Contour Enthusiasts Group Archives Forums Modifications Duratec Performance best of: s/c or turbo

which is better: a s/c or a turbo<---thats the q:

well, If you try a search, you will prolly get much info about both.

Here is the short, vague answer: Neither, it totally depends on the application, and intended use.

but here is a short primer on the subject.

In an ideal world, a turbo is better, because of its high efficiency, and its lack of need for a mechanical drive doesn't hurt either.
To further complicate matters, there are 2 different typs of superchargers, positive displacement (roots or twin screw style) and centrifugal (vortech or paxton type).

The centrifugal type is very similar to a turbocharger, only it is mechanically driven, rather than driven by a turbine in the exhaust manifold.

Positive displacement is a bit different, in that for each revolution it makes, it delivers a set amount of air. This makes this type of blower great for making lots of torque at low rpm, but tend to run out of breath at higher rpm (ie the Lightning is rev limited to ~5200 rpm because of the blower speed is too high)

Superchargers tend to be easier to package on an engine, hence the aftermarket kit popularity of them. Where as turbos are typically much harder to fit to an existing engine and engine bay, so turbo kits are usually a bit harder to find for a particular vehicle (especially for cars w/ v-type engines, V6 V8, etc.)
Turbos also typically make more power for a given boost level than superchargers because the turbo does not need the power robbing mechanical drive system of the supercharger.

The real downside to turbos is that they don't feel smooth and linear like an S/C, they make little power off idle until the turbo spools up to speed, then the power is suddenly there, big time. A turbo system can be sized properly to keep the "turbo lag" to a minimum, but then if you do that, the system is usually not capable of very large boost numbers. Additionally, turbos are typically harder to tune properly.

I like turbos, but for the contour, the supercharger is the only game in town, until Mr. Hightower's contacts develop a kit, or you want to build your own (personally I would like to build my own, but I understand everyone is not an engineer, nor has the time or proper tools, I know i don't have a proper place to build one up)

Whether one is better than another has far more to do with the application, intended use, and execution of the setup, than any theoretical efficiency advantage.

Sorry dont buy that !,latest generation of t/c have variable vane so they equal or excel the performance of an s/c

Terry, I pretty much agree on the variable vane, but not every one is using that. Also, all it really does is make it a heck of a lot easier to size a turbo properly to keep spooling time down and still make good boost. The issue still exists w/ the variable vane, it is just made a heck of a lot better than a fixed vane unit. What may be a very small spool time to you or me, may really piss someone off who is used to a positive displacement blower.

I still like the turbo route better than the S/C, because it has far more potential, and the drawbacks can be greatly minimized.

Great comparisson, but you forgot a major turbo consideration over the SC ... boostability. To increase the boost of a SC requires that you wrench off the old pully and wrench on a new one, which often requires a new belt. This leads to a lot of down time for track side tuning. A turbo on the other hand can be tuned to increase boost by simply adjusting the boost controller. It is possible to go from 10psi to 15psi in a lot less time and it requires nothing more than a boost controller/laptop. All the preconfigured settings can be loaded and off you go.

[QUOTE]Originally posted by Rara:
[QB]...The real downside to turbos is that they don't feel smooth and linear like an S/C, they make little power off idle until the turbo spools up to speed, then the power is suddenly there, big time.
...[QB][QUOTE]
Have you seen Sport Compact Car's review with dyno's of the Vortech S/C'd cougar?
Talk about nothing at idle and power coming on suddenly!! This system is hardly better than stock on take-off until the engine reaches a high enough rpm, then you have a cliff showing on the dyno where the power comes on. The article said they either bogged it down on take-off, or revved the engine and wasted the take-off with burnt rubber. Not to say that a surge of power isn't cool, it is.

Now:
The one thing a turbo does better than any other forced induction device(once it is spooled) is supply a continous source of high pressure air even at low rpm that is equal to or better than a roots blower, and a damn sight better than a centrifugal force type blower. Thats because once a little exhaust is flowing the turbo can be spinning 30K+rpms. Don't get me wrong, but the only advantage of Vortech type blowers over a Turbo is the packaging/mounting--basically simple bolt-on setup. They are easily mounted on a non-modified engine, provide lots of boost at high rpm and allow your exhaust to remain completely stock.
The main problem with them is: they use a compressor like a turbo but are directly proportional to engine rpm. If you tune it to max airflow at low rpm, then you get surge and other problems when you rev the engine. Tune it higher in the rev range and you got nothing off idle.
There is hope though...
Too many other details you probably already know...
Not trying to be smart as I think I know what you mean, but someone else who knows nothing will take it as gospel that turbos can't be sized to give a wider flatter curve than a s/c... even though they can
Toyots Supra's sequential turbo system comes to mind with two turbos, one designed to spool very quickly at low rpm, then a larger second to spool slower and provide s**t loads of boost at higher rpms.
warmonger

so being thats are cars have 2 EX.manifolds we can run twinturbos??? overal which one is better:the s/c or t/c??

warmonger,
I attempted to refer to the fact that I was writing my first post quickly w/ the "quick, vague" comment at the beginning.

I also refer back to my comment about the application and how the system is set up being more important than which method of forced induction is chosen. btw, a sequential turbo setup, like the Supra, can get pretty darn complicated, and is pretty rare to see, especially in a kit form for a vehicle that was not originally turbocharged.

Terry, I did go back and look, the VATN aerocharger can cut spool time in half, while still being able to make a decent amount of boost once spooled up. My point was, that while it is greatly reduced, the spool time does not disappear. That said, I still feel that that particular line of turbos is probably the best choice for a street driven turbo car, because of the greater flexibility over a standard turbo, or even a dual scroll type turbo.

so wat about ball-bearing t/c for street use and dependability( as far as i know those r suppossed to be the best t/c all around"the faster u go the faster it spins"right?)

emm... reading these comments makes me wonder why my friend with the Integra would say he wants S/C because it's easier on the engine than T/C...