signofinfinity

Gentlemen,

I had in mind of going twin single turbo. I heard its been done but am not quite sure if its feasable.

I have an extended steet port, 3mm, de cat 3"SS high flow exhaust. Wolf3D Plug n Play, and running anon sequencial the way it should be non sequencial set up.(that is, turbo pre control gate totally chopped off and all the in ternal mods like ported aperture etc on my stock Hitachi Turboes.

Now for the twin thing...I found two brand new Garrett Turboes T3 Compressors and clipped T255 rearend impellers with a flow rate of 6.4 ratio each. Thay have a built in internal waste gate, however that can be eliminated, for an external WG. The shop said they are good for 240-250 BHP each.

Is this claim correct? I know you guys have been there seen that and done that, but here in europe 3rd gens are not so common, and its all trial and error.

I wanted this set up 1st: so as to have low end power, with reduced lag, to improve on a turbo like the Greddy T78, 2nd, so on mid and hi range, i would have a good flow rate to support hi booost of say a combined 20psi.

Car will be used primarily for street racing, and here roads are short and winding, so low end is vital. However I would like some good times on the 1/4 mile....

I know this is a long and boring post for you chaps, but am I talkin sense on no?

Thanks all....

RacerX_IU

i would not go with those...i did a lot of pecking around on doing an independant twin set up.....those would be too small, with your port a garret gt2871 or gt3071 would work great but they are a lot more expensive

signofinfinity

hmmm ....i had in mind of using builtin wastegates, and boost control each turbo individually.... Was gonna use the wolf 'stock pre control out put' to keep one turbo off till say 3500, then open up on the second....

would the gt2871/or gt 3071 spool fast enough? i am afraid of bigger turboes due the low end concern....

RacerX_IU

both of those turbos come internally wastegated...your spool time would be camparable to the gt35r and gt40r...somewhere around there

RXciting

Unless you have expirience in building functional sequential twin turbo systems i would read up on the problems mazda came across and how they solved them.

RacerX_IU

going independant twin has absolutely nothing to do with being sequential

signofinfinity

But i am not talking of using the Mazda sequencial system.... Pretty much what i had in mind in like when we set the fuel staged injectors.....the fuel kicks in with a percentage of the fuel map value as load increases this percentage increases.

I was gonna base boost setting on rpm...i will operate the first turbo till its full boost till say 4000 rpm, but i start augmenting the boost on the other turbo say round 3500. the system can be based on TPS, MAP pressure and engine rpm.

It sounds like sequential true...but wont the low end benefit from such a set up?
Nothing beats the twin set up for low-end. All in all at WOT, i wanted to acheieve the boost and flow for a T78..delivering some 500-550 RWHP. thus the two turbo setup......

I believe some supras use that set up...but am not so sure...

This is the AUX page on a wolf....I can operate the boost solenoid for the second turbo inputting these parametes...

thats why i sai i was not using the mazda setup...its way too complicated...
anyway i removed the rats nest a long time ago!!

Manolis_D

iTrader: (2)

Only the T3 Super 60 compressor and one or two of the T04E compressors (small ones - i think the 'super 40 trim') will work OK. one or two of the new GT series compressors would work OK as well.

The surge line is a BIG problem. You can't run over ~15psi of boost from 4000-5000 or 5500 rpm with twins because of this. I PM'ed Kevin Wyum, who uses twin 60-1's, asking about this problem. He never replied, and my guess is because the turbos surge until ~7000 rpm on his motor Funny how they both blew up...

-Manolis

signofinfinity

damn...so if i had the good flow rate of two T04s say, i would still be stuck to 15psi due to the surge line??


i wanted to go on twin set up so i can run high boost, and high flow!

so you rekon that a T78 will work fine fine 20psi, but it will suck at 3000rpm....

can i use a small T25 for constant spool and dump in a t6 higher up, combining the flows?? i have always considered two mid sized turboes....how about a small non regulated turbo..and some thing on the big side for secondary?

i want that low end!!

maxcooper

Simply controlling the wastegates separately will not give you a working sequential system. You should study the FD and Supra systems first and figure out if you want to go to all the trouble to create your own sequential system. You have to manage (with valves) both the compressor output and the exhaust flow. If you just used the wastegates, you would have one turbo pushing air into the compressor on the other turbo and you would lose half the exhaust energy to spool. It wouldn't work at all. It would be cool to design your own sequential system, but there's a lot more to it than just controlling two wastegates independently.

In my opinion, you would be much better off just running them parallel, or use one single turbo, unless you are prepared to engineer a custom sequential system.

-Max

signofinfinity

i found the thread by jason....on the twin set up....

so 1. I will work in parallel
2. i will plan on the use of two similar ball raced turboes
3. i intende to go to an internal w/gate set up
4.......the turboes to be used are still a question.....

the previosly mentioned gt3071 are the likely candidates......

still i am worried on the a/ratios i need in a twin set up.....

signofinfinity

i wonder how you can blow it up? i mean, i figure that most you can get is a turbo stall.

if you got the right fuel staging...(1600 sec)/(550 pri) Ignition amplifier (HKS Twin Power) ...i think it should be safe..

why you reckon they blew up? am after all the data, so dont take my stupid *** questions like any intended pun... not at all. i am asking.
I worked till now on the non sequencial turboes (ported and primary wastegate eliminated, and also the seperating bridge removed)...i pump up a good 17psi on the stock...but...they sure will die soon on me with that boost....

MrRx

iTrader: (1)

I am nearly finished with my Twin T25 BB setup.

If you’re going to do this all your self, you’re looking at quite a project.
The biggest PITA you’re going to have is the exhaust which I finished last night.

Considering how it is nearly impossible to find a good t25 compressor map I had to develop my own.

By my calculations each turbo should flow at or around 400-500 cfm each, when you take into account the polishing done to the compressor. This when using two T25's should put you into the 350 hp mark at around 15 or so PSI. It is possible to run at 20psi but you will be running the wheels beyond there design efficiently


Another problem you will have is making the manifold, considering the small amount of space in the engine compartment making an even dual setup is difficult.


Cost is another matter, I have stopped adding up totals for all the misc parts I have had to buy. If you’re not ready to design your own turbo setup I would just recommend going with either at T60-1 or Rx7store.net's twin setup.


If you have and more questions about my setup or just general twin stuff pm me

signofinfinity

neat set up i figure.... you take any pics of the project?