Helix or Ultimate Racing cats
Just got my Ultimate Racing High Flow Cats today from Adam @Z1Performance.. They are smoking hott!! Love the gain.. You say how i know I got a gain.. First off I have been missing a pound of boost for a while.. Today I got that pound of boost back!! I think the OEM Cats were killing my Nismo headers/exhaust.. Today I finally got the gains.... Cant wait to dyno!! SGP here I come again......
In my car now for over 3 years and going strong
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From: Lakeland
I have been missing a pound of boost for a while.. Today I got that pound of boost back!!
If your boost went up after an exhaust change, doesn't that mean the exhaust is now more restricted than before?
If your boost went up after an exhaust change, doesn't that mean the exhaust is now more restricted than before?
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From: Lakeland
I believe that basic fluid dynamics shows that all else being equal, restricting the outlet increases the pressure. I have seen boost rise when a cat collapsed internally and I have seen boost go down when exhaust flow is improved. This does not mean that increased boost under these conditions translates as increased power.
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Originally Posted by bobd
I believe that basic fluid dynamics shows that all else being equal, restricting the outlet increases the pressure. I have seen boost rise when a cat collapsed internally and I have seen boost go down when exhaust flow is improved. This does not mean that increased boost under these conditions translates as increased power.
What your saying makes no sense.. Its like forcing air into a two ended balloon......... As long as you can keep the air in that balloon at constant pressure it will fly all over the place.. If you fill the balloon faster than it can release the air it will blow the **** up...... I think I broke it down barney........
Last edited by Jay'Z; Feb 4, 2007 at 03:15 AM.
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From: Lakeland
I think I broke it down barney.....
I keep forgetting why I stopped posting on forums.
Since I don't have any balloons to play with, I'll just take my garden hose and stick my finger over the end........ oops, I squirted my wife in the face because the pressure went up!
A turbo charger will spin up faster with a less restricted exhaust, thus increasing boost
A supercharger, which is what the op has, will pump the same volume at the same rpm. The same volume with a more restricted exhaust will increase boost.
I'm done
I keep forgetting why I stopped posting on forums.
Since I don't have any balloons to play with, I'll just take my garden hose and stick my finger over the end........ oops, I squirted my wife in the face because the pressure went up!
A turbo charger will spin up faster with a less restricted exhaust, thus increasing boost
A supercharger, which is what the op has, will pump the same volume at the same rpm. The same volume with a more restricted exhaust will increase boost.
I'm done
Goodbye.... Log off....
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs.
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs.
Last edited by Jay'Z; Feb 4, 2007 at 03:44 AM.
A supercharger is any device that pressurizes the air intake to above atmospheric pressure. Both superchargers and turbochargers do this. In fact, the term "turbocharger" is a shortened version of "turbo-supercharger," its official name. The difference between the two devices is their source of energy. Turbochargers are powered by the mass-flow of exhaust gases driving a turbine. Superchargers are powered mechanically by belt- or chain-drive from the engine's crankshaft.
Last edited by Jay'Z; Feb 4, 2007 at 04:21 AM.
bobd - in this case, you happen to be wrong. While your example of the garden hose holds true, in the instance of a turbo the larger your exhaust volume post turbo is, the more peak boost you can achieve.
Rather that type a long winded answer, I'll copy and paste what someone who works at garret once wrote - it should be a sticky on every turbo forum (even though it is subaru related)
http://www.tercelreference.com/terce...st_theory.html
Rather that type a long winded answer, I'll copy and paste what someone who works at garret once wrote - it should be a sticky on every turbo forum (even though it is subaru related)
http://www.tercelreference.com/terce...st_theory.html
Last edited by Z1 Performance; Feb 4, 2007 at 06:45 PM.
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From: Lakeland
A supercharger is any device that pressurizes the air intake to above atmospheric pressure. Both superchargers and turbochargers do this.
The difference is how the boost is achieved.
The article goes into great depth about how backpressure and exhaust flow affect the drive side of the turbo and how it spools up. I don't care what you do to the exhaust, you will not affect the belt that drives a supercharger - semantics aside, I'm refering to a supercharger in the common vernacular as a mechanically driven device.
Getting back to the original statement. An exhaust restriction will raise the boost on a supercharger. If you don't believe it, I challenge you to plug the exhaust of a supercharged engine and watch the boost.
It's not a hard concept, you are just confusing it with the fact that the exhaust is driving the turbo and not driving the supercharger
The difference is how the boost is achieved.
The article goes into great depth about how backpressure and exhaust flow affect the drive side of the turbo and how it spools up. I don't care what you do to the exhaust, you will not affect the belt that drives a supercharger - semantics aside, I'm refering to a supercharger in the common vernacular as a mechanically driven device.
Getting back to the original statement. An exhaust restriction will raise the boost on a supercharger. If you don't believe it, I challenge you to plug the exhaust of a supercharged engine and watch the boost.
It's not a hard concept, you are just confusing it with the fact that the exhaust is driving the turbo and not driving the supercharger
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