Turbo Education Thread

I used to do some work in a machine shop and we had to mark the part in several places to show that it was checked there and in tolerance.

 

hmmm no one posted this

if you ever need a picture, just ask me, I'm a picture pack rat

btw, this exhausts my knowlege of turbos, these pictures. Ask me anything you like and I'll find the answer though....(also works for pictures, if your looking for a picture thats interesting, I'll find it)

 

Journal Bearings vs. Ball Bearings
The journal bearing has long been the brawn of the turbocharger, however a ball-bearing cartridge is now an affordable technology advancement that provides significant performance improvements to the turbocharger.

Ball bearing innovation began as a result of work with the Garrett Motorsports group for several racing series where it received the term the 'cartridge ball bearing'. The cartridge is a single sleeve system that contains a set of angular contact ball bearings on either end, whereas the traditional bearing system contains a set of journal bearings and a thrust bearing


Journal Bearings
Ball Bearings


Turbo Response – When driving a vehicle with the cartridge ball bearing turbocharger, you will find exceptionally crisp and strong throttle response. Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings. This produces an improved response that can be converted to quicker 0-60 mph speed. In fact, some professional drivers of Garrett ball-bearing turbocharged engines report that they feel like they are driving a big, normally aspirated engine.

Tests run on CART turbos have shown that ball-bearings have up to half of the power consumption of traditional bearings. The result is faster time to boost which translates into better drivability and acceleration.

On-engine performance is also better in the steady-state for the Garrett Cartridge Ball Bearing



Reduced Oil Flow – The ball bearing design reduces the required amount of oil required to provide adequate lubrication. This lower oil volume reduces the chance for seal leakage. Also, the ball bearing is more tolerant of marginal lube conditions, and diminishes the possibility of turbocharger failure on engine shut down.

Improved Rotordynamics and Durability – The ball bearing cartridge gives better damping and control over shaft motion, allowing enhanced reliability for both everyday and extreme driving conditions. In addition, the opposed angular contact bearing cartridge eliminates the need for the thrust bearing commonly a weak link in the turbo bearing system.

Competitor Ball Bearing Options – Another option one will find is a hybrid ball bearing. This consists of replacing only the compressor side journal bearing with a single angular contact ball bearing. Since the single bearing can only take thrust in one direction, a thrust bearing is still necessary and drag in the turbine side journal bearing is unchanged. With the Garrett ball bearing cartridge the rotor-group is entirely supported by the ball bearings, maximizing efficiency, performance, and durability.


(Taken from www.turbobygarrett.com which has a ton of useful information).

In my opinion, ball bearings aren't worth it because you get maybe 400-600 rpm faster spool, but rebuilding the ball bearing turbo is a pain in the ass and will end up costing you as much as a new cartridge...

 

my main question is, is there any way to determine what makes a turbo a good pump gas turbo, and what makes a turbo a good race gas turbo? I was looking at the 60-1's by pte (dual ball bearing mitsu style turbine housing ones with T40E compressor housings), but was told that that turbo is very poor for pump gas use. Is this due to its high pressure ratio efficentcy range, or some other factors? What determines if a turbo, like the 50 trim, the "pump gas king" is good on pump gas or race gas. Is it just the larger you get the harder it is to run the high boost required on a lower octane fuel, or am I missing something?

 

You aren't missing anything. A 50 trim loves 20psi on pump gas with a good tune because its in its efficiency range to make good power. Big turbos like big boost. You don't see many guys running around with gt42r's at 20psi, whereas you don't see many people with 50 trims at 35psi either. Pick the turbo for the boost you are going to run. If you know you are going to run 30psi occasionally then go with something that will enjoy that boost pressure, a 50 trim would kinda be pushing it for that boost IMO, a 60-1 would start pettering out around there too.

 

So how much of an effect does a larger turbine wheel make on backpressure within the same a/r turbine? Say going from a stage 5 wheel to a p-trim a .63 a/r t3 turbine, would that make as big of difference in backpressure as going to a bigger a/r?

 

i found this site very infomative

so would a t4 .58 turbine housing spoolup faster than a t3.82?

 

Yes it would.
.68 t4 is comporable to a .82 t3.

 

Its hard to believe its been a year since I posted that. I don't know what happened to the images in my posts. I wonder if maybe anyone backed it up or saved the image tags so I can find those pics and re-upload them to my server? TIA

I'll get back into this and make a few more posts.

 

I can help you out, Brian. I'll do my best. What all does everyone want to know?

 

the meaning to life


or you guys could probably go into the compressor housing a little more. I've heard claims of up to 10 lbs/min increase just due to a change in the housing itself. I find this hard to believe, is there really that much to just a simple housing?

 

Well it's the same with most things. You'll obviously get more flow if you get a larger area for things to travel through. Larger injectors = more flow. Larger exhuast = more flow. Larger compressor housing = more flow. However, with turbos, it is important to match everything. And more flow doesn't necessarily make it more beneficial to your specific application. This is why .a/r is so important. Larger a/r = more overall flow, but it will decrease low-end type thing. So a huge a/r turbine housing will sacrifice spool for overall flow. Great top-end, not good low end. Dyno queen. And conversely, a small a/r will provide excellent spool at the expense of top end.

 

Well, a small a/r like that in the turbine housing would provide amazingly fast spool, but sacrifice top end. So, if you think about what a lot of those mods do, you can do them to help top end a little bit. The majority (if not all) aftermarket cams improve mid/top end at the sacrifice of low end torque. With the addition of aftermarket cams, people generally see a couple hp/ft lbs less up to about 3000 or so, then more from there on.

