Are you assuming that both turbo's flow equal amounts of air when you calculate that? I would think just for an example if the turbo you run only puts out 500cfm vs. 800cfm it would skew the comparison some. IDK thats why I ask. What do you think?
Mid 20s boost IDI !
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Are you assuming that both turbo's flow equal amounts of air when you calculate that? I would think just for an example if the turbo you run only puts out 500cfm vs. 800cfm it would skew the comparison some. IDK thats why I ask. What do you think?
tractorman86
Registered User
i think he means that at 20.25:1 the A/F ratio is more effective with 15lbs, than a 17.5:1 with 30 lbs; less boost+more compression=more efficient power(a more complete burn)
What I am saying is the bigger turbo shoves more air into the same space creating a more complete burn. So thats why I wanted to know how much that throws the comparison off. The 17 to 1 motor may be getting more air at 12psi than the 20.25 to 1 motor is getting at 25psi. So when you turn the 17 to 1 motor to 30psi will the results still be the same?
The whole idea behind upgraded turbos is that they flow more air at the same psi. The turbo on my dads 3406E at 34psi is pushing way more air than I am making 45psi. I know what I am trying to say, just don't know if I am typing it right.
The whole idea behind upgraded turbos is that they flow more air at the same psi. The turbo on my dads 3406E at 34psi is pushing way more air than I am making 45psi. I know what I am trying to say, just don't know if I am typing it right.
so a turbo off of an over the road truck displacing 16L with a 5in intake side making 17psi to the manifold will move the same amount of air my turbo does at 17psi?
Something tells me if I mounted that turbo on my truck with the volume of air it flows it would easily lift my heads at 17psi, and possibly pop something else. Anyway, I am sorry, I don't mean to hijack the thread.
Something tells me if I mounted that turbo on my truck with the volume of air it flows it would easily lift my heads at 17psi, and possibly pop something else. Anyway, I am sorry, I don't mean to hijack the thread.
FordGuy100
Registered User
Well its kind of confusing but here it goes.
Its a simple chem formula, the combined gas law:
P1 x V1 / T1 = P2 x V2 / T2
In which you would compare the turbo's, one turbo on one side, and the other on the other side.
So lets say we are trying to find the volume of air moved, in which we will solve for V for the right side.
Let P1 equal Say 29.7psi (29.7-14.7 (standard pressure for psi) = 15psi, thats what it would read on the gauge), and it fills say a 5 liter area (the intake manifold, the intake hat, and the pistons that are in the intake stroke, remember not all the pistons could be down to there lowest levels all at once. Lets say that the little turbo is out of its effeciency range, and its super heating the air to 100*C (212*F) (you then have to convert celsius over to Kelvin, you add 273 to the celcius temp to get kelvin. You have to convert to Kelvin in these equations). So it is putting out an air temp of 373 K (you dont use the degree sign with Kelvin). Then lets say the bigger turbo is putting out the same 15psi (which we have to use 29.7 in the equation), but at a temp of 30* Celcius (303 K). So I will set up the equation
29.7psi x 5l / 373K = 29.7 x V / 303K
= .3981 = .0980 x V So divide both sides by .0980.....
=:***: 4.something liters......hmmmm, one would think the bigger turbo would fill a larger area of space at the same preassure right....I assumed that going into this, but the math (might be wrong) proved me wrong. So then I will deduce what the heck I have just descovered here.
The smaller turbo, at the same pressure as the bigger turbo will fill more space because why, anyone? I'll tell ya why, because things take up more space when they are hotter. Does a hot air ballon take up more space when the gas is hot, or cold (hint, they have to do there little burn to go up, so it would increase area displacing more weight with the same gas, so it has more lift). The bigger turbo, will produce cooler boost, which I have in my head as taking up space. Remember that when a gas is compressed enough, at a low enough temp it takes up way less space, because it turns into a liquid (1 mol of a liquid gas, such as liquid nitrogen, than if it was a gaseous 1 mol). So I guess what I have descovered here is that a smaller turbo that is out of its effeciency range will actually fill an area with boost better than a bigger turbo, but the bigger turbo, filling less space, will actually cram that space with more oxygen. So if the the bigger turbo was to fill the same space as the smaller turbo, the 5liters, those 5 liters would be cramed more tightly, thus it would be denser, and the more dense, the more oxygen per volume content, therefore you have more oxygen in there.
