Originally Posted by Braineack
(Post 240053)
ok now you've gone and done it....
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you mean like the god damn fucking FAQ in my sig?
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Originally Posted by opek
(Post 240062)
:bowrofl::fawk:
what are you laughing at, the fact that you are now labeled in my mind as a complete moron? |
Originally Posted by Braineack
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
7000rpm, for this sake it can stay constant. 3456 our wonderful constant We can assume temp is constant for this example, but 14.47 will not remain. In the conversion from volume/time to weight/time we need to account for density. I will not be pushing the limits of the .48 t3 turbine with a stage 3 wheel anytime soon without a nice big compressor attached to it pressurizing my intake stream. While I appreciate the fact that a 110CID motor theoretically flows 15lb/min @ 7000RPM at sea level at 120F, I think the amount of air I'll be flowing at 7000RPM is going to be mostly dependent on my compressor. |
^^^ Agreed. I was wondering if Brain's numbers account for the boost, as everything that goes in has to come out. Watching...
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14.47 is simply converting CFM to Lb./min
it doesn't matter how much airflow is coming into it. your engine can only displace so much airflow. The volume is always the same (97.7 C.I. per every cycle / VE), the poundage varies. |
Right, but in your math 14.7 represents a conversion from a volume/time to a weight/time using atmopsheric pressure at 120*F at sea level. My intake manifold will rarely see such conditions at 7000RPM.
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then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
Originally Posted by Braineack
(Post 240139)
then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
No, you are wrong. One cfm at sea level weighs more than one cfm at altitude. You are converting from volume/time to weight/time. density/volume = mass, mass * gravity = weight.
The miata motor at sea level with 120* air in the intake manifold, based on only it's CID, flows 15lb/min. Once you pressurize that air, it is heavier. You are flowing more dense air through the same volume over time, which results in more corrected CFM or more corrected lb/min. There is more air. Arguing about what?? I politely responded to your lame point, made using some fancy mathematics most people probably don't bother to understand, and you called me a moron. Nice. Your point is lame because the airflow of the stock motor at sea level in 120* air is not nearly as relevant to turbine selection as power goals or the compressor. IMO it's not worth a damn to say, "this turbine is OK because during these completely arbitrary conditions you will never encounter that aren't even related to making power (who puts a turbo on and runs atmospheric pressure in the intake manifold?) you will be flowing less air than the turbine is rated to." What's a t04e 50 trim flow compressor flow? 40lb/min? |
You displace the same VOLUME of air all the time. To change that, boost increases density so that the same volume has more pounds of air in it. You could move an infinite amount amount of air in lbs/min by increasing boost until something breaks.
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Just so we are clear my reply was directed at the Brain.
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Originally Posted by Ben
(Post 240001)
kind of a small turbine.
The .48 doesn't seem to breath for shit in the top end and I'm only at 214 whp. I may change my mind on this after the new downpipe and exhaust arrive. |
Just to throw in my extremely uneducated 2 cents...
For 300 whp don't the internals have to be beefed up? Rods and Pistons? Pissing match aside it's one thing to make 300+ whp, it's another to make it hold together. Am I wrong about this? |
Originally Posted by opek
(Post 240151)
IMO it's not worth a damn to say, "this turbine is OK because during these completely arbitrary conditions you will never encounter that aren't even related to making power (who puts a turbo on and runs atmospheric pressure in the intake manifold?) you will be flowing less air than the turbine is rated to."
What's a t04e 50 trim flow compressor flow? 40lb/min? the more pounds of air you move, the more power you will make. pounds = mass. not volume; the volume will always stay the same. you're not increase the displacement of the motor. you know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche. |
Originally Posted by Arkmage
(Post 240164)
The .48 doesn't seem to breath for shit in the top end and I'm only at 214 whp. I may change my mind on this after the new downpipe and exhaust arrive.
Originally Posted by cueball1
(Post 240186)
For 300 whp don't the internals have to be beefed up? Rods and Pistons? Pissing match aside it's one thing to make 300+ whp, it's another to make it hold together. Am I wrong about this?
yes, the rods wont hold up. We typically start to thinking about beefing them up at 200-220rwtq. |
Originally Posted by Braineack
(Post 240037)
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
Originally Posted by Braineack
(Post 240139)
then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
Originally Posted by Braineack
(Post 240192)
more boost doesn't mean that you'll displace more air. It's a simple equation to determine a good size A/R turbine based on your displacement and airflow volume.
the more pounds of air you move, the more power you will make. pounds = mass. not volume; the volume will always stay the same. you're not increase the displacement of the motor. you know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche. Why do you keep saying pounds = mass and not volume, clearly I understand that. My first post addresses the relevancy of using a simple cfm -> lb/min conversion to a turbocharged motor. "You know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche." :bang: Ok, let me try again. I don't think I am explaining myself very well. The conversion you used factors in pressure and temperature, but the pressure you use in your calculations is 0lb. I don't care if the turbine can flow 0lb of boost, I care if it can flow 24lb of boost. An equation to determine ideal turbine size must take into account desired airflow. |
Originally Posted by patsmx5
(Post 240213)
Originally Posted by Braineak
Shit ton of boost in the intake = 15 lb/min through the exhaust
no boost in the intake = 15 lb/min through the exhaust lb/min is weight/min; and since we know what gravity is all about we know what is the mass of the air we are using. 15lb/min is 15lb/min always, but 300cfm can be 15lb/min or 30lb/min depending on it's density. A pressurized intake manifold does change the lb/min out of the tailpipe, and will also change the corrected CFM. (corrected for density). |
Can we talk about my turbo kit again?
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