Same with intake manifolds. Generally speaking, the shorter the runner, the more top. Conversely, longer runners (like stock) help out low end. There was a thread floating around recently that explained intake manifolds. You can go do a search at How Stuff Works for intake manifolds. It explains it really well. So if you get a manifold like JM or Magnus or similar, those runners are super short compared to the stock ones, so you'll gain top end.

In terms of exhaust, there is a huge amount of information to consider on exhaust theory. I'll get into that if you're interested. But if you're worried about emissions (like some of us) get a high flow cat. Some local guys have dyno proven that high flow cats and straight through mufflers don't hurt performance in the least.

 

Go to the bathroom, get something to drink, put your reading glasses on, and get comfortable. Here we go. This is taken from a thread over on 300zxclub.com. Although they're twin turbo V6's, all these points are still extremely relevant.

 

To sum it up, the more mods you have that increase volumettric efficiency, the bigger hotside you will probably need. Uprgrading from a .63 t3 to a .82 t3 means much more power for a car that already has big cams, SMIM, headwork, etc, than than it would on just an intake, exhaust, boost controller equiped car. For example, if your car is flowing 30lb/min at 20psi, a small turbine housing is not hurting peformance as much as it would on a car that is flowing 55lb/min at 20 psi.
Ultimately, it comes down to your intake to exhaust pressure ratio.

 

I know that this is kind of bringing this thread back from the dead but since it IS a sticky I'm not sure the traditional resurrection criticisms apply...

My question is can I say with a reasonable level of veracity that when a person speaks about the differences between two turbos such as a t25 and a 16g and they inform someone that the 16g will offer more power at a given psi because it is in its efficiency range and therefore offers a cooler charge that they are in fact more incorrect than correct?

My understanding here is that the t25 and 16g are both well within their efficiency ranges at approximately 13-15psi correct? If so does the 16g actually offer a cooler intake charge in these ranges or is this a fictional statement that comes from a failed attempt at explaining the differences that I assume are actually from the difference in exhaust flow because of the difference in volute size and shape?

Is there a significant difference in volute size and shape between these turbos?

Is there a difference in the exhaust housings of a 14b and 16g? I seem to remember that there is, if so is this largely because of the difference in volute size? I know that the two housings can be exchanged.

In a very specific case (in terms of turbo theory in general) will the gains that I assume exist because of the better exhaust flow of the 16g over the t25 (housing and volute size and shape) be negated if they are paired with a stock exhaust system?

Finally, I think a post on how to read compressor maps would be relevant and useful in this thread, I know that threads on the issue exist and I would post something but I honestly haven't read enough to really understand them well enough to meet the ball and string test (If you can't explain a concept with only a ball and string then you don't really understand it).

 

As you stated, there have been many write-ups on how to read and calculate compressor maps. Here are just a few examples from a quick Google search.


Compressor Maps
Turbocharger Compressor Calculations
TurboByGarrett.com - Turbo Tech103
Compressor map reading for dummies.
Stealth 316 - Turbocharger Compressor Flow Maps
Turbo Selection: A Guide to Understanding Flow Maps - Automotive Articles .com Magazine
Reading compressor maps
Compressor Maps
Compressor Flow Maps and Calculations
Engine Flow Chart (and compressor maps) - Automotive Forums .com Car Chat

This one seriously needs to be added to or updated/edited.
http://www.dsmtuners.com/forums/art...ler/128139-how-read-turbo-compressor-map.html

 

The gains will not be negated but they will not be fully realized. You understand what I'm saying. A better flowing turbine with a stock exhaust will give an improvement to power, a better flowing turbine with a higher flowing exhaust will give you a better improvement in power.

This is because it lets your engine breath better. It increases the volumetric efficiency of your engine in the high rpm's.

Any time you replace a restrictive piece in an exhaust system or fluid flow you will improve (raise) its flow over all. Hence why we port turbine inlets and even internal wastegate passages.

The name of the game in turbo exhaust systems is to get the exhaust away from the turbine outlet as quickly and restrictionless as possible. That is why an exhaust going from the turbine outlet diameter to 3 in. using a gentle 15* diffusor would do great for most DSM's, but it is not always realistic.

I believe that this is one of the reasons why you see John Shepherd and the like having there exhaust routed out of there fenders. One it is lighter and second it provides minimal back pressure to exhaust flow, oh and because it looks bad ass, .

Also, you probably already knew this but I figured that I would say it anyway. When you compare two turbine housing A/R's you must make sure that they are always in the same "family". Example of T3 turbine housing compared to other T3 turbine housings. Comparing A/R of different manufactures is not the greatest but is usually all we as tuners can do. This ensures that the volute design is the same. I believe that the tear drop volute shape is the most efficient at harnessing the exhaust energy. A turbine with a larger A/R ratio (1.01 A/R T3 vs. 0.84 A/R T3) will flow more. A turbine with a larger frame size (1.01 A/R T4 vs. 1.01 A/R T3) will flow more. (The flow area is larger, and sorry that it seems that I am negating what I said earlier in this paragraph, ) But we can not say with any degree of certainty if a 0.79 A/R T4 will out flow a 0.94 A/R T3. (If you ask around you can find relationships for different A/R's in different frame sizes, but it is not particulary easy to find).

I hope this helps.

Bill

 

guys, thanks to all who helped in this thread and v8s_are_slow for starting it,im in the same situation and this thread has helped me up my knowledge. thanks so much guys!

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