Okay people have got me completely confused. Some people are telling me that a T78 is bigger than a T04R, while others are telling me that a T78 is smaller than a T04R. Which one of these two is bigger and will produce more horsepower on a 20B: a T78 with an a/r of 1.00 or a T04R with an a/r of 1.15? Thanks beforehand for all the help guys....
-Erik

 

Looks like they are pretty mutch the same. It`s hard to find compressor maps fore them, whitout it, hard to tell. But on TO4R.COM it says 600-850 hp on supra engine, TO4R and T-78.

 

Don't know for the turbo power ,but this site is fine for turbo compressor and turbine size.
http://fc3spro.com/TECH/TURBO/tmodels.html

 

I could be wrong, but I believe there are better choices than those two when it comes to 20B turbos.

 

i'm not trying to make krazy horsepower, and i don't want to stress the engine so much (hence the low boost). this is gonna be somewhat of a daily driver for me other than the ocassional tracking that it'll see. thanks for all the info guys, and i wish you all luck with your cars (cause i'm sure as hell gonna need it, haha)....
-erik

 

yup they are about the same spec`s. Look at the link that teachermechanic gave us and you`l see.

 

You might want to re-thing your turbo choices. The 20b has a LOT of exhaust energy and can spool up BIG turbos with no problem having good streetablility. The 1.00 and 1.15 A/R's for the tubines your describing are divided manifolds, and your running a 3 rotor. It would be better to get an open valute (non divided) turbine. Also, you'd be better off running a P-trim turbine wheel.

~Mike...........

 

where would you find a turbo that is an open valute turbo?

 

a divided housing spools up faster... i would go with a larger housing and keep the divider. i would just search all the 20b setups and see what people are using, what power is being put down, their likes/dislikes, and what they are applying the setup to (track/street/drag).

 

i know what other people are using and what i would like to use (or at least wich i could get my hands on), but i just wanted to know which one of those turbos that i mentioned earlier were bigger; the t04r or the t78. a quarter of the people are telling me the t04r, a quarter are telling me the t78, and the other half are telling me that they're both the same. i have no idea on which one to believe. and everybody keeps telling me different horsepower numbers that i would get if i were to put this on a 20b. by the way: thanks to everyone who has let me know their input on the subject matter so far....
-erik

 

A divided mani is divided in half, so one pathway per rotor. There are no manis that are divided into thirds that i am aware of, thus the need for an undivided mani.

Those turbos are too small for a 20b. When looking at the power potential of a turbo, look at the size of the compressor inducer. both t04r and t78 are around 66mm. You'll probably need at least a 76mm compressor inducer on a 20b based on what i have read.

 

^^^ its really dependant on how the manifold design is for if the divided turbine housing is taking in the air. im use to dealing with v6's and 4cyl 4-2-1 manifolds. my early aquired knowledge is that a divided housing aids in spoolup timing. though now it seems after i think about it (and your post) that the 3 logs to a divided turbine housing might not be the best flowing path. yet i might not be bad either? im still toward as how the design of the manifold would be. some engineer needs to chime in here to flow charateristics to cure up this. though im probably wrong

 

My first post clears this up, I'm not a turbo newbie. 3 runners, divided flange... doesn’t take a rocket scientist (ohh, I work at NASA) to figure out its a bad idea.

GoodfellaFD3S followed up my post with more detail.

To the original poster, any Garrett or Garrett clone has exchangeable turbine housings. Simply order the proper turbine housing when you purchase the turbo. The T78 has limited turbine choices, and only comes divided as far as I know. Also like I said earlier, I'd go for something larger then the T04R and stick with Garrett type turbos (which includes Turbonetics, Innovative, PT, etc).

Found a mistake in my earlier thread, I meant a Q-trim turbine wheel.

~Mike.........

 

The turbos are too small for a 20B.


-Ted

 

yep those turbos too small for a 20b.
But out of the two you mentioned, the T78 with the 1.00 A/R exhaust and the T04R with the 1.15, the T04R with the bigger exhaust housing will produce the bigger HP number due to the larger A/R

 

i'm not looking to get 345890 horsepower. i'm looking for something from 550 and above with just 12 pounds of boost. i've seen many people with a t78 setup on their 20b's and they're making well around 550 with just 10 pounds of boost. remember, my engine is going to be ported, my fuel system is obviously going to be upgraded, all my manifolds are going to be bored out, i'm going to be running with no cats and the hks four inch titanium full exhaust system, and my intercooler is going to be at least a foot by two and a half feet by four inches with hopefully four inch inlet/outlet holes. thanks for all the help guys, and i wish you all luck with your cars. i'm actually for now going for the t04r, unless someone with a bigger turbo decides to sell theirs for a reasonable price.....
-erik

 

If you can find one, try finding a T51-R KAI. The T04R may be cheap, but they can run out of steam on 2-rotor engines, so with a setup as high-flow as yours...

 

thanks to everyone on their input for the turbo setup. unless somebody with a bigger turbo decides to sell their turbo for a reasonable price, then i'm going to go with a t04r on my 20b. good luck with your cars guys (i'm sure as hell gonna need some, haha)....
-erik

 

I don't see how this is possible.
I think a T78 does 500 on a 13B way over 15psi?
How can it make more power with less boost?


-Ted

 

if you want low boost power, you need a bigger turbo, not smaller.

you maek power based on mass airflow thru the engine. With a large turbo, you flow more volume, more efficently, at lower pressure. With a smaller turbo, you have to spin it much faster, hence more pressure, to flow the same amount of air, and make the same power.

the only turbo i've seen to make 500+ hp on a 20B at around 10 psi is the GT42R.

not to say that you cannot use those smaller turbos, but it sucks to buy one and then have to replace it in a few months when you max it out and want more.

pat