A properly setup twin setup will not be laggy. Only bad thing about it is it's expensive.
I'm also kicking around the same idea Rice has. Twin GT35's.

if your goal is only 400hp i would probably just use a single. it's alot less expensive and very simple and easy setup.

 

my goeal is between 450 - 500 rwhp. and thus too much lag... don't want a single.

 

are you kidding, im 25, ive passed 6 out of 8 of the ase tests, Im been running my own shop since i was 18, and ive designed the manifold from scratch, and will have it running within 2-3 weeks. Ive owned and worked on 7's for over 4 years, and I think its a joke that you believe you know more then half the people on this thread, if your so great then why bother coming on here?

 

I'm also building a twin setup, I'll post pics when I get them.

 

Accomplishing high HP low lag twins is something only factories(Toyota/Mazda) have been really successful at. I think a detailed study of the staging/control on the 93-98 Supra would provide some good insight. I know quite a few guys in the supra community have failed at this( up to twin T66s), maybe the exhaust energy advantage of the rotary will play into your hands. On a Supra the twin 2835s with a .58 are very laggy (spool at ~5000rpm vs ~4300 for a properly spec'd single same output), they are good for low 700s on the Supra, so probably ~500-550 on a large ported 7. I think virtually allof the twin set-ups I've seen were overly optomistic on output, and used too large of a turbo. If you do the math, you will find yourself using very small turbos. Best of luck, Carl

As an aside, everyone says my plan of running a road race car at ~20-25 psi on a constant basis will fail, I think not, and my over attention to set-up, and tuning should prove this. It is true that the build will end up taking two years though...

It occurs to me Lingfelter builds some Very Extreme twin turbo set-ups, I'd give them a call.

 

Personaly, as long as my engine works from 6500 to 10500rpm I will be happy :P

 

Pete, have you seen my car lately?

 

i have

 

I want to

 

The math says that I need arround 50-60 a/r depending on efficiency...
But I have been tinkering with an idea that some other people have done.. namely BMW on their new disel engine...
A series turbo system.... very complicated I will admitt, but making huge power with less Lag than stock... but I am working out some of the details it is in a rough desing right now... after I finish the desing I will post some details... Not all of my secrets but some of them...
Thanks Guy's for the support... guessing while making a good twin turbo setup is not a good way to go much calculations and margions for error will have to be taken into account... thus it is a DESING... not just slappping something together... this is what I intend on doing.. so that is why I asked people for their opinions and ideas or expereience with a twin setup because the more data I have the better the resulting product.
Thanks again keep it comming.

 

I wonder if it would be possible/practicle/efficient to use the sequential system incorporated in the SupraTT/RX7TT to stage your turbos. The staging system itself has little to do with output, it is really just an exhaust energy/timing strategy. Replicating the systen with larger turbos would seem to be an approach likely to succeed. Basicly take either system(they are similar), duplicate them with more efficient turbos, and manifolds. I know that is a large undertaking, and it sounds like you are past that stage, just a thought...

Aaron/Simon, fuel cell today, surge tank/ new pumps this week, maybe ready for Steve Kan to try again in a couple weeks .

 

No, I'd like to see it

 

Here's a thread, see pages 1, 3, and "tire girl" on page 5 for pictures. I currently have a T66 .81 Q trim, but the widebody/suspension is the trick bit. I am working on getting 16x12s to fit up front(currently 16x11). Fuel cell went in today. The nose, and hood are essentially one offs, more were made, but will not likely see the light of day. Peter, how long to ship a surge tank to me? Seems no one in the states has them. CAPA has them, as well as a number of other shops. LMK. I need one with -8 fittings, for a single external pump, that would be a fitting in the top, two about two thirds of the way up the tank, and one at the bottom. I think the CAPA one is 195.00AU. Sorry"J", back on topic now, tell us about your twin idea


https://www.rx7club.com/showthread.p...light=widebody

 

