turbo vs supercharger



Which is better for low end grunt, I want to use my truck with 300 for some towing and highway and off road at 1500-3000 rpm any advantage to either or niether and just leave it n/a, can they help at those rpms?
8) i would say for the application you have indicated, a belt driven rootes type blower or screw type blower would be best. turbos generally work in the higher rpm ranges as do centrifugal blowers. a rootes or screw type blower produces its boost in a linear fashion, where as the turbo and the centrifugal blower build boost geometrically.
Superchargers come in several types. The positive displacement blowers like the Roots, Eaton and Whipple make constant boost throughout their RPM range. Your 300 would pull like a 390, and drink like one.

Centrifugal blowers (Vortec, Paxton, etc. build boost as RPM increases. since they are belt driven off the engine, they provide little boost at the low RPM range where you need it when towing. They are far more suitable to racing applications.

Turbos also make boost in proportion to RPM but since they are not belt driven, their RPM is not slaved to engine RPM. Instead it is a function of demand. When you mash the throttle, the resulting increase in exhaust gas flow makes the turbo spin faster and brings the boost up. On a properly sized turbo the resulting turbo lag is very brief, especially if you've sized the turbo for max boost at cruisr RPM and are willing to give up some higher RPM performance. Turbos are more mechanically efficient than the other types of blowers since they use waste heat for their operation rather than pulling HP off the crank pulley.

Turbos also tend to be somewhat simpler to install mechanically than superchargers but usually take a bit more control work since their output varies with need rather than being constant like a Roots or RPM depenpent like a belt-driven centrifugal.
strangeranger: what size turbo would be right?I see lots on E-bay but they're a little confusing as to exact size and properties such as spin rate and trim, what ever that is! Most seem to be for 4 cyl 2-3 liter engines for high rpm use.
FWIW 2.5 litres @ 7000 RPM consumes the same amount of air as 5.0 litres @ 3500 RPM. You cannot equate engine size to turbo size without looking at RPM range and boost level. As for turbo size, I think Whittey picked the right ones, others will disagree preferring a small-trimmed T04.

If you are really interested in turbos you need to read either Turbochargers by Hugh MacInnes for carbureted applications or Maximum Boost by Corky Bell for EFI applications. Both are available from www.motorbooks.com. There's way more information you're going to need than you can ever get accurately from a bulletin board.
Not really disagree, just a matter of application.

The T3-60 for low end power up to 4000
The T-4 small trim for mid and top up to 5500

What size turbine housing for a T3-60 you guys think?... .48? or larger?.. .63?
Same here. I'd call a turbo company (turbocity.com) and see what they have to suggest.

Well, i used that site Ray Halls turbocharging and the turbo selector for a specified sizze engine and max RPM. It says to use a T3 with a .82 turbine on a 5000cc, max RPM - 5000, single turbo, intercooled setup at 10 psi boost...i thought that was a little big.

But i looked at the lbs. of air per min. it stated 43 lbs of air per minute with this particular turbo.

I figured out the lbs of air perminute using some formulas i found at http://www.gnttype.org/techarea/turbo/turboflow.html and came up with 40.7 actual lbs p...aller one. Let me know waht you think.. Adam
Well..after figuring out stuff....i found that a T04B-S3 turbo wil prolly work the best resulting in a torque peak around 3000 to 3500 RPM, and a horsepower peak at about 5000 RPM. The super 60 T3 was amost there, but it didnt do too well at high RPM's.

Of course im not looking at running high RPM's, but it was really inefficient at 5000 RPM where the peak horsepower is.

I figured out how to read those compressor maps to see how a turbo performs at certain RPM's and how efficient the turbo was at that certain RPM.

I have one question...would anyone know whatthe "S3" for T04B-S3 turbo represents....i may have to search for it online....butpossibly someone may know
Its just a designation of trim. Each manufacturer uses a different designation. So basically, it means nothing except that that particular compressor isn't the H-3 or 62-1 trim. They could have just said 'a' 'b' 'c' etc.