Why doesnt anyone believe it takes power to run a turbo?

No. turbo's are not free energy.

You'd be surprised how close turbo's actually are to superchargers.

Here is a few key points.

PMEP (pump mean effective pressure). The excessive exhaust manifiold pressure vs. intake manifold pressure takes power away from the engine through pumping losses. Trade off will be pumping loss vs. transient response. More ex. manifold pressure means smaller turbine and quicker response. A properly sized oem turbo will have high pumping loss at the top end.

On a supercharger, its the exact opposite, the high intake pressure and low exhaust actually puts engergy back into the engine through positive puming work. This esentially reduces the amount of energy the supercharger takes from the engine.


However, in the low rpm range, the turbo will have a significant edge in terms of lower power consuption.. but it also has a hard time with transient response in that area as well.. (remember... your not using power if your not producing boost!)

Everyone measures intake manifold pressure.. but with a turbo, you want to watch exhaust manifold pressure as well.

 

I understand a turbo takes exhaust energy to spool it. It doesn't however take power from the engines belt system to spin it like a supercharger. The supercharger causes a direct pararsititc drag on the engine, whereas the turbo utilizes the engines "by-product" exhaust energy creating a very minimal amount of drag on the engine. With a proper turbo and exhaust size, the exhaust will still flow freely. Once the turbo is in full motion, it will require even less effort to keep it spinning at that speed as well. Newton's laws here. That is also why turbos have great top end.

 

hmm.. well i hate to break the news to you.. but "once the turbo is in full motion" statement is false. If the turbine and compressor wheels had large moments of inertia, i may agree, however, with lighter and lighter wheels, the ineria effect is very minimal. Newtons laws are at work.. but you must apply them properly.

Here is a theoretical situation.. your boosting at 20psi.. and you instantly uncouple the turbine and compressor wheel, The compressor wheel would slow down nearly instantly and your boost would be zero before you could blink. Even supercharger with LOTS of inertia slow down VERY fast once the belt breaks under full boost.

You have completely miss how turbos work, the energy is not put into spooling the turbo. The reason turbo's take a while to spool is the fact air is compressible and you must create enough mass flow through the turbine wheel to spin the compressor wheel..

The most energy used by a turbo is during full boost high rpm situations.

The only reason most people dont understand is because they cant see it like they can see a belt.

Your parasitic drag argument is also not completely correct... Parasitic losses would be under no boost conditions.. where the pressure on the INLET of the supercharger is the same as the pressure of the OUTLET of the supercharger.. if the supercharger is still requiring energy in this condition, its considered parasitic loss. And FYI.. your M62 uses less than 0.5hp under these conditions.. Why do you think OEM's dont use screw type SC's??? Internal compresson! you must use more energy to compress air inside the supercharger and then spit it out back to the same pressure as the inlet. This happens during cruising conditions.. i.e. driving down the highway.. your using more energy for no real reason. The Roots type has no internal compression, so once the bypass valve opens, it doesnt compress air and uses very little engergy.

The belt losses can be calculated in terms of efficiency... It takes work to compress air, and the belt consumes this theoretical amount plus some inefficiecy due to bearings and gears.. but that is minimal.. just think, if you were loosing tons of energy through the bearings and gears... you would be heating the crap out of it and melting down the system.. Where else would that energy go? Do you need to run a cooler through the supercharger oil? Nope... Basic laws of Thermodynamics.

It requires energy to compress air, you cannot avoid this. Turbo's are not exempt

 

I was unaware that my blower needed its oil changed. Or are you referring to other types of superchargers?

 

We need the whipple now!!! lol

 

A little off topic, what is the final goal of your car (besides a hp number.) What I'm saying is what are you going to do with 400whp, is it going to be a track car, a dd, an auto-x car? What is your reasoning i demand to know!

 

The obvious thing about a turbo i believe someone forgot to metion is you can change the boost pressure without going haveing to change the pulley. it makes it very easy to dial in a set boost you would like. not saying changing a pulley is too difficult.

 

Right, when I saw that I freaked out...I'm rushing now to check the owner's manual!

 

I'm going with the blower swap. Love the sound, instant torque, and the time it would take to go back to stock. It just seems more practical and being able to hit between 350hp and 400hp is enough for a fwd car. I plan on getting it as soon as I see what others responses to the swap are. Yeah, I'm a chicken.

 

I always thought Eatons were good to at least 100K miles before maintenance. Usually involves replacing with 16k rpm bearings again and a new coupler if worn.

 

I for one eventually plan on running nitrous along with my SC Seems to me that The SC is a better platform to make more horsepower then a N/A 2.2 running nitrous. True it will have 2 power adders but but i think thats what this game is about!

