Effects on powerband

[Wangan Wagon]

Hey guys. This is more of a general knowledge question, and I hope it helps those trying to figure out what type of setup they want.
I was wondering how a vehicle's powerband would be effected by either supercharging, turbocharging or NA building the motor? Also how would these compare and contrast to the other setups?

From what I know:
- Supers and NA avoid low end lag of turbos and tend to give better low-end torque, more suited to tight corner areas
- Forced induction setups tend to have powerspikes when you hit the powerband
- Supers and NA builds generally won't attain higher power levels seen by turbo builds
- Turbos suffer from vacuum lag where as supers suffer from parasitic lag
- Forced induction generally produces more torque than NA

If any of this is wrong, correct me, since I just want to learn. And like I said, hopefully everyone comes out smarter and with a better idea of how they want to build their cars.

[StatGSR]

While nothing you have said is completely incorrect, some bits are too vague to be accurate.

while i dont have the time to go into it right now, please check out these links, i think you will find them helpful....

Horsepower, Torque, and Gearing (http://www.mazda6tech.com/index.php?option=com_content&task=view&id=9&Itemid=49)

Gearing I: Torque multiplication and Final Drives (http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=707)

Why Peak WHP Can Lie (http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=286)

HP and Torque. Analyzing power curves (http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=467)

Using Chassis Dynanometers For Tuning (http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=282)

[Sarra]

It depends on what kind of turbo you use, what kind of supercharger you use, and in an NA build, compression, head flow, cams, exhaust, intake, and a ton of other things. Hell, compression, head flow, cams, intake, and exhaust effect turbo and supercharger builds as well.

Typically, turbos have peaky power bands, with a really low power area before boost, then power spikes up, then tapers off as the turbo runs out of efficiency. Some have to rev to a billion RPM to even get into the 'sweet spot' of the turbo (read the NA section below for more).

A Roots style supercharger will typically have the same kind of power band as a NA motor, just the little numbers on the sides will be bigger. if you are using a small supercharger, you may gain a lot of low end off-idle power, and sacrifice top end (and sometimes have to lower your rev limiter). A Centrifugal style supercharger has the same lag as a turbo, though not nearly as bad, but it has a smoother, more NA like power band typically. Other superchargers can have different power bands depending on the supercharger and it's intended application.

NA engines... Well, the more aggressive the cam and the better flowing the intake, exhaust, and head, the worse idle will be, and the better the engine will flow at high RPM. More cam overlap (keeping the exhaust open while the intake opens) can allow for massive gains in strictly NA applications, while isn't really a good idea for Turbo/Supercharged applications. More lift and duration is good for turbo/superchargers, but it kills the engine's ability to produce vacuum at idle, same as overlap, which makes it idle like poo. The more aggressive the cams, heads, intake, exhaust, the further right the power band gos, and the higher you have to rev the engine to get power out of it.

A 2.5 turbo motor with a big turbo on it, like an FP red, would be a dog until the turbo spooled, then it would put you back into your seat. The turbo is so big, you would have to rev the engine to 9 grand to get the most out of the turbo, if not higher RPM. A 2 liter with a TD04 (stock wrx) can make usable boost right off the line, but can't hold boost to redline. There's choices inbetween. I don't think many people have run FP Reds on 2 liters.

Which brings up AVCS and AVLS, dual AVCS, and similar technology. AVCS would be the 2003+ Outback 3 liter (EZ30R), 2004 STI+ (EJ257), anything with an EJ255, and the 2005-2006 EJ253. AVLS was put on the 2007+ EJ253. The EZ36R or whatever it's designation is has dual AVCS. Oh, so does the 2009+ STI.

Anyway. AVCS and AVLS change valve lift and duration, and cam timing. AVLS is the Active Valve Lift System, basically iVTEC for Subaru's SOHC engines. AVCS is Active Valve Control System, and I believe goes on the DOHC engines. The AVCS/AVLS is used to give the engine two cam profiles, basically, one for low RPM and a smoother idle, and the other for higher RPM and more power. Unlike early VTEC, Subaru's system is pulse width modulated, so it can actually hold the actual cam profile halfway between the two cam profiles on the camshaft (simplified explination). It can even go 20% of the way between, or 21%, or 22%, etc. AVCS on most Subarus is only used on the intake, whereas the 3.6R uses it on intake and exhaust (as well as newer STI's). This gives a smoother power band with more power that can rev higher easier and breathe better at all RPM bands.

For an amazing motor that costs a fortune, you can take a 3.6R engine, pull the pistons, rods, and crank, buy a 3.0R crank, toss the crank in, put in some forged rods and forged low compression pistons, custom turbo profile cams, pop it back together, dump it into a car with a 6 speed, slap a GT40R turbo on it, tune it, and find yourself with a 3 liter engine that revs to 9 grand and makes 470 WHP on a 'conservative tune', running 17 PSI of boost (which is chump change for that turbo). Spools at like 6 grand too.

[Wangan Wagon]

Thank you much. Now I shall continue my quest to take over the world with this knowledge.

[Sarra]

Uh, good luck? Not sure how it will help you there.