Twin Turbo LS1

Posted by Eight Ball WS6, Aug 17, 2004
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.

  1. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    Hey guys (and girls),

    I'm lookin for some general (yet specific) help. I drive a 2002 Trans Am WS.6 and I'm lookin to add a custom twin turbo setup. I know a lot of you know your sh** so I decided to come here. For me to run a single turbo, it would have to be a mighty big one, with a 76 mm compressor at the very least, from what I've read, researched, and been told. Anyway, I know how to read a compressor map for a single turbo application, but does the process differ at all when considering two turbos?

    To give you all an idea, I'll give you some pretty detailed specs so you can better help me out:

    Bore: 3.898"
    Stroke: 3.622"
    346 cu in, 8 cylinders
    10.1:1 compression ratio
    VE: 81%
    Boost: 6-8 PSI (7 is my initial goal)
    @ 7 psi and 6000 RPM, 43.53 lbs/min air consumption, 615 CFM

    I have preliminary plans of going with two Garrett T04E's with:
    1.32 Turbine A/R
    .70 Compressor A/R
    57 trim comp wheel
    P trim turbine

    Any and all help will be GREATLY appreciated :thumb:
     
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  2. Coldandafraid

    Coldandafraid Proven Member

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    welcome... just so you know, that sig will be deleted. 250 pixel max.
     
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  3. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    sorry, I'll make it smaller, its allowed over at LS1tech.com :p
     
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  4. LA97GST

    LA97GST Proven Member

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    I don't know anything about twin turbo maps, but i know you better have some money ready. With 10:1 you will only run about 6-7 psi like you said, but it will still pull hard.. as you know what. Just get the two exhaust manifolds and two custom downpipes, and tuneeeee. What type of engine management will you use?
     
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  5. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    actually, Ive read a website that detailed the install of an incon twin turbo setup on an ls1 firehawk, and he actually ended up using the stock manifolds. there will be lots of custom after-turbo exhaust fabrication and of course the intake tubing. once its all hooked up, I'll be using LS1 edit to tune it, after the addition of the 42# injectors and 255lph pump or course.
     
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  6. yhype

    yhype Proven Member

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    Not to be suggesting anything different. But have you considerd putting on a Pro Charger on your car. Those F-bodys i know can be pretty sick with Pro-Chargers. But if your set on twin turbos, try goin to http://www.turbofast.com.au/javacalc.html they have some calculators on there that will help you out to find what turbos to look at.
     
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  7. GSX_RCR

    GSX_RCR Proven Member

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    Twin T04E's with 1.32 turbine A/R each. OMG

    But then again, you never know what would happen when you throw it on a V8.
     
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  8. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    yhype, have all those cals on my hard drive for a while now but thanks for the suggestion. As far as s/c, Id rather do turbo. The parasitic power loses associated with s/c'ing just isn't worth the nearly 6K price tag for the good ones, especially at higher boost levels. The more boost you run with a s/c, the more power it takes directly from the engine.

    I can put together this turbo setup for my car, theoretically, for about 1500-2000 dollars for the parts...maybe less from what Ive heard. In addition, there's plenty of s/c LS1s runnin around out there, turbos on these engines, particularly TWIN turbos, are far more scarce.

    Ive figured out all the numbers, I just need to figure out how to apply them to a compressor map when accounting for two turbos. Do I simply divide the air flow by two? Divide the pressure by two? I'm lost and I dont feel like going with a single 76+ mm turbo, WAY too much for my goals...

    -Mario
     
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  9. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    are you thinking thats too high? Im totally open for suggestions. I originally wasnt gonna go above 1.00.....
     
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  10. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    also, there are a few twin sequential turbo ls1's Ive seen, one in particular with a t-56/t-76 combo...putting out somewhere in the neighborhood or 750+ rwhp
     
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  11. pneumo

    pneumo Proven Member

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    I can tell you did quite a bit of research already. The P trim turbine wheel and 1.32 AR housing are a good choice. Do you plan on getting a turbo specific cam? Or will you stick with the stock or other NA cam? The reason I ask is because the cams on our turbo cars are set up with much less overlap between intake and exhaust. This was done because the turbo produces more backpressure, so our cars tend to do well at high boost. The greater cam overlap of a NA motor would lead to reversion if run at high boost. A NA motor needs low backpressure.

    To work out the compressor maps, just divide the airflow (CFM, lb/min) in half. The pressure ratio stays the same. For example, the 57 trim wheel is capable of flowing about 45 lb/min. Two of them yields 90 lb/min.
    It would be like having one 57 trim feeding half your engine, which is 2.8 liters.
     
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  12. awd4g63

    awd4g63 Proven Member

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    I don't really have any information, but I'm interested to see what happens with the car in the future :thumb:

    Let us know how it goes.
     
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  13. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    pneumo, thanks a TON dude thats exactly the info I was lookin for. :thumb: Glad to hear you think my selection is a good one. As far as upgrading the cam: I do have plans for that in the future, most likely a reverse split with a 115 LSA, havent quite figured out appropriate durations yet though. I'll start calculating that after I get the turbos on and get it somewhat tuned. plus, I cant really run any higher than 7 or 8 psi MAXIMUM until I lower the compression to about 8.5-8.0:1. Once I do that I can probly see 11 or 12 safely. But then again, Id probably need a pair of bigger turbos for that anyway :cool: not to mention stronger internals...

