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Turbo or Super? (Forced Induction Systems: Pro and Contra)

2K views 4 replies 2 participants last post by  Nightrider 
#1 ·
Comrades, who can explain, that from Forced Induction Systems will give greater performance gain? Well, and as it will decrease the life of engine or drivetrain?
 
#2 · (Edited)
what do you want to use the car for?
Crusing the street, drag racing, circle track?

Any forced induction will shorten the life span of an engine some. The higher the boost the more stress and the more damage potential. Low boost on a stock bottom end would probably be okay, but if you want a lot of boost then you have to put as many forged parts in your bottom end as you can.

As for differences:

There are a few types of super chargers out there. The tree main types are the centrifugal, roots and twin screw.

A roots blower is one of the cheaper ones you can throw on. They provide fairly good boost down low, but suffer poor efficiency. They don't actually put the manifold under constant boost. The way the rotars ar designed, they actually put a draw or suck air from the manifold during part of the stroke then force air back into it generating boost. This pulsating drops the efficeincy.

A twin screw makes the best low end boost and it much more efficient then a roots blower. It has two screws that turn counter to each other and intermesh. The precision in machining the screws is much more involved so they tend to cost a lot. However no other option gives you the same boost at low rpms.

Both the twin screw and roots tend to be a bit bulky which is bad for cramped engine compartments. The roots will replace your stock intake manifold and sit on top. So if you want a bird catcher sitcking out of your hood, then that will do it.

I consider a centrifugal more of a turbo then a blower. It's basicly a turbo cut in half with a pully attached to it. They tend to be pretty inexpensive and have small mounting space. They also don't tend to kick in until high RPMs, more of that with the turbo.

Turbos are quite an interesting monster. By selecting your turbine size you can control it's rpm range. Big turbines need more flow to spool, so they make lots of boost at high rpms. Small turbos don't make as much boost, but spool up quicker with less flow required, so they work well at low RPM.

This means you have a lot of options with turbos. If you plan on racing where you don't drop below 3000 rpm, then you can run a single turbo that is tuned to make maximum boost around that range. You can even run multiple identical turbos to generate more boost at a target RPM range. If you want more consistant boost throughout the range, then you can run twin staged turbos. This would be one big and one small turbo. The small one would spool quick and give you low end boost while the larger one would be bypassed through a wastegate. Once RPMs get high enough the second turbo is enguaged and the small one is bypassed. Through the use of waste gates and blow off valves, the turbo set up has a lot of potential for fine tuning.

The centrifical blower has similar options, except you can't bypass it with a wastegate. The turbine size can be tuned however.

In general the turbo is more efficient as well, but takes a lot more to get a well running set up. The rumor that turbo's suffer lag and don't deliver boost as quickly as a blower is false. A properly tuned turbo set up will provide boost just as fast as a blower because some of the exhaust will always be diverted to keep the turbo spooled and waiting. Lag is the result of poor plumbing

A twin screw or roots blower will generally be an easier install, with all the tuning being through the ECU or with adding extra injectors if need be. On a carb set up it's more complicated as the entire carb needs to be held at the boost pressure and not atmospheric.

I recomend that you go buy a book called "Maximum Boost" by corkey bell. It has a lot of valuable information.


To answer your questions on power in short, they all have the potential to make the same boost. It just depends on where in the RPM range it's made and how long it's sustained.
 
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