how can 2 turbos that look COMPLETELY different and have COMPLETELY different A/R's still be called by the same nomaclature. Im looking at what is said to be "maybe" a T3 off a 1990 Pontiac Gran Prix, but all my research says that year came with a Garrett T25 with intake A/R of .80 and exhaust of .68. And i can assure you, my t25 aint nearly that big!!! So what the hell is this? a t25 or t3 or what?





ALSO, if a turbo has the same A/R #'s, are they the same size. My t25 has A/R's of .42 and .48, so are a lot of t3's im seeing, im so confused. I thought i had this turbo sizing shit down but now im all F'ed up!!
HELP!!!!!

Bump, seriously! anyone???

Becasue there are many T3's T4's all with verying housing and wheel sizes.

For instance. I have Full garret turbo with a .48 housing,50-trim compressor wheel and a stage 3 turbine wheel.

You can get this same turbo with a 57-trim compressor wheel, you can get a stage 2 turbine wheel, you can get a .63 housing but they are still t3/t4 turbos.

Hope this helps feel free to ask any more questions or PM me.

garret t-25 and mitsubishi t-25 are not in the same!!!

is there a sight or some info for someone like me who wants to understand better how turbos are sized? I get lost in all the trims, stages, and hybridizations. Im just looknig for a good "better and bigger" unit than my Mitsu T-to small.

>is there a sight or some info for someone like me who wants
>to understand better how turbos are sized?

nope. somebody should make one.

>I get lost in all the trims, stages, and hybridizations.

The problem you have is that almost anybody with a T-3 refers to it as just that, a "T-3". This is the dilema. A T-3 isn't a SIZE, but an entire FAMILY of turbochargers that Garrett makes. They make turbos that are smaller than the T-3 family, and they make turbos that are larger than the T-3 family. The thing is, though, that in the family you can get a turbo that will support 125hp, and you can also get a turbo that can support 375hp. Yeah, they're both T-3's, but the one pumping out enough air for 375 hp is a lot bigger.

a T3/T4 is a HYBRID. It used the T3 turbine components that're smaller, and uses the T4 compressor components which are bigger. This way, you can take a small 4 cylinder to move the turbine wheel (a smaller wheel needs less gasses to keep the velocity up,) and pump a lot more air into it with the larger T4 family compressor components.

oops wrong post to reply off of. see below!!! = )

>garret t-25 and mitsubishi t-25 are not in the same!!!

Yeah, they're not. Considering Mitsubishi doesn't MAKE a T-25. :rolleyes

>a T3/T4 is a HYBRID. It used the T3 turbine components that're
>smaller, and uses the T4 compressor components which are
>bigger. This way, you can take a small 4 cylinder to move the
>turbine wheel (a smaller wheel needs less gasses to keep the
>velocity up,) and pump a lot more air into it with the larger
>T4 family compressor components.

SO then, what i should really be looking at is the A/R #'s, right?
Regardless of what family its in (relativly speaking, i aint gonna look inthe t-60 family)i should look at mildly bigger A/R numbers compared to my stocker t25 if i want a bigger HP turbo.

Ex: my t-25 is .42/.48 (i beleive off the top of my head) so a unit regardless of family nomaclature with A/R #'s of .68 hotside and .80 cold side is bigger but not to big for a 420a, yes?
even if it is to big, is that still the general idea, just finding smaller A/R's?


t_hawkins@hotmail.com

what you need to look at are both the a/r and the trims

you can have a .63 a/r compressor but have different trims like 57trim or 60trim etc...

the idea with the t3/t4 hybrid is the smaller turbine is easier to spin and should get you faster spool times to spool a bigger compressor..
but you lack in topend with small turbines...

Bill

>the idea with the t3/t4 hybrid is the smaller turbine is
>easier to spin and should get you faster spool times to spool
>a bigger compressor..
>but you lack in topend with small turbines...

Not necessarily. The A/R and the "stage" (O, P, Q) of the turbine wheel will help in determining spool.

