He lives in San Antonio. When I was in SA I used to purchase stuff from Bell engineering, well I still do. Well, I shouldnt say I know him personally like we hang out but I would like to think he remembers me when I go in. Plus, the guy that made all my downpipes used to make all his turbo kits.

art

 

Prelussion-
Here are a couple of formulas to use to determine which compressor to get.

PR = (boost + 14.7 + ic pressure drop) / 14.7
*1.5 is a good pressure drop estimation*

Di = (boost + 14.7) / [53.3 * 12 * (460 + intake temp)]
*130 is good estimate for post ic intake temp*

Mf = Di * displacement * (rpm/2) * volumetric efficiency
*displacement is in cubic in.; .9 is good estimate fo ve

Cmf = Mf * [sqrt(comp inlet temp/545) / (14.7/corrected comp inlet press.)]
*545 rankin is good estimate for inlet temp; Garrett uses 13.95 for corrected inlet press.*

The Cmf number is the lb/min result for x axis and the PR is the y axis. Go to this website:

http://64.225.76.178/catalog/compmaps/fig3.html

and look at the different maps until you find one that gives you 70% for whatever rpm points you are most interested in.

 

I appreciate your help but i don't know what the hell some of your abbreviations mean... Like DI, or Mf.
Oh yeah, I'm ordering that Max Boost book.

 

Di = Intake air density
Mf = Mass flow rate
Cmf = Corrected mass flow

If you start at the top and work your way down the values needed are determined

Meaning for example the Di value used in the Mf equation is found by solving the equation above it.

 

TTT for the sake of knowledge.

 

 

 

wow, still don't get all that stuff, but I am on it.......ehhh, someone can explain this in german too ?!

 

The intercooler is always a concern of pressure drop but just FYI for everyone else it certainly isn't the only cause of it...pressure drop can occur anywhere even at the throttle body

 

BUMP for an excellent post with useful and helpful info. Everyone should pick up "Maximum Boost" by Corkey Bell it clears alot up for the turbo savvy!

 

tttttt

 

Bump cause I wanted to know my efficiency range

 

bring this back so people stop buying t3/t4 turbos to run 7 lbs of boost on.

More importantly....what is the best method to calculate CFM????

 

notepaded

 

So for all you kiddies....a t3 60 trim is plenty...even if you're running a full bar of boost, it can handle that up to 8000 rpms on a 1.6 liter. Maybe a t3 super 60 could help a little. But if you're going to spend a bunch of money on a turbo...and only run 12 lbs of boost, don't waste your money on anything bigger than those two. I've been calculating **** all day and examining compressor flow maps...so take my advice please...otherwise I feel like I wasted my time.

 

method to figure out your own motor's CFM ? just approximate?

anyone have a compressor map for an sc61?

 

I know this is old hat, but can someone verify (prove to me) that CFM (lb/min) goes up as boost increases? ie. 1.6l@7000rpm=~14.5lb/min whereas 1.6l@7000rpm@14.7psi=~29lb/min?!!!

This would explain the tendency of the graphs to "lean" to the right, though...and, it makes sense...it's just weird to have to put that extra step in there!

 

yes, that is correct. All air being consumed by the engine is being supplied by the turbo right? So if the engine is at 7000 rpms and consuming say 200 cfms at atmospheric pressure (no boost.) Then at 10 lbs of boost, the engine is consuming 200 cfms normally, plus the cfms required to feed the engine 10 psi at 7000 rpms.

 

isnt there a formula for target hp/ , lb/min, like 10/lb /min = 50 hp pr something?

 

I'm not really sure what you're talking about....but I really doubt it. I would imagine thats gonna depend on a few factors.....engine size, flow of air, spark, advance/retard, iat, other stuff???? So just saying that x hp = x lb/min would be a huge generalization.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed &raquo;</TD></TR><TR><TD CLASS="quote">...Everyone should pick up "Maximum Boost" by Corkey Bell it clears alot up for the turbo savvy!...</TD></TR></TABLE>

Absolutely. Get the book, read it, understand. It's an easy read (I wish it had more detail & calculations).