    Ill gladly take any other suggestions you all might have, I know theres a wealth of information to be found from you DSM guys :D
     
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  14. pneumo

    pneumo Proven Member

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    Something tells me the 57 trim compressor might not be big enough for your needs. I don't spend much time studying maps at the 1.5 PR level so I can't say for sure, but down there the 57 trim tops out at about 32 lb/min. Most compressors produce their max flow up around the 2.4 PR area. What I don't know is if a compressor can still work effectively outside the maps flow area. Can it run out to 50% efficiency at 1.5 PR without choking? You might want to ask the shop where you get your turbo about that question. You just might end up with a pair of GT40 56 trim wheels, 62-1's, or a pair of T-61's.

    The good news is you won't need to upgrade the turbos as you add more mods to the engine. Just mod the engine so it can handle higher boost like you outlined above, and you'll make more power as you increase the boost without outflowing the turbos.
     
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  15. ldstang50

    ldstang50 Proven Member

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    i don't know specs but check www.lingenfelter.com he makes a twin turbo kit for the vette i'm sure you can get some good info off there
     
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  16. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    Well, like you informed me last time, with a twin setup I should just divide the flow rate at a given RPM and boost level by two and check that versus the compressor map. My calculations are as follows:

    PR=(7+14.7)/(14.7-.5)=1.52
    lbs/min@6K RPM=43.53

    Since I'm using two turbos, dividing 43.53 by 2 gives me about 22 lbs/min max flow for each turbo. Again, this is only based on what you told me before which totally makes sense to me.
    [​IMG]

    Looking at this compressor map, you can see that 22 lbs/min at the 1.5 PR level is more than adequate, in fact its damn close to the island, or at least as close as I'm going to get with this turbo at a 1.5 PR. What I worry about now is crossing the surge limit at low RPM. Upgrading to the 60 trim as far as I can tell would not hold a very significant difference for me.
     
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  17. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    Oh believe me, I've checked out all of the pre-fab kits out there and none of them meet my budget. Here's the link to the lowest powered corvette turbo kit they make:
    http://www.lingenfelter.com/pac550ttls1y.asp

    With a "Sale Price" of $18,995.00 for 500 rwhp, I think I'll take my chances with about a tenth of that money and make it myself. :thumb:
     
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  18. ldstang50

    ldstang50 Proven Member

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    ok, didnt' know if you had checked them out. I knew they were that expensive, I didnt' really look into them. But thought if it would give an idea as to what turbo you should do
     
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  19. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    Come to think of it, that may not be a bad idea... Although, I emailed Precision Turbo and asked them for suggestions on single turbo selection a while back and never received a respose... :mad: Hopefully a company like Lingenfelter that sells upgrades in excess of 100 grand would invest in a slightly better customer service department :rolleyes:
     
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  20. eclipse_20g

    eclipse_20g Proven Member

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    I hope you have some expert mechanical skills. This is going to be more fabrication than I ever want to think of. I own a 99 FRC Vette, so I've seen everything thats out there for them. Hopefully all turns out well, but how much HP are you trying to make here? Apparently if s/c isnt enough, you have got to be way up there. The D1SC from Procharger is consistently making 650whp and over and as for their F1R charger, thats just a class of its own. Is your engine forged? What kind of h/c setup you running? Drivetrain mods? Unless you want a sub-9 second car, supercharging would be a hundred times easier, more reliable, and the stock bottom end and heads can be utilized. You would not want to run over around 550 on the stock bottom unless you dont mind if something would happen to it. It gets risky after that though there are rare cases of a lot more than that being pushed. Hope some of this helps and I could continue on and on but let me know what you think first.

    Why not just talk to the people at LS1tech? There are a ton of knowledgeable ls1 guys there.
     
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  21. turbodsm999

    turbodsm999 Proven Member

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    Check out ls1.com ls1tech.com camaroz28.com .
     
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  22. Eight Ball WS6

    Eight Ball WS6 Proven Member

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    Im a member over at ls1tech.com and Ive already learned a ton from those guys. Reason I came here is because I thought I might get another point of view from you DSM owners. Ive already discussed why I dont want to go s/c, mostly because of the relative price difference, around 6K. Also, I dont really care how long this takes me as this car is soon to be my project/hobby car anyway. If it ends up sitting in a garage for the entire winter in pieces thats fine, it sits in the garage fully assembled all winter already as it is. Turbocharging seems to be growing in popularity among LS1 owners and there are more and more kits being developed every few months, but I'd still rather attempt doing it myself. If it comes to be that I simply cant do it or its out of my budget, then I'll scrap the idea, sell the parts, and keep the car stock.
     
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  23. awddsm95

    awddsm95 Proven Member

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    if i were u, i would go with a single turbo set up, but if u do go twin, deffinitly dont do sequencial, just my oppinion, but i got to run, were dropping a 3in exhaust on my friends starion
     
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  24. lx2539

    lx2539 Proven Member

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    check this site out!

    http://turbomustangs.com/forums/forumdisplay.php?forumid=20
     
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  25. 1fast97gsx

    1fast97gsx Proven Member

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    yea I think I'd just go with 1 big turbo as well. I don't really know what to help you with but definitly invest in a turbo cam if you are going turbo. Keep us posted as I am very interested in what happens with this as well.
     
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