Turbo A/R's, trims etc.....can someone school me?

[TwoLiterV8Eater]

i am trying to decide the turbo upgrade path to take and while i know a bit about cars in general and i've been racing my DSM for 2 years, i dont really know about compressor maps and A/R ratios and trims etc and would like more info about that. I know that most companies do not seem to offer compressor flow maps for the turbos they sell, and some dont even tell you what A/R or any specific specs at all. This makes it difficult when actually deciding which turbo to buy. I am hoping someone can shed some light on what different A/R numbers mean, what different "trims" mean (i.e garret 50 trim vs 60 trim vs 60-1 etc) and if there is anywhere to get compressor flow maps. i dont want to buy a 1500 dollar turbo because "some guy has one and his car is fast" Im not trying to find the best turbo in this thread, just general turbo knowledge that will help me decide on my own.

 

[RocketBoy]

Look for a book by Corky Bell, i can't seem to remember what it is called off the top of my head but it has "turbo" in the name. The guy is unreal and break all the aspects of a turbocharged vehicle down into easy to understand terms.

 

[Ben K]

The name of the book is Maximum Boost.

 

[el aguila]

Someone correct me if I'm wrong but a/r is area/radius and it's how Garret measures their housings. Like a .63 a/r. Mitsu uses 7cm^2 and all that.

 

[1_vicious_gsx]

Originally posted by el aguila
Someone correct me if I'm wrong but a/r is area/radius and it's how Garret measures their housings. Like a .63 a/r. Mitsu uses 7cm^2 and all that.

I think the Mitsu 7cm housing would equal a .50 a/r Garrett. If I'm wrong, somebody let us know.

 

[el aguila]

Originally posted by 1_vicious_gsx

I think the Mitsu 7cm housing would equal a .50 a/r Garrett. If I'm wrong, somebody let us know.

Oh...I know they aren't equivalent to each other I was just comparing how Mitsu and Garret measure theres.

 

[NOSLO2PT0]

OK Mike, I'll try to explain this the best way I know how. I'll go over each part of the turbo. We will use a T3/T4 as an example, as 99% of the people that choose a Garrett use a T3/T4 vs. a full T4.

The T3 portion is the exhaust housing. They are available in .36, .48, .63, and .82 A/R. A/R is area/radius. It's the ratio of the area of the opening of the snail (housing) in relation to the distance from the shaft to the middle of the snail. This relationship stays constant. Obviously, the bigger the housing, the bigger the A/R is going to be. And yes, a Mitsu 7cm housing falls right around a .50 A/R T3 housing. The turbine wheels available in a T3 housing are: Stage I, II, III, and V. The bigger the stage wheel, the more lag you get. But the tradeoff is more top end power. You want quicker spool, get a stg II wheel in a .48 A/R housing., but your top end will suffer some. MOST popular combo is a stg. III wheel in a .63 A/R housing. .Great spoolup with good top end. 63 A/R housing is very similar in size to a Mitsu 8cm housing, but will offer MUCH better spool properties, due to the stg. III wheel and the housing characteristics.

Moving on the T4 portion of the T3/T4 equation. T4 refers to the compressor side. YOu have 2 choices of comp. housings, a T04B and a T04E. Which housing you get usually is determined by which comp. wheel you get. Some wheels are interchangeable, and the E housing is larger than the B, allowing the combo to make more power. The Mutt turbos originally came with the B housing, and that's why they didn't make very good hp #'s. They later gave you the option for the E housing.
The "trim" refers to the comp. wheel size. This site will show just about all the comp. housing/wheels for a T04B/T04E combo. The "trim" is the size of the comp. wheel in terms of the blade sizes. That site will show you the physical measurements of each wheel, and the respective housing it should go in.

That site also has the diff. combos for the T3 side, as well as options for full T4 turbos, their parts, etc. It also has some limited compressor flow maps as well.

Hope this helps ya out, and anyone else wanna chime something in, please be my guest. I'm always willing to learn more about Garrett turbos, since they seem to be a mystery to most.

Mike

 

[TwoLiterV8Eater]

Mike, thanks for breaking that down..that is EXTREMELY helpful and exactly the kind of info i was looking for. i read about 3 or 4 posts the other day (all of which were very detailed and helpful) about VE and cfm's, flowrates etc. I felt like i was in physics...but thats good because i want to know these things. im going to look for that book Maximum Boost...and check out that site you linked above.

I know about the 7cm vs 8cm housing on the mitsu turbos, but it seems like the only options ive seen for mitsu turbos compressor housings are Td05, Td05H,Td06,Td06H and as far as different wheels go, i might be confused but the standard term "16g" or 20g" is referring to the compressor wheel right? how do you determine which exhaust wheel is best and what are they called? ahh so much to learn ...

 

[TwoLiterV8Eater]

mike..just found out that the link above is the wrong one, it links to a DSMforum post about car stereos...

 

[NOSLO2PT0]

Very sorry about that link. It's fixed now. Had to teach some more newbies about wiring car stereos since they like to give BAD advice on here.