FAQ/Knowledge Base



Q: What do all of these turbocharger terms (A/R, trim, etc.) mean?

A: See the Turbonetics Glossary here

Q: How can I buy Turbonetics products?

A: Turbonetics does not sell direct to the public. Please use our dealer search page or contact a Turbonetics salesman/customer service representative for a dealer in your area.

Q: What is Turbonetics warranty policy?
A: Turbonetics offers a 1 year No-Fault/No-Hassle warranty on all of our products from the time of purchase. This includes all turbochargers, intercoolers, turbo systems, you name it. Even if you break your Turbonetics product racing, sens it in through the distributor that you purchased it from and we will fix it no questions asked. You won't find another warranty in the forced induction industry like it. We feel that our product is manufactureed to the highest standards possible and our warranty backs it up.
Q: Does Turbonetics build and upgrade all of the turbos at their plant in Simi Valley, California?

A: Yes! All of the upgrades and new units are worked on and built in-house at our modern, state-of-the-art facility.


Q: Do you perform installations at the Turbonetics facility?

A: No, all installs and or service must be performed by an Authorized Turbonetics Distributor or by the consumer.


Q: Does Turbonetics perform re-man/re-build services for all types of turbochargers?

A: Turbonetics only re-builds and/or upgrades Turbonetics turbochargers


Q: How do I get my Turbonetics turbocharger, intercooler or other product serviced/re-built?

A: First contact the Turbonetics distributor that you purchased the product from. They will then contact our customer service department to receive an Inspection, Return, or Warranty number. ONLY products with the appropriate number will be accepted/serviced by Turbonetics.

Engine/System Information
Q: What is boost?
A: "Boost" is the amount of pressure, measured in pounds per square inch (PSI), kilopascals (101.285 = 14.7 PSI, or BAR (based on 1 BAR equaling 1 atmosphere of pressure - 14.7 PSI) that the turbocharger is forcing into the engine/intake manifold/cylinders. PSI tends to be the most common way of measuring boost pressure but the Japanese market frequently uses BAR and many high end engine management programs utilize kilopascals.

Think of boost as how hard the turbocharger is working. When looking at a compressor wheel map to decide what trim to use, you will notice that there are oval lines (efficiency islands) that are drawn on the maps. Attached to these efficiency islands are speeds that the wheel is turning at a certain efficiency and air flow. The faster the wheel turns "boosts", the harder it has to work to flow air. So at its basic level, boost is just how fast the compressor wheel is turning at any given time. It would be rediculous to have readings such as, "Hey man, how much boost are you running?" - "I'm running 120,418"...dont you think?

It is important to remember a few things in regards to boost:
1. Boost DOES NOT equal horsepower. Lots of air, plus fuel in the cylinder and a timely ignition spark equals horsepower. A small turbocharger can be running at 20 PSI and make less horsepower than a turbocharger larger than it running 10 PSI. This does not mean that sizing a larger turbo is necessarily better though. The opposite can hold true as well. A turbo sized too large can make less power than a unit much smaller. But lets get back to boost.

2. Boost at the turbocharger and boost in the intake manifold may not be the same. Be careful where you measure boost pressure from. The system is only as strong as its weakest link. If you have an intercooler that is too small then the turbocharger will be working (remember above) "boosting" more than the air inside the intake manifold. This is because the intercooler is too restrictive to flow the correct amount of air to make a certain HP at a given PSI. Or think about if you had a leak in your intercooler piping. What if a clamp was loose and air was escaping without you knowing. The turbo would have to work (theres that word again) extrememly hard to make the "boost" that you want it to. On a side note overspeeding of the turbocharger is a leading cause of its death and destruction.

3. Once pressure is applied to air the measurement CFM (cubic feet per minute) can not be used to calculate airflow. The density of the air changes, and this means that PPM (pounds of air per minute) must be used to determine the volume/flow of air at a given PSI or "Boost" pressure.


Q: Is either a manual or electronic boost controller necessary?

A: No. All of the Turbonetics Turbo Systems are designed to run at a pre-determined boost pressure when you receive the kit. If you have made internal engine modifications (connecting rods, forged pistons, etc.) then a boost controller can be used to achieve higher horsepower levels.

NOTE: As a rule thumb stock vehicles should not run higher than 7-8 PSI without having other high performance modification performed to the vehicle.


Q: What is the difference between a manual and electronic boost controller?

