2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

twin s5 turbos

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Old 11-21-06 | 06:15 AM
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twin s5 turbos

this was posted by another forum member named 2STROKE in the 1st gen section


Old 11-21-06 | 06:30 AM
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These were originally HIPSI's off ausrotary.com They were Highflowed S4 turbo's though from memory. 330 or 350 RWHP (98 octane fuel) on a bridge port at 7 psi. Took a while to spool though.
Old 11-21-06 | 08:16 AM
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That's a lot of weird angles and joints.
Old 11-21-06 | 08:35 AM
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Wow, lots of cool fab work...but personally I would have chose something to work better as a twinsetup...ie. instant boost, but very cool nonetheless...
Old 11-21-06 | 08:54 AM
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That's cool. If you have the turbos hanging around, the pipe, some time and a welder, then why not? It's something I've often thought of doing since stock turbos are a dime a dozen and there's only a few hours of welding and about $300 in pipe represented in the that picture...

A lot of weird angles and bends though. It would have been better to tie the runners together and then split them off again as opposed to the weirdness with the far right turbos and all the bends. Obviously space is a concern so that probably had something to do with it.
Old 11-21-06 | 09:11 AM
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I'd like to know where the charge pipes lead to...doesn't look like they're routed to a FMIC....
Old 11-21-06 | 09:53 AM
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^^+1...nice welds also....looks like a pretty crazy setup
Old 11-21-06 | 09:57 AM
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wouldn't all of teh bends sorta screw up the flow, but i guess that is just me....but it look really cool
Old 11-21-06 | 10:11 AM
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Cool stuff...

I have a question
Does the distance traveled for the exhaust pulse have anything to do with creating a better manifold? Should the lenght from block to turbo(s) be similar as well as the lenght from block to wastegate be similar?
Old 11-21-06 | 01:19 PM
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That's pretty sweet. I've considered doing this. More power from less boost is always a good thing.
Old 11-21-06 | 01:48 PM
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Originally Posted by camman
That's pretty sweet. I've considered doing this. More power from less boost is always a good thing.
Don't forget that's also a BP'd motor...
Old 11-21-06 | 01:50 PM
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funky setup and could be better designed imo.
Old 11-21-06 | 04:19 PM
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nice set up, i would have done it a little diffently but its still cool. and the welding wouldnt be hard, as you can see from the picture it looks like a O.A. weld (can do anything with a O.A.). the only thing that would be hard would be getting the angles of the pipe cut right to weld.
Old 11-21-06 | 06:21 PM
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Here's the original ausrotary.com thread about the setup guy's. I was a tiny bit off with the psi level and they aren't highflowed. I was going from memory when I considered buying 'em.

Ausrotary thread

No Offense to the guy who posted the original pic in the first gen forum, but those pic's aren't of it installed in his car (Yet). Look forward to seeing pic's of 'em installed though

Bit of advice to anyone considering a twin setup. It's a Freaking nightmare (twin td05 and twin external gates). It's WAY harder to do than it sounds.
Old 11-21-06 | 06:35 PM
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that looks sweet
Old 11-22-06 | 03:45 AM
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The only reason that set-up looks weird is because he decided to use an external wastegate, which I don't really see the need for. Without that, all you have is one pipe feeding each turbo, which is pretty simple. 500hp potential from a couple of cheap second-hand turbos isn't bad when you consider what this would cost to do with a big single turbo. Obviously this would be a project for someone with good fabrication skills, not someone who prefers bolt-on kits...
Old 11-22-06 | 05:02 AM
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Why is an external wastegate used or needed? Depends on the level of boost you wish to run. *Work out the details* Secondly the "runners" to each turbo have been "bridged/joined" (sorry for the loose terminology) because each rotors exhaust pulses are different, the bridge is used that the turbo's each get spooled the same. That's why it looks wierd. Sticking with the internal wastegates would deffinately make things easier though plumbing wise.

Having said all that my setup isn't "bridged/joined"
Old 11-22-06 | 06:14 AM
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Originally Posted by Worm Burner
Why is an external wastegate used or needed? Depends on the level of boost you wish to run.
Not really. If you want lots of boost then you wouldn't need to do anything to the stock wastegate(s). If you want lower boost then a heavily ported S4 wastegate is very effective. The only advantage I can see for an external in this case is to eliminate the turbulance at the turbine discharge that internal wastegates cause.

