B&M vs Procharger for 540??
10-25-2004, 01:27 PM
#31
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Re: B&M vs Procharger for 540??
Michael1:
It is a huge loss, and it is very typical for a remotely mounted intercooler. But the restriction of the core is only a small part of the loss; the problem is all the elbows and abrupt changes in cross-sectional area.
Pretend for a moment that there is no blower. Do you think a big V-8 is going to be happy sucking it's air through 3" diameter twisted hose? At WOT the air velocity in that hose is 100+ mph. Do you think that air wants to make a turn? And yet that is exactly the plumbing supposedly needed to hook up a centrifugal supercharger and intercooler and carb box. Overall, when you add the blower, HP goes way up, but it is a case of 2 steps backward, then 3 forward.
The supercooler has no elbows, all turns are made at high cross-sectional area to reduce air velocity. This is a very powerful technique because resistance or pressure loss, whatever you want to call it, is proportional to air velocity squared. You can't eliminate all losses, but if you just take 1 step backwards and 3 steps forward you're much better off. People don't think about this because all attention is focused on manifold boost, not compressor discharge pressure.
To answer your other question; we measured compressor discharge temperature and temperature before the carb in this test (Family & Performance Boating, March 2004). The Procharger dropped temperature from 214F to 115F. The Supercooler dropped it to 90F, at the same time as an additional 100 HP of air flow was being handled (8.5mph X 12 HP/mph). The only way the Procharger would be able to deliver this much additional air is by spinning the blower much faster, which means a lot more heat. You probably would not achieve the HP before detonation called the party off.
"Pressure" and "pressure loss" both have the same units (psi) but they are different things. These numbers from our first dyno testing (F&PB, May 2003) show that loss is a calculation, the difference between two measurement points.
Procharger: Discharge Pressure 12 psi - Boost 7 psi = 5 psi loss
Supercooler: Discharge Pressure 11 psi - Boost 9 psi = 2 psi loss
These pressure loss measurements include the carb, which accounts for an unavoidable loss of about 1 psi, so the procharger intercooler setup loses 4 psi, the supercooler only loses 1 psi, and it does this at a higher flowrate, so it's actually even better.
The increase in air flow and HP comes from the decrease in overall system resistance, from 12psi to 11 psi. Since blower speed has not changed you can plot these points on a compressor map and read off the x-axis how much more flow is delivered. Since the heads and cam were not changed, this extra flow causes a higher manifold pressure (boost). You can estimate the power increase by taking the square root of the pressure increase.
square root of (9/7) = 1.134, or +13%
Sure enough, when we did this dyno test, engine HP increased from 650 to 740, just a bit over 13%. And air temperatures dropped at the same time. Not enough to make much difference in HP, but a significant change for preventing detonation, the true limit to power.
It is a huge loss, and it is very typical for a remotely mounted intercooler. But the restriction of the core is only a small part of the loss; the problem is all the elbows and abrupt changes in cross-sectional area.
Pretend for a moment that there is no blower. Do you think a big V-8 is going to be happy sucking it's air through 3" diameter twisted hose? At WOT the air velocity in that hose is 100+ mph. Do you think that air wants to make a turn? And yet that is exactly the plumbing supposedly needed to hook up a centrifugal supercharger and intercooler and carb box. Overall, when you add the blower, HP goes way up, but it is a case of 2 steps backward, then 3 forward.
The supercooler has no elbows, all turns are made at high cross-sectional area to reduce air velocity. This is a very powerful technique because resistance or pressure loss, whatever you want to call it, is proportional to air velocity squared. You can't eliminate all losses, but if you just take 1 step backwards and 3 steps forward you're much better off. People don't think about this because all attention is focused on manifold boost, not compressor discharge pressure.
To answer your other question; we measured compressor discharge temperature and temperature before the carb in this test (Family & Performance Boating, March 2004). The Procharger dropped temperature from 214F to 115F. The Supercooler dropped it to 90F, at the same time as an additional 100 HP of air flow was being handled (8.5mph X 12 HP/mph). The only way the Procharger would be able to deliver this much additional air is by spinning the blower much faster, which means a lot more heat. You probably would not achieve the HP before detonation called the party off.
"Pressure" and "pressure loss" both have the same units (psi) but they are different things. These numbers from our first dyno testing (F&PB, May 2003) show that loss is a calculation, the difference between two measurement points.
Procharger: Discharge Pressure 12 psi - Boost 7 psi = 5 psi loss
Supercooler: Discharge Pressure 11 psi - Boost 9 psi = 2 psi loss
These pressure loss measurements include the carb, which accounts for an unavoidable loss of about 1 psi, so the procharger intercooler setup loses 4 psi, the supercooler only loses 1 psi, and it does this at a higher flowrate, so it's actually even better.
The increase in air flow and HP comes from the decrease in overall system resistance, from 12psi to 11 psi. Since blower speed has not changed you can plot these points on a compressor map and read off the x-axis how much more flow is delivered. Since the heads and cam were not changed, this extra flow causes a higher manifold pressure (boost). You can estimate the power increase by taking the square root of the pressure increase.
square root of (9/7) = 1.134, or +13%
Sure enough, when we did this dyno test, engine HP increased from 650 to 740, just a bit over 13%. And air temperatures dropped at the same time. Not enough to make much difference in HP, but a significant change for preventing detonation, the true limit to power.
