Turbo 101

SpdRcrChk

Spectator
Turbo 101 - some info about GARRETT and Garrett based turbos
Originally created/written by M.A.R.C. (I'm sure he wont mind me passing on his very good writeup)
Some credit goes to Sonny from Honda-Tech for the general premise and layout.


Disclaimer: All of the following is correct to my knowledge. Please feel free to jump in and correct anything that is wrong or feel free to add anything. This post is pretty long, but hopefully it will help out some newbies that are getting into turbochargers.



LESSON #1: Turbocharger Disection

Before we launch full boost into the course (sorry i had to), let's just make this clear... all turbos have the following parts:

Compressor (Coldside, Frontside, etc)
-Housing, Cover, also called Front housing sometimes
-Wheel (in that housing)


-->Center Section<---
-comprised of the shaft, bearings, etc etc etc


Turbine (Hotside, Exhaust side, Exhaust housing etc)
-Housing, Cover, also called Rear housing sometimes
-Wheel (in that housing)

So when you're describing a turbo to say umm... PTE to make an order (this means you Trent) remember saying "I want a turbo with a 60 front and a 63 rear really doesn't completely describe the turbo.

A quick run down of some Garrett Turbo "Families"

The T25 family = super fast spooling "small" turbo that makes good low rpm torque, but lacks top end power. This turbocharger is commonly used where throttle response and low rpm torque are desired without much regard to high rpm power.

The T3 family = "intermediate turbo" that spools slower, but has the ability to make substantially more power than the T25 family. This turbocharger has been used on A LOT of production vehicles (Ford, Nissan, Volvo, Saab). They can make impressive power, but were known to be laggy.

The T04 family = "big turbo" that makes huge power, but is very very laggy. Without the beauty of being able to make a hybrid turbo, a T04 would probably not even be an option.

The new GT Series family is a new line of turbos from Garrett that promise quicker spooling, more efficient, more powerful turbos. They're a whole other animal and I'll cover that as soon as I can figure them all out and how to explain them. But usually They're named GTXXYYA,B,C. Like i said, I'll explain more another time.

Compressor
There are a couple factors that have impact the performance of a turbo:

* Physical wheel size (usually in mm)
* Trim
note: trim is actually more of a ratio than an actual size, expressed as a whole number ex: 60 trim
* Housing size (a/r)
note: also a ratio and usually expressed as a decimal/fraction

The compressor a/r does affect performance, but not as much to make a HUGE difference for most setups.

Common compressor housing a/r "sizes"
T3: .42 a/r, .50 a/r, .60 a/r, .82 a/r
T4: .50 a/r, .60 a/r, .70 a/r
T25: I don't have much info on them, and (except for the nissan boys :p ) not many people use T25 compressors as much anymore.

Common T3 compressors:
40 trim (20lb/min -- haha...don't even think about it)
45 trim (21lb/min)
50 trim (30lb/min)
60 trim (34lb/min -- biggest "production" T3 compressor, excellent for a street D series)
"Super 60" (36lb/min -- note: this is NOT the "60-1" or a 60 trim T3 compressor)

Common T04B compressors:
S trim (37 lb/min)
V trim (48 lb/min)
H trim (49 lb/min)
60-1 (flows a shitload, never seen a compressor map for it)
edit: provided by M4nfred
[/img]http://64.225.76.178/catalog/compmaps/Fig9.gif
62-1 (bigger yet -- I believe this is a T04S compressor...correct this if it is wrong)

[B]Common T04E compressors:[/B]
40 trim (36 lbs/min)
46 trim (41 lbs/min)
50 trim (47 lbs/min)
54 trim (45 lbs/min <-- Note: that the 54 trim flows less than the 50 trim
57 trim (49 lbs/min)
60 trim (50 lbs/min)

Generally people say it's something like 1lbs/min = 10hp at the crank or something like that. So that's almost like saying the lbs/min will tell you how much hp it supports, give or take a few. Of course there's a lot of factors that affect that.

