# twin turb with 2 different turbos ?



## Skoodles (Jul 31, 2004)

i kno this guy and he has a 91 240sx. i think its a 91. well hes ben doing months and months of slow work putting a 350v8 in it. well he plans to make it a twin turbo. he has 2 turbos for it already. one is from a 93 eagle talon. and the other is from a nissan skyline not sure what year.. said somethin about being a twin spline or soemthin. well my question is the turbos will put out different boost what kind of affect will this have on his motor. wouldnt it hurt it from the different boost pressure. keep in mind im new to the turbo thing.. dont flame me too hard


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## captain_shrapnel (Sep 10, 2004)

Apparently, so is your friend....


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## chimmike (Oct 17, 2002)

your friend=total idiot. He's putting relatively TINY turbos on a V8, and probably doesn't even know how to run sequential turbos.

if I'm not mistaken, weren't some of the supra TT's sequential? 

Anyways.....those little turbos will choke that V8, if anything bro. lmao.


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## Skoodles (Jul 31, 2004)

chimmike said:


> your friend=total idiot. He's putting relatively TINY turbos on a V8, and probably doesn't even know how to run sequential turbos.
> 
> if I'm not mistaken, weren't some of the supra TT's sequential?
> 
> Anyways.....those little turbos will choke that V8, if anything bro. lmao.


hey wait who nope not my friend i just seen the guy a few times and he was talkin about it i dont really kno him too well. but i was just gonna ask cause it didnt sound like it would work either. but then again if he does get it to work and it runs good then ill stop back here and have to say somethin about it. but till then i doubt it too


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## BII (May 13, 2004)

I won't flame:


All the V8 twin turbo setups I've seen use equally sized turbos, one on each manifold (this makes routing/piping and equal distrbution of air A LOT easier). And yes, those turbos are two small, hell he might be able to suck more air with a somewhat built NA 350, I'm not 100% sure as I don't recall what size turbos the DSMs use. Your "friend" should really invest some time in researching turbo sizing and understanding the basics, as it is appearent "he" is not ready to TC this 350.

The 350 is a VERY popular motor, the B18 of the domestic crowd (although probably more popular, certainly more information is out there since this motor has been out for decades). There's kits ready to bolt-on out there (like Banks, which is a great way to go, but expensive, you can try others, too).

There's a Chevy turbo forum I used to read, I don't remember the name, if you google, you'll find it, lots of info. A Ford one too, different motors, same principles and practicalities exist for both crowds.

Once you see how complicated the piping is, you'll understand one of the reasons those guys supercharge.


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## Zen31ZR (Mar 24, 2004)

One is a 14B and the otehr is a T28, if I'm not mistaken. Both far too small for a V8, even if one was placed on each bank, let alone sequential. Figure the 14B is boosting a 2.0 liter to about 12 psi, the T28 is pushing about 11 psi into a 2.6 (very rough guesstimate). Each bank of a 5.7 is _almost_ 3.0 liters, that makes for a great possibility for an overrun condition even if a turbo was used on each bank, let alone run in sequential. Not to mention the Skyline turbo is what is called "twin scroll" not _twin spline_ (  ) makes for a far different exhaust manifold setup than the 14B does, I'd like to see the manifold work for that setup, I really would........
Tell your friend if he wants to boost a V8, at the very least he needs twin T3s........


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## asleepz (Feb 24, 2004)

Look at the Banks Chevy Twin Turbo. The turbo's on it are massive, even for the lower horsepowered engines.


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## chimmike (Oct 17, 2002)

ballistic..........the T28 from the skyline essentially pushes into 1.3 L....twin turbo, remember?


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## SPECTRE72168 (Jan 20, 2005)

*turbo v-8*

remember this...when it comes to american v-8s...size matters! i have been building street rods most of the last 20 years i have only just gotten smart and switched to imports the last 2 yearsif you want to know how big the turbos have to be, just look at the size of a supercharger for the chevy sb.it was originally designed forsemi diesels. if he puts those tiny turbos on his car all he will accomplish is making it slower and heavier. if he wants to really make the car fast and fuel efficient, tell him to look on ebay and find a complete tuned port injection set up. a good friend of mine has done numerous install of them in street rods. he makes his own harness( its not that hard)he even runs one in his tow vehicle, he gets 25mpg(really!!) and this full size truck huals! he has one in his 1931 chevy and is running 11s in the 1/4(i just wish i could get this guy into imports!)


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## BII (May 13, 2004)

♣AsleepZ♣ said:


> Look at the Banks Chevy Twin Turbo. The turbo's on it are massive, even for the lower horsepowered engines.


Banks doesn't make lower horsepowered engines 

But yeah, I would assume you want to push in more air than it could suck in by itsself, _nes pas_? This would mean figuring out how much air it could breath in and then picking turbos accordingly. If you do sequential turbos, you still have the issue of feeding the first turbo equally from both banks. Putting two differently sized turbos on each bank I would think is bad, since you somehow have to make it so the air come in straight and equally to the carb, manifold, whatever, so one bank doesn't run leaner/richer than the other.


