Quote:
Originally Posted by racerxj17
this+++
i have used the same blower used in the GTM kit on my old tacoma 4.0. when i installed headers, i did drop about 1.5 psi, but i also gained 15+ rwhp from 2500 rpm and up.
i generally stay out of these types of arguments, because in general people are to ill informed on how a supercharger actually works.......the people that DO know the above, already know it  |
A lot of people are just ignorant in understanding the process and to the terms used. Boost is loosly used in conversations about turbos and supercharges in large part because boost is the only parameter that can be measured and used to "compare" peformance in like applications. Unfortuanately we can't measure the actual air volume entering into the intake.
As mentioned above boost refers to the amount of resistance to the air flow produced by FI systems. Boost is relative to the amount of air that can be "forced" (hence the term "Forced Inductions") into the engines cyclinder while the intake valve is open. There is only a small duration that the intake vavle is open on any given cylinder while all the others are closed. This is going to provide resistance to the air being forced into the intake by the FI system.
Just remember that boost can only be used to compare peformance of like engines with like FI sytems. All Z's for instance will make the same horsepower (provided all peformance accessories are the same, i.e. headers, cats, etc.) at the same boost levels provided from different FI systems, PROVIDED that the the FI sytems are delivering the same amount of air at the same rpm. Since different FI sysytems spin faster or have larger impellers they will move more air than smaller ones and will produce more "Boost" at lower rpms and produce more power. The reason for the increase in boost is due to the larger systems trying to "Force" more air into the cylinder when the intake valves are open.
"More air being forced against the same resistance will increase pressure (boost)". Example: a fan moving 100 cfm through a 4" diameter pipe may produce .5 psi at the discharge of the fan. When you replace the 4" pipe with a 2" the air flow decreases and the pressue at the discharge of the fan increases. Now install a larger fan that can overcome said resistance and make it large enough to produce 100 cfm throug the 2" pipe than you will see 100 cfm at a much greater pressure at the discarge of the fan.
P2/P1=(cfm2/cfm1)squared
Where P=pressure and CFM=cubic feet per minute of air volume
The equation above is a statement that states: that an increase in air volume through the same area (say a motors intake) will increase the pressure in the intake by the "square" of the cfm or air volume increase.