A: A manual boost controller uses the pressure of the compressed air in the intake manifold or exiting the compressor housing to control a diaphragm that opens or closes a valve in the wastegate to allow excess exhaust gases to by-pass the turbine wheel to slow it down and reduce the boost pressure in the engines cylinders. An electronic boost controller will use a sensor to read the pressure in the intake manifold or exiting the compressor housing and then use either a solenoid or stepping motor to control the diaphragm. Either can be used equally well, although an electronic controller general provides a more precise control of when, and how quickly the valve opens and closes. Both can be used on internal and external wastegates.


Q: How much boost can my car run?

A: Remember boost is not horsepower. Boost is just a measurement of how hard the turbo is working to force air into the engine. When an engine cannot flow any more air into the cylinders on its own, the boost must be increased to force it in. Maximum boost is determined by the tuning as well as by the engine's internal components. It is the responsibility of the car owner and tuner to take steps that will ensure that the increased boost will not harm the engine, and will have taken care of the necessary fuel and ignition requirements of the vehicle.


Q: What is the difference between an internal and external wastegate?

A: An internal wastegate (see here) is part of the exhaust (turbine) housing itself. The exhaust gases exit a small hole built into the exhaust housing to allow boost pressure to be controlled. Only T3 turbine housings from Turbonetics can utilize internal wastegates. T4 and larger exhaust housing do not contain this opening built into the housing. It is not recommended to use an internal wastegate for HP levels greater then 325 HP.

An external wastegate (
see here) usually mounts somewhere on the exhaust manifold, well before the entry to the turbine housing. This allows the external wastegate to have much greater control over boost pressure and prevent overboosting/overspeeding of the turbocharger that could potentially cause damage to the turbocharger or worse the engines internals. External wastegates are also mandatory when HP levels above 325HP are run.


Q: Should I run a Blow-Off/By-Pass Valve (BOV) on my turbocharged car? What does it do?

A: Yes, all turbo cars can benefit by running a BOV on their vehicle. A BOV works by relieving the compressed air pressure trapped in the piping when the throttle body closes. The turbocharger continues to spin from the exhaust gasses exiting the engine and the compressed air has nowhere to go. The BOV opens and prevents the compressed air from "backing up" onto the compressor wheel causing surge. By venting or re-routing the trapped air, the BOV allows the turbocharger to spool up quicker between shifts and prevents long term damage from continual surging of the compressor wheel.

NOTE: If your vehicle has a Mass Air-Flow Sensor, it is important to re-route or By-Pass the air back into the inlet of the turbocharger (behind the MAS) so that the vehicles computer does not raise/alter the air-fuel mixture, causing the car to potentially run rich between shifts.

Turbocharger Sizing
Q: What is the best turbocharger for my car?
A: This is very hard question to answer in a FAQ section but here goes... first take a look at our Turbo Matrix and see what general area your vehicle fits into. There should be a two or three turbo part numbers that would work nicely depending on your engine size, HP wants, and spool up requirements. The smaller the unit in A/R and wheel sizes will provide the best response but may not give you the top level HP you are after. The key is to find the right balance between the spool up of the turbo and the HP that it will deliver. Also remember that the Ceramic Ball Bearing option Turbonetics makes will give the turbo remarkebly quicker spool up and be incredibly durable since it can handle extreme levels of boost pressure. If you have any questions please feel free to call and speak to one of our turbo specialists.
Q: I want to run the biggest turbo possible, what should I get?
A: Once again take a look at the Turbo Matrix and see what HP range you fit into. The more power the turbo is capable of making the slower it will spool up so keep that in mind when first selecting a unit. One of the most common sizing problems for street applications is choosing a turbo that is too large. The turbo takes so long to spool up that it's efficiency and power range often falls outside the vehicles RPM band and power capabilities. Unlike intercoolers bigger is not always better with turbochargers.

Q: Why do Turbonetics ceramic ball-bearing turbos only use one ball bearing?

A: Turbonetics created the ceramic ball bearing turbocharger for durability. By utilizing a single, ceramic, angular-contact ball bearing on the compressor side instead of the more common bronze piece, the ball bearing can absorb the thrust loading that all too often can lead to turbo failure in high performance gas applications. The Turbonetics ceramic ball bearing turbo can withstand up to 50 times the thrust load capacity, compared to a conventional floating bearing unit. Dual ball bearing turbos can only withstand 2-3 times more thrust loading than standard turbos. Learn more about Turbonetics Patented Ceramic Ball Bearing turbos.


