compressors and turbines and housings oh my. WTF is going on !
 

so I decided to do a bit of reaserch since there isnt much good reaserch out there.

ok lets get to talking about A/R

WTF is A/R exactly how many people really know ? im not sure. i kind knew that A/R reffered directly to housing size but didnt understand its exact relationship to anything else.

Ok if you familar with tire sizing the a/r is actuall Aspect ratio.

yeah its that simple.

A/R is the Aspect ratio of the wheel.

So how does this affect your turbo decisions ?

well. for instance in the turbine side of things there are stage 1,3,5 turbine wheels ( from garret) so that means that there a nine possiable combinations of t3 turbine setups

a stage 1 a/r .48 is ------- tiny. a stage 3 .48 is a might bit bigger a stage 3 .48 is bigger yet

So if you wanted to compare outflow vs outflow a stage 2 .48 is almost the same as a stage 1 .63. but the .63 stage 1 will have a slithgly higher spool up time. but they will both flow the same or fairly close to the same amount of overall exhuast

it goes on so on and so forth with other turbine housing wheels combos ( im only talking about t3 trims but this is universally applicable to other turbos)

however the same holds true for compressors

IE a 42 trim with a 40 mm inducer vs a .42 with a 45mm inducer are completely diferent units.

the 45mm inducer ( the aspect ratio is derived from this ) will flow more total air then the 40mm. even though the housings share the same a/r the wheels will dictate the size of the housing. even with the same A/R

So when selecting your next turbo make sure to ask all the right questions

Ill see what i can do to come up with a guide to turbine side's etc.

Sean out.

Re:compressors and turbines and housings oh my. WTF is going on !
 

Good info. Nice work. Something like this should be added to the FAQ. ;)
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

Re:compressors and turbines and housings oh my. WTF is going on !
 

wow seam just when I think ive figured it out... damn youre good ;)

Re:compressors and turbines and housings oh my. WTF is going on !
 

Nice writeup Sean. Straight forward and in laymens terms...

Re:compressors and turbines and housings oh my. WTF is going on !
 

Yeah man Nice writeup....Now I know what to choose

Re:compressors and turbines and housings oh my. WTF is going on !
 

Well if anybody wants to get in on this id like to make Garret turbo spit up the info on the hot sides of there turbos.

Re:compressors and turbines and housings oh my. WTF is going on !
 

Ok I had 2 turbos
#1 SVO .60/.63
#2 volvo .42/.48 both were T3 garretts

The turbine housings ( .48/and .63 ) were totally swapable with out changing anything, just take one off and put the other one on.

My question lies at the compressor side. Lets say I wanna use a 50-trim wheel in my SVO turbo that comes with a 60-trim. Can I just get a 50-trim .60A/R compressor wheel and slap it in the SVO turbo, get it balenced and I'm good to go ?

OR do I have to match the compressor wheel with the compressor housing. Like a 50-trim has a "50-trim .60A/R compressor housing" and the 60-trim has a " 60-trim .60A/R compressor housing" and they both are different and can't be interchanged like the turbine side.

BTW I'm pretty sure both the volvo and SVO have stage1 turbine wheels.

Re:compressors and turbines and housings oh my. WTF is going on !
 

IMO the housing has nothing to do with the wheel. IE there could be a .42 a/r housing on a 60 trim or a 50 trim wheel. the housing would of course if designed for each wheel be different in terms of overall size. A/R has to do with wheel size. Not anything else. The wheel determines flow and the A/R determines peak effiecncy etc etc etc. they are related but not in the snese your trying to make them related.

Re:compressors and turbines and housings oh my. WTF is going on !
 

nice write up, sean.

The turbo I want for my d16 is a 60 trim 48ar tubine and 60ar compressor.

What do these numbers mean? and do you think this too big of a turbo for a mild 8 psi application?

Re:compressors and turbines and housings oh my. WTF is going on !
 

A/R =
The "A" is the AREA or size of the opening at the end of the turbine housing where the exhaust gasses exit into the turbine blades.
The "R" is the RADIUS of the turbine housing measured by the distance from the center of the turbine shaft at a given position on the turbine housing.

Re:compressors and turbines and housings oh my. WTF is going on !
 

yes thats true. but there are directly related to the diameter of the turbine wheel. There no getting around that either.