 

Thats a stupid statement. Superchargers have a bypass valve to get rid of excess air. Just run the smallest pulley you can then use a boost controller to limit the amount of boost. This will cause full boost earlier if being limited lower then what the pulley wants to spit out.

 

In my opinion the statement in bold is enough not to buy from this guy. Maybe I'm old fashion but I think running down competitors is just childish and unpoffesional. If he has a better product he should back it up on the track and by putting good products out on the street not by telling you Hahn sucks. It's just unproffesional and basically he is just trying to sell you his crap. You didn't think he would say "oh yeah Hahn's product is far superior to ours and their track record is impecable, but yeah go with us, please please please!!!"

By the way I have no affiliation with Hahn, I've never used their products, and I have never had any contact with them. Their product may very well be inferior, if so this is the place to hear it, not from a guy trying to sell you his stuff. It's just everytime I hear a vendor run down another I just roll my eyes because it seems childish.

 

I'm interested. On Blown 4-bangers car the computer is commanding a .8 pulse width with the idle set at 1050rpm. Minimum recomended by Siemens is 1.0 if I remember correctly.

 

I think we're on the same page here, and I agree with you. What I wanted to say, and what I typed wasn't quite coming out quite right I guess. When I say parasitic drag, I'm referring to the power it takes to spin the blower. The faster the blower spins, the more power it requires to spin it at that speed, thus it's a increasing "parasitic" drag. I realize that the turbo at full spool and producing max boost would slow down quickly like your theretical situation suggests. Where I was basically going with the turbo was that once it's compressing air and forcing it into the intake tract, the air coming out of the cylinder head will be moving more quickly as well and keep the turbo spinning fast. The turbo actually helps itself out in that aspect whereas the supercharger doesn't benefit from helping itself out. Does that make a little bit better sense of what I was trying to say?

Oh, and on the supercharger oil changing, it's different for your stock Eaton. Please do not get worried. I'm not sure what the Eaton's requirements are off the top of my head. I pulled that oil change info off Kenne Bell's website for the twinscrew applications.

 

How does a supercharger not help itself? It creates more forces inside of the chamber and foces the piston down which rotates the crank which spins the supercharger. How could make such a stupid statement as a supercharger does not help itself create power?

 

No, it was commanding a .9 pulse width at like 850, but at 1050 its like 1.0.

 

Whipple All The Way!!

 

Put it this way. Take the same car with a turbo and take the same car with a supercharger. If both the turbo and supercharger theoretically put out the same CFM's, the turbo'd car would make more power in the end because it isn't directly pulling power from the crank to drive it. This is where I am going with this whole ordeal. No more and no less.

 

Then stat it that way, thanks.

 

I understand what you are saying but i think your thinking about it wrong. Look at it this way: It doesnt matter where the energy comes from (belt or pumping losses) power is power. If your using 35hp to drive a supercharger through a belt and then get 5hp back in positive puming work for a grand total of 30 hp used. Then if you have a turbo that takes 30hp in negative pumping work you will end up at the same point... does not matter if your driving through a belt or not, again, power is power. Pumping losses DO pull energy from the crank.. the pistons are acted on by the pressure, forces sent through connecting rod and finally.. the crank!

Now finding the best setup for your engine will be a compromise of a number of factors and energy used to drive the boost system will only be one part..

 

Very true. There is no such thing as free power.

 

I think were at a stand still here. I just did some more research, and to an extent we're both right. Added exhaust backpressure caused by the turbines impeller will rob power. Superchargers pull power from the crank to create power. Both systems rob power and do not give "free" power. The turbocharger is usually more efficient however at making the total net power. The supercharger is great at making torque and power down low.

The decision is based on what the person wants ideally here in the end. I hope we all can at least agree on that. I personally am going with the Lysholm 1200AX twin-screw swap because I want the flat torque curve, great power down low, and a decent gain overall.

articzap, I'm sorry if I offended or pissed you off somehow because it seems like you’re angry with me for some reason. I'm not sure if you were intentionally being rude or just came off that way, but I was just trying to provide a decent and informational comparison with the assistance of the fellow ss.net members here to answer the question that started this whole post. Either way I'm hoping we can just end the confrontation and go about our business on here.

 

Turbos are much more efficient than a comparable flowing blower. Efficiency ranges on well chosen blowers at redline usually fall around 50% where most comparable flowing turbos will come in around 75%. On an M62, at 16000 RPMs, making 10psi (even worse for us with our mouse motors and intake manifolds) the blower leeches 40hp+ off the crank. Since we run much higher PRs on this car than most typical M62 applications, that number is probably almost doubled. However, the added torque down low, and a constant PR across the power band is what makes the blowers such an attractive choice, obviously.

 

I was trying to **** anyone off or make anyone angry. I just want to make sure stuff is said correctly so everyone has the correct information. I'm cool if your cool.