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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 04-09-2008, 03:11 PM   #61
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Originally Posted by Opek 2 View Post
But you didn't account for that! holy **** man, just say "I'm sorry I was wrong."

You still haven't responded to my point, and keep saying I have none. You need to consider power or flow goals to choose a turbine, not the flow of a naturally aspirated motor at sea level.

the exhaust flow of the same motor, at the same sea level with 1bar of boost will still be the same. compressor flow goals, is not the same thing as exhaust flow, a factor of the displacement of your engine.



so lets say i want to make 400BHP, how would you pick your turbine?

lets say i want to flow 44 lb/min out of the turbo, how would you pick your turbine?
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Old 04-09-2008, 03:23 PM   #62
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Quote:
Originally Posted by Braineack
compressor flow goals, is not the same thing as exhaust flow, a factor of the displacement of your engine.
Explain to me how an 800whp 1.8liter honda flows the same mass/time as the same 1.8liter honda with the boost turned down to 200whp.
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Old 04-09-2008, 03:28 PM   #63
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Originally Posted by Braineack View Post
the exhaust flow of the same motor, at the same sea level with 1bar of boost will still be the same. compressor flow goals, is not the same thing as exhaust flow, a factor of the displacement of your engine.



so lets say i want to make 400BHP, how would you pick your turbine?

lets say i want to flow 44 lb/min out of the turbo, how would you pick your turbine?
I would look at real world examples of people who have my same displacement engine and a similar flowing head, and see at what power level the turbine combination chokes and dies.

Seriously man, if what you were saying is correct ALL 1.8liter engines would use the same turbine/wheel combination regardless if they were making 200whp or 800whp.
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Old 04-09-2008, 03:32 PM   #64
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because it's still a 1.8L. turbos don't increase the displacement of your motor. The VE will increase.....the ratio of the volume of outside air to the engine displacement. Since I assume 100% VE to make life simple, I leave it out of the equation....if you wanna add it back in, do so. so lets say a N/A motor at 80% VE makes 160 CFM (based off our 198 number) and the same turboed motor may make 120% VE, so 236 CFM. Either way, take that number and look at a turbine map.
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Old 04-09-2008, 03:35 PM   #65
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dude, more CFM is more lb/min. ESPECIALLY when you are not only increasing CFM, but density.
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Old 04-09-2008, 03:38 PM   #66
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Originally Posted by Opek 2 View Post
I would look at real world examples of people who have my same displacement engine and a similar flowing head, and see at what power level the turbine combination chokes and dies.
yep, youtube videos for all your turbo information. There are plenty of hondas making 650rwhp with a Stage I .63 A/R T3 turbine.

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Originally Posted by Opek 2 View Post
Seriously man, if what you were saying is correct ALL 1.8liter engines would use the same turbine/wheel combination regardless if they were making 200whp or 800whp.
no. because the a/r has a lot to do with ultimate power output, like i posted the graph of previously. If i wanted to make **** tons of power, I'd choose a larger A/R and possible go with a stage higher turbine wheel. This lessens the overlap of the blades on the wheel to further reduce backpressure and increase the velocity. It's all a compromise. Since I chose overall performance me T3 utilizes a .48 A/R, if I want top end only for that 2000RPM powerband, I'd go with a .63 and make more power per psi. If I went with a larger turbine and a larger a/r, chances are it may not spool at all.
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Old 04-09-2008, 04:38 PM   #67
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Quote:
Originally Posted by Braineack View Post
im not wrong. opek had no points other than i was wrong. explain to me why im wrong.


DISPLACEMENT = VOLUME

MAP = PRESSURE

PRESSURE VOLUME


I only converted engine CFM to lb/min since the garrett turbine flow maps are in lb/min. still flow. the temp and pressure of the air must be know to correctly convert this. however it's the density ratio, not the pressure ratio you use for the conversion....so again, boost pressure does not factor in.
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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 **** cares, what are you arguing again?


so to sum up:

**** ton of boost in the intake = 15 lb/min through the exhaust
no boost in the intake = 15 lb/min through the exhaust
Sure. Conservation of mass comes to mind.

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law of conservation of mass/matter, also known as law of mass/matter conservation states that the mass of a closed system will remain constant, regardless of the processes acting inside the system. An approximately equivalent statement is that matter cannot be created/destroyed, although it may be rearranged. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products.
Does that make sense? It clearly goes against your statement you made above. Do you agree with the Law of Conservation of Mass? It doesn't list any exceptions to the rule. I've read this in many science and physics text books and it seems to be generally accepted, so much that it's called a "Law" rather than a rule. My guess is it's impossible break the Law. If we could build a mechanism that put out less, or much more desirably, more, of a given substance, there would be no oil crisis or shortages in the world.

