Ball Bearing and Ceramic Roller Bearing Turbos

by  Chris S (PCS74), Steve Wood, and Jack Cotton

With the talk and hype about Garrett Ball Bearing center sections, Turbonetics Ceramic Roller Thrust bearings, low drag and standard floating bearings, testing, reliability and cost I though it would be a good idea to clean up the terminology, expand on some of the benefits and provide a little better picture of what it all actually means as it has been explained to me by various professional engine builders and turbo engineers.

First, there are three common types of bearings for the turbocharger. They are: Garrett Ball Bearing, Turbonetics Ceramic Roller Thrust Bearing and conventional floating (don't know if there is a specific term for these). There are very prominent differences between these bearing types and the Turbonetics Ceramic Roller Thrust bearing is no more a Garrett Ball Bearing than it is a conventional floating bearing, and vice versa.

First the Garrett Dual Ball Bearing center section. This design was developed by Garrett of Japan in association with Nissan, or by Nissan (I have heard both) and was designed to reduce lag in road situations on standard transmission vehicles and improve durability, that's it, lag and durability only. These center sections are what is used in CART and other top of the line motorsports competitions where "price is no object". They are used in conjunction with exotic material wheels, housings and center sections and are very expensive. If you want to see what I mean go pick up RACETECH or RACECAR ENGINEERING magazine and you will find plenty of them.

There is a SAE paper, reference number 900125, which details the testing and the results obtained from a comparison of a true ball bearing turbo and a floating bearing turbo. This paper details the generation 1 ball bearing and they are now at generation 4(I have been searching for generation 4 info, but it's all internal documentation I guess).

Performance wise they do offer a benefit, but not what the average GN owner would use it for nor care to pay for. The ball bearing center section primarily provides response and performance benefits in rapidly changing load conditions, such as road courses or passing maneuvers. For instance, if you were driving a Porsche on the Autobahn and wanted to pass another vehicle it would remove the necessity to downshift. Just roll on the throttle and the boost comes up very quickly.

However, on a drag strip vehicle, that runs a high stall converter and is launched under boost the performance difference between a dual ball bearing turbo and an otherwise identical floating bearing unit would not justify the cost increase. But take these two turbos out on the road and you will notice the difference, especially if you run a hugely oversize turbo like we all want.

The best way to test the ball bearing turbos against conventional bearing units would be to make repeated runs from 30 to 50, 40 to 60, 50 to 70, 30 to 100 and the standard 5 to 60. They were not designed to be a drag strip component, so any e.t. benefits would probably be from other support modifications made in addition, such as stall speed change , fuel and spark changes and maybe some heat reduction if you can stage second and still reach your desired launch boost before the lights come down.

Next, the Turbonetics Ceramic Roller Thrust Bearings. These units use the ceramic roller bearing on the compressor side and a conventional floating bearing on the turbine side. The bearings are called ball bearings by Turbonetics, but that is for marketing reasons. The original intent was to create a stronger thrust bearing to improve durability on large diameter compressors. The Turbonetics style is said to handle 50X the thrust load of a conventional bearing vs the Garrett Dual BB of about 2X the load of a conventional bearing. As a side benefit they reduce friction greatly.

A while back I got the chance to play with a Turbonetics unit at a local shop. The difference from it compared to the te61 I have was amazing. There was absolutely no drag that I could "feel", it is there, just not noticeable to the hand. For instance, if I spin the wheel on my te61 it stops rather quickly. On the Turbonetics unit it doesn't stop. Even turning it while pushing down on the wheel as hard as possible, at the advice of the owner, it would exhibit no drag that I could feel (I'm 6'5", 270 and push real hard). With a conventional bearing this would have likely ruined it. They said the vehicle was much easier to launch with the Turbonetics piece making it more consistent and therefore easier to tune and evaluate changes. A big plus.

Performance wise I would put this under the same constraints as the Garrett. You will not likely see a great e.t. gain between two otherwise identical units in just bolting them on. The major differences will be on the street or from small gains in related components and tuning.

Now, when Turbonetics released these units one of the benefits they took the time to explain was that you could move up one turbo "size" without affecting streetability. They would tell you then that the performance increase came from the larger unit. I do not think they have changed their story, but I will call and ask.

So what can you see from this. The ball bearing and the ceramic bearing were not designed with the intent of e.t. improvement on the drag strip. The Garretts were designed to improve response and durability, and the Turbonetics were designed for large compressors and the loads they deal with.

I fail to see how anyone can ask how a turbo bearing change, all by itself, is going to directly pick up et. Especially when they are looking for gains worth $500 to $1200 from a bearing.

For the majority of consumers this is all you need to know: If you want a more powerful turbo you need to be focusing on the aerodynamics. If you want a more streetable turbo look into the bearings along with the aerodynamics. If you want a more durable turbo look into the bearings and shaft. Or just ask a tech. Others of us like to optimize everything and spec it ourselves.

Finally, price is where they all stand apart. A fully built big shaft Garrett Dual Ball Bearing turbo will cost around $2200 plus or minus a couple hundred depending on when you order. A fully built Turbonetics Ceramic Roller Bearing unit will cost around 1200 to 1500. The built conventional unit will cost around 800 to 1000.

Chris S

-----------------------------------------------------------------

I think what some of us want to know is the value received for the additional money.

It appears from your information that a big shaft race turbo should last longer and seeing the life spans of some, this might be an investment that pays off.

On the other end of the spectrum, I find it hard to justify the price for a small turbo such as a TA49 as the life span is normally pretty good and the potential improvement in "spoolability" probably won't be that substantial as it already spools well.

That leaves us with the middle spectrum with turbos like the TE45-T64E range that normally require 3400 rpm or so converters to rapidly spool from any speed/load. My 45 spools pretty good under load with a 3000 rpm converter but is a bit unpredictable at a slow roll in first gear....one time fries the tires....next time fries the tires about 3/4 second after the pedal hits the floor.

I think your test criteria above is about as good as it will get for determining the benefit and then it is an individual decision to spend 50% more for a little more response on the street from a roll with a turbo that is really bigger than we need.

Steve Wood

-----------------------------------------------------------------

Excellent info Chris,

I have tried a few times in the past to give an explanation to that question and have not been able to get a few points across, it seemed.
You have said the design of the ceramic roller bearing allows for a more durable center section, lets see, if we hurt a center section of a conventional style turbo the cost to repair can easily be in the $500 and up range. I see you also have stated that the low amount of friction also allows for better spool-up which can give us the luxury of moving up a size or so with the same stall convertor, I like that since that also helps to support what I have said all along, that when comparing the same size turbos to each other, whether it be CRB or conventional, the power each will put out should be basically the same, but when we are able to use a larger turbo with the same combo, the result obviously should be better for the CRB turbo. Not only power wise, but all around drivability and street performance. Of course it should only make sense when we reverse that equation and put a smaller RCB turbo on a car that had a larger conventional turbo, the car should slow down!! I think it is important to really look at these facts, as when we are evaluating which way to go, some people will no doubt be better off with a CRB and some will be more suited with a conventional. I personally have used many different turbo of both types, since I also sell both types and prefer the CRB turbo. To date, we have yet to have a CRB failure or a failure in our conventional turbos related to thrust or any other unexplained failure. One of the reasons for this is in the machining process in the compressor assembly and the balancing that is done to each and every turbo center section, that only a few in this country do.
Thanks again Chris for the info!

Jack Cotton
Cotton's Performance

HOME

You are visitor