TRD 3.4l Supercharger

The TRD Supercharger for the Toyota 3.4l V-6 is one of the most sought-after performance modifications for 4Runners and Tacomas. It is a modified roots-type blower that is manufactured by Magnuson. The installed supercharger replaces the entire upper intake plenum, and is driven by the crank off of an extended alternator belt.

Toyota factory claimed gains for the supercharger are:

Maximum horsepower gain: 75hp at 5200 RPM

Maximum torque gain: 77lb.ft. at 5200 RPM

Peak horsepower increase: 64hp (187hp to 251hp)

Peak torque increase: 50lb.ft. (225lb.ft. to 275lb.ft.)

According to TRD, the TRD 3.4l V-6 Supercharger is compatible with the following vehicles:

- 1997-2004 Tacomas

- 1997-1998 T-100’s

- 1996-2002 4Runners

Why the supercharger is not compatible with 1995.5 & 1996 Tacomas is the subject of quite a debate. Most guesses revolve around the possibility of the early Tacomas being equipped with an early-model ECU which is unable to compensate for increased air flow brought by the supercharger. It is likely that any 1995.5-1996 Tacomas require the upgraded 1997+ ECU before supercharging.

It’s no secret on many Toyota-related forums that the TRD supercharger is not necessarily the best thing to ever happen to the 3.4l V-6, especially when the supercharger is added to the engine without supplementary modifications. A large percentage of engines that have the supercharger installed experience a variety of dangerous issues that may eventually lead to chatastrophic engine failure:

The 3.4l V-6 was originally designed as a naturally aspirated engine. As such, it is not necessarily happy with a supercharger bolted to the top of it, especially when it comes to timing advance. A naturally aspirated engine will advance it’s timing much farther than a forced induction application might, to increase efficiency and assure complete combustion of the fuel. The problem with this is a supercharger (especially a modified roots-type supercharger) will heat the air it is pushing into the engine, creating the possibility for a dangerous condition where the fuel spontaneously ignites before the spark plug purposely ignites it. This will dramatically raise the temperature and pressure in the cylinder, possibly damaging very expensive and hard to get to components.

Drivers usually describe spark knock as a “rattling” sound in the engine bay, like marbles in a can or even like a pulley is loose. This is a very dangerous condition, and can severely damage any engine which is exposed to spark knock for an extended period of time. When supercharged, ping in the 3.4l V-6 is most prevalent when the transmission is in a high gear, and the throttle is pressed down to climb a hill or accelerate, hence the symptom’s moniker: high-gear/low-rpm ping.

Why ping is most likely to appear in the high-boost low-RPM region has to do with how timing advance in the 3.4l V-6 works. Because the knock sensors in these vehicles have limited sensitivity, they can only distinguish ping over the other sounds in the engine above 3000rpms. Due to this fact, the ECU only actively retards timing above 3000rpms, and below that level the computer “guesses” at how much timing retard is required. Obviously, it usually isn’t very good at guessing the required timing retard with the addition of a supercharger.

Finally, it’s important to note that ping is not always audible, and some may be present even if it isn’t heard; however, the most dangerous ping is the audible variety.

Toyota’s 3.4l V-6 is a very reliable engine, with specifically chosen parts that work best with it, including the fuel system. The fuel pump located in the gas tank was specifically chosen to deliver fuel at a specific pressure and operating flow rate for a naturally aspirated engine putting out about 185 hp.

Unfortunately that fuel system is not necessarily capable of delivering the fuel required by the addition of TRD’s supercharger. While around-town driving may not show any negative effects, several full-throttle applications of the engine can cause a dangerous drop in fuel pressure, resulting in an extreme lean condition in the engine. Symptoms of this condition may include sputtering or loss of power after a full-throttle run, extreme ping/detonation, and excessive EGT’s. Detonation can be very dangerous for the engine, possible causing damaged internal components including valves, pistons, connecting rods. Excessive EGT’s can cause pitting on the piston, or in extreme cases valve or piston failure. Needless to say damaging any of the internal components of your engine will end your supercharged fun in a hurry.