So while what your saying is technically tue. your also missing the larger point of the post. its actually

a /r is actually a equation of

Area / radious or

If the housing is 3CMsq then

it would be 3cmsq divided by the radious of the wheel would be the A/R

in this case lets say the wheel is

50mm in diameter

so the radious is 25mm or 2.5cm

if we had a Area of 3CM sq then the a/r would be

0.83 a/r

there interelated not at all seperate. And thats why its so important to understand these things.

Re:compressors and turbines and housings oh my. WTF is going on !
 

The A/R has nothing to do with the turbine rotor or "wheel". It's the shape of the housing.
The size of the turbine rotor effects the "gearing" of the compressor wheel. A small turbine rotor will spin faster with a given amount of ehaust energy in comparison to a large one.
Effenciency has to do with how hard the compressor has to work
to create a certain amount of boost pressure.
All these dfferent combos are availible to allow the turbo system designer
to keep max effenciency in a desired rpm range(of the engine), inlet charge temp. and correct airflow for the engine.

Re:compressors and turbines and housings oh my. WTF is going on !
 

I'm not trying to stir anything up with my posts. I'm sure that we are very much alike... but, I would like to ask if you've read chapter three of Max. Boost?

Re:compressors and turbines and housings oh my. WTF is going on !
 

again.. sean.. you are a very smart guy.. but stretch-d is correct. I just read that article of understanding turbo #'s in SCC. Older issue, but he more or less had the exact wording down.

It also states if you divide the .60/.63 or .43/.48 or whatever the hell the numbers are you should always get the same #.

Re:compressors and turbines and housings oh my. WTF is going on !
 

Im not sure i really care what corky bell has to say. This is info directly from garrets engineering department.

Also the size of the exducer on the turbine wheel does directly affect the Radious of the housing. As there are not one but serval types of turbine wheels all having different circufrences and consequnetly raidious !

as i siad. Corcky beel understate the relationship has for yrs. That book has been a constant thorn in my side for a long time. a/r is a Ratio of area to radious.

Re:compressors and turbines and housings oh my. WTF is going on !
 

The trick though is to use the least retrictive Turbine housing to generate the desired pressure ratio. and the whole point of this post is to bring to light that there are alot of potential A/R and exducer wheel size combos avaiable and based on engine size and head outflow we should be calculating the desired A/R for the turbine housing to create the compressor inducer speed to generate the boost levels were after.

To small of a turbine housing will just make the engine strangle itself to death.

thats the point of this post.

Re:compressors and turbines and housings oh my. WTF is going on !
 

I understand the point of the post and the information (most ;) ) in it. Now my question is application. With this information, how can it be applied by the thirsty minds of those putting together their "well assembled" turbo setups?

BTW sean, have you been drinking on christmas eve, or are you just typing really fast ;D

Re:compressors and turbines and housings oh my. WTF is going on !
 

Both drinking and typing fast. I cant answer how aplication friendly this info is just yet becuae i cant get the remaining hot side info out of there engineering dpartment as of this moment. When i do ill be glad to pass it on.

Re:compressors and turbines and housings oh my. WTF is going on !
 

I thought the point of your post was to educate people about the subject of A/R.
You used the term "aspect ratio" to define A/R. This is simply not correct. As you refer to this in later posts, you changed your description of the term to "area & radius".
Furthermore, The radius of the Exducer does indeed effect the radius of the housing but...as a whole. It doesn't mean a change in ratio or relationship of the area to radius. You can have a larger turbo with a larger turbine rotor and still have the same ratio as on a smaller turbo with a smaller turbine rotor.
All of the info on calculating which turbo will suit your needs can be found in the pages of Max. Boost along with a wealth of other important design info. I would hardly call this book a thorn in one's side.
The point of this post is to say," If you're going to take the stance of being an educator, be sure to get every piece of info correct." Merry Christmas

Re:compressors and turbines and housings oh my. WTF is going on !
 

Well i find it interesting that Corky bell has such simple calculations for turbo in his book. considering Garret ( the people who actually make the turbos) has pretty much decided to keep the hot side information to them selves.

the a/r is techincally an apsect ratio for all intensive purposes.

As for your commects. As the diamter of the Wheel goes up the radious gets larger as does the. The Radious of the curvature of the wheel also changes as the wheel or Exducer get larger.

his has an over all effect on the actual A/r of the turbine hosuing.

