into the 'don't use fucking rotella, you gonks' rant but oil may as well be religion. For anyone reading this, on an old 7M-GTE especially with the original oil cooler in place, I like Valvoline VR1 20w50, Mobil 1 15w50, and Mobil 1 Euro formula 0w40. Along with the Napa Gold, Wix, or Mobil 1 oil fiters. And always let the engine get up to temperature before beating on it!

Some may disagree with me, but having blown up a lot of 7M's since 1999 I've found the 'high flow, low pressure' garbage about the 7M-GTE's oil system to be exactly that - garbage.
 
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Key bit here IMO. Especially on turbo cars, where the factory intercooler acts almost as a deflector of incoming air if you don't have anything channeling air through the exchanger stack, and let's be fair, after over 30 years none of our cars retain the factory undertray.
I fabricated an intercooler duct that quite resembles a bbq lid, for my setup. Just a thin strip of aluminum is shaped into a duct for the large oil cooler behind that, all of which can only flow into the radiator from there. The only time I've ever seen temperatures over 200掳F are after hard autocross runs (low speeds and 8000+ rpm will create some heat) and one time when the wiring for one of my fans failed in stop and go Vegas freeway traffic.

Apart from that, this car has its cooling system pretty well dialed in. I'm even using a modified OEM under tray that I bought new in 2008. :)

Brad - my 'good idea' list does include the 7M-GE union bolt and eliminating the factory bypass oil cooler...

I considered getting into the 'don't use fucking rotella, you gonks' rant but oil may as well be religion. For anyone reading this, on an old 7M-GTE especially with the original oil cooler in place, I like Valvoline VR1 20w50, Mobil 1 15w50, and Mobil 1 Euro formula 0w40. Along with the Napa Gold, Wix, or Mobil 1 oil fiters. And always let the engine get up to temperature before beating on it!

Some may disagree with me, but having blown up a lot of 7M's since 1999 I've found the 'high flow, low pressure' garbage about the 7M-GTE's oil system to be exactly that - garbage.
I'm not as familiar with 7M oil mods, so I didn't understand the purpose of that mod. My understanding of the 7M is that they like to trap oil in the head, if held at high rpm for long periods, such as a big burnout. My understanding may be incorrect, that is definitely a possibility.

I absolutely and wholeheartedly recommend Donaldson filters. Crossing a Wix 51348 comes up with Donaldson P550335. My reasoning? I work for a Caterpillar dealership. Short of perhaps Nismo, Mines, or Spoon, I don't know of anyone who is more considerate about oil contamination prevention. If their filters are good enough to protect $100k+ Cat engines, they will protect my engine well enough. I have the oil sample reports to back up my confidence too. :)

Also, "high flow, low pressure" worked great for me until I needed pressure to move the flow... :p
 

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Also, "high flow, low pressure" worked great for me until I needed pressure to move the flow... :p
I'm generally one from the 'If the manufacturer did it, there must be a reason' school, but in the case of the 7M, I can't help but wonder why on Earth is the factory oil cooler a pressure bypass style.

I get the rationale, the fluid expands as it gets hotter which in turn displaces the relief valve and flows the excess into the cooler stack... but that depends on the particular oil being used (different blends have different expansion coefficients, and oil is a particularly high-K fluid), likely that switchover point isn't the same with current oils as it were back in the late 80s, also a factor is how stuck (or not) that valve is...

But then again the whole T aspect of the 7M-GTE all seems an afterthought to me, always has.

Admittedly, I run a factory oil setup, but I don't drive my car particularly hard. I definitely have a proper thermostatic setup planned out when budget allows.
 

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My theory. I think they felt a thermostatic bypass system would not be reliable. Would not pass QA Those things fail faster than coolant thermostats with the added "benefit" that you would never know it failed unlike a coolant thermostat where the temp gauge gives you a clue. The pressure bypass on the other hand is dead reliable. Mine still holds 40 psi 31 years later.

It sort of works in that it cools only for higher rpms where oil flow is large so the bypass doesn't really hurt. I think Toyota saw it as an acceptable cooling approach that was reliable.

Now they use exclusively coolant/oil exchangers that gets around the thermostat reliability issue and heats cold oil which is an added bonus.
 

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I have a Setrab oil cooler and thermostatic bypass in my system, I honestly had no idea that failure was even a thought. 3p, wouldn't you know if you were the type to have an oil temperature gauge? I know that this perhaps exceeds the scope of this thread and is more of an advanced mod, but I'd think oil temp monitoring would be a good idea.
 

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My theory. I think they felt a thermostatic bypass system would not be reliable. Would not pass QA Those things fail faster than coolant thermostats with the added "benefit" that you would never know it failed unlike a coolant thermostat where the temp gauge gives you a clue. The pressure bypass on the other hand is dead reliable. Mine still holds 40 psi 31 years later.

It sort of works in that it cools only for higher rpms where oil flow is large so the bypass doesn't really hurt. I think Toyota saw it as an acceptable cooling approach that was reliable.

Now they use exclusively coolant/oil exchangers that gets around the thermostat reliability issue and heats cold oil which is an added bonus.
Yes, that makes sense. Reliability is also the only reason I could think of. A pressure relief doesn't fail unless your oiling system is so dirty that it gets stuck, or if the spring breaks (case #1 would lead to more critical issues than just oil not flowing through the cooler stack, and case #2 is... let's be fair, almost an impossibility).

As for the oil to water exchanger solution, I have considered going down this route in my car. Since I'm running a Koyo radiator there is still capacity despite dumping oil heat into the coolant loop, and removing the air restriction caused by the coolers would probably offset this extra heat load.

Definitely going to give it some more thought.
 

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Yes, oil temperature monitoring would be a great way to monitor the oil cooling thermostat and the overall health of the oil cooling system. I've looked for an oil/coolant exchanger but never found anything I liked. Its a little tricky because you need to tap into the cooling system. The OEM coolers integrate thoseconnections into the block but the 7M doesn't support that.
 
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