THE LAST Z

iTrader: (5)

Take this vid for example.
http://videos.streetfire.net/video/B...EA78971EDF.htm

I know the power curve in the vid is ridiclious but Why do i never see high #'s like this with a S.C. or N20 set up?(93 octane)

BigE

iTrader: (2)

You can make power a number of ways. Turbo just happens to be one of the most efficient. There are folks making big power on nitrous and superchargers. That particular truck is running a lot of pressure and methanol. If you put enough time, money or knowledge into a project, you can get there a few different ways.

MSURacing

iTrader: (1)

Because a supercharger uses more power to make the same amount of power. You spinning gears and that creates drag. At peak power, a typical street supercharger is eating up well over 120 hp.

Gm-LSX

more or less simple: A Turbo or Supercharger adds displacement in compressed form. And as you may know: No Replacement for Displacement.

andereck

You would have to qualify that statement with some actual data, and you are incorrect. It takes a 12rib drive to transfer that kind of power and a typical street supercharger does not use or need a 12rib drive.

A turbo car also operates against exhaust backpressure and that pressure is multiplied across the area of the piston creating an additional load, similar to the load required by a belt driven centrifugal blower. A belt driven blower actually uses the same above phenomemon in reverse. Boost pressure can lower pumping losses by applying boost pressure to the piston area reducing its parasitic loss somewhat without the backpressure loss offset.

A supercharger is less mechanically efficient than a turbocharger at the same airflow levels, but not by the drastic margin some like to believe. Usually about .05 bsfc difference. On an 800hp engine that's about 40#/hr of fuel.

MSURacing

iTrader: (1)

well, i know for a fact that a LSJ at 6500 takes about 100hp of power.

CHarris

iTrader: (5)

You want data... look up the numbers for a Eaton supercharger. Once one gets into the 10 psi area 100-120 hp used to turn the compressor is about right. And it doesn't take a 12 rib pulley system.

andereck

huh? I don't need a homework assignment, the poster should substantiate their claim with some actual data. The point is that the statement isn't true. BTW an Eaton can make 10 psi at 2000 rpm and it does not take 100 hp to do that. Roll your eyes all you want. It does take substantially more surface area than a 6 or 8 rib system to transfer 120 hp.

CHarris

iTrader: (5)

Are you retarded? Why are you wasting everyone's time? Here's proof of a Belt driven Supercharger with less than 12 ribs that requires more than 100 hp to drive it once you're in the 10 psi range. In the chart below you'll be looking at the black line:



with a 2.75 pulley- thats 10 psi on a 6.0 liter- its possible to turn it well over 19000-20000 rpms when you're shifting above 6200 ENGINE RPM.


If you still think you know everything you've got a lot to learn... here's a good place to start:

http://www.magnusonproducts.com/mp112.htm

KraZy

iTrader: (4)

With my procharger I dyno'd w/ the bypass valve open and made 90hp less than stock.

I havent done that w/ the turbo yet, maybe I should.

CHarris

iTrader: (5)

Ahhh.... so another leading brand of supercharger has a similar appetite for horsepower. Thanks for bring some real world tech to the board, KraZy!

ou812/z28

parish made impressive #'s but can he get it down the track. on a blower car at 500 rwhp it takes ruffly 50hp from the motor.a turbo set up around 9hp loss. this is what i have noticed thru the years of my studies. i may be wrong but i know that turbo is free hp due to driving it with the exhaust and blower/sc aps you use force from the crank,so you will lose more than turbo.

Frost

iTrader: (45)

not free, you pay with backpressure.

eviltwins

Except that's not tech at all, because the blower inlet restriction is probably what caused most of the power loss, and spinning a blower when there's no resistance on the other end takes much less horsepower than when you're pumping into a motor. Think of it this way, stick a straw into glycol and try and blow through it. You have to exert a lot of pressure to get the air to bubble through the glycol. Stick that same straw in water and blow and you're using much less force to push the air through the water. A supercharger being vented to atmosphere is consuming much less horsepower than a supercharger feeding the motor.

I remember about 2 years ago there was a guy on some old mustang forums who built a 490" FE-block stroker, with a Vortech YS-trim. He had an engine dyno, and set up an outlet restrictor on the YS-trim to simulate the blower forcing air into the motor, then measured power loss through the supercharger. I really wish I saved the stuff he posted, but with the same blower pulleys on the YS-trim as it took to make 10 psi and 1000 horsepower he was reporting power consumption to the tune of about100 horsepower.

CHarris

iTrader: (5)

Good catch Eviltwins... caught me in a brain fart... lol

Even the Radix is said to only take 1/3 hp at 60 mph or so.... when in bypass mode (not building boost).

However, once it starts making boost the power required to turn it increases dramatically. The faster the blower spins the more power it takes to drive it. Any belt driven supercharger is going to behave similarly. As with anything... you begin to see diminishing returns in that it takes more HP to drive the supercharger so you get "less" HP from the supercharger as you reach its upper limits. With a turbo its just a better ratio.

Even in Eviltwins example of 100 hp consumed on a 1000 hp combo.... its not a "x hp to make y psi (or z total hp)" it's about how fast you're turning that blower. If its spinning faster and making more boost its working harder and takes more hp... period. On my truck I could see 10 psi at 4000 rpms for example... I'd still have 10 psi at 6300... but it was moving a lot more air to maintain that 10psi restriction reading... and the blower was turning a hell of a lot more rpm thereby eating more hp.