Does Twin Charging Actually Work?
02-15-2006, 01:54 PM
#51
1.5 BAR
Join Date: Aug 2004
Posts: 1,098
Re: Does Twin Charging Actually Work?
Originally Posted by ****
***** not going to combine folks.
both measure boost as intake manifold pressure (psi)
if you have a turbo with a wastegate set to open at 10psi, its gonna open when the intake manifold sees 10psi. if you have a supercharger pushing 10psi, its gonna push 10psi, one way or another, wastegates are gonna open and the system is gonna see 10psi total.
think about it....if that supercharger spins up 10 pounds of boost right away, whether or not that turbo is spooled isn't gonna matter, the wastegates gonna open.
both measure boost as intake manifold pressure (psi)
if you have a turbo with a wastegate set to open at 10psi, its gonna open when the intake manifold sees 10psi. if you have a supercharger pushing 10psi, its gonna push 10psi, one way or another, wastegates are gonna open and the system is gonna see 10psi total.
think about it....if that supercharger spins up 10 pounds of boost right away, whether or not that turbo is spooled isn't gonna matter, the wastegates gonna open.
Like if you are going turbo to sc, if you jsut got the signal from post turbo/pre sc, then that would be 10 lb turbo, and then just regulate the sc to a higher boost because it's going to be pushing turbo/sc air.
02-15-2006, 09:27 PM
#52
1.0 BAR
Join Date: Mar 2005
Posts: 397
Re: Does Twin Charging Actually Work?
Originally Posted by ****
***** not going to combine folks.
both measure boost as intake manifold pressure (psi)
if you have a turbo with a wastegate set to open at 10psi, its gonna open when the intake manifold sees 10psi. if you have a supercharger pushing 10psi, its gonna push 10psi, one way or another, wastegates are gonna open and the system is gonna see 10psi total.
think about it....if that supercharger spins up 10 pounds of boost right away, whether or not that turbo is spooled isn't gonna matter, the wastegates gonna open.
both measure boost as intake manifold pressure (psi)
if you have a turbo with a wastegate set to open at 10psi, its gonna open when the intake manifold sees 10psi. if you have a supercharger pushing 10psi, its gonna push 10psi, one way or another, wastegates are gonna open and the system is gonna see 10psi total.
think about it....if that supercharger spins up 10 pounds of boost right away, whether or not that turbo is spooled isn't gonna matter, the wastegates gonna open.
it depends on where you get your vaccum source from. if you get your source from the intake mani then yes the wastegate will open at 10psi in the IM, but if you take the vaccum from say the compressor housing, then the wastegate will open at 10psi at the compressor housing.
03-02-2006, 02:04 PM
#53
1.5 BAR
Join Date: Jan 2003
Posts: 1,037
Re: Does Twin Charging Actually Work?
Originally Posted by josh19wrc
yep, because diesels dont generate vacuum, especially 2 stroke ones.
twin charged AE86:
http://www.geocities.com/MotorCity/Lane/1231/page2.html
my idea (drawn for a 240sx group)
Turbo and supercharger draw through the same intake, with a check valve blocking the turbo from it. This way the supercharger could feed the turbo inlet at low rev's w/o blowing back out the intake. The turbo then feeds the intercooler, then TB.
At low RPM the supercharger would boost, it would be fed through the turbo compressor (aiding in spooling here) which is not boosting, then through the intercooler, then TB, then engine, and out the turbo (helping spoolup again). At higher rev's the turbocharger would be drawing more air than the supercharger was pumping, so the check valve would open and the turbo will operate normally. The supercharger will basically freewheel.
-Dustin
03-02-2006, 02:26 PM
#54
1.5 BAR
Join Date: Aug 2004
Posts: 1,098
Re: Does Twin Charging Actually Work?
Originally Posted by krustindumm
They don't generate vacuum because they don't have a throttle plate. It's like a gasolione engine at WOT, no vacuum.
twin charged AE86:
http://www.geocities.com/MotorCity/Lane/1231/page2.html
my idea (drawn for a 240sx group)
Turbo and supercharger draw through the same intake, with a check valve blocking the turbo from it. This way the supercharger could feed the turbo inlet at low rev's w/o blowing back out the intake. The turbo then feeds the intercooler, then TB.
