Boost Curve/Efficiency of Whipple vs Centrifugal
02-20-2004, 10:46 AM
#16
Three Wheelin'
Originally posted by SteveM928
So at that 500+ hp, 874 cfm, 11psi level, it looks like the Lysholm's efficiency is about 60%, the Vortech S-Trim about 70% , and the Vortech T-Trim about 72%. That means that a smaller amount of the power put into the Vortechs ends up being used to make heat instead of boost at that horsepower, boost, and cfm point. Since the goal is the amount of boost you want, it would mean that more power would be required by the Lysholm to get that level of boost, since more of the power being put into that one would be used producing heat. In order to run that much boost with the same detonation protection on otherwise equal engines, you'd also have to get rid of more of that heat with a better intercooler on the Lysholm than the ones on the Vortechs. You'd need either a bigger or more efficient intercooler with the Lysholm to get to the same intake temperature as the Vortechs, but even then you would have still had to be putting more power into the Lysholm initially. Interesting comparison of the different units for the specific goal or application used for the example. It also really helps to show that knowing the power level you want, or may want to someday upgrade to, can be pretty important when planning out the combination that will work out best for you.
So at that 500+ hp, 874 cfm, 11psi level, it looks like the Lysholm's efficiency is about 60%, the Vortech S-Trim about 70% , and the Vortech T-Trim about 72%. That means that a smaller amount of the power put into the Vortechs ends up being used to make heat instead of boost at that horsepower, boost, and cfm point. Since the goal is the amount of boost you want, it would mean that more power would be required by the Lysholm to get that level of boost, since more of the power being put into that one would be used producing heat. In order to run that much boost with the same detonation protection on otherwise equal engines, you'd also have to get rid of more of that heat with a better intercooler on the Lysholm than the ones on the Vortechs. You'd need either a bigger or more efficient intercooler with the Lysholm to get to the same intake temperature as the Vortechs, but even then you would have still had to be putting more power into the Lysholm initially. Interesting comparison of the different units for the specific goal or application used for the example. It also really helps to show that knowing the power level you want, or may want to someday upgrade to, can be pretty important when planning out the combination that will work out best for you.
02-20-2004, 01:45 PM
#17
Drifting
i dont think so.
"Since the goal is the amount of boost you want,.."
not in isolation, in my view. the amount of boost at a given road and engine speed is what is important. i only ever hear jap rice rockets caning around at max rpm and i cant seriously imagine driving allways at 6500 rpm in my 928, so what about the rest of the time?
i think that to focus on absolute max hp and efficency can be usefull but may also be so constricted as to miss some things, perhaps the point entirely!
im off snowboarding...
"Since the goal is the amount of boost you want,.."
not in isolation, in my view. the amount of boost at a given road and engine speed is what is important. i only ever hear jap rice rockets caning around at max rpm and i cant seriously imagine driving allways at 6500 rpm in my 928, so what about the rest of the time?
i think that to focus on absolute max hp and efficency can be usefull but may also be so constricted as to miss some things, perhaps the point entirely!
im off snowboarding...
02-20-2004, 01:48 PM
#18
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Interesting point Nick, the same one I have been making on here for over a year now...
The Aerochargers have been successful on many car applications, including some GM applications for conceptual vehicles.
The Aerochargers have been successful on many car applications, including some GM applications for conceptual vehicles.
02-20-2004, 02:36 PM
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I am curious if anyone has compared the discharge temperature at specific RPM or boost level of centrifugals vs lysholm blowers.. In addition, what about the engine load and aerodynamic resistance load in combination with the gearing throughout the powerband..
A quick tip on CFM to HP ratio... It takes about 1.5CFM of air for 1 HP...
A quick tip on CFM to HP ratio... It takes about 1.5CFM of air for 1 HP...
02-20-2004, 03:24 PM
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Originally posted by drnick
i dont think so.
"Since the goal is the amount of boost you want,.."
not in isolation, in my view. the amount of boost at a given road and engine speed is what is important. i only ever hear jap rice rockets caning around at max rpm and i cant seriously imagine driving allways at 6500 rpm in my 928, so what about the rest of the time?
i think that to focus on absolute max hp and efficency can be usefull but may also be so constricted as to miss some things, perhaps the point entirely!
i dont think so.
"Since the goal is the amount of boost you want,.."
not in isolation, in my view. the amount of boost at a given road and engine speed is what is important. i only ever hear jap rice rockets caning around at max rpm and i cant seriously imagine driving allways at 6500 rpm in my 928, so what about the rest of the time?
i think that to focus on absolute max hp and efficency can be usefull but may also be so constricted as to miss some things, perhaps the point entirely!
02-20-2004, 07:50 PM
#21
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Hey Lags, schoolboy. 
THIS IS HOW YOU DO IT.
CFM = (cid x rpm x 0.5 x VE) / 1728
based on your dyno chart for 512rwhp...done at 5900rpm NOT 6500
CFM = (302ci x 5900rpm x 0.5 x 88%) / 1728 = 453.69cfm
So, the stock S4 at 5900rpm is consuming 453.69 cfm of air.
PR=(14.7psi + boost) / 14.7
PR=(14.7psi + 11psi) / 14.7 = 1.748 Bar
New CFM = (Orig CFM x PR)
New CFM = (453.69 cfm x 1.748 Bar) = 793.06cfm
So, your S4 at its 512 rwhp mark at 11psi is pushing 793.06 cfm of air through the engine....this is at 5900rpm!...not 6500
In a nut shell then you made your 500rwhp number at 793cfm , not 874?