Instead of a sequential system, (which is running one turbo smaller while the larger one starts to spool then shuts off the smaller one and runs only the larger one...
With the turbos in seris as I have suggested all of the intake air will run through the larger turbo as it begins to spool compressing it a little then sending it to the smaller turbo where it is compressed even further then when rpm rises the exhaust gases from the smaller turbo will be shut and the throttleplate (or actuator plate) in in the intake tract will open allowing the larger turbo to unleash it's vengance... allowing for a very large amount of power... with super super low end performance. This is my current desing that simply needs some mathimatical tunning...a dn some dimensions to get her to work properly.
thanks for the suggestions... again keep them comming.

 

get out on Google and find some technical info on the Audi RS4

As far as I know it'was not available in the US. It's an Audi A4 Break with 2.7 inline 6 twinturbo engine with the first smaller than the second.
The managed to get 380HP out of it standard. and an easy 600HP with some extra goodies and tuning

 

Get in touch with me via PM and I will e-mail you details about the surge tank *delivery is pretty fast !*

DUDE ! Your car looks insane !!! I love that colour to death Not sure about the wheels though ? *personal taste* One of the nicest FC's I have seen though.

The twin set up is just the ultimate extension of what I realy always wanted to do, and is my last chance realy before other priorities take over in life and I decide to grow up and stop playing with cars I'll have pics/videos/write ups etc in a few weeks time all going well. Still waiting on parts to come back from over your way actually

 

Hot rodded diesel trucks have run setups similar to this for a long time, daisy chaining one turbos compressor into the next.-edit-hot rod semi's go really crazy linking like 3 or 4 together.

http://www.rankmyride.com/?page=journals/view&JID=211

BTW-I woulnd love to be able to watch my boost gauge do that.

 

daisy chaining the turbos generates HUGE heat....you'd probably need to be on a full alcohol setup to do that. In addition you run crazy high boost like that.

Stephen

 

why not just run feed forward cascade twin turbo setup.

its a joke

 

You are right not corrected for, it will create huge heat that is why you control which turbo produces the boost...this is why one turbo would feed the other a little then the smaller one would turn off at lower boost (not overspinning it) and then the larger one would take over from there, no difference in heat there from a large single. so the reality of it all is quite simply the a little bit better than sequencial the power of a single and the response of a small twin setup. (in theory)

 

check this out...this is broken93's independent twin turbo setup ...looks and sounds like you have described you wanted your turbo's to be check out these two threads
Initial build up
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/joy-elation-prototyping-independent-twins-%5Bpics%5D-341531/
Progressing
https://www.rx7club.com/showthread.p...light=broken93

 

that looks very similar to the setup I have originally designed but I have come accross another more potential idea... more to come when i finish initial calculations.

 

ok here is the setup I have designed the math and physics seems to check out thus far I will input it into the modler and see what will happen. but for now this is what I have any idea's on this setup let me know.

 

it's kinda hard to see what you were trying to draw but from looking at it. I dont see any restrictor plate for the exhaust side of the larger turbo? If both the smaller and larger were open to the exhaust port, you'll not get enough pressure to spool the small turbo because pressure always tend to go from high pressure to low pressure, the larger turbo turbine housing is the easiest way out. IF there's a plate for the exhaust side blocking the large turbo, I don't see anything that will help spool the large turbo (at given rpm). I know that you're trying to use the small turbo to create a vacuum chamber to spin the larger turbo (intake) but I think it'll create compressor surge and also create stress load for the blade (they're intend to create pressure, not suction) to the smaller turbo by cascading the turbo this way. I guess there's only one way to find out (testing).


just my .02

 

well there is a restrictor plate just before the flange in the exhaust stream that will open at the desired rpm. at the same time the restrictor plate will open in the intake piping to the intercooler. because of the way that the piping is there will be no real compressor suge to the small turbo because there would not be enough flow towards it.

You are right testing is the only way but mathematical calculations can predict what will (should) occur.