BTW: You could get an approximation for fuel requirements off the compressor maps. You know the maximum cfm you'll be flowing (off the map) and you know what Air/Fuel ratio you want...

 

CAN this be a sticky!

 

Just curious from the very first post, 500cfm is used for an example. How would anyone find out what their CFM is in the first place? Just from specs?

 

there is an equation in there for CFM. you need to know engine displacement and engine RPM i believe.

 

Hey guys,

I thought I would post up some new information which I found today on http://www.stealth316.com

It looks like the guys on that site knows how to convert the CFM to in/lbs. Those numbers at the bottom of the compressor map is actually the formula to convert mass flow to volume flow.

This is taken from http://www.stealth316.com

http://www.stealth316.com/2-3s-compflowmaps.htm

Air Flow

he amount of air entering the turbo is usually measured in cubic meters per second (m3/s), in pounds per minute (lb/min), or in kilograms per second (kg/s). I personally like the m3/s that Mitsubishi Heavy Industries (MHI) uses on most of their compressor flow maps because there is no ambiguity in converting to cubic feet per minute (cfm) a rate more familiar to American hotrodders. Multiply every 0.10 m3/s by 211.8882 to get cfm.

Garrett Turbochargers (GT) uses lb/min for the air flow rate. To convert this mass flow to volume flow, the temperature and pressure of the air (that is, the density) must be known. This information is on the flow map. The number that T1C, the inlet air temperature, is divided by is GT's "standard" temperature in degrees Rankine. On the flow map above this temperature is 545ºR, which is equivalent to 85.31ºF or 29.6167ºC. The number that P1C is divided by is GT's "standard" pressure in inches of Mercury (in. Hg). On the flow map above this pressure is 28.4 in. Hg, which is equivalent to 13.9487 psi (pounds per square inch). You can use the first calculator on my web page 2-air-fuel-flow.htm to find that the density of air at 85.31ºF and 13.9487 psi is 0.0691 lb/cf. Knowing the density, the lb/min mass air flow units are converted to volume air flow units. For GT compressor flow maps using these conditions, every 10 lb/min is equal to 144.7178 cfm.

MHI will use on occasion kg/s for the air flow. On the flow map for the TD05H-16G small wheel compressor, the "standard" temperature is 298º Kelvin (equivalent to 76.73ºF or 24.85ºC) and "standard" pressure is 750 millimeters Hg (equivalent to 14.5025 psi). For MHI compressor flow maps using these values, 0.10 kg/s = 181.2415 cfm.

Note that absolute pressure (any scale) and absolute temperature (the scale is either Kelvin, K, or Rankine, R) are always used on the flow maps. One degree on the Kelvin scale equals one degree on the Centigrade scale; and one degree on the Rankine scale equals one degree on the Fahrenheit scale. ºK = ºC + 273.15. ºR = ºF + 459.69.

When volume air flow is used, the flow shown on the map is the amount of air volume entering the turbo. The volume of the air leaving the turbo is inversely proportional to the pressure (volume decreases with pressure) and is directly proportional to the temperature (volume increases with temperature).
V = n x R x T/P,
where V=volume, T=temperature, P=pressure, and n x R represents the mass. When mass air flow is used, the flow shown on the map is representative of both the amount of air mass entering as well as leaving the turbo.

Please note that horsepower is calculated using mass flow in lb/hr. For example, 30 lb/min is 1800 lb/hr of air flow. At a 12:1 mixing ratio, 150 lb/hr of fuel would be needed. Using a brake specific fuel consumption (BSFC) of 0.5, that 150 lb/hr of fuel might produce 300 crank horsepower. For an engine able to use this much flow from two turbos, 600 bhp could be developed.