The issue of building a set up with 2 single turbo's has been tried and done by a few people now.

In contradiction to the stock sequential setup the above build up would be 2 turbo's of thesame size working at thesame time.

Why would you wanna do that?? You might ask.

Well in my case, I still have 2 identicall turbo's laying around, doing nothing. A single setup would implicate buying a complete kit for an average of 3500$ (no shipping to europe,a.s.). and just to be different



Back to topic, there have also been several discussions about the exhaust manifolds between egine and turbos to be 100% split or a come-together in one port.

As the setup would consist of 2 identical turbo's it would be possible to put on one turbo on each exhaust port, spooling one turbo.
The choice of keeping both ic ducts coming from the turbo's separate is a matter of taste or the ability to fabricate a double cored IC (front mount?)

next issue would be the choice to have the IC ducts towards the Tb hav come together.
If yes, you can keep the stock TB.
if not, well a lot of custom work ahead I think.

Choice of the turbo's???

Hot side must be a quick spooler I guess, because you haveonly one exhaust port feding it, Advantage in my opinion is that it's rotary, so there is a constant flow of gases.

What turbo's would be recomendable? I got 2 Garrett T3 turbo's with 45' trim and 40mm diameter compressor wheel

see
http://web.inter.nl.net/users/turbo-...e/compress.htm

Would these turbo's be of any use in the above mentionned setup. having them spool equally at thesame time, each supplying air o 1 rotor?
Of course with the right engine steering and fuel supply (upgraded fuel pump, fuel regulator and Halltech)

Any input would be appreciated

 

Whatever floats your boat

 

It sounds like having a turbo feed of each exhaust mani pipe would be ideal (don't connect them). However, you may want to test the compression in each rotor to make sure they are the same, or else one will be spooling before the other. You would have to have to 2 intakes (1 for each turbo), don't connect the two into 1. And you'll need 2 small wastegates (one for each exhuast mani) to control the boost (35mm to 38mm). Your turbos sound like a good size. You will experience much more lag than regularly, but the top end and your driving skills should compensate.

As far as the intercooler is concerned, well you could have the 2 intercooler pipes coming from each turbo to join and make 1 3" pipe. Also you may want to run 2 bov's and it would be best if they were to be placed somewhere before the 2 intercooler piping joins. But I don't think 2 BOV's are needed, but I think it would be better if you did.

Fuel system, any stand alone should suite you fine. Just try to find a good local tuner, and use the system the prefer. Also it depends what your goal is. If you're looking at up 450 whp, a supra fuel pump and hks fuel pressure regulator will due just fine, but if you want more than 450whp you may want to look into a cosmo fuel pump or twin supra fuel pumps (the hks fp regulator will still work fine). For injectors, you may want to run 1600cc secondaries and 550cc or 720cc primaries. If you're looking to put down 600 whp you could always go with larger primaries.

Finally the motor... Well most likely you will want to port your 13B (street port) and rebuilt it.

Well that's all I can really think of right now. Much or all of this you may know, but I think it may come handy if you didn't. Just some thoughts or ideas to consider.

 

thx for the info.I'm not looking for big power just +- 400HP. For me it's more the availability of the turbo's and the idea of doing something different.

A streetport was more a necessity than an option if I would do this. This issue of lag is something else. Here we don't have long roads, just small, narrow streets so quick spool would be good.

Some other thought...

13B rew's have equal turbo's, primary and secondary..
why has noone ever tried putting in a bigger turbo as a secondary like the Audi RS47 setup. small turbo for low rpm, big turbo for high rpm?
I know the vacuum issue willl return, but audi seems to cope with it very well

 

It seems that you will have more lag than you bargained for. I don't think this would be ideal for a quick spool. Maybe if the you had smaller trim you could get a quick spool. Remember a turbo is spooling off of only 1 exhaust mani pipe not 2. I never heard of people putting bigger secondary turbo. I like your idea of twins, I could see you pushing 450 whp. Maybe you could run a smaller t3 turbo for a primary and a to4s for secondary? But the lag on the T04S would be rediculous.

BTW this is FC Alex, I accidently posted under my brothers user name.

 

You could always do it up like that ridiculous Ford F-350 in the video that we have all seen. He had one average sized turbo and one HUGE turbo. When the first one spooled, the compressor side of it fed the turbine of the HUGE second turbo. Then when it spooled it went through the IC and into the intake. Just another way to look at it.

Zach

 

yes, the concept of one turbo driving a bigger one has crossed my mind also, but practically not within my range of finances as the engine would hav to be seriously rebuiold and tested.