You can't put 40 lbs of something in and get 15 out. 40 pounds of something has to come back out. If you were forcing air, water, liquid gold, or protons through the intake, you will not always get 15 pounds out. You will get out what you put in.

Opek had several points I agreed with, do I need to quote them all? I agree with his point that exhaust flow is dependent on boost. Conservation of Mass at work here. I also with most of his statements so far. I don't agree with all of yours. It seems every one of your post your talking about displacement. Yea, I understand that. It's constant. Mass in and out of the engine is not constant. It's proportional to HP.
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Old 04-09-2008, 05:08 PM   #68
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15psi of boost does not mean 15psi of boost inside the chamber.

the same amount of volume is always entering the chamber. the same mixture gets compressed further and ignited. This creates your torque, the exhaust volume is still the same. the pressure has increased, the power has increased, the amount of exhaust has increased, but the volume will remain the same. when you add boost does it it bore out your cylinder walls?

exhaust flow is not dependent on boost. Boost is dependent on the exhaust flow to spin the turbine. the faster engine spins, the faster the turbine spins, the faster the compressor spins, the more air you can stuff into the engine and burn, the more power you make; the volume is still not increasing.


again for the 17th time: the 15 lb/min number was a conversion from 198 CFM assuming 545R and 28.4 in. Hg Absolute (0.0691 lb/cf Density Ratio).
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Old 04-09-2008, 05:25 PM   #69
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Brain, the above post makes sense. Earlier, you stated that MASS is not conserved. This started a huge debate. Now, you acknowledge that it's conserved. Pounds of air per time, the time rate of mass, is conserved. Earlier you said it was not, and that was the reason all this started. So why don't you go and unban the guy you banned that correctly pointed out your mistake? You apparently got volume and mass per unit time mixed up 2 pages ago. Now, you have corrected this misunderstanding.
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Old 04-09-2008, 05:28 PM   #70
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WTF read post number 26.
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Old 04-09-2008, 05:30 PM   #71
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Post 26 you state that poundage varies. Correct.
Post 28 you state it's constant. Wrong.
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Old 04-09-2008, 05:31 PM   #72
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I'm pretty sure I agree with Scott. (braineack)

Were this not true turbo's would not spool based solely on RPM. They'd spool based on some function of how much boost per RPM.
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Old 04-09-2008, 05:37 PM   #73
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Originally Posted by patsmx5 View Post
Post 26 you state that poundage varies. Correct.
Post 28 you state it's constant. Wrong.
i'm stating the exhaust volume displaced is the same, yes. be it n/a or 15psi of boost. give or take the amount of change in VE and the atmospheric conditions.
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Old 04-09-2008, 05:40 PM   #74
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I believe the confusion stems from the fact that Scott is using lb/min to indicate a volumetric flow rate, which it is not. Converting a volumetric flow rate, i.e. CFM to lb/min using a conversion factor derived for a specific physical state is not meaningful, and worse, is misleading.
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Old 04-09-2008, 05:44 PM   #75
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Originally Posted by Atlanta93LE View Post
Converting a volumetric flow rate, i.e. CFM to lb/min using a conversion factor derived for a specific physical state is not meaningful, and worse, is misleading.
yes, i wonder what this thread would look like if Garrett simply used CFM as thier air flow rate of their turbines as opposed to CFM. I wonder if anyone read the 10 times I posted this information and even posted the turbine air flow map to validate my point. It's also good that garrett flow everything at the same atomsphereic conditions....again: 545R and 28.4 ~Hg.


But let's keep arguing a minute point...the whole point that everyone keeps forgetting is that turbos don't increase displacement, therefore the same volume is displaced. that's my entire point. thats it.
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Old 04-09-2008, 05:47 PM   #76
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I think everyone agrees that the engine (air pump) displaces the same volume of air per stroke, regardless of pressure.
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Old 04-09-2008, 05:50 PM   #77
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I think everyone agrees that the engine (air pump) displaces the same volume of air per stroke, regardless of pressure.
if that were the case, then why have i been arguing that all day.

im spent, im going home to get laid. and yes my wife is hot. **** all you.

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Old 04-09-2008, 05:50 PM   #78
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yes, i wonder what this thread would look like if Garrett simply used CFM as thier air flow rate of their turbines as opposed to lb/min.
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Old 04-09-2008, 05:53 PM   #79
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im spent, im going home to get laid. and yes my wife is hot. **** all you.
See you in 2 minutes.
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Old 04-09-2008, 05:58 PM   #80
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in for video stream
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