I've been researching power adders, and most sources tell me that turbos are mor efficient than superchargers. It makes sense to me, since turbos draw power from heat, while superchargers draw power directly from the crank.

http://members.tripod.com/tomak3/page10.html

But most people on here use superchargers. The ATI ProCharger seems particularily popular.

So, why does everyone use superchargers?

 

A supercharger is simply a lot easier to install. Nobody makes a bolt on turbo kit that I'm aware of for C4's. Turbos take a lot of extra plumbing in an already fairly cramped engine compartment. It's not that it can't be done but all the custom fabrication makes it somewhat costly.

Several companies make supercharger kits that could be considered "bolt on" ready. They are simply cheaper and easier, so that's probably why most people use them. :cheers:

 

Functionally, the two are very similar. Nathan's right - the install on a turbo can take years off your life. But absolutely nothing makes power like a turbo. And once it's installed, tuning is just like a centrifugal supercharger like the ATI. I had a procharger on my mustang for years, and it's a great unit. I'd really like to see someone step up and document a turbo install on their car.

 

A SC will also make more streetable power, meaning torque, though less hp than a turbo its still a great deal more than your engine will make. Turbo's usually make HP, but you have to get them some rpms before they make anything, so you wont get that great power boost from a redlight, youll have to get up to speed to get em moving.

 

Uhh... turbo's make insane torque. Look at the TT Callaways. 375 hp and 575 ft/lb. A roots style supercharger will make full boost the instant your put your foot down though.

Another point.... tuberchargers put almost no load on the engine itself compared to a supercharger that uses a decent amount of power to turn in the first place.

 

I think the point Vader was trying to make is that turbochargers add more power to the upper end of the rpm curve because they take time to spool, while superchargers take no time at all. However, a SC will still add more high-end power than low-end because it relies on engine rpms.

So, the ultimate advantage of the turbo is that it doesn't rob your engine of as much power as the supercharger does. The disadvantage is the complexity of the installation.

I think I'll go for a SC considering my lack of experience with modifying engines. Maybe my next hot rod will be turbocharged.

:auto:

 

I'll disagree with the old "turbo lag" problem. Today's turbos can make full boost in the 2300 rpm range. I have friends who race turbo V8's, and it's amazing how these things behave. If you're talking about a huge 90mm turbo, that's a difference story. But the smaller street ones make more boost, sooner, than a centrifugal blower.

 

http://www.jdhcon.com/Vette.html

Not my car, but fun to read.

 

Turbo lag if set up properly is pretty much non-exsitant in V8s.... In my eyes... The V8 by it self has enough power to propel it up and out of the
hole..... the turbo will just help that


FullBoogie----> This guy did a great job

http://www.meacham.pointclark.net/Home1.htm


[Modified by StealDads67, 8:53 PM 1/10/2003]

 

You're going to have some lag and, more importantly, a boost threshold when running turbos. If they'e small enough to make boost off idle, they will superheat the air at 3000rpm. With the small block, you can make enough torque to not worry about a boost threshold. A centrifugal blower will not make as much boost throughout it's operating range as a properly sized turbos because pulley size is the boost limiter; max boost arrives at max rpm. With roots or screw blowers, you'll have near full boost just off idle.

 

ALL forms of forced induction heat the air, because it's compressed. That's what an intercooler is for.

 

Yes, but my point was that a turbo small enough to make boost off idle will have very bad thermal efficiency higher up. Basically, you can't have your cake and eat it too. If you want a turbo to work off idle, you won't be able to make a lot of boost and/or work well in the mid to high range. If you want a turbo to work in the mid to high range, you'll have a higher boost threshold. VATNs and low friction bearings can help a turbo work better throughout the rev range.

 

Following on Nathan's reply says it best, space utilization. Go look at a few engine compartments with an open mind, but viewing the empty space, where it is, and what could be put there.

Open the clam-shell on your car and stand next to either wheel. Now look down at the plugs and the exhaust. How much space do you see between the frame and engine down there? Could you squeeze a child's hand down through there? That's where a turbo has to live to get the most exhaust energy for boost. If you route the plumbing up above this point then you bring superheated pipes up to the top of the engine compartment. Now how do you move this air out?

Now step back a litle bit from your wheel and look at the empty spaces surrounding the top of your engine. You can fit a lot of plumbing in here, and it hooks up naturally to a SC that is driven as an accessory. Plus the SC plumbing is not superheated. Make sense?

Now to get a grasp of why the ricers love turbos so much, go to a rice fest somewhere. Heck go do a Honda dealer and ask to look under the hood of a Civic. What do you see between the radiator and the engine? About a foot and a half of space? And what is the first thing you see on the engine, the exhaust? Whoa, a natural space right front of the engine to fill with turbo goodies an that is the exhaust side. And there is only one exhaust side to deal with, not two. Plainly speaking, even with an intercooler it naturally fits the space that is available in a front wheel drive car with the sideways engine. It's almost like the designers were thinking ahead, but they were just keeping heat away from the firewall and the passenger compartment. And on the Hondas in particular they moved the front bumper forward to add crush space for accident protection. But it sure makes a great space to put a turbo.