Q: What is on the turbine side of the turbocharger in the ceramic ball-bearing turbochargers?

A: The turbine side of the ceramic ball-bearing turbo uses a floating bearing to dampen the harmonics and vibrations that are transmitted through the turbocharger. This allows Turbonetics to balance the turbo to the most demanding tolerances.


Q: Do the ceramic ball-bearing turbos "spool up" faster than a normal turbo?

A: YES! The ceramic ball-bearing design reduces the frictional loss that occurs with a conventional floating bearing-and-thrust system turbo. The ceramic ball-bearing design allows the turbo to accelerate much quicker, thus decreasing spool-up time. In most cases we have found our ceramic ball-bearing designs require 50 percent less energy to drive the turbo.


Q: What is a "hybrid" turbocharger?

A: A "hybrid" turbo uses parts from two different families of turbochargers to create a completely new turbo to meet a specific need. This can be done with the same brand of turbos, or two different makes can be combined to form something totally new. An example is the T3/T4. This turbo uses T3 turbine parts combined with T4 compressor pieces to make a turbo that fits a certain horsepower and displacement range.

Q: What is the difference between TO4E turbos and TO4Bs?

A: They are related. The "E" and "B" signify different families of compressor wheels. Each family was optimized for certain applications. One family is not better than the other. In some circumstances, the "E" may perform better than the "B." In other situations, vice versa. The key is to choose which wheel works best for your vehicle's needs.


Q: What is the difference between an "on-center" turbine housing and a "tangential" turbine housing?

A: These are the two styles offered with Turbonetics' T4 turbochargers. The difference is the way that they mount in the engine compartment and the manner in which the exhaust is evacuated from the housing. The "on-center" uses a standard T4 inlet flange, as well as a four-bolt discharge flange. The reason that it is called on-center is just that, the housing sits right on top of the inlet flange.

The "tangential" turbine housing differs both in form and function. The housing sits off to one side, similar to that of a snail shell. The other difference is that to connect an exhaust down-pipe, a V-Band flange-and-clamp assembly must be used. This setup sometimes proves to be more convenient for race applications. The "tang" housings are 4 to 5 percent more efficient in flow. Neither the "on-center" nor "tangential" necessarily perform better than the other in regards to attaining your horsepower goals, but tangential housings often times can not be used due to physical space restraints. The decision to use one over the other should depend completely upon the installation of the turbos in the engine compartment.

*If you are still unclear, please refer to the turbine housing section of our on-line catalog or call one of our qualified sales people.

Q: Do I need to run water-cooling lines to the turbocharger?

A: Water provides a certain margin of safety when the engine is shut off. Thanks to engine heat, coolant normally continues to circulate through the bearing housing, thus drawing heat away from the bearings. If the car is shut down properly and the engine is allowed to cool it is not mandatory to use water lines. Whether to use water lines depends on the convenience of plumbing the car and the vehicle's intended use.

Q: How is a turbocharger lubricated? Where does it come from?
A: A turbocharger is lubricated with regular engine oil. It comes from anywhere that you can provide clean filtered oil to it. Usually this is anywhere after the oil filter, before the oil gets to the block. Many turbochargers are oiled however from a fitting tapped into the block itself. As long as you have filtered, cool, and sufficiciently pressured oil your turbo will be happy. Note: Oil PSI should be at least around 20-30 PSI at idle and 50-70 psi under boost. Race applications do not apply here.

Q: What size oil inlet and oil drain line sizes should I run for my turbocharger?

A: Turbonetics recommends no larger than a -4 oil inlet line and no smaller than a -10 (1/2") oil drain line. For most street vehicles a -3 (1/8") is ideal and if a -12 line can be accommodated for the drain even better. NOTE: For racing applications and large frame turbochargers ie. Y2K and Thumper units, a -4 is perfect to accommodate the extra oil capacity and pressure that these units are usually faced with.


Q: My turbocharger is leaking oil... what is the cause and does it mean my turbo is no longer good?

A: Take a look at the TROUBLE GUIDE here. If you do not see anything that fits the problem, give our Tech Department a call and they will be happy to help solve your problem.

Turbo Systems

Q: How much more power will a Turbonetics Turbo System give my vehicle?

A: It depends on the modification performed to the vehicle (exhaust, cams, etc.) but for a stock vehicle a good rule of thumb is 80-100 HP at 8 PSI.


