Turbo guys :: What A/R are your turbos and why?
07-11-2009, 01:42 PM
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Turbo guys :: What A/R are your turbos and why? I've been doing a bit of research in the world of FI and I've gotten to the point where I understand the schematics and technology alot more that I did before. My question is what A/R are your turbos and what influenced the you to use that selection? I'm planing a stock cubed TT build and I've concluded that a Stage V T3/T4 Hybrid with .63 A/R would do the trick. My understanding is the the Stage 5 Turbine, which is 62mm, will allow me to make adequate power with a stock LS1 as well as all me to turn up the boost once I forge my bottom end. The 0.63 A/R will spool early, but the only thing I'm concerned about is if they will consistently produce boost up to 7k. So please, share you experiences with me.
07-13-2009, 01:47 AM
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I run a .96 a/r hotside with a 6.0 litre and I shift around 6k. I chose it because a .68 would have fallin off a little early and I still have full boost by around 3500/3600
07-13-2009, 11:55 AM
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the best thing to do would be to find out how much air those turbos can push each then find out how much air your engine will need at 7k. Forcedinductions.com has a chart that goes up to 6800 rpm and 15psi.
but with a twin turbo using to small turbos that will spool fast anyway you might want to think about a higher ar. call sponsers and ask them.
but with a twin turbo using to small turbos that will spool fast anyway you might want to think about a higher ar. call sponsers and ask them.
07-14-2009, 01:14 PM
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My twin .68 AR stage V 60-1 Garretts get full boost as early as 3500 and hold to 7200. The ability to spool sooner or later can be controlled with an EBC as well.
07-14-2009, 02:46 PM
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Correct. You can change the way it spools to a degree. By changing the gate pressure ( what psi it starts to open the wastegate ) you can move the spool time. For my application, my low boost is on spring pressure ( 7# ) the factory GP set was 3#. By holding the gate closed longer ( say 4# ) I can make it reach full boost sooner. Change it to say 2# and it will reach later.
Other things to consider is what is the AF while going into boost? By maker it slightly richer ( from what Ive been told ) it will achieve boost faster. Just some more things to look at.
Other things to consider is what is the AF while going into boost? By maker it slightly richer ( from what Ive been told ) it will achieve boost faster. Just some more things to look at.
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07-15-2009, 12:49 PM
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Correct. You can change the way it spools to a degree. By changing the gate pressure ( what psi it starts to open the wastegate ) you can move the spool time. For my application, my low boost is on spring pressure ( 7# ) the factory GP set was 3#. By holding the gate closed longer ( say 4# ) I can make it reach full boost sooner. Change it to say 2# and it will reach later.
Other things to consider is what is the AF while going into boost? By maker it slightly richer ( from what Ive been told ) it will achieve boost faster. Just some more things to look at.
Other things to consider is what is the AF while going into boost? By maker it slightly richer ( from what Ive been told ) it will achieve boost faster. Just some more things to look at.
hmmm... thanks for the useful info, I might be picking up the twins this weekend; Turbonetics T3/T4 Stage 5 (62mm c.w.) .81 A/R; hopefully i can start my build thread by Halloween....
07-15-2009, 06:07 PM
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Not trying to hijack the thread but will my turbo be to small? Its a forged 347 with a precision t76 .75 compressor and .96 ar hot side. I plan on running 16-18 psi will it not do that? Will it max to early?
07-18-2009, 02:09 AM
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can anyone explain those numbers in bold? i think the .96 determines how large the tubo flows or am i dead wrong? i don't know crap about what a compressor does on a turbo?
07-18-2009, 02:37 AM
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Check out the stickies and also www.forcedinductions.com for some good info. Basically the turbine AR determines how quick you spool up vs. how much top end power you are going to make. It's a delicate balancing act so you still spool well, but don't choke yourself out on top.
