Somethign I came across on OZWRX The VF39, VF29, and VF24 are all at the bottom of the list. There are slight differences, but not enough to notice. The VF30 and VF34 are in the middle. They are the same turbo, but the 34 has a ball bearing center section which lets it spool up a little quicker. The VF22 is at the top. It is the largest of the VF series. There is also a limited production VF35 that I believe is a VF34 turbine with a VF22 compressor. But, those are not very easy to find, and when you do, they are expensive. For 2.0l engine (most common WRX turbos) ... if you need 2.5 let me know. (some of these numbers can not be produced because of the RPM needed to create that much CFM, but the scaling is the same) Also note these are at ~ 1bar Turbo Type ----------- Approx flow @ pressure Stock Turbo ---------- 360 CFM at 14.7 PSI IHI VF 25 ------------- 370 CFM at 14.7 PSI IHI VF 26 ------------- 390 CFM at 14.7 PSI T3 60 trim ------------ 400 CFM at 14.7 PSI IHI VF 27 ------------- 400 CFM at 14.7 PSI IHI VF 24/28/29 ------ 410 CFM at 14.7 PSI IHI VF-30/34 --------- 435 CFM at 14.7 PSI SR 30 ----------------- 435 CFM at 14.7 PSI IHI VF-22 ------------- 440 CFM at 14.7 PSI T04E 40 trim --------- 460 CFM at 14.7 PSI PE1818 --------------- 490 CFM at 14.7 PSI Small 16G ------------ 505 CFM at 14.7 PSI ION Spec (stg 0) ---- 525 CFM at 14.7 PSI Large 16G ----------- 550 CFM at 14.7 PSI SR 40 ----------------- 595 CFM at 14.7 PSI 18G ------------------- 600 CFM at 14.7 PSI PE 1820 -------------- 630 CFM at 14.7 PSI 20G ------------------ 650 CFM at 14.7 PSI SR 50 ---------------- 710 CFM at 14.7 PSI GT-30 ---------------- 725 CFM at 14.7 PSI 60-1 ----------------- 725 CFM at 14.7 PSI GT-35R -------------- 820 CFM at 14.7 PSI T72 ------------------ 920 CFM at 14.7 PSI some info i found while looking around
IHI Turbos VF22 This turbo has the highest output potential of all of the IHI VF series turbos and is the best choice for those who are looking for loads of top end power. The top end power however, does not come without a cost. The VF22 spools significantly slower than the rest of the IHI models due to the larger P20 exhaust housing and large 40 mm compressor wheel. it is much less suited for daily driving than some of the other models. Although the largest VF series turbo, the VF22 is not quite optimal for stroked engines or those who wish to run more than 20PSI of boost. Utilizes a standard ballbearing center design. Recommended for use on cars with significant modifications and where flow capacity is more important then response time. Expect flows around 490 CFM at 18.0 PSI VF23 This turbo is considered a great all-around turbo. Like the VF22 it utilizes the largest P20 exhaust housing. This housing is mated with a smaller compressor housing of the of the VF24 for fast response and excellent low and mid-range performance. It does not have the same top end power of the VF22, but spools up significantly quicker. Standard ball bearing center section. Excellent bolt-on replacement for the standard WRX turbo on cars without any other major modifications. Expect flows around 430 CFM at 18 PSI. VF24 This turbo shares its compressor housing with the VF23 however, this housing is mated with a smaller (P18) exhaust side. The smaller characteristics of this turbo allow it to provide ample bottom end power and quick spool. This turbo is very popular for Imprezas with automatic transmissions and Group N rally cars. Not recommended for stroker engines or engines with high boost as turbo is small and can over speed. Best turbo for cars that want the best bottom end and least lag. Expect flows around 425 CFM at 18 PSI VF28 This turbo came standard on the STi Version 5. In terms of overall size, it is smaller than the VF22, VF30 and VF34, and about same size as the VF23. Expect flows around 425 CFM at 18 PSI VF29 This Turbo is nearly identical to the VF24, with the same compressor and exhaust housings. However the compressor wheel in the VF29 is has been changed slightly. The changes made to the compressor wheel in this model are generally viewed as improvements, and as such this unit is typically chosen over the VF24. Has a different location for the pressure hose on the waste gate actuator Expect flows around 425 CFM at 18 PSI VF30 The VF30 is commonly considered the best bang for the buck turbo in the IHI