Pros and cons between turbo and supercharging

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Valiantap6

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What is the pros and cons about turbo and centrigual supercharging a smallblock, I'm supercharging mine (vortech) but wondering what difference turbo would have been and weather should have gone that way
 
The difference is with a turbo you usually get a totally inexcessible enginebay because of all the plumbing.
And most of the power comes in at higher rpms, not immediate like with a supercharger.
 
Also know that a supercharger takes power to make power while a turbo uses no power to make power.
As far a lag goes if you do it right, you can reduce lag greatly.
 
Fastest street cars in the world use turbo chargers. That should tell you something.
 
I have had all of the above I will not use another centrifugal super charger again I had problems with the belt it was 12 grove also at 100 bucks a pop I bough two after the original popped and then I seen how a lot of guys was running good numbers with a turbo so on my experience I changed and never looked back yes there is pluming involve but it's not that hard and there are people that is going tell you different stuff to do you just need to set a goal on what HP you want I had a my Dakota blow through set up went 10.90@124 0n 10Lbs it was 3420lbs check out topfueldart build he has a nice build with a 318 runs 11's .Good luck
 
Fastest street cars in the world use turbo chargers. That should tell you something.


And the quickest cars on the planet are supercharged... So what?

I haven't had the chance to build a turbocharged car yet, I've only messed with centrifugal and twin screw blowers. My next build will be a big inch twin turbo build, though. Turbocharing is pretty interesting to me. The obvious advantages of having no belts do deal with, and being able to adjust boost levels so easily, are just the begining.

Blower cars done correctly, can be pretty reliable and fun! Can't go wrong either way imo.
 
Also know that a supercharger takes power to make power while a turbo uses no power to make power.
Not quite. Laws of physics essentially says that something can't come from nothing. So the turbo cannot make power from nothing.

Supercharger takes power directly from crank. Turbocharger takes power from exhaust gas velocity and heat. Does turbo motor lose more power due to exhaust back pressure than supercharger cost in drag on the crank? Up to a point, no. While the fastest street cars in the world use turbochargers, the most powerful, fastest accelerating cars use rootes-type superchargers.

As far a lag goes if you do it right, you can reduce lag greatly.
Simplistically
1. There is a balance between the size of the turbo and volume it will put through. Small turbo: spools up quick, may not let motor reach full potential. Large turbo: takes more engine rpm to reach boost pressure (lag), plenty of compressed air on top end.
2. Keep the run of cool air tubing as short as possible. Reason? Smaller column of air to keep pressurized. An intercooler adds to length of column of air but cools charge.

Longevity:
Because of extreme heat of turbocharger, lubricants are stressed. When the engine is shut off, oil pressure goes to zero stranding lubricant in the shaft bearings of the turbo. These lubes get cooked (coked) in place. When the engine is re-started, fresh oil cleans it out. Sometimes the residue is broken up, sometimes it gets pushed up into bearings and seals eventually causing them to fail. The supercharger typically does not run nearly as hot, so much less bearing/seal issue. Solution for the issue: Let engine idle 3-5 minutes after hard run to let engine oil cool.
 
And the quickest cars on the planet are supercharged... So what?
The quickest "race cars" are, and he's not building a race car. Nitro cars use a blower because of the volume of liquid fuel that needs to be physically pushed into the engine, not because it is a better system are makes more boost.They are making 8000HP with only about 45lbs of boost.It's basically more of a liquid pump than an air pump..Your not going to get a turbine to be able to do that sort pumping action.
Turbos are just easier to manage , more reliable and make power from a waste product. Also they are easier to bleed the boost down on when you want to do some street miles on poor fuel.
 
A buddy of mine had a small B&M blower on a Chevy 350 sb. He always had a can of "belt grip" in the glove box as well.
 
And the quickest cars on the planet are supercharged... So what?

It's a moot point because the NHRA rulebook specifically outlaws turbochargers in the Fuel classes, and has for years.

The Flowrite-sponsored team of Gordie Bonin and Jerry VerHuel ran a twin-turbo, FUEL funny car back in the eighties and because clutch and tire technolgy weren't up to the task, they only succeeded in blowing the tires off the car, run after run... too MUCH power to control at that time.

There has to be a reason NHRA won't let them run...:blob:
 
It's a moot point because the NHRA rulebook specifically outlaws turbochargers in the Fuel classes, and has for years. There has to be a reason NHRA won't let them run...:blob:
IMO it has to do with regulating boost. I read the NHRA's rule book concerning use of turbos in Pro Mod. It's severe. They are showing signs of loosening up, but don't hold your breath. Rule making bodies aren't known for moving quickly, except when showing someone the way out.

In defense of NHRA (or NASCAR for that matter), they don't want anything that will screw up the show. A track oil down from a grenaded motor or domination of a particular car tends to screw up the show.
 
Never have run a supercharger so cannot comment on that. I have been running turbos in rally for about 15 years. One thing that I have learned is that there is a big difference in low end response on a turbo depending on the blade designs in the impeller. Some outfits have become specialists in this area, and the tweaks on the blade shapes and edges can signficantly lower the low end RPM's where the turbo will start producign usable boost. I have gone from a standard 14G to a 16G to 16GSuper and the overall performance has picked up, especially with the Super 16G.