You can take a .48 A/R with a Q trim wheel and have just as much top end as a .63 A/R and an O wheel. Chances are you'll have better top end with the smaller A/R because the Q turbine wheel isn't restricting flow like the O wheel does.

Like I said, talk to someone who knows their shit when it comes to turbochargers.

>SO then, what i should really be looking at is the A/R #'s,
>right?

Nope.

A/R is a ratio. It's basically the ratio of the outlet size of the turbo compared to the radius of the scroll. You take a measurement of the radius from the center of the inlet to the center of the outlet of the housing on a compressor. Here we go:

If you've got a 2" outlet, and the radius of the entire compressor housing from the inlet to the center of the outlet is 3.5", then the A/R of that housing is .57 This is all hypothetical, of course. Let's pretend...

We've got this magical turbo with a 2" outlet, and a 3.5" radius. Let's pretend it's got a 2.5" inlet, and we know the A/R is .57 right? okay.

Take another magical turbo, this one has a 4" outlet, and a 7" radius, with a 5" inlet. Know what it's A/R is? .57.

Which turbo would you rather have? I'll take the BIG ONE, please!

>so a unit regardless of family nomaclature with A/R #'s of .68
>hotside and .80 cold side is bigger but not to big for a 420a,
>yes?

NO!

The A/R's typically go up in size as the numbers grow larger, if they're in the same family. Garrett just does this to be nice to people I guess.

You can also have the same compressor wheel with two different A/R's. Nice, huh? Call up someone who knows their shit when it comes to turbos. They'll be able to help you out.

Oh no, I might know a thing or three about turbos, too! :thumbsup

Moochus Grassy Ass, tool!!
so what about the turbo pictured above? any thoughts, ideas?

>Moochus Grassy Ass, tool!!

You should give me points. I'm a points whore.

>so what about the turbo pictured above? any thoughts, ideas?

It's cute. I slept with it's mother last night. She's a huge bitch!

Seriously, though, I can't tell. I have nothing to reference it to. Looks like an upgrade from your T-25, though. I can't check the shaft endplay from here regardless of how hard I try, is it any good?

i'd recommend the book "maximum boost" by corky bell. it has a/r ratios proportionate to how much boost you want to run as well as turbine inlet pressure

if you want more power at say 6+ psi a good A/R is 1.4-1.15, for better low speed response a good A/R is .7 but the compressor efficency will suck at anything above 6psi. generally, more power comes from a bigger A, with the R staying constant.

any more quaetions shoot me a pm...
_________
96 talon esi-t
san clemente, ca

Uberingram> I bow down to the Geo

>it has a/r ratios proportionate to how much boost you want to run
>as well as turbine inlet pressure

You're leaving out HALF the equation here. A/R on the turbine, and turbine inlet pressures aren't the only thing to take into account. The trim of the turbine blade plays an extremely important role in spool as well. Not only that, but the clip, and the types of bearings used in the turbo play a role in spool. too.

All this half-assed information...

>if you want more power at say 6+ psi a good A/R is 1.4-1.15

This is only partially true. I have people skills... what the hell is wrong with you people?!

>for better low speed response a good A/R is .7 but the
>compressor efficency will suck at anything above 6psi.

What drugs are you on? Your nonsensical posts make my brain palpitate. You're a crack donkey.

Throw all this shit out the window. Just listen to what I said. Go find a guy who knows what he's talking about. This guy reads a book, and all of a sudden he thinks he's corky bell himself. :rolleyes

Your turbine A/R doesn't effect compressor efficiency for all practical purposes. your compressor A/R affects your compressor efficiency. Your turbine A/R, turbine inlet pressures, and turbine wheel affect spool.

A/R is not the total equation. Throw that thought out the window.

>generally, more power comes from a bigger A, with the R
>staying constant.

R has to go up with A. You can't have a 4" inlet on your turbine with a 2" radius. your inlet would be touching the center of your turbine wheel.

