Twin Turbo guys please help

hd2500

New member
Oct 1, 2013
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Im looking for a little help with which turbo to get to compound my lb7. I know little about turbos and thought this would be the place to ask! I am just looking for turbo info and not a kit to buy because i will be building a kit myself. I have stock internals, so i would imagine a larger turbo would make my internals last a little longer because of the turbo lag so torque in the lower rpm range would be a little lower. Is this correct? What A/R ratio should i be looking for? turbine and compressor wheel mm? My goals are for around 550hp and to make the internals last as long as they can at this hp level. thank you for any input, and I will keep searching the forums for knowledge
 

SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
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Arizona
I would do a s475.
1.32AR T6 96mm turbine wheel. Add a race cover if you can afford the extra $.


Sent from my iPhone.
 

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
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Des Moines, Iowa
I would go with the S480, the only difference is the compressor wheel. I would get a standard cover if your wanting to do it on a budget. You can get the S480 for a bit more then the S475.
 

Dirtymaxx03

Active member
Aug 4, 2009
3,109
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Adding a turbo is going to greatly increase low rpm power (torque). So it will have a negative affect, if any (self control), on your bottom end.
 

hd2500

New member
Oct 1, 2013
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Thanks guys I really appreciate it. With my current mods, and adding a s475 to her with new tunes to accommodate, what go do you think I will be at? I don't want to be too high, but I could always just have it tuned down a little. Thanks again
 

hd2500

New member
Oct 1, 2013
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Also, is a turbo something I should worry about buying used, say from a forum or ebay, is is this something everyone buys new and not something to leave to chance?
 

moparkxracer

Well-known member
Jun 25, 2010
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Out and about
my personal opinion is if you don't plan on building the engine don't go bigger then a S475, I would get a new one they are cheep if you get a used one you'll have a 50/50 chance it will need to be rebuilt costing the same or more as what you would have spend to get it new to begin with.
 

SickLL7Crenshaw

Billy The Kid
Mar 10, 2013
1,088
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Mexico
My buddy has a customer that has a kit for sale. 4202 Garrett over stocker. Lb7 kit. PM if your interested and I'll let him know.
 

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SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
1
36
Arizona
The idea behind the race cover is that it is a more free flowing cover, and respectively relieves the IHI from having to suck air through a restrictive compressor cover.

As far as spool time/making the engine live etc: proper de-torqueing the tune calibration that is in the truck is more beneficial than turbo lag.
 

plowboy_lbz

Farmer
Aug 6, 2013
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If your only looking for 550hp why not go with a modified stocker? It would be cheaper than a twin kit, but twins are nice. Most people go with the box stock s475 96mm 1.32 a/r because they are cheap and actually work very well. You can spend some more money and upgrade to a 1.10 a/r. This is becoming an ever more popular topic. Many people seem to think the 1.10 a/r will deliver better spool up and greater drivability. I have no complaints about my s475 1.32 a/r

My buddy has a customer that has a kit for sale. 4202 Garrett over stocker. Lb7 kit. PM if your interested and I'll let him know.

Whats the specs on the Garrett?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,685
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Thanks guys I really appreciate it. With my current mods, and adding a s475 to her with new tunes to accommodate, what go do you think I will be at? I don't want to be too high, but I could always just have it tuned down a little. Thanks again

on a max effort tune with rail that will hold with stock injectors. id say around 600hp

Also, is a turbo something I should worry about buying used, say from a forum or ebay, is is this something everyone buys new and not something to leave to chance?

unless you dont mind the chance of possibly rebuilding it, i would buy new unless its from a well known user here.

my personal opinion is if you don't plan on building the engine don't go bigger then a S475, I would get a new one they are cheep if you get a used one you'll have a 50/50 chance it will need to be rebuilt costing the same or more as what you would have spend to get it new to begin with.

475 or 480 are already beyond the limits of a motor so dont use that as a "safe zone".


Also the power difference and spool up time between them are hardly any different. A well fine tuned wastegate on the stock charger or vanes makes all the difference in the world.
 

mackthehack

DUH...
Apr 16, 2007
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I have the exact turbo you need for this setup, a box Borg Warner 475/96/1.32ar. If you're interested in it pm me.