Above all these you have the larger "T4 turbos" such as your T67's, T70's, etc which are usually named after the size of the wheel in mm. So a T67 is a 67mm compressor wheel (actually 66.5mm but who cares). These turbos usually flow upwards of 650hp.

Turbine

* Physical wheel size (same as above)
* Trim (same as above)
* Housing size (same as above)

Common turbine housing a/r "sizes"
T25: .64 a/r, .86 a/r
T3: .36 a/r, .48 a/r, .63 a/r, .82 a/r
T4: .58 a/r, .68 a/r, etc

In terms of turbine a/r, the larger the a/r, the later the power comes. A small a/r gives you a fast spooling turbo but limits top-end power. A large a/r gives you a laggy turbo with big top-end power.

[B]Common T25 turbines:[/B]
DSM trim (?? not sure how big it is, but it's quite small)
60 trim (small)
76 trim (medium)

[B]Common T3 turbines:[/B]
Stage 1 (small -- most common turbine on junkyard turbos)
Stage 2 AKA T31 69 trim
Stage 3 AKA T31 76 trim
Stage 5 AKA T350

[B]Common T04 turbines:[/B]
69 trim
76 trim AKA P-trim
70 trim AKA GTQ-trim (yes... the 70 trim is bigger than a 76... ill explain later)
85 trim AKA GTS-trim (supports HUGE power)

There's A LOT more to come but that's enough to think about for now


[B]LESSON #2: How do I find out the trim, a/r, etc?!?!? What's it all mean?!?!?![/B]


Now that you know a few of the basic and common turbo configurations out there, now you can learn what all the numbers mean.

Trim (wheel spec)

If you've ever looked at a turbo with the housing off, you'd notice the the wheel looks like it's actually made up two wheels, or some would say it looks tapered or something. Well the compressor and turbine wheels have what's called an inducer and exducer. On the compressor, the inducer is usually smaller and is usually called the minor, and the exducer the major. However, on the turbine section, the inducer is usually larger and the exducer smaller. And are usually sized in inches. Generally a larger combination of the two flows more ex: 2.5" in/3 ex" flows more than 2" in/3" ex. From these two numbers you calculate the TRIM of the compressor wheel. If you remembered above I said that it's possible for a 70 trim to be bigger and flow more than a 76 trim, you'll see why now...

Trim is more of a ratio calculation. To formula for calculating the trim for a compressor wheel is as follows:

(inducer^2/ exducer^2) x 100.

The formula for finding the turbine trim is the opisite of the compressor (if you remember, exducer on the turbine is usually smaller than its inducer):

(exducer^2/ inducer^2) x 100.

We all know the average 60 trim T3/T04E and we're all familiar with the ever popular SC61. So let's calculate an example and compare the two turbos' compressor wheels.

60 Trim
2.290" inducer
3.950" exducer
actually a 58mm wheel
TRIM = (2.290^2/2.950^2) x 100

= 5.244/8.703 x 100

= 0.60 x 100 = 60 Trim

SC61
2.416" inducer
3.227" exducer
actually a 61mm wheel
TRIM = (2.416^2/3.227^2) x 100

= 5.837/10.414 x 100

= 0.56 x 100 = 56 Trim

Now you notice that the trim of an SC61 is 56 vs 60 of the other turbo. This shows what I was saying earlier, that it is possible for a larger (physically), more powerful turbo to actually have a smaller (numerical) trim than a smaller one (physically). To simplify the concept of trim consider basic arithmetic or whatever you wanna call it. 1/2 is .50, and 4/10 = .40. Well the ratio (decimal) number is smaller, despite the actual numbers being larger. Same concept. Also, you could have two turbos with the same trim but support different power levels just like 1/2 and 5/10 both = .50. Makes sense? If not PM me. Either way, it's obvious to tell from the physical size of the wheels to tell which turbo supports more power.
[B]
A/R[/B]
Credit to Dee from Honda-Tech

Compressor A/R is determined by dividing the radius of the compressor housing by the smallest diameter of the compressor outlet . Exhaust housing A/R is determined by dividing the radius of the exhaust by the smallest diameter of the exhaust inlet . As the A/R numerically increases so does the housings ability to induce/exduce a specific volume of air. Lag and effective power range will also be affected by A/R changes. Look at the A/R pic below.

