Boost & HP Level

[Turbo&Auto]

who me

 

[phunky.buddha]

Yup, that 20g would be nice. You want to spend as much time in the best efficiency island as possible. I'm still going to use the 14b on mine even though I'll be all over the map. At least it will be cheap and spool almost instantly. I won't have much power up top, but at least I'll be able to maintain at least a power curve that tapers off to flat past 5000rpm. It will be a very full torque curve.

 

[hondatur62d16]

then what is the sence of a turbo upgrade if it just switches your boost RPM s and dont give you more H/P does nt make sence to me bigger turbo more air more H/P right or wrong on any motor bigger turbo more H/P not saying how long it will last like that but

 

[Cashizslick]

Well, at least most of us have car's where there are a few 'no brainer' turbos on the market to choose from.



Just wait till i get a GT2871R and some 550cc injectors . . .

 

[Turbo&Auto]

Thats what I WAS going to use on my Matrix, good choice in turbos. There's a guy on MatrixOwners that's using a GT2876R, 4" inlet. WAY too big

 

[Cashizslick]

Too big for a Matrix . . .

 

[Turbo&Auto]

The 4" inlet I meant, the position of teh turbo on our cars is behind the motor. There was just enough room for a 3" intake pipe on mine and even that was tighter then I would've liked. I'll be impressed if this guy can get that turbo in there nicely.

 

[Cashizslick]

The 4" inlet I meant, the position of teh turbo on our cars is behind the motor. There was just enough room for a 3" intake pipe on mine and even that was tighter then I would've liked. I'll be impressed if this guy can get that turbo in there nicely.

Actually mine is on the side

 

[Turbo&Auto]

Ya, Nissan's are nice like that, looks HOT too The Sube's have a reverse mount kit that makes it look similar, just the other side of the engine bay.

 

[tloc]

ok i somewhat understand how to read compressor maps but i dont understand how or Why T&A said that it would run better at 15-18 psi or why he would do better with a larger turbo, such as the b20g... 15 psi would have a pressure ratio of about 2.02 or 2... but how do u read the bottom so u know where to line up the turbos at or how do u know which one is for u... i didnt understand mikes part about reading the bottom

 

[reikoshea]

youre not alone, bro...i always kinda guesstimate the bottom...itd be kool if there was a super understandable way to read it.

 

[tloc]

ok but what does it actually mean how do u even guess im completely confuessed on that part i have no clue how to figure out about what rpm it will be at or what the bottom actually means

 

[Turbo&Auto]

Its some formula that calculates what Airflow is what RPM or something like that. Hopefully someone can jump in here with the formula and explain it a lil

 

[MikeBergy]

Here is what the equation on the bottom means.
w = air flow, in pounds mass of air per minute. this is uncorrected for atmospheric pressure and temperature. Any change in the local temperature or pressure will change the actual performance of the compressor.

The quantity under the radical are temperature correction. 519 is a standard correction term, but we'll use 545 to be consistent with the map.
T1c = local temperature, expressed in degrees Rankine. To convert degrees Fahrenheit, deg R = deg F + 459

The quantity in the denominator is the local pressure correction.
P1c = local atmospheric pressure, expressed in psia. Like I said, I think the 28.4 is a typo, but i could be wrong. Normal pressure corrections have 14.7psia; i am not sure why 28.4 is there. We'll use the 28.4 to be consistent with the map.

edit: found out the 28.4 is actually the measurement for standard (or close to) pressure measured in inches of mercury. I should have known that. We'll use 14.7 instead of the 28.4.

Here is an example:
The local temperature is 65 degrees fahrenheit, and the local pressure is a little low, say 14.5 psia. We want to run at 8psi on the street, and want to see how much flow that will be pushing. We will be needing the pressure ratio to read the vertical axis, so adding 8 psig (boost) to 14.5 psia(atmospheric pressure), and divide by the 14.5 psia. (8+14.5)/14.5 = 1.55.
We'll be using a T3 super 60 turbo
According to the map, within the best efficiency island, at a pressure ratio of 1.55, corrected flow will be anywhere from about 12 to 17 lbm/min, eyeballing the map. To give to an idea of what the uncorrected flow will be, the temperature correction factor will be sqrt((65+459)/545) = .98
The pressure correction factor will be 14.5/14.7 = .986


12lbm/min corrected will be 12*.98/.986 = 11.99 lbm/min actual.
17lbm/min corrected will be 17*.98/.986 = 16.98 lbm/min actual.

You can see that at near standard conditions, the actual and corrected values will be similar. If you're are living in arizona however, and the local temperature is 110 degrees F, and 14.5psi, you'll be seeing actual flow numbers from 12.4 to 17.6 lbm, a 3.5% difference. Not a big difference, but a 3% difference can mean the difference between a safe engine and a broken engine if you are tuning aggressively. Again, this is just one application.

 

[Turbo&Auto]

Thank you, thank you Coming in again with more GREAT info!!

 

[tloc]

Thanks, you always supply me with great information that alwayz helps.... but how do u know the air flow for your particular application... heres and example... running a GT35R in colorado springs pushing 19 lbs.... i dont know how to figure it for ur car i now know how to figure out the corrected values and the range that ir would run best in... i know that the pressure ratio would be about 2.3 but how would you get your car to be able to have 40lbs/min to be in the best effiecientcy island?... i might be thinking about this in the worng way but please help

 

[tloc]

someone should reply b/c im not sure how to find out how much air flow your car would put out... do you use an equation or do you have to have your car dynoed....