Turbochargers Vs. Superchargers

by Jerry Smith on Tuesday, March 8, 2011 05:01

The natural world is a good thing––after all, we live there––but sometimes it needs a little help, like when it comes to engine performance. Naturally aspirated engines rely on atmospheric pressure to fill the cylinder when the intake valve opens and the piston moves downward in the bore. But nature has its limits, and the more air you want to pump into your engine, the more you have to juggle cam timing and other factors that can make an engine a screamer on the track but a dud on the street.
One alternative is to connect an air pump––either a turbocharger or a supercharger––to the engine to do what nature can’t. Turbochargers and superchargers do the same job, but they go about it in different ways, and it’s important to know the pros and cons of each before you decide which path to power works best for you.
Turbos are often called “free power” because they use the engine’s exhaust gas to spin a small turbine that forces air into the intake system. The turbo is plumbed in line with the exhaust system, so the higher the engine revs, the faster the turbo spins, and the more air it pumps into the engine.
Turbos are relatively simple to install, but they suffer from what’s called turbo lag, which is the time it takes for the exhaust gas to spin up the turbo. Lag is most noticeable from a standing start when the engine is idling, but it can also show up when you want to pass another car and you mash the throttle––and nothing happens until the turbo spins up. Finally, since they’re connected to the exhaust system, turbos generate a lot of heat. A tight engine bay might need to be insulated to protect other underhood components.
Superchargers do the same job as turbos, but go about it differently. Instead of being plumbed into the exhaust system and spun up by exhaust gas, they’re belt-driven by the crankshaft, so they spin up as fast as the engine does with none of the lag of a turbo, and nowhere near as much heat.
Superchargers have their own drawbacks, however. It takes power to run them, making adding one to your engine a sort of two-steps-forward-one-step-backward proposition. And because they’re driven by the crank, the mounting options inside the engine bay are limited to those that have access to the front pulley.
Turbos are winning the war for car manufacturers’ hearts because they’re easy to add to existing small-displacement engines to boost power output, and because a properly sized turbo on a small engine doesn’t have a lot of lag, making it easier to drive on the street. But superchargers still rule the quarter-mile, where big-displacement engines are the norm and instant torque off the line is vital to a winning ET.

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I like this, simple to the point, great education for anybody looking for it. Should be a sticky under gerneral tech

 

Thanks, and thanks 2 `Space

 

Centrifugal superchargers are making gains (as they are less complex) on the Turbo crowd with the addtion of intercoolers to cool the intake charge and bigger step-up ratios to "Spool" the impeller up faster the crank.

Either way FI is big $$$$.

I am looking at N2O injection as an alternative as the intial expense is less and does not affect driveability like a big solid roller cam/high compression N/A engine does.

Hopefully this post complements the OPs original intent.

 

i was told that if you want power a lot quicker go with the supercharger, which is what you put, but if you want more overall power, go with a turbo, now i want to go with a turbo, but on an 05 LS i think it would be hard to go with the RIGHT type of turbo, for i dont want anything to small, and definately dont want one that is too big, so i was gonna go with a supercharger since the SS Supercharged brnad of the Monte, so after reading about the superchargers, will it be better to buy, and install all supporting mods for the supercharger, then getting the supercharger, so that i can have all the needed parts, have the car tuned, so that there will be no problems in the long run, right?

 

Great write up for sure!!!! Thanks for posting, I'm a huge Turbo Fan, but I do appreciate both types of power adders, nothing like a Turbo GN or a SC Cobra....I plan on eventually going the supercharger route with the GTO eventually.

Again great post!,
Joe

 

Things to note about the original article:

A good quality, properly sized turbo won't have hardly any lag. I notice a lot of comparisons between SC and TC use this as a big negative point for turbo setups, but it can be extremely minimized. They talk about lack off boost off-idle, but we have a little different situation with these FWD cars- they can't hook big power from a dead stop anyways- so having full boost just above idle is rather useless since you're likely going to be pedalling through 1st, and maybe even part of 2nd anyways.

