any way to get more psi out of sc without new pulley?

mr2kydd1790 · 09-24-2009, 12:05 AM

i was wondering if their was a way to get more psi out of the stock pulley on my sc. also if i where to get a new pulley any suggestions on what one to get and how much is the most psi i can get while still safe for stock internals and motor?? and one more thing. i know the hks twincharger kit is discontinued but does anyone kno where i could get my hands on one or any tips for way to make one similar to it or wat people are doing to twin charge the 4agze???

div0 · 09-24-2009, 03:17 AM

The SC12 supercharger is a positive displacement Roots-type blower. This means that it moves a fixed volume of air per rotation of the supercharger lobes. Boost is generated by moving more air into the engine than it can consume at atmospheric prerssure... boost increases until the engine will swallow the same volume of air that the supercharger is feeding it. Changing the pulley changes the ratio between engine speed and supercharger speed, so the supercharger feeds an increased volume of air for each revolution, thus increasing the boost pressure.

You could actually increase boost pressure by putting restrictor plates into your intake. The boost would increase until the pressure was high enough to force the same volume of air through the restrictors. But this would be counterproductive in increasing power. Conversely, you could port out the head and intake manifold to make the intake less restrictive. Your boost pressure would actually drop, but the engine would have increased flow and increased power.

Without changing pulleys, you can slightly increase boost pressure by trying to improve the volumetric efficiency of the supercharger. First you would want to minimize intake restrictions in front of the supercharger, as any pressure loss in front of the supercharger will drop your boost. You can also port out the intake of the SC12 supercharger to help minimize the pressure losses. Finally, I have also heard of water injection in front of the supercharger to help seal the supercharger rotors and increase the volumetric efficiency of the supercharger.

I don't expect you would gain much from any of the efforts I just listed, while going with a new pulley will provide known significant gains in boost for probably less money.

As for twin charging the 4agze, my twincharger project is still in progress. It is taking a lot longer than I had hoped, and the current economy is somewhat to blame as part suppliers no longer keep items in stock, but rather build to order these days which causes significant delays. My twincharger project is fully custom with all the work being performed by a reputable local shop. And as such, I am taking a very expensive path for this project, but I hope the final results will be worth all the effort and expense.

You can find more details about my twincharger project on my garage page of this site.

-div0

curvesrgood · 09-25-2009, 01:51 PM

You can simply change out the rubber coupling pipes that go from the Supercharger to the charge pipe, charge pipe to the intercooler, intercooler to intake pipe, intake pipe on in. They are the couplings with a factory bulge in them. There are 4 and you can use harder pipe (I used radiator hose in 4 inch sections and it cost me 12 bucks and with an upgraded NST pulley I picked up an extra lb of boost and better throttle response.

mr2kydd1790 · 10-05-2009, 02:23 AM

i was wondering if it would be a good idea to change out al the stock intercooling piping and couplers with all aluminum piping to get better engine performance? also i am trying to find a better cold air intake. wondering if any manufacturer makes one? right now i just by-passed the intake and put a filter on it. the only thing i dont like about it is i feel like it is counterproductive because it sits right under the intercooler and doesnt seem like it would be getting the fresh cool air i would like. and if they dont make one just wondering if anyone could maybe hit me up with some pictures or ideas how they fabricated their own. with my old n/a 87 i fabricated one that bent down under the battery next and poked out to the right of the tire where their was an opening. i would try that again but the filter got dirty pretty fast and was a pain in the ass to take off the filter and clean it. any ideas and help would be great. thanks to all the people that have gave me ideas in the past.

Jackstand Queen · 10-06-2009, 01:59 AM

I pondered the same problems and goals as Mr2kydd1790.

I ended up installing a funnel in the end of the OEM passenger side intake. I increased the intake opening surface area by over 50%.

I also installed an 4age N.A. throttle body to replace the narrower SC TB. I had to bore out the J-pipe underneath the TB to match the larger TB.

The Jpipe and the inlet and outlet pipes were smoothed out, I won't say polished, but the rough interior surfaces were all smoothed out. Same with the inside of the intake manifold. And during a rebuild of the head, the combustion chamber got smoothed up a bit, along with intake area under the valve.

Rather than put on a larger main pulley, I installed a larger SC (SC14).

I intalled a two stage water alcohol injection system with the spray going into the intake downstream of the SC. I was concerned that even tiny water droplets hitting the SC rotors would erode the rotors.

I'm just about to re-install the motor and tranny in a couple of weeks from now. It should be just about "Stupid Fast" if all the parts and mods work as intended.

09-24-2009, 12:05 AM	#1 (permalink)
mr2kydd1790 No Skills Join Date: Sep 2009 Location: minnesota Posts: 10 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	any way to get more psi out of sc without new pulley? i was wondering if their was a way to get more psi out of the stock pulley on my sc. also if i where to get a new pulley any suggestions on what one to get and how much is the most psi i can get while still safe for stock internals and motor?? and one more thing. i know the hks twincharger kit is discontinued but does anyone kno where i could get my hands on one or any tips for way to make one similar to it or wat people are doing to twin charge the 4agze???