Secondly the "runners" to each turbo have been "bridged/joined" (sorry for the loose terminology) because each rotors exhaust pulses are different, the bridge is used that the turbo's each get spooled the same.
I can't see any bridge between the two turbo other than at the wastegate flange. I don't see why you would either. The fact that one runner's longer than the other is not going to have any noticeable negative effects. One turbo will just react fractionally faster. The exhaust pulses should be exactly the same unless there's something wrong with the engine.
Old 11-22-06 | 08:03 AM
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Wink

NZConvertible :

Here is the THEORETICAL reason for a joined manifold.

The pulse's won't be exactly the same. The cycle of each rotor is never the same ( stoicometric ratio - I believe is the correct term to apply here - Education was many years ago now ). Differrent pressure from the exhaust ports will result depending on the burn efficiency of each phase. So one turbo might spin harder and slightly earlier.

As I said MY system isn't setup like this. I'm not really stressed about it at present.

As for internal wastegates, in this application in vehicles in australia (Rotormaster rx4 - Buzaka and a Dyson rotory rx7 and this setup pictured - from the horses mouth) they have struggled to regulate the boost.
Old 11-22-06 | 10:00 AM
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Originally Posted by Worm Burner
The pulse's won't be exactly the same. The cycle of each rotor is never the same ( stoicometric ratio - I believe is the correct term to apply here - Education was many years ago now ). Differrent pressure from the exhaust ports will result depending on the burn efficiency of each phase. So one turbo might spin harder and slightly earlier.
I would think you'd lose too much turbine efficiency merging the exhaust pulses.
Mazda did a lot of R&D on this, and the S4 versus S5 shows the advantage of keeping the exhaust split.
Even with the uneven front versus rear exhaust pulse, there is no such thing as a totally even runner length to the turbo.
It would take a LOT of R&D to arrive at a design that allows the front versus rear exhaust pulse to hit the turbo turbine at exactly at 180-degree phase intervals.
We are not really concerned with the phasing; we're looking for the impact an unmolested exhaust pulse coming straight from the exhaust port hitting the turbo turbine blades.

Personally, I think the turbos are still too big to run two of them...even on a BP.

But, seeing as they are on a BP motor, low RPM power is probably not even a concern?


-Ted
Old 11-22-06 | 05:24 PM
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. They are actually on my car as we type. Except my engine bays less cluttered, green and with a gilmer belt. But pretty much exactly the same.

My 60mm HKS GT2 wastegate regulates from 4psi up to 20 psi very effeciently.

I went with this setup just for the uniqueness.
Old 11-22-06 | 05:38 PM
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pics?
Old 11-22-06 | 06:00 PM
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Talking

RETed : Thank you for your reply. As I said that was the theory behind it, one which doesn't worry me. I was simplely explaining why the manifold looks "wierd" I'm quite happy for anyone to pick holes in it, I just get irritated by condescending replies

I'm 100% with on the turbo's being to large. Even on a BP they were only seeing positive by about 3300 from memory and the boost curve was "interesting". Just my personal opinion, but not what I call streetable. A guy over here has recently bought another just built "backyard" TT S4. Turbo's are a s5 compressor (unsure of the hotside, he didn't tell me) supposedly inside a 12a rear housing. Anyway the poor bugger's been having a crap time with it, partially because one of the wastegates don't close (incorrect actuator - what was lying around was used) and just the shoddy job done building it. Once this is sorted ($$$ - cheap TT romance does not exist) I'll let you guy's know how it goes if anyone is interested.

As for that joiner loosing to much effiency, I'm not technically literate to argue that effectively. I'll simplely point out that in the TT manifold made by amemiya (for 1st gen, 2gen and 3rd gen) always have the runners bridged by an external wastegate. If this is an arguement for that theory or because internal wastegates weren't upto the job don't ask me.

Here's a picture of a former TT manifold I had (HKS??)
Old 11-22-06 | 06:09 PM
  #24  
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2STROKE : Excellent, look forward to seeing pic's of them actually installed in your car Not to mention a dynograph of them spooling Got good heat shielding and engine ventiltion in the setup? Especially considering your in the NT aren't ya?
Old 11-22-06 | 06:20 PM
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looks nice a lot of crzy bends tho...


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