[IMG]http://www.tiora.net/%7Ecivicryda2k/car/misc/trim_ratio.jpg

OK, so you got sizing figured out... so now you know how to pick a turbo that is best for you...?

WRONG... WRONG...

Beyond sizing and power level support comes the topic of compressor (and turbine) efficiency. This is a whole new topic altogether when it comes to choosing the "correct" turbo which i'm not going to talk about because it involves too many numbers and a lot more math and know how and well... i'm an MIS major, not an engineering geek So be happy............... Bitches....

A few links of interest

Some turbo math stuff:
http://www.turbobygarrett.com/turbobygarrett/kits/basics_techinfo.html

More indepth explanation of the stuff I covered:
http://www.turbobygarrett.com/turbobygarrett/kits/basics_turbospeak.html
 
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z4k

Super Mod
Driver
^^^I wish people wouldn't copy and paste thing unless they understood what it was they were copying.
 

m4nfred

ima let the steel hit ya
Driver
Oh ChET 240 said:
60-1 (flows a shitload, never seen a compressor map for it)

Fig9.gif
 

Tonymac

P I Z Z A
Driver
Oh ChET 240 said:
Generally people say it's something like 1lbs/min = 10hp at the crank or something like that. So that's almost like saying the lbs/min will tell you how much hp it supports, give or take a few. Of course there's a lot of factors that affect that.

That's poo and totally misleading the reader into thinking compressor efficiency determines HP.

Oh ChET 240 said:
In terms of turbine a/r, the larger the a/r, the later the power comes. A small a/r gives you a fast spooling turbo but limits top-end power. A large a/r gives you a laggy turbo with big top-end power.

This is misleading too.
 

Tonymac

P I Z Z A
Driver
Oh ChET 240 said:
Exactly how is that misleading? (the a/r part)

Misleading in that it doesn't directly correlate engine output (or better said, engine efficiency as an air pump) with turbine ar.

I see your disclaimer. I'm not a mod so I can't change it. Not to mention that me replacing the little fallacies with proper information would mean I'd have to work at something and right now, i've got too much school work to do.
 

SpdRcrChk

Spectator
^^ it's a basic information post. and the a/r information does generally apply, i don't see why you would say that it's misleading. having had both .60 and .82 a/r's i know there is at least some truth to that statement. this thread would have to be a million pages long in order to cover every facet and detail.
 

Tonymac

P I Z Z A
Driver
It does generally apply to an extent, I agree. Yes, turbine ar does have a direct affect on spool but it also has a direct affect on engine output. Why do you think adding a larger turbo while running the same boost pressures leads to greater engine efficiency/output? Think of the case of a GT2871r v a GT3071r. Same compressors, different turbines, similar spool, yet drastically different engine outputs. Now think of the case of a GT2876r v a GT2871r - different compressors, same turbines, same engine output, but with very different spool characteristics. As I said, its fine that the post is basic but it is also misleading in that it doesn't directly correlate engine output with turbine efficiency - only compressor flow rates (poppycock). Not to mention the importance of a matched compressor/turbine combination. I'm sorry you don't understand why.
 
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m4nfred

ima let the steel hit ya
Driver
lmao omg...nice post.....eXACTLY wut i was thinking...but you...are thinking like a white man...so u typed it
 
a book that i foiund really helpful understand turbos is street turbocharging its pretty indepth shit you guys should read it its by mark warner
 
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