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Thread: Turbo selection

  1. #1
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    Turbo selection

    I'm doing my first turbo build. 5.3 with a tremec magnum. Street/ autocross car, looking for around 500-550 whp. I have a precision 7275 .96, but can get my hands on a Garrett 7675 .96. Which would you guys run?

  2. #2
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    Turbo selection is a lot like camshaft, stall speed, and carburetor size...when in doubt go with the smaller of the two.

    Andrew
    1970 GTO Version 2.0
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  3. #3
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    I love my turbo but it would not be my choice for a autocross car, boost comes on fast and and will be difficult to manage in corners...that and 500-550 is to obtain na in lsx.

  4. #4
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    Having power hit like a sledgehammer may be completely fine on the street if you tend to point the car in a straight line, but certainly less than optimal while auto-crossing. I have smaller twin T04Bs (60mm compressor wheels, P trim 0.69 A/R hotside). They aren't as effective at building massive top end power as much as building boost right away when I want it on the street. For an autocross car I would look at a turbo that is easier to control power delivery and might consider a boost by gear setup to regulate the power delivery.

  5. #5
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    I would want more details, but if these are your only choices, T4 1.10 or smaller housing on both, I would pick the 7675 although for your goals it won't make a huge difference either way. The spool should be roughly the same between the two turbos, only difference being amount of air forced in with a larger flowing compressor wheel. You probably will not notice any major driveability differences between the two units during autocross.
    Justin N.

    1966 Chevelle
    1992 GMC Typhoon
    1989 Jeep Wrangler CJ 6.0 Twin Turbo
    1981 Jeep CJ7

  6. #6
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    you might want to check ou Sloppy Mechanics wiki and youtube channel, you'll find all the answers you need.

  7. #7
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    Both t4 .96. As far as turbos not being ideal for auto cross, I know, this car will be a jack of all trades, master of nine. Realistically I know this car won't be competitive or anything, just looking to have fun. I'm looking for more power, I want to try my hand at fabricating a turbo system and something that won't destroy the druveability of the car. U will be using a boost controller with boost by gear as suggested by twinturbo69.

  8. #8
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    take it from me if your going turbo 550 is just the tip of the ice berg . really not worth it imo.
    that being said pretty easy to make 650 700+ rwhp in a turbo lsx. my car behaves like a stock 6.0 until you mash the throttle then it's warp speed ahead....

  9. #9
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    You could get an advanced boost controller and ramp in the boost..... also boost by gear. You could modulate the power quite a bit simply with your right foot.... but remember that you are going to have probably 500rwtq to manage so you better have some sticky tires.



    I'm running a 3.25 gear with a Wavetrac LSD out back in my Chevelle. Hope to be driving it this summer. I'm also an alum 5.3 and shooting for around 900rwhp on kill. Holley Dominator EFI allows boost by gear/time and multiple programs for different uses/surfaces/racing. I'm also at around 10:1 compression and running e85 so hoping for good power when not in boost due to the higher compression.
    69 Chevelle 1000hp turbo LS, T56 Mag, JRi coilovers, Watts/torque arm 9", 14" Wilwoods, Recaro CTSv seats, cromo cage, a/c, p/s, built by Coffey Fab Nashville, TN.
    93 RX-7 1200hp turbo LS9, T56 Mag, 8.8", [email protected] + 197mph 1/2 mile