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Benefits of twin turbo over single

This is a discussion on Benefits of twin turbo over single within the Forced Induction forums, part of the LSx Technical Help Section category; Foudn this http://www.harlan-engineering.com//hawk/mods/mods.html but his website is falling apart, half the links dont work. thanks for the info, that pretty ...

  1. #21
    Foudn this http://www.harlan-engineering.com//hawk/mods/mods.html

    but his website is falling apart, half the links dont work.

    thanks for the info, that pretty much sums it up

  2. #22
    So would a pair of these:

    COMPRESSOR: 45 trim : 60.12mm wheel, 0.42 a/r housing, 2.5" inlet, 2" outlet
    center section: oil cooled, carbon seal upgrade included!
    turbine, big T4 74.22mm wheel, 1.15/1.32 a/r split scroll housing, slip fit or v clamp downpipe joint available!

    (rebuilt to 60 trim)

    At 5psi be better then a single sts setup with the gt trim at the same psi?

    i ask cause i can get these at a rediculous price, although installation is going to be pricey since it will all have to be custom. (under hood, not remote mount)

  3. #23
    Member ericwilloughby's Avatar
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    AT 5 psi, or anything less than 15 any one will be just as good as any other 2. Provided they are matched to the system\design.

  4. #24
    So two is a waste under a 15psi setup?

  5. #25
    Quote Originally Posted by ericwilloughby
    AT 5 psi, or anything less than 15 any one will be just as good as any other 2.

    thats like saying "below 30 the size of your tires doesnt matter"



    correct turbo size is important at any pressure level

  6. #26
    Member ericwilloughby's Avatar
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    Quote Originally Posted by Zakar
    thats like saying "below 30 the size of your tires doesnt matter"



    correct turbo size is important at any pressure level
    It was only 2 posts ago I said "AT 5 psi, or anything less than 15 any one will be just as good as any other 2. Provided they are matched to the system\design."

  7. #27
    Member ericwilloughby's Avatar
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    Quote Originally Posted by grandkodiak
    So two is a waste under a 15psi setup?
    As I said the BIG OVER WHELMING factor is the ease of installation.
    The only REAL, Major I mean, differance is the logistics of the install and efficiency. One big turbo will not fit beside the transmission. You need 2 small ones there. One large one will fit under the hood but do you want that heat in there? One large one does the job at the rear. You will pay double the price for a twin setup and get the same boost pressure and airflow. Yes, I said pressure because that is what we measure the airflow via. The size of the restrictions in the intake tract of the engine did not change hear. More boost is more airflow. Up to a point of course when the efficiency goes to crap and more heat is being produced compared to airflow. That point is over 20 PSI. Which is why I said it really doesn't matter what kind of setup you use as long as The turbo(s) are matched to the engine.

  8. #28
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    It seems like, everything else being equal, the turbine/compressor that had the greatest diameter would take longest to spin up because of rotational inertia. However, I've also read that there have been a lot of advances in both turbine blade design and materials science (lighter ceramics in place of iconel, for example) that have minimized turbo lag in modern turbos. So, theoretically speaking, the smaller diameter of a twin turbo setup would spool up faster; but I've also read of a single turbo setup on a GN going from 0 to 26 lbs of boost in .6 seconds - hardly much lag at all, even to make full boost.

  9. #29
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    Quote Originally Posted by stonebreaker
    It seems like, everything else being equal, the turbine/compressor that had the greatest diameter would take longest to spin up because of rotational inertia. However, I've also read that there have been a lot of advances in both turbine blade design and materials science (lighter ceramics in place of iconel, for example) that have minimized turbo lag in modern turbos. So, theoretically speaking, the smaller diameter of a twin turbo setup would spool up faster; but I've also read of a single turbo setup on a GN going from 0 to 26 lbs of boost in .6 seconds - hardly much lag at all, even to make full boost.

    I have messed around with the Buicks for a number of years so I can help you on this one. On a race car with a dual ball bearing 80 turbo, we should make 850 hp at the wheels.

    This is a single turbo and the A/R ratio on the hot side is an X trim so it is at least 1.10 or better. That is a very big exhaust side but since its a race car that stages at 4000 rpm and will hit max boost of 30 psi it works very well for the application. This car uses 9 inch converter with a stall of 3800 rpms to spool the turbo. On a street car the exhaust side is usually .69 to .81. The smaller housing on the exhaust side makes the same turbo spin faster.

    Now with a V8 you dont need the high stall speed in the converter because there is a lot more exhaust gas to spin the turbine side faster. The benefit of 2 more cylinders. The housing on the exhaust side can be bigger as well so the turbo flows the maximum amount of air at the right rpm range of the motor.

    Something else I have noticed with LS-1s and turbos. The max psi level I have seen on big turbos on these motors is 15 psi, that is on race gas and the best tune possible. That same turbo will go to 28 to 30 psi on a Buick V6 motor. Both motors will make the same hp with the turbo so why the difference in boost levels?

