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JK Fab video:    • MaxPeedingRods "GT2871" Turbo Review ...  

So here we have two MaXpeedingRods turbo chargers. At first glance they look pretty much identical right? They're both "GT28" turbos with nearly identical specs but one costs almost four times as much as the other? Why? Because one is a lot stronger than the other and today we're going to use these two turbochargers as an example to learn what makes a turbo strong and better capable of handling higher boost, more abuse and more racing use.

These two turbine housings may look similar but they're made of completely different materials. The low cost turbine housing is made from nodular iron while our other turbo has a stainless steel turbine housing. Now stainless steel is definitely the superior choice for a turbine housing due to two main reasons. Reason one is that it has a higher temperature resistance and reason two is that it offers better resistance to oxidation.

Now we're moving onto the compressor housing. Now both of these compressor housings are made from the same material ZL104 aluminum. The compressor housing together with the compressor wheel comprises the cold side of the turbo and obviously it never sees temperatures anywhere near of what the turbine housing sees which is why temperature resistance is much less of a factor on the cold side.

The zl104 is the alloy name according to the Chinese GBT standard and the ISO equivalent is AlSi10Mg. This is a pretty nice aluminum alloy traditionally used for casting. As aluminum alloys go It's a pretty tough alloy with good hardness and good strength. Because of it's good casting properties it's ideal for cast parts with thin walls and/or a complex geometry – of which compressor housings are a clear example.

Both of these compressor wheels are aluminum, but this one is cast and this one is MFS, or machined from solid. In other words this is a billet compressor wheel.
So why is this one better? It's better because of the same reason anything billet or forged is better than anything cast when it comes to automotive applications and it all comes down to the internal grain structure of the part.
The grains structure refers to the size and orientation of the little microscopic individual grains that make up a chunk of something. This size and orientation of these grains depends on the type of the material but also on the way a material is made and parts grain structure ultimately plays a key part in it's strength. The more uniform it is the better.

Although casting has come a long way it is still impossible to prevent a relatively random grain structure with cast parts and it's also difficult to guarantee there will be no internal porosity with casting, especially with lowtech methods.

On the other hand the billet process is completely different. It starts out with a solid chunk of metal that has been previously forged or extruded giving it a good grain structure and then you simply machine away whatever you don't need from that chunk giving you a finished part of the desired shape with the preserved grains structure of the initial billet.

Now both of these turbos are pretty identical inside and are full floating journal bearing turbos. Now I do plan to make a detailed comparison video between ball bearing turbos and journal bearing turbos in the future so for now I will say that although many people prefer ball bearings and they do offer faster spool and are ultimately a superior choice in many aspects there are still significant benefits to be had from journal bearings. Journal bearings need more oil which means that they ultimately help the cooling of the core and when everything is running properly journal bearings can last infinitely as they are a no contact bearing, they ride on a film of oil which also means they can be very effective at absorbing abuse and vibrations making them pretty handy in racing scenarios.

So what are the the lessons we can learn from this? Well it's actually pretty simple. The more extreme your application and the more boost you want the more heat resistance and mechanical strength you will need.

A special thank you to my patrons:
Daniel
Peter Della Flora
Daniel Morgan
William
Richard Caldwell
Pepe
Brian Durning
Brian Alvarez

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