VF series line. A relatively new model the VF30 features the same exhaust housing as the VF24 (P18) but a larger compressor side similar to the VF22. The compressor inducer is 47.90mm. The combination of these two parts results in increased output potential without the lag associated with the VF22. Utilizes a sleeve type bearing design. Although it doesn't offer the top end supremacy of the VF22, the VF30 is a great compromise between these unit and the quicker spooling models. This is the ideal turbo for the average customer looking for fast excellent mid-range performance and response. This is not a ball bearing turbo as it utilizes a sleeve type design. Expect flows around 460 CFM at 18.0 PSI VF34 The VF34 is nearly identical to the VF30, with the same exhaust housing and compressor inducer size. However the VF34 goes back to the ball bearing design, and in doing so achieves full boost approximately 500RPM sooner than the comparable VF30. The VF34 is a more recent IHI design and as such costs slightly more than its counterpart. Top end performance and maximum output are identical to the 30. Expect flows around 460 CFM at 18.0 PSI VF35 The VF35 utilizes the same compressor housing as the VF34 however it also features a divided thrust or offset ball bearing design. The smaller P15 exhaust housing for quicker spool up and a slightly more limited top end. The compressor inducer size is the same as a VF30/or 34 turbocharger.
Nice write-up Nate. You should get with Russ (WRX1) so you can add any needed information to his thread from a couple years back http://www.mnsubaru.com/forums/showthread.php?t=5449
some other pirated info so here's a bit of info about the o2 sensor and its function, borrowed from wrx.com.au forums. i found it very useful The O2 sensor is the primary measurement device for the fuel control computer in your car to know if the engine is too rich or too lean. The O2 sensor is active anytime it is hot enough, but the computer only uses this information in the closed loop mode. Closed loop is the operating mode where all engine control sensors including the Oxygen sensor are used to get best fuel economy, lowest emissions, and good power. An Oxygen sensor is a chemical generator. It is constantly making a comparison between the Oxygen inside the exhaust manifold and air outside the engine. If this comparison shows little or no Oxygen in the exhaust manifold, a voltage is generated. The output of the sensor is usually between 0 and 1.1 volts. All spark combustion engines need the proper air fuel ratio to operate correctly. For gasoline this is 14.7 parts of air to one part of fuel. When the engine has more fuel than needed, all available Oxygen is consumed in the cylinder and gasses leaving through the exhaust contain almost no Oxygen. This sends out a voltage greater than 0.45 volts. If the engine is running lean, all fuel is burned, and the extra Oxygen leaves the cylinder and flows into the exhaust. In this case, the sensor voltage goes lower than 0.45 volts. Usually the output range seen seen is 0.2 to 0.7 volts. The sensor does not begin to generate it's full output until it reaches about 600 degrees F. Prior to this time the sensor is not conductive. It is as if the circuit between the sensor and computer is not complete. The mid point is about 0.45 volts. This is neither rich nor lean. A fully warm O2 sensor *will not spend any time at 0.45 volts*. In many cars, the computer sends out a bias voltage of 0.45 through the O2 sensor wire. If the sensor is not warm, or if the circuit is not complete, the computer picks up a steady 0.45 volts. Since the computer knows this is an "illegal" value, it judges the sensor to not be ready. It remains in open loop operation, and uses all sensors except the O2 to determine fuel delivery. Any time an engine is operated in open loop, it runs somewhat rich and makes more exhaust emissions. This translates into lost power, poor fuel economy and air pollution. The O2 sensor is constantly in a state of transition between high and low voltage. Manfucturers call this crossing of the 0.45 volt mark O2 cross counts. The higher the number of O2 cross counts, the better the sensor and other parts of the computer control system are working. It is important to remember that the O2 sensor is comparing the amount of Oxygen inside and outside the engine.