Yeah boys, thats how its done right there
Its a simple chem formula, the combined gas law:
P1 x V1 / T1 = P2 x V2 / T2
In which you would compare the turbo's, one turbo on one side, and the other on the other side.
So lets say we are trying to find the volume of air moved, in which we will solve for V for the right side.
Let P1 equal Say 29.7psi (29.7-14.7 (standard pressure for psi) = 15psi, thats what it would read on the gauge), and it fills say a 5 liter area (the intake manifold, the intake hat, and the pistons that are in the intake stroke, remember not all the pistons could be down to there lowest levels all at once. Lets say that the little turbo is out of its effeciency range, and its super heating the air to 100*C (212*F) (you then have to convert celsius over to Kelvin, you add 273 to the celcius temp to get kelvin. You have to convert to Kelvin in these equations). So it is putting out an air temp of 373 K (you dont use the degree sign with Kelvin). Then lets say the bigger turbo is putting out the same 15psi (which we have to use 29.7 in the equation), but at a temp of 30* Celcius (303 K). So I will set up the equation
29.7psi x 5l / 373K = 29.7 x V / 303K
= .3981 = .0980 x V So divide both sides by .0980.....
=:***: 4.something liters......hmmmm, one would think the bigger turbo would fill a larger area of space at the same preassure right....I assumed that going into this, but the math (might be wrong) proved me wrong. So then I will deduce what the heck I have just descovered here.
The smaller turbo, at the same pressure as the bigger turbo will fill more space because why, anyone? I'll tell ya why, because things take up more space when they are hotter. Does a hot air ballon take up more space when the gas is hot, or cold (hint, they have to do there little burn to go up, so it would increase area displacing more weight with the same gas, so it has more lift). The bigger turbo, will produce cooler boost, which I have in my head as taking up space. Remember that when a gas is compressed enough, at a low enough temp it takes up way less space, because it turns into a liquid (1 mol of a liquid gas, such as liquid nitrogen, than if it was a gaseous 1 mol). So I guess what I have descovered here is that a smaller turbo that is out of its effeciency range will actually fill an area with boost better than a bigger turbo, but the bigger turbo, filling less space, will actually cram that space with more oxygen. So if the the bigger turbo was to fill the same space as the smaller turbo, the 5liters, those 5 liters would be cramed more tightly, thus it would be denser, and the more dense, the more oxygen per volume content, therefore you have more oxygen in there.
Yeah boys, thats how its done right there
FordGuy100
Registered User
Nope, because pressure and volume (or the cfm's its moving) are totally different, and you cant interchange them. The turbo will just have to spin way less to creat that 17psi as compared to how fast your turbo will have to spin. Make sense?
sootman73
Registered User
you happen to be taking a chemistry course right now?
i understand what it means but i would have to go back and look through my chem notes to find that equation!
very good class teach!
i understand what it means but i would have to go back and look through my chem notes to find that equation! very good class teach!
FordGuy100
Registered User
you happen to be taking a chemistry course right now?
Yup, taking chem this year, next year advanced chem. I like it more than any other class
FordGuy100
Registered User
Yeah, I used to enjoy math, but the stuff we are doing now is over my head. I dont think I will be going any farther next year, I'll wait until college. FYI I'm in calc. and I have a crappy grade, at least we have a couple of review tests (from like Algebra 2
)
sootman73
Registered User
i wasn't a fan of chem(still got another year of college level required though) but i liked my HS physics class.
sorry to get off the topic
sorry to get off the topic
so what i said is correct, pressure is pressure no matter what it is coming from. could be a leaf blower or a turbo feeding it. dousent matter, now there are other factors like efficiency and cooler denser air but the bigger turbo IS flowing the same as a smaller one if they are both 17psi.
the bigger one just has more potential.
the bigger one just has more potential.
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