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--- performance:turbocharging [2020/04/15 19:25] – ben
+++ performance:turbocharging [2020/04/29 02:56] (current) – ben
@@ Line 13: / Line 13: @@
 It's pretty important to keep charge air temperatures down on a 3800. Switching to a turbo makes this pretty simple and can easily net a lot of power just by converting a supercharged car to turbo with the same boost pressure. An intercooler is definitely recommended as well.
-===== Turbocharging vs the M90 Supercharger =====
+===== Turbo Sizing =====
-Consider that a stock L67 with an M90 produces 240 horsepower at the crank at 8 psi.\\
+Generally when picking a turbo you should match the turbo size to the engine perfectly based on power goals and a few details of the engine such as volumetric efficiency, displacement, and rev range. There are a lot of factors into sizing a turbo though and most guides on the internet are pretty loose in determining what should be run with each motor.
-A turbocharged L67 without an M90 will produce 300 horsepower at the crank at 8 psi and can consistently reproduce that without as much heatsoak.
-An M90 will also struggle to produce more than 10 psi without introducing a ton of heat into the intake resulting in knock retard.\\
+Too small of a compressor on the turbo will result in the turbo spinning itself out of its efficiency map, creating a lot of heat, and becoming a restriction on power.
-A turbocharger tends to be more efficient at higher speeds so it can easily produce a much lower temperature air charge at higher levels of boost. Because of this it will require a lot of boost pressure to introduce knock retard on a turbocharged L67.
-A 3800 with a stock cam and no engine mods can easily make well over 300 wheel horsepower with an intercooled turbo. It would require a lot of engine mods to do this with an M90 supercharger. \\ The highest horsepower builds all utilize turbochargers. Just take a look at the [[:records|records page]] to see for yourself
+Too large of a compressor could result in a turbo that needs a lot of rpm to spool up and create boost, or in the worst case scenario could cause compressor surge.
+Too small of a turbine housing would cause extremely quick spool times, but would choke the motor from making power in the higher rpm ranges.
+Too large of a turbine housing would cause very laggy spool times.
+Every turbo will be different in the amount of power it can make and how quickly it will spool. Turbocharger technology has come a long way since the 90's so a more modern turbocharger might be a better option than an older design.
+Generally a good street turbo size would be in the 56-62mm range on the compressor housing. These will have very quick spool times and can likely make 500-600 wheel horsepower depending on the rest of the setup. \\ Generally a medium performance size would be in the 60-68mm range. These can make around 600 wheel horsepower depending on the turbo and the intercooling setup.
+{{  https://www.researchgate.net/profile/Shahab_Alaviyoun/publication/323279786/figure/fig1/AS:596027748937729@1519115497755/Turbocharger-internal-components-1.png?nolink&|Turbocharger internal components [1] | Download Scientific Diagram}}
+===== Other Considerations on Turbo Selection =====
+==== Bearings ====
+Generally most older turbochargers will use a journal bearing that only requires oil to lubricate and cool the bearings.
+Newer turbos will use ball bearings in the compressor housing and will typically use engine coolant to help cool the bearings as well as oil to lubricate them. \\ Generally ball bearing turbos can spool faster and create less pre-turbo back pressure due to the decrease in friction in the bearings.
+{{https://www.turbosbytm.com/sites/default/files/u25/jbvsbb.gif?nolink&|journal bearing vs ball bearing}}
+A ball-bearing turbocharger with a billet compressor wheel will spool faster and have more room to make power than a similarly sized journal bearing turbo.
+==== Compressor Wheel ====
+Some turbos will also have billet aluminum compressor wheels that will help speed up the spool times due to the decrease in rotating mass.
+Other main factors that can improve spool times are:
+  * variable vane technology usage
+  * twin-scroll turbine housings
+  * size of the turbine housing and turbine itself
+  * A/R ratio of compressor and turbine housing
+  * camshaft selection
+However there a lot of other things that play a big factor here as well. This are just some of the more commonly discussed heavy hitters.
+===== Resources =====
+[[https://www.turbosbytm.com/blog/journal-bearings-vs-ball-bearings|https://www.turbosbytm.com/blog/journal-bearings-vs-ball-bearings]]