Whether you choose a small turbo for quick spin up and low end boost, or a BIG turbo for extreme top end boost is just a component choice, they still have the same packaging problem (or ideal space available).

 

turbo is better in almost every way except for expence and installation (on regualar cars- maybe not on hard core strip only cars)

You can also spray a nice 30hp shot (reccomended) on a turbo to cool it down :)

Turbo is also much more tunable and efficent.
Lag doesn't exist on our motors (unless you go radical)

 

I never said that they didnt, you have to make torque before you can make HP. Its just that the SC's power will be on demand off-idle, and you usually have to get the turbos spooled up before they kick in. On V8s, as these guys have pointed out, this isnt as big a problem, but i was just pointing out to him what some differences were.

 

On a roots system, yes... but the centerifugal ones need a little spin time to get things pumping.

 

Well, I have discussed this extensively in the past regarding Mustangs and learned quite alot from that as well as personal experience with several friends that had them (being turbos and superchargers).

First and foremost , turbos utilize exhaust to spin them and can make tremendous power and are very efficient. Down sides are lag (and there is some lag with all turbos), heat , and packaging. With relatively large V8's like ours you start with alot of low end already so things feel more seemless but turbos can be set up in several ways. You can have a relatively small one that spools up quickly at low rpms but is limited in top end. You can have a large turbo that makes tremendous top end but spools more slowly and lags alot. You can sequence them (ala Supra or RX7) so one comes on to spool up quickly at lower rpms and one comes on later for more top end. And everything in between. You HAVE to control heat, turbos make tons and it kills power , reliability and everything under the hood. This means big intercoolers to really work well.

With supercharging you can go one of two basic routes. First is very popular today, centrifical superchargers like a Vortec or ATI. These are very similar to turbochargers but are driven by the cars crank instead of exhaust gases. Because they (all superchargers , actually) are engine driven , they use some of the engine's power just to be turned and thus are not as efficient as turbos. The advantage to this is instantaneous boost. When the engine is accelerated the supercharger is turned and boost is made. With centrificals , more boost is made the faster they are turned and they are strong top end performers and relatively weak low end performers. The other type of blower is the positive displacement type , like a roots or whipple (ala almost all production supercharged vehicles like Lightning and Cobra etc.) These blowers generally sit atop a modified intake on top of a V8 . They usually compress air with two screw like devices instead of the turbine like or fan like centrifical (which is similar to a turbo). These blowers are also driven by the crank and can produce boost as soon as they are turned but they can make much more boost at much lower rpms creating alot of power lower in the rpm band relative to a centrifical of the same capacity. They dont have the top end flow of a centrifical generally though.

Supercharging also generally requires heat management like turbocharging though not to the same extent because they dont spin as high or get as hot. Air to air intercooling and air to water intercooling are the two types generally used. Packaging superchargers is a bit easier because of this . Both are good sources of power and have their advantages but a well setup turbo system on the right engine is really the best IMHO. Both are relatively tricky to tune correctly and generally are not as reliable as a well made naturally aspirated engine. I still would prefer large displacement N/A power myself with good linear power bands , reliability, and less complexity.

Supercharging is most cost effective these days because they can be used without intercooling for most low boost installations and they are relatively easy to find room for in most engine bays. With turbos there is more plumbing involved with the exhaust, special headers usually, a NEED for large intercoolers etc. This also generally makes them a bit more expensive as well (as far as a kit goes) and more labor intensive to install. Because of these things , there are alot of superchargers available and few turbos .

Tried to keep it as simple as possible . Hope that helps...... :seeya

 

There's been a bunch of really good comments on this thread - I like it. We've got a lot of knowledgable people on the forum. I've got one more comment:

I don't hear anyone talking about supercharger "lag". I don't think this guy is going to put a roots blower on his car, so we're talking about a centrifugal. And ANY street centrifugal (<10lbs) is going to be making around 4 lbs of boost at 4000 rpm. The 9 or 10 lbs peak boost will come on at around 6000 rpm.

A "street" single turbo will be blazing away at full boost by 3000-35000 rpm, and can put a 3400 lb car into the high 10's at over 120mph. I've had both a centrifugal and a turbo race car, so this isn't just guessing I'm doing. A turbo will make more power, sooner, with more hp under the rpm curve than any street centrifugal blower. Period.

Now, as far as practicality, everyone is absolutely right. The average hot rodder won't want to touch a turbo with a 10 foot pole. They're a nightmare to plumb, and the heat considerations are enough to turn most people away. That said, if I ever go back with another power adder, it's going to be a turbo. To me, they're worth the extra hassle on initial setup!

 

Excellent points, fullboogie.......centrificals are really top end performers. Turbos on V8s really are awesome.....I especially like a twin turbo setup with two "medium"sized turbos , one for each bank of cylinders-similar to the setup LPE is doing for LS1 cars..... These spool relatively quickly and still yeild pretty good top end flow , performance , even at very mild boost psi is breathtaking. Man the cost and install is big though...... :seeya