spd579
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« on: July 22, 2013, 10:40:51 AM »
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Hey guys, I've known about this site for a while but now having to pick a turbo for my STK and my car will be 99% street driven daily driver so I'm looking for the best response and also having built heads so I need top end flow(spinning to 8000 rpms) as well. Right now I've chosen to go with a BW EFR 7670. With this turbo I should have full boost(25-30psi) by ~3500-3750 but as the rpms go up and boost holds I'll start to overspin the turbo by ~6000 rpms. To counteract this I thought I could have the boost taper back to around 18-20 psi by redline and keep the turbo in a safe range. Is this impossible? The turbo comes with a boost controller built into the compressor housing but I'm not sure how to link that to the ECU. The other option I've considered was using the BW EFR 8374 which is basically a step up and I wont have to worry about over spinning but I'll loose about 750-1000 rpms of spool which is not what I'm looking for. Please dont just tell me to go with the larger turbo because that's not really what I'd like to do....I'd rather have the smaller turbo and hold out 600hp throughout the power band. Thanks guys!!  |
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phila_dot
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« Reply #1 on: July 22, 2013, 11:21:55 AM »
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Of course, there's numerous ways to limit boost pressure.
Look at LDRLMX in the FR, KFLDHBN allows a max permissible PR by RPM and IAT and is best suited for your needs here.
It is my understanding that the integrated boost control valve can be controlled the same as the N75, but I can't confirm that.
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spd579
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« Reply #2 on: July 22, 2013, 01:04:18 PM »
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Of course, there's numerous ways to limit boost pressure.
Look at LDRLMX in the FR, KFLDHBN allows a max permissible PR by RPM and IAT and is best suited for your needs here.
It is my understanding that the integrated boost control valve can be controlled the same as the N75, but I can't confirm that.
Thanks for your response and I'm not sure what the second section of your response is referring to(looks like I've got some research on my hands to do) but from what I can tell the n75 has a two wire plug just like the built in ebc on the turbo. It looks like it might also be a good idea to add a speed sensor to the turbo to make sure I dont over spin it. Has anyone ever tried anythnig like this? |
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NOTORIOUS VR
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« Reply #3 on: July 22, 2013, 01:43:17 PM »
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25-30psi at that RPM? How did you come up with such a figure?
I'll believe it when I see it, I think you would be lucky to make 20 psi by that RPM. Are us using a kit? or making your own manifolds?
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Snow Trooper
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« Reply #4 on: July 22, 2013, 10:10:32 PM »
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Bigger turbo = Better  |
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cartoons?
6A 61 72 65 64 40 76 6C 6D 73 70 65 63
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Bische
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« Reply #5 on: July 22, 2013, 10:32:35 PM »
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EFR solenoid is PnP in ME7 harness'
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spd579
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« Reply #6 on: July 23, 2013, 07:05:48 AM »
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25-30psi at that RPM? How did you come up with such a figure?
I'll believe it when I see it, I think you would be lucky to make 20 psi by that RPM. Are us using a kit? or making your own manifolds?
25psi by 3500 and 30psi by 3750-4000. Here's a precision 5858 for comaprison(has a slightly larger compressor wheel inducer and a heavier turbine wheel(more inertia). He also has boost rising were I will be tapering(due to overspinning and power will fall off if overspun as he did)  I have a friend making a manifold for me |
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spd579
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« Reply #7 on: July 23, 2013, 07:06:42 AM »
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Bigger turbo = Better No, bigger turbo= more lag which is not good for street driving |
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spd579
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« Reply #8 on: July 23, 2013, 07:07:13 AM »
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NOTORIOUS VR
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« Reply #9 on: July 23, 2013, 07:55:31 AM »
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I find that graph hard to believe... but I'll wait to see your results. FWIW, here is also a graph of a PTE5858 on an S4:  |
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spd579
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« Reply #10 on: July 23, 2013, 08:09:45 AM »
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I find that graph hard to believe... but I'll wait to see your results.
FWIW, here is also a graph of a PTE5858 on an S4: This one isnt that bad....could have to do with exhaust housing, restrictive stock heads, gas, ect.... |
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NOTORIOUS VR
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« Reply #11 on: July 23, 2013, 09:17:34 AM »
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I just re-read the graph you posted... 25psi happens AFTER 4500 RPM.
I think you're mixing up desired vs actual boost on that graph.
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spd579
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« Reply #12 on: July 23, 2013, 09:36:25 AM »
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I just re-read the graph you posted... 25psi happens AFTER 4500 RPM.
I think you're mixing up desired vs actual boost on that graph.
No, i saw that too but that is with the 5858(less advanced turbo), on stock IM, heads, TB, 93. I have +1 valves, RS4 IM and TB, better turbo, more efficient IC, I expect better spool. |
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« Last Edit: July 23, 2013, 10:53:52 AM by NOTORIOUS VR »
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NOTORIOUS VR
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« Reply #13 on: July 23, 2013, 10:53:57 AM »
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No, i saw that too but that is with the 5858(less advanced turbo), on stock IM, heads, TB, 93.
I have +1 valves, RS4 IM and TB, better turbo, more efficient IC, I expect better spool.
You will gain some spool, but I would not expect 1000RPM gain in spool. |
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« Last Edit: July 23, 2013, 11:25:37 AM by ddillenger »
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julex
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« Reply #14 on: July 23, 2013, 12:15:48 PM »
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You will gain some spool, but I would not expect 1000RPM gain in spool.
The spool will actually be delayed with bigger intake tract. I see that happening on my new intake setup, RS4 intake, etc, etc. Remember, small port/intake promotes faster spool/more pressure in low/mid range but chokes in higher RPMs. |
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