Q: What does a Turbonetics Turbo System come with?

A: See the Turbonetics Turbo Systems Component List here.

Q: What vehicles are Turbonetics Turbo System made for?

A: See the Turbonetics Turbo Systems Vehicle Application List here.


Q: How long does it take to install a Turbonetics Turbo System?

A: Usual installation time for a four cylinder system will be around 8-10 hours for a qualified mechanic. 6 cylinder systems take a little longer. Please keep in mind that these times can be performed much quicker if you or your mechanic is familiar with our systems. These times are also based upon having all of the necessary tools at hand.


Q: Are Turbonetics Turbo Systems CARB/Smog legal?

A: No, none of the Turbonetics Turbo Systems are CARB exempt.


Q: Do I have to run an intercooler?

A: Turbonetics and Spearco would like to see everyone run an intercooler of course but it is not mandatory in order to turbocharge your vehicle. That said, all of the Turbonetics Turbo Systems include a custom sized Spearco intercooler to maximize your systems performance. With out an intercooler on most turbo systems the boost pressure and thus horsepower will have to be much lower. This is because as the boost pressure is increased, the air temperature is increased significantly and the engine cannot fit as much air into the cylinder. As air temperature goes up it is not possible to squeeze as much air into the cylinder and without as much air as it could have with an intercooler the HP will be lower.


Q: What size intercooler should I run?

A: There are specific sizes for racing applications that must be used to meet a required HP target but in street vehicle applications fitting enormous intercoolers or running super cold liquid to air units is not an option. Therefore you should try to use the largest possible core size that will fit in the space available and still allow efficient end tanks to be utilized. Bigger is definitely better when it comes to air to air intercoolers on the street.

Q: What is the difference between a "tube & fin" and Spearco's "Bar & Plate" intercoolers?
A: The most noticeable difference between a tube and fin intercooler and bar and plate intercooler is the header plate.   The header plate is also where the end tanks are welded to. Tube and fin intercoolers utilizes header plates to seal the charge rows from the ambient rows. The header plates seal around the oval tubes during the brazing process. Generally around 0.125" thick. However, over time, and constant vibration, the header plate starts to crack away from the tube. You won't find this problem with bar and plate intercoolers. The end tanks for the bar and plate intercoolers are welded directly to the core. Tube and fin intercooler uses extruded tubes to carry the charge air across. Thickness of the tube ranges, however, they are generally around 0.020" thick as compared to the 0.125" solid extruded bar on the bar and plate intercooler. Another noticeable difference between tube and fin cores vs. bar and plate cores are the thickness of the cores. Tube and fin cores are always slightly thinner than the header plate used because the header plate is required to seal the charge from the ambient air. As compared to the bar and plate, even thickness is throughout the core.  
Q: What is the difference between a Spearco core vs. other bar and plate cores?
A: Spearco utilizes W.A.V.E. technology. A technology which is also used in the aerospace industry where space is a constraint but performance is very critical. Spearco cores undergoes strict manufacturing processes which required numerous of cleansing steps to ensure a 100% braze throughout the entire core.  
Q: What is W.A.V.E. Technology?
A: W.A.V.E. Technology (Wide.Area. Vane.Effectiveness) is the ultimate combination in strength and efficiency in heat exchanger cores. Specifically designed to maximize cooling by utilizing the most surface area possible in a given space. The Spearco W.A.V.E. core incorporates a complex network of highly effective vanes to regularly decrease temperatures by as much as 30 degrees over conventional tube n’ fin units. In addition to their phenomenal cooling ability, W.A.V.E. Technology cores are manufactured to be “BOMB PROOF”. Due to Spearco’s Pat. Pending manufacturing process these unique cores are capable of comfortably withstanding pressures in excess of 200+ psi. W.A.V.E. Technology cores set the standard for high-pressure forced-induction durability and cooling effectiveness. Whether you are a high performance enthusiast or a Pro Drag racer seeking the peace of mind to make the next round the W.A.V.E. Technology intercoolers and radiators are for you.
Q: Why do some intercooler cores flow top to bottom (up & down) while some flows left to right (side to side)?
A: The direction of flow inside an intercooler core does not affect its performance in any way. The air does not care what direction that it is traveling, what matters is that you have selected the properly sized core for your given boost pressure and horsepower levels. It is often necessary to use a top to bottom core in order to properly fit the a properly sized core in your vehicle so that the flow and pressure drop is correctly matched to your turbo application.