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## 92redwhiteandblue (Jan 1, 2005)

OK well im not to sure about doing it on a 350.....or any moroe, for that motor, but i have read about 3rd gen RX-7s. They were sequentially turbo's out of the box, which brough up boost at about 3k, and kept an incredibly flat power curve all the way up to near 8.5k, at which point the turbos car keep up w/ exhaust flow, and the wastegates are nearly all the way open, to maintain boost pressure, since RX's expel high amounts of exhaust....any who, the moral of the story is, each turbo is controlled indepentently, in every aspect....all the way down to the vacuum lines, which makes an already complex system twice as hard......im not sure how it will work on a v8, since you would have unequal backpressure in each bank, making the system virtually impossible to tune, along with leavign you with incredible turbulance when the intakes are joined. It would also leave you with needing 2 different control systems.....now im getting a headache

btw, why would anyone toss a big, heavy small block into an sx anyway. whats he have planned for suspension to hold it up? ass-end weight to balance it? drivetrain to bring it to the ground. w/o any weight in the back, he'll just smoke the tires.


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## morepower2 (Apr 19, 2002)

[email protected] said:


> One is a 14B and the otehr is a T28, if I'm not mistaken. QUOTE]
> Its a T25, a small one at that.


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## Zen31ZR (Mar 24, 2004)

chimmike said:


> ballistic..........the T28 from the skyline essentially pushes into 1.3 L....twin turbo, remember?


Wasn't sure if we were talking about the GTRs or the RB25 powered units, for sure. Is the RB26DETT system full twin or sequential........? Seems to me with what Mike K just stated, it being a T25, is far too small to be part of a sequential system, unless it was the low end turbo. So what then size is the high end turbo?


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## chimmike (Oct 17, 2002)

the GTR had smallish T28s that were ball bearing and had ceramic turbine wheels. They were regular twins.


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## BII (May 13, 2004)

92redwhiteandblue said:


> OK well im not to sure about doing it on a 350.....or any moroe, for that motor, but i have read about 3rd gen RX-7s. They were sequentially turbo's out of the box, which brough up boost at about 3k, and kept an incredibly flat power curve all the way up to near 8.5k, at which point the turbos car keep up w/ exhaust flow, and the wastegates are nearly all the way open, to maintain boost pressure, since RX's expel high amounts of exhaust....any who, the moral of the story is, each turbo is controlled indepentently, in every aspect....all the way down to the vacuum lines, which makes an already complex system twice as hard......im not sure how it will work on a v8, since you would have unequal backpressure in each bank, making the system virtually impossible to tune, along with leavign you with incredible turbulance when the intakes are joined. It would also leave you with needing 2 different control systems.....now im getting a headache
> 
> btw, why would anyone toss a big, heavy small block into an sx anyway. whats he have planned for suspension to hold it up? ass-end weight to balance it? drivetrain to bring it to the ground. w/o any weight in the back, he'll just smoke the tires.


Well that and if you really want to run a 350 why not get a "coke bottle" Corvette? The handling is probably going to be comparable (or dare I say it, better?). Or a Camaro or whatever. Actually a 240/260/280Z would be a better choice (than a Silvia) since the Chevy 350 swap has been done to those cars with success. I guess the Z won't have the _Super Street_ "mAAd tYte JDM dRiFt cReD Y0" that a "2-fizzle" will.


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## Zen31ZR (Mar 24, 2004)

chimmike said:


> the GTR had smallish T28s that were ball bearing and had ceramic turbine wheels. They were regular twins.


Yeah, I remember now. Ceramic turbine wheels, and plastic compressor wheels. It was to help response time and lag but severely limited boost potential.......


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## tupacglock (Jan 25, 2005)

All I will say to this, that assuming your friend isnt lieing which is a huge assumption, those turbos will choke that motor. Two of the DSM dodge turbos are relatively average for a 5.0 Mustang. Those (Dodge/MHI)turbos are famous for blowing seals though, going from WOT to closed throttle a couple of times will put a real hurtin on them because thats a lot of vaccum that just got made. His car will make a great sump pull though, and basically anything else that doesnt require him to rev over like 4000 rpm. (Number pulled outta my ass but probably pretty close.) 

BTW I like twin turbo mustangs, I am just here to get info for my friend.


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## asleepz (Feb 24, 2004)

tupacglock said:


> All I will say to this, that assuming your friend isnt lieing which is a huge assumption, those turbos will choke that motor. Two of the DSM dodge turbos are relatively average for a 5.0 Mustang. Those (Dodge/MHI)turbos are famous for blowing seals though, going from WOT to closed throttle a couple of times will put a real hurtin on them because thats a lot of vaccum that just got made. His car will make a great sump pull though, and basically anything else that doesnt require him to rev over like 4000 rpm. (Number pulled outta my ass but probably pretty close.)
> 
> BTW I like twin turbo mustangs, I am just here to get info for my friend.



Lots of BOOST! Just has been made not vaccume silly...


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## tupacglock (Jan 25, 2005)

♣AsleepZ♣ said:


> Lots of BOOST! Just has been made not vaccume silly...



Its vaccum that hurts the turbos, thats why they dont have positive seals on diesel turbos and why they leak oil, the vaccum cause the seals to leak.


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## asleepz (Feb 24, 2004)

tell me one place on a turbo where it has vaccume hitting it besides the wastegate and that's only if it's internal.. Any other time there is no vaccume coming out of or into a turbo.


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