Alright...any engineers in the house?

[longlivetheZ]

I'm looking to settle the "Turbo vs Supercharger" thing once and for all.

I just don't get it...there are who knows how many cars out there with superchargers (beltdriven) on them and seemingly very few with turbos.

Is this a misconception? Is it really not like this?

Here's my main question. And I'm looking for people who actually KNOW...not just oppinion or the usual "well, I drove a gashbvoiashfgshoie with a supercharger on it and it was really fast so superchargers are better" crap. We all have those stories. I'd like input from people with some education to reply, if possible.

Why do top fuel dragsters use superchargers and not turbo(s)? I don't get it. A ~500 cid top fuel engine puts out ~5000 hp. Impressive...kinda. But look at the turbocharged Formula 1 engines of the mid/late 1980s. They were getting ~1400 - 1500 hp out of 90 CUBIC INCHES! Kinda makes that big ass, supercharged, 500 cid, top fuel drag engine look a bit less then magnificent in some ways, doesn't it?

Are they not ALLOWED to use turbos in some classes? Is there some magical thing about beltdriven superchargers that I don't know about? I've read a fair amount about forced induction in books and online and I have seen TONS of info that makes beltdriven superchargers seem completely obsolete for lack of a better way to put it. Am I missing something? I'm sure they have their uses and all that, but still...what's the big deal?

[beyondloadedSE]

iirc, turbos are against the rules in top fuel dragsters.

[longlivetheZ]

I figured they had to be. That's the ONLY thing that makes sense.

How fuckin cool would it be to see a turbo charged top fuel dragster, though?! That would ROCK!

[sv650s]

but it would still kinda suck to have a turbo since dragsters need really good acceleration. the person you're racing against would be way past you and your turbo would have just started spooling.

[curtis73]

It depends on the application. Hate to give such a copout answer. Turbos can be tuned to come in at any RPM. You can have them act like a supercharger and give all their push at low RPMs, but it comes at the cost of poor high RPM performance and poor compressor efficiency. Conversely, you can tune a turbo for high RPM boost but it comes at the expense of having to wait for it to reach the boost threshold. (not to be confused with lag)

Newer designs like VATN turbos close the gap allowing full boost from off-idle all the way to redline

Superchargers are always on. They provide the same amount of boost regardless of whether or not you're idling in traffic, or screaming down the 1/4 mile. They are always there sapping power from the crankshaft, but some of their benefits are that they are usually less expensive and less complicated, provide a good boost in performance, and don't usually require modifications to the oiling system or oil change intervals.

There are a thousand reasons, most of which are answered in the stickies at the top.

I personally would prefer a VATN aerocharger turbo; variable nozzle for wide and efficient boost, and its own oiling: No oil plumbing, no wastegate, excellent boost. But that is also the most expensive way of force-feeding an engine.

Some of the main reasons why you don't see as many turbos:
1- cost. They usually cost more and are bit more complex to engineer
2- misconception. It used to be thought that diesels were the only engine that really benefitted from turbos
3- EFI. In the grand scheme of things, effective EFI is still a relatively new thing, and carbs take a lot of work to do well with a blowthrough turbo.
4- slow market response. Since not many people entertained the idea of running a turbo, the aftermarket didn't put an emphasis on developing smog-legal turbo kits.

[beef_bourito]

It deffinately depends on what your application is, your mechanical skill, your wallet, and how much time you're willing to spend. turbos are generally better, especially with new technologies. the turbine supercharger (turbocharger) concept in itself is more efficient than the belt driven supercharger. you're using wasted energy to make more power as opposed to stealing power from the engine. this means that you can get more power out of one.

now there are reasons for wanting a supercharger. if you want a quick install without many mods, it's great. also the power's always there and you don't have to tune it an awful lot. there is no lag whatsoever so you get that great thrust back into your seat. if you like the whine. but all in all, you can make a turbo setup perform just as well or better than a supercharger system.

As for turbochargers, they're only there when you want them so they're better on gas, superchargers are always chugging away. they make more power, etc, etc.

[longlivetheZ]

Originally Posted by curtis73

It depends on the application. Hate to give such a copout answer. Turbos can be tuned to come in at any RPM. You can have them act like a supercharger and give all their push at low RPMs, but it comes at the cost of poor high RPM performance and poor compressor efficiency. Conversely, you can tune a turbo for high RPM boost but it comes at the expense of having to wait for it to reach the boost threshold. (not to be confused with lag)

I was gunna say that.