The fuel injectors on Toyota’s 3.4l V-6 are rated at about 240cc/min of flow; plenty for a naturally aspirated 185 hp engine, but not necessarily enough for a supercharged application. Additionally, the engine’s CPU was designed to know exactly how much fuel to put in each combustion chamber based on how much air was flowing into the cylinders. However, with the addition of the supercharger more air can flow in to the engine than the fuel injectors can handle. This will tend to make the engine operate under leaner conditions than anticipated, especially in medium to full throttle scenarios. Running lean is very dangerous for a forced induction engine, leading to astronomical exhaust gas temperatures and pre-ignition.

The automatic transmission that comes with Toyota’s 3.4l V-6 is specifically tuned for soft shifts while being able to handle about 185 horsepower. Unfortunately, when a supercharger is added in to the mix (and especially a supercharger with fuel delivery modifications) the automatic transmission does not apply enough pressure to its shift plates, and excessive slippage can occur causing burned shift packs and overheating. this can in a very short amount of time lead to catastrophic transmission failure and a very expensive rebuild.

To properly adjust the 3.4l V-6 in order to allow it reliably and efficiently make the horsepower available with the TRD supercharger, it is necessary to modify three fundamental properties in the engine:

Fuel delivery is the foremost problem the 3.4l V-6 faces when modified with a supercharger. First, the stock fuel pump is not able to supply enough fuel to the engine during repeated full-throttle applications. Second, the fuel injectors on the engine are not physically large enough to supply fuel into the engine during full-throttle applications. Finally, when the previous two modifications are performed, the owner also has to gain control of how much fuel is put into the engine.

It is best to replace the stock fuel pump with an aftermarket unit capable of keeping up with the newfound demands of the engine. A Walbro 190lph unit is sufficient for supplying fuel for up to about 350 hp, and there are ones available that can be installed with minimal modification to the vehicle’s gas tank.

The 3.4l V-6’s stock fuel injectors are rated at a flow rate of approximately 240cc/min, sufficient to safely supply fuel for a maximum of about 200hp. However, the addition of a supercharger drastically increases the amount of fuel used by the engine. Because of this limitation, most owners choose to upgrade their injectors to above 300cc/min , or add a 7th injector. Underdog Racing Development sells both upgraded fuel injectors and a 7th injector system for the 3.4l V-6.

A new issue that has also arisen is the necessity of a well-atomized fuel mixture when the fuel is injected into the cylinder. It’s important to take a long hard look at the fuel injector’s nozzle read about the injector’s properties to determine if fuel will enter the engine as a stream or finely atomized spray (finely atomized spray obviously being better).

In addition to increasing the amount of fuel that can be put into the engine, it is also necessary to gain control of how that fuel is delivered while the engine is running. The ECU’s in 4Runners, T-100’s, and Tacomas cannot be re-flashed, and so it is instead necessary to find another way; in this case, a piggyback fuel/timing calibrator can be added to the vehicle. A piggyback fuel/timing calibrator is able to intercept a host of the engine inputs taken by the factory ECU, and can then “trick” the ECU into adding more or less fuel into the engine. The user can program a fuel map into the fuel/timing calibrator using a laptop and in this way control how much fuel is being delivered to the engine. Fuel/timing calibrators are discussed more thoroughly in the Piggyback Fuel Timing Calibrators section.

All modern engines automatically advance their timing in order to make as much power as possible. This can be a problem for a naturally aspirated engine that is converted to forced induction however, as forced induction engines use much less timing advance than their naturally aspirated counterparts. Too much timing advance in any engine can lead to spark knock (ping) and in very extreme cases detonation. To combat this problem on the 3.4l V-6, a fuel/timing calibrator can be used to forcefully retard the timing advance in the engine. By manually reducing the timing advance in specific areas of the engine’s operation, spark knock can be completely eliminated.

In order to handle the extra power developed by a supercharged 3.4l, vehicles equipped with automatic transmissions have to make a few modifications to be able to safely shift at full throttle.

