400rwhp Stock Motor.
02-19-2009, 12:38 AM
#43
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When i put in my numbers, It tells me that i'm going to need 63psi to get my power goal. Maybe i'm doing it wrong.
According to garrett's website, here is their calculation.
Where:
· MAPreq = Manifold Absolute Pressure (psia) required to meet the horsepower target
· Wa = Airflowactual(lb/min)
· R = Gas Constant = 639.6
· Tm = Intake Manifold Temperature (degrees F)
· VE = Volumetric Efficiency
· N = Engine speed (RPM)
· Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61.02, ex. 2.0 liters * 61.02 = 122 CI)
If i do the math, that comes out to 48.1 total psi or 33.4 psi of boost. That doesnt seem quite right either. Pretty sure my ****'s going to pop if i try and put 33psi to it with any turbo. Am i missing part of the equation here?
According to garrett's website, here is their calculation.
Where:
· MAPreq = Manifold Absolute Pressure (psia) required to meet the horsepower target
· Wa = Airflowactual(lb/min)
· R = Gas Constant = 639.6
· Tm = Intake Manifold Temperature (degrees F)
· VE = Volumetric Efficiency
· N = Engine speed (RPM)
· Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61.02, ex. 2.0 liters * 61.02 = 122 CI)
If i do the math, that comes out to 48.1 total psi or 33.4 psi of boost. That doesnt seem quite right either. Pretty sure my ****'s going to pop if i try and put 33psi to it with any turbo. Am i missing part of the equation here?
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02-19-2009, 12:46 AM
#47
When i put in my numbers, It tells me that i'm going to need 63psi to get my power goal. Maybe i'm doing it wrong.
According to garrett's website, here is their calculation.
Where:
· MAPreq = Manifold Absolute Pressure (psia) required to meet the horsepower target
· Wa = Airflowactual(lb/min)
· R = Gas Constant = 639.6
· Tm = Intake Manifold Temperature (degrees F)
· VE = Volumetric Efficiency
· N = Engine speed (RPM)
· Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61.02, ex. 2.0 liters * 61.02 = 122 CI)
If i do the math, that comes out to 48.1 total psi or 33.4 psi of boost. That doesnt seem quite right either. Pretty sure my ****'s going to pop if i try and put 33psi to it with any turbo. Am i missing part of the equation here?
According to garrett's website, here is their calculation.
Where:
· MAPreq = Manifold Absolute Pressure (psia) required to meet the horsepower target
· Wa = Airflowactual(lb/min)
· R = Gas Constant = 639.6
· Tm = Intake Manifold Temperature (degrees F)
· VE = Volumetric Efficiency
· N = Engine speed (RPM)
· Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61.02, ex. 2.0 liters * 61.02 = 122 CI)
If i do the math, that comes out to 48.1 total psi or 33.4 psi of boost. That doesnt seem quite right either. Pretty sure my ****'s going to pop if i try and put 33psi to it with any turbo. Am i missing part of the equation here?
Yeah, some of your numbers were wrong. I copied what I was running, (max power at 7500, full boost 4k, etc) and kept flywheel hp to 430 (357whp) and got this: (24.5 PSI Boost BTW)
Squirrel Performance - Turbo Calculator Version 4
Turbo ain't big enough for 350whp
Same turbo at 380fwhp/315whp
http://www.squirrelpf.com/turbocalc/...&product_id=32
Bout all it's good for.
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02-19-2009, 12:48 AM
#49
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Yeah, some of your numbers were wrong. I copied what I was running, (max power at 7500, full boost 4k, etc) and kept flywheel hp to 430 (357whp) and got this: (24.5 PSI Boost BTW)
Squirrel Performance - Turbo Calculator Version 4
Turbo ain't big enough for 350whp
Squirrel Performance - Turbo Calculator Version 4
Turbo ain't big enough for 350whp
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02-19-2009, 01:12 AM
#54
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I would like to go with a turbo that's easy to get ahold of. This is close. I'm still riding that surge line, however.
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02-19-2009, 01:17 AM
#55
I would like to go with a turbo that's easy to get ahold of. This is close. I'm still riding that surge line, however.
Part of the "problem" is spool. If you build boost at low RPMs, there's low flow, and you surge. You could "fix" this problem with a shitty wastegate and manifold so that you didn't get full boost till say 4500 and say boost onset at 2500 (note they use a linear rise in boost, where in my experience, it's not linear, but exponential).
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02-19-2009, 09:31 AM
#56
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lol. Scroll down and select GT3271 with those numbers and have a look. If you could settle for 350whp, the GT3271 ain't bad.
Part of the "problem" is spool. If you build boost at low RPMs, there's low flow, and you surge. You could "fix" this problem with a shitty wastegate and manifold so that you didn't get full boost till say 4500 and say boost onset at 2500 (note they use a linear rise in boost, where in my experience, it's not linear, but exponential).
Part of the "problem" is spool. If you build boost at low RPMs, there's low flow, and you surge. You could "fix" this problem with a shitty wastegate and manifold so that you didn't get full boost till say 4500 and say boost onset at 2500 (note they use a linear rise in boost, where in my experience, it's not linear, but exponential).
I'm thinking with a turbo that is slighty off to the left, i can use an anti surge housing.
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02-19-2009, 10:08 AM
#57
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Looks like newbsauce is using this turbo. 4300ish for full spool. Not terrible.
https://www.miataturbo.net/forum/t26984/
https://www.miataturbo.net/forum/t26984/
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02-19-2009, 10:17 AM
#58
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the 2876 wont spool as early as your simulation suggests unless you're running VVT for high and low end.
Here's roughly how it does on a non vvt optimized setup:
that said, maybe we can swap your 2860 for my 2876 (chra + comp hsg) and play around
Here's roughly how it does on a non vvt optimized setup:
that said, maybe we can swap your 2860 for my 2876 (chra + comp hsg) and play around
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