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10-25-2004, 05:01 PM
#33
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Re: B&M vs Procharger for 540??
When I read this thread this morning I was going to respond but I figured Tom would do a way better job at it then I.
"Procharger: Discharge Pressure 12 psi - Boost 7 psi = 5 psi loss
Supercooler: Discharge Pressure 11 psi - Boost 9 psi = 2 psi loss "
Tom, is the reason the supercooler has 11 psi is because it has less restriction getting air thru it?
Tom, some bench racing
In my setup are we going to see the boost go up 3psi? from 11 to 14?? & my air temp come down? If so then when I put a bigger pulley on to bring the boost back down to 11 psi will my air temp go down still further?
FYI, we are talking about a 540bbc M4 procharger with EFI & 2000cfm throttle body with existing 504 procharger intercooler compared to the suppercooler.
"Procharger: Discharge Pressure 12 psi - Boost 7 psi = 5 psi loss
Supercooler: Discharge Pressure 11 psi - Boost 9 psi = 2 psi loss "
Tom, is the reason the supercooler has 11 psi is because it has less restriction getting air thru it?
Tom, some bench racing
In my setup are we going to see the boost go up 3psi? from 11 to 14?? & my air temp come down? If so then when I put a bigger pulley on to bring the boost back down to 11 psi will my air temp go down still further?
FYI, we are talking about a 540bbc M4 procharger with EFI & 2000cfm throttle body with existing 504 procharger intercooler compared to the suppercooler.
10-25-2004, 05:30 PM
#34
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Re: B&M vs Procharger for 540??
Jack: Discharge pressure, which is the same thing as the total resistance of the air pathway, drops to 11 psi because the supercooler is less restrictive. This allows the blower to move more air automatically. Discharge pressure would be more like 9 psi if we changed pulleys to keep manifold boost at 7 psi in both cases.
You are definitely going to add boost with the supercooler, but not 3 psi because your existing setup is not as bad as the Procharger setup tested (less elbows, bigger hose). I would recommend putting the larger pulley on first so that you don't go too far. Your temperature will drop due to the lower discharge pressure from both the supercooler and the pulley change. Better air distribution across the supercooler core will help too.
When I look at your temperature log I also wonder if you have adequate water flow. How do you pick up water for the intercooler now, and have you ever back flushed it? If there is a problem here we need to address it before any back to back testing, to keep things valid.
You are definitely going to add boost with the supercooler, but not 3 psi because your existing setup is not as bad as the Procharger setup tested (less elbows, bigger hose). I would recommend putting the larger pulley on first so that you don't go too far. Your temperature will drop due to the lower discharge pressure from both the supercooler and the pulley change. Better air distribution across the supercooler core will help too.
When I look at your temperature log I also wonder if you have adequate water flow. How do you pick up water for the intercooler now, and have you ever back flushed it? If there is a problem here we need to address it before any back to back testing, to keep things valid.
10-26-2004, 12:41 AM
#35
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Re: B&M vs Procharger for 540??
Originally Posted by tomcat
You can estimate the power increase by taking the square root of the pressure increase.
square root of (9/7) = 1.134, or +13%
Sure enough, when we did this dyno test, engine HP increased from 650 to 740, just a bit over 13%.
square root of (9/7) = 1.134, or +13%
Sure enough, when we did this dyno test, engine HP increased from 650 to 740, just a bit over 13%.
Thank you for posting this test data. Great to see some numbers!!! Very informative and interesting! It looks like you really did your homework developing the Supercooler. Nice to see some good engineering, too.
I haven't quite figured out your equation for the horsepower increase. It seems like if your starting boost pressure were nearing zero (unboosted), then the horsepower increase would go to infinitity.
Anyway, here's the formula I use:
% increase = (P2/P1) x (T1/T2)
P1, P2 absolute pressure = 14.7 + boost
T1, T2 absolute temperature = 460 + degrees Fahrenheit = degrees Rankine
With your numbers:
% increase = (14.7+9)/(14.7+7) x (460+110)/(460+90) = 13.2%
Estimated power = 650 starting hp x 1.132 = 736 hp, also fairly close to the 740 you measured.
Of course, these calculations do not take into account blower drive horsepower requirements, so it's just an estimate.
Cheers,
Michael
10-26-2004, 08:26 AM
#36
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Re: B&M vs Procharger for 540??
For quick and dirty predictions of HP that might be achieved with higher boost levels, you can use the square root of the boost increase to estimate the new flow rate through the head. This ignores changes in density and is only good when the change in boost is relatively small. It's kind of a bad habit of mine to find the edges of a problem with simple formulas.
Calculating the density ratio based on before and after measurements is the better way of estimating the new HP. Since blower RPM hasn't changed, drive HP won't change much.
Real numbers and real world experience are what the tech section is all about! You can look forward to some good bench racing here as guys develop their winter projects.
Calculating the density ratio based on before and after measurements is the better way of estimating the new HP. Since blower RPM hasn't changed, drive HP won't change much.
Real numbers and real world experience are what the tech section is all about! You can look forward to some good bench racing here as guys develop their winter projects.