Did i do that right?
I recalled from your post that you never hit redline or the limiter on your 512 pull so i went back to see what CFM you were actually pulling at the 512 point. Then based on the way you did your calcs, I just change 6500 to 5900 in the first equaion.
Ya left a bunch on the go pedal Lags!
Please correct me if my reasoning is flawed because my math, LIKE my spelling on here...is POIFECT!
THIS IS HOW YOU DO IT.CFM = (cid x rpm x 0.5 x VE) / 1728
based on your dyno chart for 512rwhp...done at 5900rpm NOT 6500
CFM = (302ci x 5900rpm x 0.5 x 88%) / 1728 = 453.69cfm
So, the stock S4 at 5900rpm is consuming 453.69 cfm of air.
PR=(14.7psi + boost) / 14.7
PR=(14.7psi + 11psi) / 14.7 = 1.748 Bar
New CFM = (Orig CFM x PR)
New CFM = (453.69 cfm x 1.748 Bar) = 793.06cfm
So, your S4 at its 512 rwhp mark at 11psi is pushing 793.06 cfm of air through the engine....this is at 5900rpm!...not 6500
In a nut shell then you made your 500rwhp number at 793cfm , not 874?
Did i do that right?
I recalled from your post that you never hit redline or the limiter on your 512 pull so i went back to see what CFM you were actually pulling at the 512 point. Then based on the way you did your calcs, I just change 6500 to 5900 in the first equaion.
Ya left a bunch on the go pedal Lags!
Please correct me if my reasoning is flawed because my math, LIKE my spelling on here...is POIFECT!
02-20-2004, 08:22 PM
#22
Three Wheelin'
Originally posted by Tony
Hey Lags, schoolboy. THIS IS HOW YOU DO IT.
...
Did i do that right?
I recalled from your post that you never hit redline or the limiter on your 512 pull so i went back to see what CFM you were actually pulling at the 512 point. Then based on the way you did your calcs, I just change 6500 to 5900 in the first equaion.
Ya left a bunch on the go pedal Lags!
Please correct me if my reasoning is flawed because my math, LIKE my spelling on here...is POIFECT!
Hey Lags, schoolboy.
THIS IS HOW YOU DO IT....
Did i do that right?
I recalled from your post that you never hit redline or the limiter on your 512 pull so i went back to see what CFM you were actually pulling at the 512 point. Then based on the way you did your calcs, I just change 6500 to 5900 in the first equaion.
Ya left a bunch on the go pedal Lags!
Please correct me if my reasoning is flawed because my math, LIKE my spelling on here...is POIFECT!
Yep, that's right!
When I did 492 rwhp I spun it pretty close to 6500 RPM which is pretty close to the 500 rwhp you were asking about. So as you noticed, there is usually a range based upon various factors. All in all, it will give you a good idea of what's happening, and get you in the ballpark.
02-20-2004, 09:22 PM
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Ok, i guess i have a question on how to interpret/apply the info shown on these charts.
lets say you pulley this SC for a max rpm of 12000 (max is 13500). This flows 26m^3 or appx 918cfm. What determines the boost you end up with..8..11 or 13psi for example.
I feel like im missing some part of the equation?
lets say you pulley this SC for a max rpm of 12000 (max is 13500). This flows 26m^3 or appx 918cfm. What determines the boost you end up with..8..11 or 13psi for example.
I feel like im missing some part of the equation?
02-20-2004, 10:49 PM
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Originally posted by Tony
Ok, i guess i have a question on how to interpret/apply the info shown on these charts.
lets say you pulley this SC for a max rpm of 12000 (max is 13500). This flows 26m^3 or appx 918cfm. What determines the boost you end up with..8..11 or 13psi for example.
I feel like im missing some part of the equation?
Ok, i guess i have a question on how to interpret/apply the info shown on these charts.
lets say you pulley this SC for a max rpm of 12000 (max is 13500). This flows 26m^3 or appx 918cfm. What determines the boost you end up with..8..11 or 13psi for example.
I feel like im missing some part of the equation?
The above resulting boost is just the quick rough calculation. Things like the intercooler efficiency and pressure drop through it aren't factored in.
Last edited by SteveM928; 02-21-2004 at 12:50 AM.
02-21-2004, 12:55 AM
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Thanks a bunch Steve. Now it makes sense. 
I can can see where i had things messed up in my head. In short CFM flow greater than the engine can take in at a given rpm becomes a certain amount of boost.
I can can see where i had things messed up in my head. In short CFM flow greater than the engine can take in at a given rpm becomes a certain amount of boost.
02-21-2004, 12:39 PM
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That seems like alot of power to drive that positive displacement blower.
Do we have any charts that say how much power the Centrifugal is taking?
Do we have any charts that say how much power the Centrifugal is taking?
02-22-2004, 04:08 PM
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Originally posted by BrendanCampion
Do we have any charts that say how much power the Centrifugal is taking?
Do we have any charts that say how much power the Centrifugal is taking?
02-23-2004, 02:42 AM
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Thats pretty interesting, thanks again Steve. I haven't been able to find data on the vortechs Delta T. Anyone have a source?
If some of you haven't seen this, its pretty trick engine animation of the GT 40
http://www.fordvehicles.com/fordgt/m...E_VIDEO&bhcp=1
If some of you haven't seen this, its pretty trick engine animation of the GT 40
http://www.fordvehicles.com/fordgt/m...E_VIDEO&bhcp=1
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