The automatic transmission’s valve body is its brain; it controls how much pressure is applied to the transmission’s shift plates, and how quickly the shifts take place. To handle the extra horsepower of a supercharged 3.4l, an automatic transmission’s shift plates have to be engaged faster and with more pressure in order to prevent the friction plates from slipping and overheating.

Import Performance Transmissions in New Jersey is a popular provider of modified valve bodies for Toyota Tacomas and 4Runners. They can modify valve bodies to allow the automatic transmission handle up to approximately 350 crank horsepower. To have the valve body modified, however, it is necessary to remove the valve body from the vehicle’s transmission and ship it to them; lengthening lead-time in some cases.

With the extra power of a supercharged engine, the automatic transmission will also tend to run much hotter than originally expected. Although vehicles equipped with an automatic transmissions have a small transmission cooler built-in to the radiator, it is necessary to add an additional cooler in addition to the stock one, especially in warmer environments.

The 3.4l V-6 is a very specifically engineered engine, and as such Toyota’s engineers decided it wasn’t necessary to add many gauges found in other automobiles. This can present quite a problem when the owner adds a supercharger into the mix, since it becomes quite important to be able to assess the condition of the engine while it is running. There are a few fundamental accessories that need to be added to the 3.4l V-6 in order to assure it is running properly with the supercharger, and to assure that problems may be caught early, before catastrophic failure.

This is by far the most important metric that can be added to your supercharged engine. By seeing the actual air/fuel ratio running through the engine, it is possible to diagnose and directly fix problems in the engine’s fuel delivery. There are fundamentally two kinds of air/fuel ratio sensors:

• Narrow-Band Oxygen Sensors
• Wide-Band Air/Fuel Ratio Sensors

Narrow-band sensors are used in earlier-year engines to measure a qualitative state of the mixture in the engine. However, narrow-band sensors are only able to see a very small number of AFR values around stoichiometric (AFR=14.7, or λ=1.0) and as such is not very effective at determining AFR when the mixture is too rich or too lean. When a user tries to use the narrow-band oxygen sensor on an engine to tune it, it is usually used in conjunction with an exhaust gas temperature gauge, to assure the cylinders are not getting too hot.

Wide-band air/fuel ratio sensors, on the other hand, are able to detect a very wide array of air/fuel mixtures, and are excellent for use in determining the AFR in an engine. When a wide-band oxygen sensor is used to tune an engine, an EGT gauge is typically not necessary. Unfortunately, wide-band sensors are more expensive, typically around $300-$400 for a sensor and gauge, and the sensors themselves are also more expensive to replace than narrow-band oxygen sensors.

This straightforward gauge is often very useful when used to detect possible problems in the engine’s combustion cycle. Excessively rich or lean conditions, along with ping and detonation, can cause a major spike in exhaust gas temperature. When not caught early, excessive exhaust gas temperatures can cause major damage to the engine’s cylinders and valves, necessitating costly repairs. By installing an EGT gauge, with the probe 6-8” from the #6 exhaust port, it is possible to see a problem and prevent damage to the pistons or valvetrain.

The TRD Supercharger’s drive belt is somewhat difficult to find, so it is recommended that anyone with the supercharger purchase an extra belt. It is a Dayco 62” 4-Ribbed Belt.

Toyota supercharger drive belt-

Toyota Part Number: PTR30-35040

Dayco Part Number: 00602-17620-026

Gadget’s Dayco Part Number: 491C-1575-DB

The TRD Supercharger installation kit includes a slightly modified throttle body gasket that ensure the supercharger is able to put out its maximum rated boost. Using the stock gasket will result in slightly reduced boost to the engine. This is because the hole in the the TRD gasket is circular while the stock gasket’s hole is D-shaped, reducing available flow.

Replacement TRD Throttle Body Gasket-

Toyota Part Number: PTR26-35041

Piggyback Fuel Timing Calibrators

Oxygen Sensor Calibrators

Underdog Racing Development

Import Performance Transmissions