TURBO BASICS &TIPS Turbos provide enhanced fuel economy and performance. A turbo is a basic "air pump" that pushes a volume of air into the engine, which increases the power output. This turbo "air pump" is driven by a fan located in the exhaust by a direct shaft. The more exhaust that flows, the more air is pumped into the engine. In most automotive and some other applications, a wastegate is provided which opens as pressure is increased by the "air pump". This device prevents an overboost from damaging the engine. As air is pumped and compressed into the engine by the turbo, it rises in temperature. To reduce this problem and make the turbo more efficient, vehicle manufacturers have been adding intercoolers. An intercooler is a radiator for air and is usually located in front of, or behind the main radiator itself. To add to the life of the turbo unit, some turbos are also water-cooled by coolant system connections. This feature limits the operating temperature of the turbo to the temperature of the cooling system, thus, protecting the bearing assemble from excessive exhaust temperature. Turbo units may obtain speeds up to 100,000 RPMs, depending on the application, so it is extremely important that a sufficient supply of clean oil always be entering the turbo while the engine is running. If for any reason, whenever the oil supply is interrupted or becomes contaminated, "good-bye turbo". Turbo failures are mostly caused by lack of lubrication or abrasive material in the oil. Other failures occur when heavy particles enter the air stream on the suction side. Therefore, a clean air filter and ducting is necessary. Another type of failure may be caused by objects from within the engine leaving via the exhaust. This could be hard carbon, broken engine parts, manifold rust, etc. To prevent most failures, may we offer the following suggestions: Change the oil at least every 3,000 miles, or more frequently if you wish. Always use the oil that is recommended by the engine manufacturer. Do not use cleaning additives for it may loosen particles in any used engine. Always let the engine warm up when starting. 30-60 seconds in warmer weather and longer as the temperature drops. COLD, THICK OIL DOES NOT FLOW AS FREELY AS WARM OIL! Do not rev engine during warm up time, the turbo may not yet have received a full supply of oil. Always let the engine idle for a period when stopping. The faster you have driven, the longer you should let it idle down. YOUR TURBO IS FREE SPINNING AT HIGH RPMS WHEN THE ENGINE IS SHUT OFF THE OIL SUPPLY IS ALSO SHUT OFF, WHICH MAY RESULT IN BEARING DAMAGE ALMOST IMMEDIATELY. When oil is changed, always prime the filter and crank over engine without starting until oil pressure is observed. By following these suggestion, and practicing good driving habits, your turbo should last as long as the engine. FROM WWW.UNITEDTURBO.COM View attachment 8389 View attachment 8390
yep.. why not.. its helpful?!!??! sure beats half the crap people actually come up with themselves on here
like me? lol, i think i am going to copy and paste this all and repost it tomorrow...but all hand drawn with crayons and fingerpaints.
still more... We seem to recieve a tremendous number of questions about WRX gearbox issues, gear oil recommendations, etc. I thought I would post an overview of some of these questions and provide answers based on our experience and research. I am sure that some of this info may be floating around in various places but perhaps it will help to have it compacted into a single thread. "Why did Subaru put a 5-speed gearbox into the WRX that is not strong enough?" The answer is that it is strong enough for what they considered to be normal useage of the car. At standard power & torque output, with standard clutch, and grip levels provided by the standard tires the WRX 5MT is more than sufficient to hold up to even aggressive driving styles. What Subaru can be accused of, however, is providing a gearbox with insuficient safety margin to handle the degree of modifications a significant portion of the owners are making to their cars. Why is the WRX 5MT gearbox weak? This origin of this gearbox design dates back more than 20 years. The original engineering criteria were probably a lot different than they would have been now or even 5 or 10 years ago. The biggest problem is the gear centerline spacing. The 5MT uses a 75mm gear centerline spacing. This is the primary limitation for producing gears with teeth large enough to handle big torque levels yet quiet enough for the general public and not wear out within the normal life expectancy of the car. Combine this with splash lubrication, a longitudinally split case, inexpensive material choices, etc. and it is clear that it is not going to support power levels not typically seen even on many so-called exotic sports cars. What is the exact cause of failure in these gearboxes? We've done some testing in this area. While many people have promoted case distortion as