    2 more cylinders to fill.

    So I have to agree with Ericwilloughby. Ease of installation is a big part and matching the components in the kit is just as important.

  10. #30
    Quote Originally Posted by stonebreaker
    It seems like, everything else being equal, the turbine/compressor that had the greatest diameter would take longest to spin up because of rotational inertia. However, I've also read that there have been a lot of advances in both turbine blade design and materials science (lighter ceramics in place of iconel, for example) that have minimized turbo lag in modern turbos. So, theoretically speaking, the smaller diameter of a twin turbo setup would spool up faster; but I've also read of a single turbo setup on a GN going from 0 to 26 lbs of boost in .6 seconds - hardly much lag at all, even to make full boost.

    Wheel and housing design have ALOT to do with spool and output characteristics.. with modern VNT turbos it is a non issue...as long as you want to fork out the cash (not me)


    Quote Originally Posted by Reggie West
    Something else I have noticed with LS-1s and turbos. The max psi level I have seen on big turbos on these motors is 15 psi, that is on race gas and the best tune possible. That same turbo will go to 28 to 30 psi on a Buick V6 motor. Both motors will make the same hp with the turbo so why the difference in boost levels?
    Thats because 600hp is about the limit on a stock LS1 bottom.. which it will make @ 15psi with a big turbo.. with aftermarket pistons/rods assuming that turbo wont run out of breath @ 30psi it probably make 1100hp..

    buick GN's are so badass.. i wish they were cheaper

  11. #31
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    Quote Originally Posted by oneBADDz
    The ideal twin turbo setup is a large turbo and a small turbo. The benefit over a single turbo is that you can have a small turbo that spools quickly to help you down low, then the larger turbo to push more boost and help make major power up top. Simply put you get a quick spooling turbo so that you don't have lag, and a large turbo for big power rather than having to compromise with one or the other
    Good explaination, thats exactly why they use twin turbo setups.

    However, I don't think they are nearly as beneficial on a V8, because theres plenty of low end power to begin with, and then the turbo spools for midrange and top end.

  12. #32
    Has anyone gone to http://www.airpowersystems.com.au/ls1/ls1.htm to check out their TT setup for LS1? I like the turbos being down by the tranny...keeps nosey CHP's from eyeballing my mods.. and if there is a substantial amount of heat generated, it can vent separately from the under hood components and doesnt require a new hood that might edge you out sleeper status. I do think the underhood setup is GORGEOUS but as I said I like the undercar mounting better... When I get my LS1 I plan on doing the TT mod with as big of an intercooler as I can fit.

  13. #33
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    I was wondering if anyone knows a bout a good universal twin turbo kit unfortunately I don't have an ls1 and I have been doing some research but no luck besides the sts twin turbos and iv been seeing around then net there no good so I just hope one of you car guys(or gals) can help me out alittle thanks for any help

  14. #34
    Member ericwilloughby's Avatar
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    The STS or rear mount type is the only "universal" system. They work just fine up to a point. That being about 10 psi.

  15. #35
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    Quote Originally Posted by ericwilloughby View Post
    The STS or rear mount type is the only "universal" system. They work just fine up to a point. That being about 10 psi.

    People don't seem to understand what the STS was made for....from what I gathered, it's a cheap way to make 500rwhp and easy to install. If you don't get too crazy you can even run it on the stock fuel system no? Seems like a somewhat cheap way to make power to me.

    There's nothing wrong with STS other than the parts aren't the best and this is what people tell me that actually own an STS setup, it makes good power just like a front mounted turbo would.

  16. #36
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    PBM 366ci TC78 E85
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    What are you looking to do?
    Last edited by JAX04; 04-15-2009 at 11:01 AM.

  17. #37
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    Quote Originally Posted by ericwilloughby View Post
    AT 5 psi, or anything less than 15 any one will be just as good as any other 2. Provided they are matched to the system\design.
    eric, whats going on man, just wanted to let you know, we are doing a front mount on my goat now, if you remember i was pounding you for info on the rear mount. but since i can fabricate and i have cnc at my disposal i am now doing a custom front mount with my t70.

  18. #38
    Member ericwilloughby's Avatar
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    Send me a link to your build. I'd love to see it.

  19. #39
    Member ericwilloughby's Avatar
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    Quote Originally Posted by allbaugh_04 View Post
    People don't seem to understand what the STS was made for....from what I gathered, it's a cheap way to make 500rwhp and easy to install. If you don't get too crazy you can even run it on the stock fuel system no? Seems like a somewhat cheap way to make power to me.

    There's nothing wrong with STS other than the parts aren't the best and this is what people tell me that actually own an STS setup, it makes good power just like a front mounted turbo would.

    They aren't cheap, not much less than a front mount.
    Stock fuel system on the LS2 GTO with 32# injectors only took mine to 4 psi. It does make good power but it hits a brick wall when you get to the double digit psi. Unlike a front mount.

  20. #40
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    Not much less? link for proof of your prices?

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