The one other good trick has been to raise the compression ratio a bit and limit the boost. Low CR's in the 7 to 8 range are not abnormal, but moving the CR up to 8.2:1 on this particular engine (Misubishi 2.6L) brought the low end response up to where there is no noticable lag effects. Boost is limited to 15 psi to run on pump premium. This experience has made me think that for sprited to hard street use, there is a happy medium between CR and max boost. Most tuning focusus on max HP numbers, which I think is a mistake unless you are at the drag strip.
 
IMO it has to do with regulating boost. I read the NHRA's rule book concerning use of turbos in Pro Mod. It's severe. They are showing signs of loosening up, but don't hold your breath. Rule making bodies aren't known for moving quickly, except when showing someone the way out.

In defense of NHRA (or NASCAR for that matter), they don't want anything that will screw up the show. A track oil down from a grenaded motor or domination of a particular car tends to screw up the show.

MY opinion... I am of the opinion that the NHRA is "in bed" with the rootes blower manufacturers and by outlawing turbos, are protecting their market for them. Just my opinion after watching this dog-and-pony show since 1955......

Likewise, the pneumatic valve spring that are illegal in ANY NHRA class. The Alcohol Funny Car racers spend huge amounts of money on metallic valve springs. HUGE!

Formula-1 engines spin 20,000-rpm for hours on end.... with valve springs that they only have to buy ONCE, because they never wear out.... You can't wear out AIR...
You do the math...:supz:
 
OP's question was about belt drive centrifugal compressor vs exhaust drive centrifugal compressor.

The answer is not much. Both take time to spool. If you overdrive the crap out of a belt drive & use a blow off if will make boost earlier - just like a turbo with a waste gate

.
 
Might be silly question but what does overdriven mean and how do I do this obviously it's change of pulleys I'm guessing
 
If the output RPM is greater than the input RPM, it is overdriven. So if the pulley on top is smaller than the pulley on the crankshaft, it's overdriven.
 
The turbo is driven by what is mostly waste heat in the exhaust. It is NOT driven by exhaust gas flow, which takes some mind-bending to grasp. I'm not sure that I fully grasp it. A lot of 'cold' exhaust flow won't produce as much boost as will a lessor flow that is 'hot'.

There probably is some parasitic loss to the engine, but for the most part it is driven by the heat in the exhaust that is otherwise just wasted. When you figure that about 1/3 of the total energy in the fuel tank is destined to go out the exhaust pipe, the available heat is pretty substantial.

Also note that turbo-charged engines benefit from larger than expected exhaust systems downstream of the turbo itself. There is a reason that the norm for a 5.9L CTD is a 4" tube and the really hot diesels are running 5" & 6" tubes.

Anyone who has ever been around a racing Rotary Engine knows how unbelievably loud they are. They're easily more painful to be around than a top fuel dragster! Easiest/best way to quiet one down is to turbo-charge it. Sound is a form of energy, what better way to muffle an engine than to put that energy to work?

The various variable geometry turbo's out there address the lag inherent in using a turbo sized for the top end. Then there are the compound turbo systems with a big and small turbo on the same engine.....
 
There probably is some parasitic loss to the engine, but for the most part it is driven by the heat in the exhaust that is otherwise just wasted. When you figure that about 1/3 of the total energy in the fuel tank is destined to go out the exhaust pipe, the available

I looked at a number of turbo forums, searching "exhaust back pressure vs. Boost."

I found that boost that equaled back pressure in the exhaust was a pretty rare thing... only couple of instances. That tells me that the back pressure from the turbo/restriction was probably costing a LOT of horsepower, because some of the examples had boost/back-pressure ratios of 1.5:1 and more. That meant that with 20 pounds of boost, the exhaust valve was opening to an environment of 30 pounds of back pressure (and, more.)

I fail so see how a sizeable horsepower loss could be avoided under those circumstances. I don't think turbocharging is "free" ot anything close to it...

Just my 2-cents...:glasses7:
 
Valiant, pick up or download Corky Bells 'maximum boost'. It will give you a great insight on why to go turbo over other conventional methods, and may even answer some questions you may have about turbocharging. It is the beginners handbook to all things turbo. I can't tell you the number of people who are dumbfounded seeing a turbo on one of these old Mopars, many are still stuck somewhere between the lines in a vintage Direct Connection engine manual; still attempting to get the 'quench effect' and ordering porting templates for their 906 heads..
 
Valiant, pick up or download Corky Bells 'maximum boost'. It will give you a great insight on why to go turbo over other conventional methods, and may even answer some questions you may have about turbocharging. It is the beginners handbook to all things turbo. I can't tell you the number of people who are dumbfounded seeing a turbo on one of these old Mopars, many are still stuck somewhere between the lines in a vintage Direct Connection engine manual; still attempting to get the 'quench effect' and ordering porting templates for their 906 heads..

What he said!!! :supz:
 
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