Take this thread, print it out, and show it to someone who actually knows about turbos. See who that person agrees with.

>>You're a crack donkey<<
ROFL!! LMAO!!!! LOL!!! (sorry turbo8u)

Anyway, i have "the bible" in front of me as i type and it doesn't do a real good job of explaining A/R in detail, or the significant relevence of it in regards to choosing a turbo. It only goes into what it is and how its figured.

As far as finding a "good turbo guy" your gonna have to be him or at least share the title with a few others!! i live in a smaller "non-turbo" town. im surrounded by the kind of people that when i pull up and open my hood they lean in and say "that looks hella cool dude" as they reach out to touch the turbine housing!! Not in-bred, just not well-bred!!

So henceforth you shall be known as "G.T.G.T.K.", "Good Turbo Guy To Know"! Or till i forget and no one else uses it!:P

>>>You're a crack donkey<<
>ROFL!! LMAO!!!! LOL!!! (sorry turbo8u)

:thumbsup

>Anyway, i have "the bible" in front of me as i type and it
>doesn't do a real good job of explaining A/R in detail, or the
>significant relevence of it in regards to choosing a turbo.

hm... I didn't know moses talked about turbos. I need to reread the bible!

>im surrounded by the kind of people that when i pull up and open my
>hood they lean in and say "that looks hella cool dude" as they
>reach out to touch the turbine housing!!

You mean like turbo8u? :rolleyes

>So henceforth you shall be known as "G.T.G.T.K.", "Good Turbo
>Guy To Know"! Or till i forget and no one else uses it!:P

I'm guessing here, but that turbo is definitely in the T3 family. I know nothing about the turbine part of the turbo, as it's encased in that cut off piece of a downpipe. Take that thing off, and let a few people see the size of that exhaust wheel.

Either way, I'm guestimating that the compressor wheel is either a 45 or a 50 trim T3 wheel. If it's a 45, you're not going to make more than 240 horse with that thing. If it's a 50 trim, you're not going to be able to make more than 275 with it. That's on more boost than you're going to want to run, too.

I don't know what your goals are. It's bigger than your T25, and the larger compressor housing will help keep intake temps cooler, but it's not all that large as far as turbo standards go. It's cute though.

How about you guys end the name calling right here? Get back on topic (remember the turbos) or this thread will be locked.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

Quote
How about you guys end the name calling right here? Get back on topic (remember the turbos) or this thread will be locked.

You're no fun.

ok if i may hijack the tread for an instant.. i had to buy this t3/t4 turbo in an instant as mine blew as i was in a different city and i had to buy one there an then. I have no clue as to what the A/R is.. all i know is that the housings are bigger than my previus t3/t4, but as I now know that does not necessarly mean anyting. any ideas as to how to find out?

Quote
any ideas as to how to find out?

Let me use my telepathic powers to deduce the size of your turbo...

;( (what the hell kind of smiley is this?)

Tapping into my mind and soul I believe your specific turbo is a T3 with a .80 compressor A/R and it's a 50 trim! On the turbine side you've got a .72 A/R and a P trim turbine wheel! Feel the power of the 'tool!

Sorry, I'm not that telepathic. :wary

Post pics of the compressor housing. The A/R is written on the outside of it. Hold a ruler across the inducer on the compressor housing and take a pic of that, too. NOT the turbo inlet, the incuder size of the compressor wheel.

Then, do the same thing with the exhaust. Take pictures and post them so that others can see them.

Nice name calling match. If it weren't for some excellent information beig given (yes, mostly by the tool), this thread would be completely useless.

"I now only use all the brains I have, but all I can borrow." - Woodrow Wilson.

Remember stubborn pride and not being able to admit you are wrong, will never let you learn anything new. Learn what you can, no matter how it is delivered. Take th eknowledge when you can. Sometimes an explanation of somethign you;ve red in a different presentation will explain the premise all that better.



15.9 @ 86.7mph

Smooth idle? We don't need no stinking smooth idle.

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