the cause of the failure (we were probably guilty of promoting this theory very early on)....strain guage testing of the case showed only a small level of distortion even at very high torque levels. While even a small amount of distortion is bad because it misaligns bearings and gears increasing friction and heat generation, it is not the main cause of failure. The main cause of failure is excessive gear tooth separation due to shaft flex. We found that at only 275lb-ft of input torque the gear tooth separation exceeded the recommended engineering limit for a helical gear profile. This separation occurrs because the mechanical leverage provided by the gears also creates a reaction force that wants to push the gears away from each other. The more torque you apply to the gears the more force there is trying to separate them. The input shaft is particularly thin so it can flex quite a bit. When the teeth separate the bending loads on the root of the tooth go up quite a bit. Ultimately the weakest tooth fails and creates a domino effect by wedging between the next set of teeth tearing them free and so on. It is very common to see every tooth on the gear torn clean off. What can be done to strengthen the gears? The best option is to increase the root width of the teeth on the highly stressed lower gears. This is done by changing the gear tooth pitch. Tooth pitch is basically the number of teeth per inch of gear circumference. A comparison of RA and standard WRX gears will show a large difference on 1st and 2nd gears in this regard and a lesser increase on 3rd gear. Also, early WRX gearboxes (mid-2003 and earlier) had narrow (face to face width) 1st, 2nd, and 3rd gears. After mid-2003 the width was increased by 1mm on these gears and therefore matches the width of the RA and STi gears we sell. There are space limitations preventing further widening of the gears. The other thing is to alter material specification and treatments to improve either the ultimate strength or the fatigue life. What about dog gears, aren't they a lot stronger? Most dog gears use a straight cut (spur) gear design instead of the helical gear profile used by Subaru. Spur gears are actually weaker than helical gears for the same width and tooth pitch. This is because there are fewer teeth meshed at the same time and the curve of the helical profile creates more surface area. However, replacing the synchronizers with dogs allows the manufacturer to significantly widen the gear widths so this loss in strength is reclaimed and then some. We've seen that some of the cheap aftermarket gearsets (dog or synchro) can be actually more prone to failure than an RA set. This is usually a result of insuficient heat treatment or excessively hardening the gears (creating a brittle gear not capable to absorbing high shockloads). What is close ratio gearing? Gear ratios represent a ratio of the number of teeth on the driven gear to the number of teeth on the drive gear. A short gear (higher numeric ratio) creates a higher torque multiplication but at the same time requires the drive gear (driven by the engine) to spin very fast. So therefore a short gear ratio will provide a higher torque to drive the wheels and accelerate the car quickly but will require the engine to spin very fast (and it will reach redline very quickly). When you shift up the next gear is taller (lower numerically) so the torque multiplication is less but the engine speed decreases compared to road speed. A close ratio set means the numeric difference between the ratios (1st to 2nd, 2nd to 3rd, etc.) is reduced. Therefore when you shift the engine speed does not drop as much. The effect is to allow the driver to keep the engine operating in the optimum potion of the power band between peak torque rpm and peak hp rpm. Ideally for maximum acceleration you want to be able to shift a few hundred rpm after peak power and have the revs drop right to peak torque. However, if the engine has a wide torque band (as may be the case with a 2.5L w/ fast spooling turbo vs. a 2.0L with a big laggy turbo) then the need for a close ratio is not as important. Why is the choice of gear oils so difficult for the 5MT?Two reasons. Number one is the fact that the front final drive gear is packaged inside the gearbox and shares the gear oil with the main portion of the box. The final drive gear is a hypoid gear design (tapered helical profile) and requires special additives to keep wear to a minimum (there are high loads combined with heavy sliding friction). On the other hand the synchronizers work best with a minimal level of these additives. Thus there are conflicting requirements. Number two is that when this gearbox is highly loaded it generates a lot of heat which is difficult to dissipate with just splash lubrication alone. This heat generation lowers the viscosity of the oil which also creates problems with the synchros (because to achieve a fast shift speed the synchro relies on oil drag between baulk ring