FMIC installed!.......on a Supercharger :)
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From: Gie
Originally Posted by tof,May 21 2007, 11:16 AM
Slimjim, about your comment on boost drop: you are thinking like a turbo guy which, I see by your sig, you are. 
When you introduce a restriction to the intake system (like an intercooler) you WILL reduce boost at the throttle body...UNLESS you increase the boost ahead of the restriction. Your boost control system (mbc and/or boost gauge and/or ebc, and your waste gate compensate for the loss but your turbo is working a little harder to make up the difference. One of the big advantages of a turbo vs. a supercharger is the turbo has "boost to burn" up to the limits of the torbo's design.
Since superchargers boost levels are completely dependent on engine rpm they don't have the luxury of just turning up the boost to compensate for new restrictions.
In my experience a quality FMIC of reasonable flow efficiency won't result in more than a pound or two pressure loss. But my experience is with turbos putting out between 12 and 25 lbs boost where a couple of lbs isn't a big deal and where you can turn the boost up a little to compensate (at the cost of reduced thermal efficiency).
Not surprised the S2K "aftercoolers" (more on that in a sec) get heat-soaked. BTW, you may find your air/air setup does too in heavy traffic. Mine (in a turbo galant) does. Of course it's a little hotter down here on the Gulf Coast than up there in the Great White North.
Now the rant...
WHY do these supercharger companies insist on calling an air to liquid intercooler an "aftercooler"? Maybe this has been discussed before and its a minor point but it has always bugged me. An "aftercooler"? Like there might be such a thing as a "precooler" or (worse) a "beforecooler"? Like you would cool the intake air to ambient BEFORE you compress it? Like it isn't ALREADY ambient? /RANT
BTW... in my turbo world, an air to liquid intercooler is a hot setup. (as in good, not as in thermally sucky) Simplifies packaging and permits a really short rout from torbo to throttlebody.
oh...and I don't think bigger pipes cause pressure drop...they only improve flow. And longer pipe routs don't cause significant pressure drop either. Additional lag, maybe.
When you introduce a restriction to the intake system (like an intercooler) you WILL reduce boost at the throttle body...UNLESS you increase the boost ahead of the restriction. Your boost control system (mbc and/or boost gauge and/or ebc, and your waste gate compensate for the loss but your turbo is working a little harder to make up the difference. One of the big advantages of a turbo vs. a supercharger is the turbo has "boost to burn" up to the limits of the torbo's design. Since superchargers boost levels are completely dependent on engine rpm they don't have the luxury of just turning up the boost to compensate for new restrictions.
In my experience a quality FMIC of reasonable flow efficiency won't result in more than a pound or two pressure loss. But my experience is with turbos putting out between 12 and 25 lbs boost where a couple of lbs isn't a big deal and where you can turn the boost up a little to compensate (at the cost of reduced thermal efficiency).
Not surprised the S2K "aftercoolers" (more on that in a sec) get heat-soaked. BTW, you may find your air/air setup does too in heavy traffic. Mine (in a turbo galant) does. Of course it's a little hotter down here on the Gulf Coast than up there in the Great White North.
Now the rant...
WHY do these supercharger companies insist on calling an air to liquid intercooler an "aftercooler"? Maybe this has been discussed before and its a minor point but it has always bugged me. An "aftercooler"? Like there might be such a thing as a "precooler" or (worse) a "beforecooler"? Like you would cool the intake air to ambient BEFORE you compress it? Like it isn't ALREADY ambient? /RANT
BTW... in my turbo world, an air to liquid intercooler is a hot setup. (as in good, not as in thermally sucky) Simplifies packaging and permits a really short rout from torbo to throttlebody.
oh...and I don't think bigger pipes cause pressure drop...they only improve flow. And longer pipe routs don't cause significant pressure drop either. Additional lag, maybe.
At a specific engine RPM, the blower will also spin at a specific RPM. The blower's flow output is a function of a lot of things...air temperature, blower speed, pressure differential across the blower...
With the added restriction downstream of the blower, the blower delta P will rise, hindering the flow output. Less flow rate will lead to a lower blower pressure rise. Essentially, the blower will be operating a different point on it's pump curve at any given engine/blower speed. I'd need to take a look at the pump curves and know the blower delta P, but it is concievable that the restriction causes a higher delta P across the actual blower, with the pressure loss across the downstream restriction resulting in a lower manifold pressure. This would also result in a slightly lower blower flow rate, hence the need for a smaller pulley to compensate for the change.
Aftercooler, intercooler, blah blah blah. When referring to turbo-machinery, an intercooler is a heat exchanger placed in between two compression stages. A heat exchanger placed after a single compressor stage is not an INTERcooler but an AFTERcooler. Technically, all of our turbo setups use an aftercooler and not an intercooler.
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From: Gie
Originally Posted by pushin9,May 21 2007, 01:27 PM
That is correct because the supercharger is belt driven from the crank pulley and the impeller speed is RPM dependent. VS a turbo being driven from the exhaust you will see a surge and need the BOV.
The operation of a bypass valve or blow-off valve is very similar between turbo and centrifugal setups. They both function to exhaust downstream pressure under low-throttle conditions.
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From: AZ.& So. Cal.
Originally Posted by Eri_S2k,May 21 2007, 04:40 PM
This is My Setup!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi
) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi
) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!
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From: schaumburg/joliet
Originally Posted by Eri_S2k,May 21 2007, 07:40 PM
This is My Setup!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi ) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi
) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!
