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| twr7cx |
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Induction piping, does it's size have much effect?
Bloke was telling me on his Supra he runs 2 1/2" to keep the air flow up and avoid lag instead of 3". Obviously I relise going too small is going to be a restriction, and going too large 7"'s would be silly. But is there much to be had in a .5" difference such as that? |
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| EFFalcon |
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if theres a difference between 2" and 7", then ofcourse theres going to be difference between 2.5" and 3", just not as bigger difference.
i'm fairly sure as a rule of thumb its best to go turbo outlet size from turbo to intercooler. then throttle body size from intercooler to throttle body.
_________________ FALCN6 - EF GLi Turbo, 20" Rims, Air Bag Suspension, Straight LPG, 225rwkw |
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| Eu-GenixX |
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yeah.. thats what i've heard about pipe sizing too
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| ebs_4l |
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i have a combination of 3" and 4" in my cooler piping, and it is basically lag free... will make full 15psi boost in less than a second at 3k rpm>
i HOPE you understand the difference between LAG and BOOST THRESHOLD?? as 99% of the people that talk about turbo lag arent actually meaning lag but the boost threshold... P.S, if you watch serious performance 6, the tech boost section has an interview with a guy from GCG turbos, even he fuks up the description of lag...!!!! he discusses lag as the amount of rpm it takes to spool up the turbo..
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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| twr7cx |
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Mind giving me a dumbies explanation of what lag and boost threshold and the difference between the two is pleasE?
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| Kilma |
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twr7cx wrote: Mind giving me a dumbies explanation of what lag and boost threshold and the difference between the two is pleasE?
Seconded.
_________________ The fast fun: Suzuki GSXR1000
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| xcabbi |
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Boost threshold is the RPM at which the turbo starts to build boost and wind up.
Lag is the time it takes from when you smash your foot to the floor to when you begin to feel it shove you into the seat. That's the basics, or do you want me to give you a more technical description? |
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| xcabbi |
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Oh and another point. You have to be passed the boost threshold in order to measure lag. No point nailing it in top gear off idle then saying its laggy.
Bring it up to an RPM where it would be making lots of boost at full throttle, baby it gently on the throttle then nail it. Lag is that slight delay. Got it yet? |
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| twr7cx |
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I get ya. Ta.
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| ebs_4l |
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exactly xcabbi...
for example, if i look at my autronic datalog, during a full throttle gearchange, i will see about 30kpa manifold pressure once the throttle is lifted, then mash the pedal and .9-1secs later it sees 212kpa.. those figures are absolute pressure... so it means 1.1bar of boost (16psi) it will produce 10psi at 2300rpm, and 15psi at about 2800, and the boost gauge goes over 0 at about 1800rpm...
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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| fnp |
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Age: 39 Posts: 4401 Joined: 25th Mar 2005 Ride: BA XT, BA XR6T, ED Ghia 5.0 Location: Perth |
Is it also true that the length and not just diameter of the induction piping has a fairly marked effect on turbo lag? I'm told that's why a lot of the fairly serious XR6T tuners relocate their batteries and air intake to the opposite sides of the engine bay, to reduce the length of intake plumbling.
_________________ What's the difference between a Holden and a sheep? It's less embarrasing getting out of the back of a sheep.. |
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| ebs_4l |
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that is correct, the larger the volume of air that the turbo needs to compress to produce boost, the longer it will take to do so
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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| xcabbi |
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So that goes for all of the volume from the back face of the inlet valve right through to the compressor housing and everything in between. All of that air has to be compressed. And tha takes time.
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| Kilma |
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Learn something new every day.
Cheers.
_________________ The fast fun: Suzuki GSXR1000
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| pyroay |
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Age: 44 Posts: 2121 Joined: 14th Dec 2004 Ride: FG Turbo Territoty Ghia Location: Traralgon |
I went from 2.5" to 3" piping all around and it made a significant difference in response.
The 3" was much better and i would certainly recomenend going that way to begin with. Of course it depends on what power your chasing. At 200rwkw i doubt it makes much difference. at 400rwkw it made a big difference
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