and synchro cone to help match gear speed). What gear oil should be used? Some people are recommending the use of GL-4 gear oil. GL-4 has a low level of additives mentioned above and therefore improves synchro performance. However, this is going to be at the expense of final drive gear wear. GL-5 has more EP additives which is better for the final drive but worse for synchro performance. Synthetic GL-5 oils tpically make this issue worse because of the properties of the base stock. Any synthetic GL-5 designed for "use with limited slip diffs" is going to be the absolute worst. To combat the heat issue, anyone running extended periods at the track or just putting long duration severe loads on the gearbox might consider running a 75W140 gear oil instead of 75W90. The gear oil should also be changed more frequently because the heat breaks down the oil and changes the properties. What about GM Synchromesh gear oil?In theory this sounds like it should work very well because it was engineered for just this type of situation (synchros w/ hypoid gear). However, it was engineered specifically for GM synchro components which are not exactly the same as Subaru. Worth experimenting with though if you are having difficulty finding an oil that works well for you. It is important to note that GM synchromesh has a base stock similar to engine oil. It probably will thin out too much with high heat levels so for track day or competitive use its not ideal. Do synchros wear out and are there upgrades available?Yes, the baulk ring portion (sometimes called synchro ring) of the synchronizer assembly is the wear item. Only a small amount of wear is enough to create issues. Forcing a very quick shift or forcing a shift when there is a large speed difference between road speed and shaft speed (like downshifting into the wrong gear) will accelerate the wear very quickly. In competition use it should be expected to replace baulk rings once or twice a season. If you drive your car every day like its a race car then expect to be replacing synchro parts. Unfortunately there are no upgraded synchros available for the 5MT that I am aware of. For the 6-speed STi gearbox a carbon-reinforced baulk ring is now being used on 4th, 5th, and 6th gears (which we can offer to '04-'05 STi owners who are having problems with synchros). It would be nice if a carbon-reinforced baulk rings were available to 5MT owners....perhaps there is a company out there that can produce a low volume run of them. What about shot peening, cryo treating, microfinishing of gears?Shot peening helps with the fatigue strength by creating a compressive layer on the surface. Gear teeth are subjected to continuous load variations as the teeth engage and disengage from each other. Shot peening can improve life of the gears if the load levels are high but obviously will do nothing if you are exceeding the tensile strenght limit. Unfortunately, shot peening can distort the component in the process so it should only be done just prior to finish machining of the component. If done to a finished part then it may affect the fitment.
Cryo treating, although a controversial subject, has been shown by reliable sources to provide benefits to components such as gears. One effect of the cryo treatment is stress relieving. The gears are heat treated and then stress relieved by the factory but very often the level of stress relief is incomplete if only allowed to cool to room temperature. By taking the part down to cryogenic temperatures a more complete stress relief is achieved. Also, cryogenic treatment can compact and tighten the crystalline structure of the metal which improves the toughness and wear resistance of the metal. Cryo treating can also help extend the life of the gears when heavily loaded similar to shot peening by through a different approach. Microfinishing is essentially a polishing of the gear surfaces. The process we subject our RA and STi gearsets to is a chemical-mechanical process that leaves the gear surfaces nearly mirror smooth without no measurable removal of material. This eliminates the need to break in the gears. It also reduces frictional losses between the gears and reduces the heat generated by the transmission. It can also improve fatigue life by eliminating micro-welding and pitting of the gear surfaces which can be a starting point for surface cracks. --Dave Rallispec, Ltd.
they are pretty much all cited some way byt he original poster that I plagurised and I have NEVER claimed I wrote them... they are all cut and past from OZWRX which I do believe I posted in my original post... READ FIRST then comment ..
Just throwing this out there, Adrewtech dissagrees with Rallispec as to the main cause of gear failure in 5mt's. They say gear size and tooth profile are the root cause. If you look at the tooth profile of PPG gears, the forces stay much more normal througout the mesh of the gear. The shafts are going to flex no matter what, but proper gears prevent breakage.