Also note that there are sevral combinations of exducer wheel and turbine housing for each exducer wheel.ie

for stage 1 wheels there is .48 .63.
for stage 2 wheels there is

.48 .63 .80

for stage 5 whesl there is

.48 ( turbonteics part ) .63 .80 1.00

Maybe you shouldnt take everything you read in maximum boost ( read the disclaimer at the front ) so highly regarded.

Re:compressors and turbines and housings oh my. WTF is going on !
 

Well, 25 years of experience holds quite a bit of water in my opinion. I'll take his word for it unless you can prove that he's wrong.
Also, why would anyone want to over-complicate an already complex subject. The equations and guidelines found in that book provide a usefull reference for people getting started. The answers to the questions that most of the people on this site ask are in that book. To steer people away from this resource in an injustice to the aquisition of knowledge on this subject.
Besides, the calculating side of turbo system design is to get the designer in the ballpark of where he wants to be. Real world testing & trial & error are what goes the distance.
Somehow, even though Garrett hasn't released all the info on their turbo's design...People are putting together great turbo systems.
Let the people decide.

Re:compressors and turbines and housings oh my. WTF is going on !
 

Alot of turbo systems just straight out suck. thats the plain truth of it all.

Also corky bells 25 yrs of experience mean nothing to a guy with a 1.6L vtec engine with a VE capablity per liter hes never seen.

then again engine design and cylinder head design have changed oh 100 fold over the last decaded and theres been a revolution in head flow.

Also never mind the fact that the new GT series garret turbos look really promising for the future ( if there prices come down) becuase they are low restriction turbine housings.

the thing is and Yet again you dance around this peice of commons sense i keep bringing up. You want to run the largest turbine housing you possiably can on your engine and still get the turbo to spool up and behave properly. Theres only one way to do that. Punch and crunch some numbers.

If you have a big lopey cam and its got an extremly high rpm oriented grind on a b18 your not gonna put a turbine housing and wheel combo on that would only be able ot breateh to say 6000rpm when the cam and the rest of the running gear are targeted for peak HP around 7500rpm are you ?

Its this type of ( eveyrbody else does it ) ignorance thats pis's me off. IF you knwo what you need up front then you buy the right stuff the first time Youll be happier with the end product itll go faster make more HP and COST LESS TO BUILD becuase you bought the right parts the first time.

Re:compressors and turbines and housings oh my. WTF is going on !
 

The dispute was not about the correct points of your post. It was about the incorrect points.

No matter what engine you have, the basic measurements of cfm, rpm, temperature and turbo size haven't changed.
If you're running a 750cc motorcycle engine or a 12 cyl. Ferrari engine, the process and calculations of turbo selection are the same.

If you have a head that flows more cfm than another, you just adjust the number in the equation accordingly. But it's the same equation. By saying that calculating procedure has changed over the last decade due to increased headflow capacity...in essence you are saying that Algebra has changed. Not true.

Question: Do you think that the people that design turbo race cars (Indy or strip) choose thier turbo's dimensions with calculations only? Do the figuring but don't assume that you're finished.

More times than not, an adjustment will be made to get it "spot on". This site is filled with people
making changes to their turbo's dimensions.

A lot of people have a difficult time with this subject for several reasons including (but not limited to); common misconceptions, inacurate info, lack of research, lack of patience and lack of funds. The result: A lot of turbo systems that just plain suck.

Why blame Corky Bell for that?

Re:compressors and turbines and housings oh my. WTF is going on !
 

Im saying and to sum it up. the design of turbos,heads etc has changed over the last decade in a substial enough manner to warrant looking at the calculations to determine proper turbo size.

IF youve been following the changes in turbo design over the last 10 yrs youd be vastly aware of the fact that exducer design has changed termendously.

And again. Corky bell states that his book is a rough over view on the subject of turbo charging.

Yes with testing youll find the best turbo but if you do the correct math with modern design turbine wheel and housings then youll end up with a much beter combination of parts that makes more ouput per $ spent.


im done arguing with you. Obviously youve decided that Corky bell knows everything. Im simply suggesting to think out the aproach in a more thurough mnner. I dont have the time or nergy to sit here and discuss everybodys turbo selection. Im simply encouragin thought on the subject. the more well thought out your turbine housing selection the more power youll make per $ invested.


Just think !

Re:compressors and turbines and housings oh my. WTF is going on !
 

I didn't know that we were arguing.

I thought it was just a good debate on a subject we obviously are both interested in.

I would like to wish you & everyone on this site a Merry Christmas. So no hard feelings.

I hope Santa brought everyone the turbo parts that they wanted.