Wow...someone else that knows about variable vane technology. It's stuff like this that just COMPLETELY negates any of the lingering pros a beltdriven s/c may offer...variable vanes, ball bearings, current level of knowledge about how turbo designs work...all this stuff has made the turbo the ONLY way to go.

[beef_bourito]

Speaking of which, how exactly does that work. how is it controled, tuned, etc. do you need to hook it up to a computer? I've heard about it but haven't found any info on how they work.

[19malibu70]

Turbo's usually consist of 2 seperate units connected together by a housing and by a shaft. Turbo's use a turbine which spins with the help of exhaust gasse's. The other internal part of the turbo is the compressor wheel which draws in fresh air and crams it into the cylinders under pressure. The faster the turbine spins the higher the output pressure or boost is achieved. When boost pressure gets to a certain level an actuator opens up the wastegate, this allows some of the exhaust gasses to bypass the turbine, reducing boost levels. Boost control is used to help prevent engine damage, boost control is accomplished either using a boost controller, map sensor, wastegate, or by engine speed (crank sensor, tach signal)!

[beef_bourito]

no, i know how a turbo works, i meant the variable vane turbos.

[curtis73]

Originally Posted by beef_bourito

no, i know how a turbo works, i meant the variable vane turbos.

The fins in the turbo change their pitch. At low exhaust flows they remain pretty flat, in effect making it so that if the little exhaust wants to get through, it has to move the turbine. As flow increases, the vanes open up letting more exhaust through. The vanes can be controlled by boost pressure just like a wastegate in a way that the vanes start closed and open up as boost reaches its peak. If you want 10 psi, you set it in such a manner that the boost is achieved early, and as flow increases, the vanes open up to retain the same boost throughout the load/RPM range.

With fixed vanes, you can set the wastegate to start opening as boost peak is reached, but you have to put up with the fact that your turbine is only tuned for peak work at a certain spot. Anything below that point is not making as much boost, and anything above that you're "wasting" excess exhaust flow. The VATN captures the best of all of it. It uses no wastegate, so you can utilize the most heat possible from the exhaust to efficiently turn the turbine.

Corky Bell's "maximum boost" book has a great writeup on VATN.

[longlivetheZ]

Here are a few places to get some info about them.

http://www.audifans.com/archives/1998/03/msg02356.html

http://www.realbig.com/miata/1995-04/332.html

For some reason, one place you will find these types of turbos in widespread use is in the Miata crowd. Not really sure why...

http://www.new-cars.com/news/030213-...-e400-cdi.html

http://www.honeywell.com/sites/ts/tt...2155701757.htm

That last one is awesome. All this just from about 10 min of pokin around. You guys want more info, lemme know.

Oh...and that Corky Bell book WILL BE the next book I buy. I've been tossin around the idea of working one of these types of turbos into the build of my VG30ET. I believe it's GREAT technology and it's a shame you don't see it much. It would definatly shut up the beltdriven supercharger guys.

[nissanfanatic]

Well if you listen to top fuel dragsters, they really aren't using much of their lower RPM range. They slip their clutches all the way down the track.

I highly doubt power is the problem with top fuel dragsters.. but no doubt, I agree that they could benefit greatly from running them. I bet they would blow up less engines.


lol nothing shuts any car person up... I am reminded everytime I see a decently set up foxbody that I pay way too much for my speed, but I love the feel of a turbocharged 4 cylinder plus I love to beat people that think my car is slow. Simple as that.

[Black Lotus]

Originally Posted by longlivetheZ

But look at the turbocharged Formula 1 engines of the mid/late 1980s. They were getting ~1400 - 1500 hp out of 90 CUBIC INCHES!

Now now, don't get all starry eyed! Remember that was qualifying using max. boost. During the race they toned it down to only 900 HP or so.
Almost as much as one of Curtis' popcorn smelling diesels.

Originally Posted by nissanfanatic

lol nothing shuts any car person up...

Especially Mustang or Neon drivers, jeez!

[Schister66]

one thing i was thinking of is that if you were boosting, you'd have a lot more tubing and more hassle that if you just bolted on the SC and put the carbs on top. IDK if those cars have computers or not, but if not, they'd need them. They'd need some big damn fuel injectors and probably IC's....idk since its soo short of a run.....

Turbo = more power, but more hassle on that application