At low RPM the supercharger would boost, it would be fed through the turbo compressor (aiding in spooling here) which is not boosting, then through the intercooler, then TB, then engine, and out the turbo (helping spoolup again). At higher rev's the turbocharger would be drawing more air than the supercharger was pumping, so the check valve would open and the turbo will operate normally. The supercharger will basically freewheel.
-Dustin
twin charged AE86:
http://www.geocities.com/MotorCity/Lane/1231/page2.html
my idea (drawn for a 240sx group)
Turbo and supercharger draw through the same intake, with a check valve blocking the turbo from it. This way the supercharger could feed the turbo inlet at low rev's w/o blowing back out the intake. The turbo then feeds the intercooler, then TB.
At low RPM the supercharger would boost, it would be fed through the turbo compressor (aiding in spooling here) which is not boosting, then through the intercooler, then TB, then engine, and out the turbo (helping spoolup again). At higher rev's the turbocharger would be drawing more air than the supercharger was pumping, so the check valve would open and the turbo will operate normally. The supercharger will basically freewheel.
-Dustin
*edit*
I jsut read that page completely... that's awesome...
So, the sc provides instant boost, and that closes the 1 way valve?
And then when you figure out that the valve is open you can set that to when the sc turns off?
Do you usually run more boost on the turbo or sc?
If you have a motor that can handle.. 25 psi of boost or like 500hp.. and the boosts mulltiply.. how much psi on each is that?
And you don't want a super big turbo? Why wouldn't you run a big turbo like a holset and then have the sc disengage later?
03-03-2006, 11:10 AM
#56
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Thread Starter
Join Date: Jul 2005
Posts: 260
Re: Does Twin Charging Actually Work?
Originally Posted by krustindumm
it's not my car, and boost levels don't multiply, they add.
Originally Posted by JDMFantasy2K
the whole 8+4=12 theory is totally wrong. There's a good write up in this book called "How to tune and modify engine management systems", forgot the author but basically i think you need to calculate actual pressure ratios ( 14.7 [aka sea leve pressure] + psi of boost) and then some other math ----. But the boost doesn't just "add up".
and yes twin charging is awesome if done right.
and yes twin charging is awesome if done right.
03-03-2006, 10:35 PM
#58
1.5 BAR
Join Date: Aug 2003
Posts: 1,194
Re: Does Twin Charging Actually Work?
Some Volvo-Penta diesels are twincharged stock. They use an electronic control system which is awesome.
The supercharger has an electric clutch and every time you accelerate the supercharger is coupled in until the turbo is in action, then bypassed.
Some people here don't seem to understand how a roots blower works. It is a fixed displacement compressor. You can't stick a turbo after the roots blower, it just wouldn't do anything. The roots blower pumps a fixed displacement of air every revolution.
You have to feed the outlet from the turbo into the inlet of the supercharger for a system like this to work. Or you can use an electronic control and have the supercharger clutched and with a bypass valve to let the turbo breathe some air as the supercharger is useless once the turbo has picked up enough revs.
The supercharger has an electric clutch and every time you accelerate the supercharger is coupled in until the turbo is in action, then bypassed.
Some people here don't seem to understand how a roots blower works. It is a fixed displacement compressor. You can't stick a turbo after the roots blower, it just wouldn't do anything. The roots blower pumps a fixed displacement of air every revolution.
You have to feed the outlet from the turbo into the inlet of the supercharger for a system like this to work. Or you can use an electronic control and have the supercharger clutched and with a bypass valve to let the turbo breathe some air as the supercharger is useless once the turbo has picked up enough revs.
03-03-2006, 11:03 PM
#59
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Join Date: Dec 2005
Posts: 397
Re: Does Twin Charging Actually Work?
But what about supercharger to supercharger?
I have one. going to install another on the other side. Would I benefit more from combining the airflow? Or plumbing one into the other? 7-9 psi ratio each.
I have one. going to install another on the other side. Would I benefit more from combining the airflow? Or plumbing one into the other? 7-9 psi ratio each.