10-05-2009, 02:23 AM	#4 (permalink)
mr2kydd1790 No Skills Join Date: Sep 2009 Location: minnesota Posts: 10 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	intercooler piping and cold air intake i was wondering if it would be a good idea to change out al the stock intercooling piping and couplers with all aluminum piping to get better engine performance? also i am trying to find a better cold air intake. wondering if any manufacturer makes one? right now i just by-passed the intake and put a filter on it. the only thing i dont like about it is i feel like it is counterproductive because it sits right under the intercooler and doesnt seem like it would be getting the fresh cool air i would like. and if they dont make one just wondering if anyone could maybe hit me up with some pictures or ideas how they fabricated their own. with my old n/a 87 i fabricated one that bent down under the battery next and poked out to the right of the tire where their was an opening. i would try that again but the filter got dirty pretty fast and was a pain in the ass to take off the filter and clean it. any ideas and help would be great. thanks to all the people that have gave me ideas in the past.

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09-24-2009, 03:17 AM	#2 (permalink)
div0 No Skills Join Date: Jul 2008 Location: San Jose, CA Posts: 22 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	The SC12 supercharger is a positive displacement Roots-type blower. This means that it moves a fixed volume of air per rotation of the supercharger lobes. Boost is generated by moving more air into the engine than it can consume at atmospheric prerssure... boost increases until the engine will swallow the same volume of air that the supercharger is feeding it. Changing the pulley changes the ratio between engine speed and supercharger speed, so the supercharger feeds an increased volume of air for each revolution, thus increasing the boost pressure. You could actually increase boost pressure by putting restrictor plates into your intake. The boost would increase until the pressure was high enough to force the same volume of air through the restrictors. But this would be counterproductive in increasing power. Conversely, you could port out the head and intake manifold to make the intake less restrictive. Your boost pressure would actually drop, but the engine would have increased flow and increased power. Without changing pulleys, you can slightly increase boost pressure by trying to improve the volumetric efficiency of the supercharger. First you would want to minimize intake restrictions in front of the supercharger, as any pressure loss in front of the supercharger will drop your boost. You can also port out the intake of the SC12 supercharger to help minimize the pressure losses. Finally, I have also heard of water injection in front of the supercharger to help seal the supercharger rotors and increase the volumetric efficiency of the supercharger. I don't expect you would gain much from any of the efforts I just listed, while going with a new pulley will provide known significant gains in boost for probably less money. As for twin charging the 4agze, my twincharger project is still in progress. It is taking a lot longer than I had hoped, and the current economy is somewhat to blame as part suppliers no longer keep items in stock, but rather build to order these days which causes significant delays. My twincharger project is fully custom with all the work being performed by a reputable local shop. And as such, I am taking a very expensive path for this project, but I hope the final results will be worth all the effort and expense. You can find more details about my twincharger project on my garage page of this site. -div0

09-25-2009, 01:51 PM	#3 (permalink)
curvesrgood three mk1's Join Date: Feb 2006 Location: NC Posts: 345 Thanks: 7 Thanked 26 Times in 21 Posts iTrader Rating: (0/0% )	You can simply change out the rubber coupling pipes that go from the Supercharger to the charge pipe, charge pipe to the intercooler, intercooler to intake pipe, intake pipe on in. They are the couplings with a factory bulge in them. There are 4 and you can use harder pipe (I used radiator hose in 4 inch sections and it cost me 12 bucks and with an upgraded NST pulley I picked up an extra lb of boost and better throttle response.

10-06-2009, 01:59 AM	#5 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 677 Thanks: 52 Thanked 56 Times in 53 Posts iTrader Rating: (1/100% )	I pondered the same problems and goals as Mr2kydd1790. I ended up installing a funnel in the end of the OEM passenger side intake. I increased the intake opening surface area by over 50%. I also installed an 4age N.A. throttle body to replace the narrower SC TB. I had to bore out the J-pipe underneath the TB to match the larger TB. The Jpipe and the inlet and outlet pipes were smoothed out, I won't say polished, but the rough interior surfaces were all smoothed out. Same with the inside of the intake manifold. And during a rebuild of the head, the combustion chamber got smoothed up a bit, along with intake area under the valve. Rather than put on a larger main pulley, I installed a larger SC (SC14). I intalled a two stage water alcohol injection system with the spray going into the intake downstream of the SC. I was concerned that even tiny water droplets hitting the SC rotors would erode the rotors. I'm just about to re-install the motor and tranny in a couple of weeks from now. It should be just about "Stupid Fast" if all the parts and mods work as intended.