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Twins or Big Single?

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Old 12-17-2014, 11:24 PM
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Default Twins or Big Single?

What would be some opinions on Twin Turbos vs Single Turbo for my LQ4 going in a 69 Camaro?

Daily driver car, i have a heavy right foot, 6 speed trans, I like the look (symmetry) of the twins but I really have never built or messed with a turbo system very much.

Just looking for opinions so I may start to channel my research.
Old 12-17-2014, 11:32 PM
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Its basically a toss up between fitment and preference.

Twins are often more expensive. You have to pay for two turbos, two wastegates, an intercooler set up for twins, etc, a way to feed/drain the oil to two turbos, route two downpipes, etc. This also gives you twice the room for error or failure.

However a large single like the Borg Warner turbos can make it difficult to find a place to put it since its dimensions don't make it easy to cram in a tight engine bay the way you can tuck smaller twins in different places.

I personally prefer to run a large single, even though I like the look of twins much much more. Either will likely meet your goals and then some.
Old 12-17-2014, 11:51 PM
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That is the frustrating thing too, they are so dang expensive. I'm fairly mechanically inclined and i like a good challenge, so I've wanted to fab a turbo kit for my car for the last three years, just seems like a lot of trial and error as far as fitment goes. Not sure exactly which I will lean towards yet, is it true that twins have less lag because they tend to be smaller compressor wheels then one big turbine?
Old 12-18-2014, 12:53 AM
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"Choosing between a single or parallel twin turbo setup is primarily based on packaging constraints in the engine bay, or a personal choice by the tuner. In most cases, for top performance, a single turbo is preferable because larger turbos are generally more efficient than smaller turbos. However, often there is not room for one large single, or the tuner wants the visual impact of twin turbos. The notion that two smaller turbos will build boost faster than one large turbo is not always accurate because even though the turbos are smaller, each one is only getting half of the exhaust flow."

Quote taken from this web site.
http://www.turbobygarrett.com/turbobygarrett/faq
Old 12-18-2014, 08:52 AM
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I should have room to run either, fairly open engine compartment, i guess it sounds like its all up to my preference. A big single does sound like alot less work as far as fabrication goes, but twins too look pretty mean under the hood. Interesting.
Old 12-18-2014, 08:53 AM
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Here's another question, how to you know what size or style turbo to get? Like is an 70mm ish turbo the right ballpark for an stock bottom ended lq4? is that too big? what you got boys?
Old 12-18-2014, 10:01 AM
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Originally Posted by gsteele
"Choosing between a single or parallel twin turbo setup is primarily based on packaging constraints in the engine bay, or a personal choice by the tuner. In most cases, for top performance, a single turbo is preferable because larger turbos are generally more efficient than smaller turbos. However, often there is not room for one large single, or the tuner wants the visual impact of twin turbos. The notion that two smaller turbos will build boost faster than one large turbo is not always accurate because even though the turbos are smaller, each one is only getting half of the exhaust flow." Quote taken from this web site. http://www.turbobygarrett.com/turbobygarrett/faq
What is your definition of "Top performance?"
Old 12-18-2014, 10:04 AM
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oh yeah, he we go, discussion baby. I want to explode the rear tires!!! haha.
Old 12-18-2014, 10:08 AM
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Do not put anything smaller than a 76mm compressor on there if you go single. Make sure the turbine is at least 75mm as well. You'll really limit yourself on a 6.0 with anything smaller than that. Something in the 80mm range will give you a very large window to work with on that motor.

With twins, 57-67mm will do on the compressor side, the turbine side should be in the 6xmm range as i think thats your only option among common turbos.
Old 12-18-2014, 10:18 AM
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Originally Posted by Ryans99ls1
Do not put anything smaller than a 76mm compressor on there if you go single. Make sure the turbine is at least 75mm as well. You'll really limit yourself on a 6.0 with anything smaller than that. Something in the 80mm range will give you a very large window to work with on that motor.

With twins, 57-67mm will do on the compressor side, the turbine side should be in the 6xmm range as i think thats your only option among common turbos.
This question may help the OP; could you list out a few "budget friendly" 80mm range turbos?
Old 12-18-2014, 10:22 AM
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Is there a chart of thread that talks about fuel delivery as well with a turbo set up, i'm assuming the injectors and fuel pump will have to be bigger, maybe even two fuel pumps, a puller and pusher?
Old 12-18-2014, 10:24 AM
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With twins, is mirror image, like what Nelson racing is doing the way to go or is compound turbos, a smaller one and a bigger one that feed inline better or even an option? I'm just brainstorming.
Old 12-18-2014, 02:48 PM
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BWs476 for cheap, or for a few more buck an s478would be my choice, if spending over a $1000 a gt91...
Old 12-18-2014, 02:53 PM
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Twin Turbonetics 60 series turbos..less than $1400 total. If you want over 1100+ I say get a set of twins. Big singles are cool and can make great HP Efficiently. Twin turbos cars are cooler IMO and can make more power in a max effort fashion. The biggest question which no one has asked is how much power do you want to make and what are you going to do with the car?
Old 12-18-2014, 05:03 PM
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Originally Posted by oscs
Twin Turbonetics 60 series turbos..less than $1400 total. If you want over 1100+ I say get a set of twins. Big singles are cool and can make great HP Efficiently. Twin turbos cars are cooler IMO and can make more power in a max effort fashion. The biggest question which no one has asked is how much power do you want to make and what are you going to do with the car?
He said in the first post...
Old 12-18-2014, 05:08 PM
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you dont need a huge single to meet your needs.. unless your shootin for crazy #'s
Old 12-18-2014, 05:11 PM
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My car is my daily driver that I very commonly can be found racing every civic, subi wrx, and audi I can get beside. I would like to do some autocross some day but really I like to drive, I take the car on 500+ mile road trips, fuel efficiency and reliability are important to me, but I understand that power and fuel economy can be achieve very carefully together with the right setup. The car is my summer toy and hobby, so the building of it is as fun as the driving of it.
Old 12-18-2014, 05:14 PM
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I honestly wanna shoot for 550-600 hp to the wheels, I will need to build the rear end and trans as well which i'm planning for, but I have a good buddy that is building a 69 Charger with a NA 440 that is putting 575hp/650#'s to the crank, so I think if I could get that to the wheels, and have a lighter car, I would smile alot around him...
Old 12-18-2014, 05:29 PM
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Originally Posted by TT427
He said in the first post...
Just saw the DD comment but nothing about HP goals.
Old 12-18-2014, 05:30 PM
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Originally Posted by snowhunter87
I honestly wanna shoot for 550-600 hp to the wheels, I will need to build the rear end and trans as well which i'm planning for, but I have a good buddy that is building a 69 Charger with a NA 440 that is putting 575hp/650#'s to the crank, so I think if I could get that to the wheels, and have a lighter car, I would smile alot around him...
Don't even bother with a set of twin for those numbers IMO. Could you get an insanely fast spooling twin setup in that range? Sure but a good single will make what your looking for without even batting an eye.


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