If you're talking about at a track- for drag racing, its no big deal. A loose torque converter or a transbrake/2 step setup will help you get you into a little boost out of the hole, if you can put the power down. On an autocross or tight road race, I could see it being a minor disadvantage, but since these cars aren't really particularly competitive in those events anyways- I don't see that many people using them for that purpose anyways.

However, one benefit of a turbo is it is remote mounted- so adding an intercooler to cool off that heated air is very easy to plumb inline. The people with positive displacement superchargers have to deal with building oddball manifolds to run an A-A IC, or have to use a heater core to use as a W-A IC (which is typically less efficient because you have heat transfer efficiency losses due to using a separate fluid to convey the heat).


They don't really separate them out here- but there are two different supercharger types used- positive displacement (think top fuel V8), and centrifugal (basically the intake side of a turbo spun by the crank). A centrifugal doesn't have the 'lag' of a turbo, but it does slowly ramp up in boost- instead of being at near full boost instantly like a positive displacement supercharger. Also, they're referring to heat put off externally here again- the primary concern should be heat added to the air going into the engine- and positive displacement superchargers are notorious for heating the heck out of the air (especially overdriving the snot out of them like the L67 guys do)- and as mentioned above, they're also harder to intercool to pull that heat back out of the intake air before it goes into the engine.

I understand top fuel and such still run superchargers- but aren't there a lot of other drag racing classes where turbos are becoming the norm?

I have two problems with nitrous- one being having to fill the bottle (which definitely isn't cheap), and two being the car is still slow 99% of the time, so its less fun to drive. With a boosted setup, all you have to do is press the throttle down harder- and you can have the extra power 24/7- no need to worry about refilling anything, making sure a bottle or switches are turned on, etc. The other thing is, while the bare bone kits are dirt cheap- if you get a fully optioned kit with all the safety features and controls, the price adds up real quick, and some of the cars on here (ie the 3800 cars) can usually do a top swap for the price of a well optioned nitrous kit.

Its not as hard as you think. I'm not sure if they make any turbo kits for the 60* engines in these cars, but if you're making your own kit- any decent performance shop should be able to look in their turbo selection catalog, and pick a turbo setup that has your desired flow rates right in the middle of the efficiency islands. As long as you don't buy some cheap knockoff junk turbo, and it is sized correctly- selecting the right size should be no problem.

I could be wrong, but the 05 LS came with the 3400 right? If that's the case, there isn't currently a bolt on supercharger kit that I'm aware of, unless you plan to build a custom setup.

Obviously, the best way to do it would be to do it all at once. I'd say its most important if you're going to lower compression or change to a SC specific cam (or both)- since you don't want the car to be a total dog (ie slower than stock) until you can afford the SC. Plus, it'll save you from having to retune the car, and keep changing SC pullies- if you have all the supporting mods in at the same time, you can pick the single best pulley size- tune for that, and be done.

 

Just want to add 2 things for me regarding nitrous, it better be installed correctly, I have seen lotsa cataclysmic melt downs at tracks and such...obviously this goes for any setup, but I tend to see them blow up...literally much more for some reason...I think newer kits are better these days to setup.

Also, people really need to geta feel for nitrous...when it kicks in some aren't ready, or know what to expect and that ussually causes the car to jerk in one direction or another at a decently high speed, which ussually ends up with bad results.

JMO, but I'm with Bumpin' I'd rather have a turbo/supercharger setup any day over Nitrous.

Joe

 

..WoW, thanks Chad, Joe, member's for sharing your experience, and knowledge on this powerful subject
I learn more everyday on the MCF ~> Thanks for taking time from your life to `Share ~> 4-Sure

 

i thought they had a supercharger at least for the 3400 division engine, but if not i will look into a turbo, but if that does not wirk out, i will learn how to drive a manual trans and buy me a V8 GTO or something and use the Monte as a daily driver and just do some simple mods. thz for the info