It would be stupid to set this up and have to run "normal boost" (let's say upto 15-16psi) . Technically a true challenge, no doubt.

As for the the turbo's. The ones I have here will need to be rebuild before usage anyway so it might be possible to exchange some parts 'hotside/compressor side" wheels to get them more suitable for the project.

I'm now still running the stock turbo's but I noticed when I took of the inlet ducts that the primary turbo has some slight oil glance.

As I have never driven another FD I cannot say wether my car pulls normal or not.
Just from theoretical poinof view as well before as after 4500rpm the turbo pressure should be upto 10psi.
What I experience is that the cars pulls hard towards the 4500rpm barrier, then slightly holds(normall) and then really puts his *** in the ground an takes off.
My boost gaugeis on the way, so maybe that one will get things into perspective.

Does anybody has some kind of a calculator to look for the perfect trimming for a turbo? Exhaust flow->hotside turbine diameter->compressor diameter->compressed air flow??

I know there is this drag rae team with a 20B tripple turbo RX7 around in the US. It would be sort of like that , only with 2 rotors, 2 turbo's and a more streetable usage.

thanks for your interest...

 

You do have a good point about running the turbo setup I was talking about only to run 16psi or so. That F350 truck was seeing right at 55psi or so into the manifold. That would be some seriously non-streetable boost. But I just wanted to add a different viewpoint to the conversation. Best of luck to you.

Zach

 

Yeah the setup would be trully an eyecatcher from every point of view.

This week or next week I'll go by a Belgian race team would had their 2004 season rx7 fd built in the US. they run a 450HP 13B single turbo setup. I will ask them what they think about it.

 

We're working on a couple set-up's like that.
One is an FC with twin T3's on a 13BT.
The other is a big buck 13B-REW running a pair of GT2530's.


-Ted

 

Hy reted, glad to see I'm not alone thinking about somewhat unusual things to do with rotaries.

It would be great to keep up with you on your progress as my knowledge on rotaries is not that extended (yet). I'm coming from the piston powered world, so I'm not that unfamiliar with mechanics.

What bothers me the most is, when I but the engine management on (probably Halltech E6K) what to expect as a base programm?)

 

I think a twin TD04 would work good, they are of a more modern kind then Garrett T03:s, so they spool better and have greater efficiency.

Maybe I will try that soon, after my HX-50...

 

suppose you find 2 suitable turbo's which spool fairly early (around 3000rpm???)

What would be the main benefit between one big single (GT3540/R85,...) and the double setup?

Let's be honest it will take you 2 turbo's to rebuild when they should go...

 

I would have to say that big twins is not any better than a bigger single. The only reason I did it was that I had all the **** laying around. Makes for a plumbing nightmare. Most people don't realise how much the temps go up also. I would have to say that the only good place for a big twin setup is the dragstrip. As far as rebuild costs, it is less money for the parts to rebuild 2 to4s's than it is for the parts to rebuild one turbo that equals their flow.

 

Wouldn't that be TWIN turbos?

 

That's called staged turbocharging, not uncommon on Diesels.

You can get 200+psi boost with three stages and somewhat decent efficiency.

Say all three turbos are running at a 2.5:1 pressure ratio. To make things simple I'll work in absolute pressure (14.7psi = ambient) and then subtract the ambient pressure at the end, to find boost pressure.

First turbo compresses from 14.7 to 36.75psia (22.05psi boost).

Second turbo compresses from 36.75 to 91.875psia (77.175psi boost).

Third turbo compresses from 91.875 to 229.6875 (round to 215psi boost) !

Compare that to the kind of turbo you'd need to generate over 15:1 pressure ratio all by itself... I dunno if there *is* a turbo that can do that!

edit: I should add that industrial air compressors that are designed for VERY HIGH CAPACITY (like THOUSANDS of SCFM) don't bother with piston-type compressors, they go right for multi-staged centrifugal compressors.

 

I know some guy with 65psi of boost in a dually... damn you gotta love diesel engines.... to bad they are so noisy..

 

I'm not sure how relevent this is, but there has been people who have used two stock FC turbos (HT18s) on a streetported 13BT with decent results. I've *HEARD* numbers like 400-425 whp @ 15-17 psi tossed around, but since this is rarely done it's very hard to find out any concrete info on it.
I think Dyson Rotary even used to sell a manifold made specifically for this.

 

What did the dyson manifold look like? Sequential turbo's would be the best. A small one that lets you boost quick and a bigger one for some serious power.

 

2 garret gt25's provide exceptable boost reponse. of course that is running independently of a single rotor each. 200kw at the wheels on 6psi of boost.