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From: Long Beach, MS
Originally Posted by slimjim8201,May 21 2007, 12:08 PM
You could most certainly surge a centrifugal blower. The bypass valve prevents this, however. If you got rid of the bypass valve and revved the engine to 9,000 RPM then closed the throttle, you would be spinning the blower at about 50,000 RPM and the pressure delta across the blower would be massive. So massive, that the air would have no where to go but back through the blower...also known as surge. The bypass valve opens under manifold vacuum (low throttle opening) to allow the compressed air to exit and not surge the crap out of the blower.
The operation of a bypass valve or blow-off valve is very similar between turbo and centrifugal setups. They both function to exhaust downstream pressure under low-throttle conditions.
The operation of a bypass valve or blow-off valve is very similar between turbo and centrifugal setups. They both function to exhaust downstream pressure under low-throttle conditions.
After reading the reply about blower speed being dependent on engine speed (which is true) I had a SECOND brain fade and started thinking in terms of an immediate reduction in pumping action. Of course when you let off the gas pedal (more on that later) you immediately close the throttle but all that rotating mass...crank, flywheel, etc...takes a few milliseconds to slow down. Meanwhile the ol' charger is just pumping away against the closed throttle plate.
At least with a turbo, when you get some surge at throttle close there isn't anything but the mass of the turbocharger's moving parts and some force from the exhaust stream working against the backpressure. With a supercharger you have a situation where the impeller WILL keep turning, driven by its belt, in spite of the fact that it is now working against high pressure levels.
Re: aftercoolers...you are absolutely right...now that you mention it I seem to recall someone pointing out this misnomer a few years ago in a thread on ClubSi about this very topic. (Vortech had just released their B16 supercharger with "aftercooler" option.) But everybody in the world (except vortech and a few engineers
) calls it an intercooler. Although technically correct, referring to these devices as aftercoolers just adds to the confusion of enthusiasts who are still climbing the forced induction learning curve. Language should be useful first and foremost. But I'll call 'em all aftercoolers when we exchange posts in the future, Jim. If you will agree to refer to that long skinny pedal next to the transmission tunnel as an "air pedal" rather than a "gas pedal" and to the act of depressing said device as "stepping on the air".
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From: Gie
Originally Posted by tof,May 22 2007, 08:57 AM
Great explanation re: pressure changes w/intercooler, Slimjim. Thanks. Also thanks for confirming that I am NOT crazy.
After reading the reply about blower speed being dependent on engine speed (which is true) I had a SECOND brain fade and started thinking in terms of an immediate reduction in pumping action. Of course when you let off the gas pedal (more on that later) you immediately close the throttle but all that rotating mass...crank, flywheel, etc...takes a few milliseconds to slow down. Meanwhile the ol' charger is just pumping away against the closed throttle plate.
At least with a turbo, when you get some surge at throttle close there isn't anything but the mass of the turbocharger's moving parts and some force from the exhaust stream working against the backpressure. With a supercharger you have a situation where the impeller WILL keep turning, driven by its belt, in spite of the fact that it is now working against high pressure levels.
Re: aftercoolers...you are absolutely right...now that you mention it I seem to recall someone pointing out this misnomer a few years ago in a thread on ClubSi about this very topic. (Vortech had just released their B16 supercharger with "aftercooler" option.) But everybody in the world (except vortech and a few engineers ) calls it an intercooler. Although technically correct, referring to these devices as aftercoolers just adds to the confusion of enthusiasts who are still climbing the forced induction learning curve. Language should be useful first and foremost. But I'll call 'em all aftercoolers when we exchange posts in the future, Jim. If you will agree to refer to that long skinny pedal next to the transmission tunnel as an "air pedal" rather than a "gas pedal" and to the act of depressing said device as "stepping on the air".
After reading the reply about blower speed being dependent on engine speed (which is true) I had a SECOND brain fade and started thinking in terms of an immediate reduction in pumping action. Of course when you let off the gas pedal (more on that later) you immediately close the throttle but all that rotating mass...crank, flywheel, etc...takes a few milliseconds to slow down. Meanwhile the ol' charger is just pumping away against the closed throttle plate.
At least with a turbo, when you get some surge at throttle close there isn't anything but the mass of the turbocharger's moving parts and some force from the exhaust stream working against the backpressure. With a supercharger you have a situation where the impeller WILL keep turning, driven by its belt, in spite of the fact that it is now working against high pressure levels.
Re: aftercoolers...you are absolutely right...now that you mention it I seem to recall someone pointing out this misnomer a few years ago in a thread on ClubSi about this very topic. (Vortech had just released their B16 supercharger with "aftercooler" option.) But everybody in the world (except vortech and a few engineers
) calls it an intercooler. Although technically correct, referring to these devices as aftercoolers just adds to the confusion of enthusiasts who are still climbing the forced induction learning curve. Language should be useful first and foremost. But I'll call 'em all aftercoolers when we exchange posts in the future, Jim. If you will agree to refer to that long skinny pedal next to the transmission tunnel as an "air pedal" rather than a "gas pedal" and to the act of depressing said device as "stepping on the air". 
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From: Long Beach, MS
Originally Posted by Eri_S2k,May 21 2007, 04:40 PM
This is My Setup!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi ) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!
380WHP@12psi(one of my friends sold me a pulley and he told me it was a 14psi pulley but it was a 12psi
) Stock Botom End, No GAY HEADGASKET, NO AEM EMS, Just STOCK ECU and a APEXI VAFC!I was going to ask if you ran the car hard very often at anything like those power levels and, if so, how long you expeced the engine to last.
Then I saw your location in your sig. You guys in PR have a reputation (well earned, I expect) for making crazy power and using it regularly. Is there something in the water over there that turns everyone into a gearhead?
