Age old question. Turbo Vs. Supercharger - Page 4 - Hot Rod Forum : Hotrodders Bulletin Board
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View Poll Results: Turbo or Supercharger?
Turbo!! 26 37.68%
Supercharger!! 43 62.32%
Voters: 69. You may not vote on this poll

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  #46 (permalink)  
Old 10-31-2004, 06:33 PM
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Quote:
Originally posted by killerformula
This makes sense to me, does anybody disagree with the statement? It seems that a turbo doesn't NEED or USE the heat from exhaust gas, but rather it just uses the energy of the motion of the gas like one fan blowing on the blades of another. Seems if the exhaust of an ICE were cool, but had the same velocity and volume, it would still spin up the turbo and make power, correct?

K
Correct, but you will not be able to explain it to anyone here, they were tought something different and that is that. One way to explain it to them maybe? Torque converter.

BTW you explained it better than I ever could.

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  #47 (permalink)  
Old 10-31-2004, 07:12 PM
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I think the point of this discussion is being miixed up a bit too much.
No matter what you "believe" about it, the heat released by rapidly burning fuel causes a rapid expansion of gas. The pressure created by this heat causes the piston to move. It also makes the impeller spin, this in turn creates pressure in the intake tract by forcing a larger volume of air into the same space. This in turn means that more air and fuel are present at the time of combustion and therefore creates a more powerful bang. The the denser charge burns and creates more heat. More heat causes a more rapid expansion of gas.The larger volume present means more pressure. The rapid expansion of gas, caused by heat from combustion, makes the piston move. Then it exits at even greater velocity due to greater density and heat. This makes the turbine spin faster, creating more boost.

Starting to see a pattern here? The key is heat, without heat an internal combustion engine will not work. Gases don't expand and pistons or rotors won't move, period.

If that doesn't do it for you, I'm sorry. I don't know how to explain it any better.


I suppose the rest of us will keep on making more and more power with our outdated unproven methods. You can tell us that 500hp isn't really 500hp because hp isn't really the time it takes for a given amount of work to be done.

Larry

Last edited by coldknock; 10-31-2004 at 07:17 PM.
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  #48 (permalink)  
Old 10-31-2004, 07:46 PM
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Originally posted by killerformula.

Hmmm. I don't have a degree in engineering or chemistry. IN fact its in Biological Psychology and Cognitive Science....

Boy I'm useless to this discussion!

I do remember something from my under-grand in CHEM: 130...

Let me just patter away uselessly and see where it gets me... Bear with my undereducated butt.

ANyway, as far as I learned, heat is a catalyst which mixes with the oxygen in the air and is compressed to combust (gas has to be compressed to comubst, this is why shooting gas tanks and watchin cars explode on the movies is so silly, right?). The oxygen and gasoline is catalyzed by a high voltage spark. From the pressure gas laws we know that absolute zero is theoretically where molecules cease motion. This is the coldest theoretical temperature, but I don't think its been reached by anything man-made, yet (although I think my mom's old freezer comes close... ). ON the other end we know as we increase temperature for a gas up from A0 that the molecules start moving faster and faster, and become more volatile, right? So the more heat you can introduce to a gas, the more volatile it becomes. If I remember correctly, in a confined space, this volatility becomes "pressure" (as described by the force on the surfaces of the container, conveniently measured in PSI). So if we have a catalyzed reaction in a combustion chamber, and the earth's atmosphere is 80% nitrogen, that works out well! We can burn the gas and oxygen to heat up the nitrogen, create force on the internals of the engine and push the piston down! In fact, if you can decrease the amount of space in which that reaction takes place, you could create even MORE heat and make MORE power, correct?

So I guess the logical question that follows is, if heat is only a byproduct of the reaction and not a product, then regardless of weather heat is produced or not, the engine should run without NEEDING any heat. Is that true?

Well that's all I got. Liberal arts education and all... How far am I off?

K


Well you are sort of right. Actually, the blowing up gas tanks on TV aren't likely, not because of lack of heat, rather it is because the gas tank is full of liquid gasoline and gasoline vapor. Gasoline is not explosive until it is 1) in a vapor phase, and 2) it is mixed with a stoichiometric amount of oxygen. When those two criteria are met, a spark will ignite a very impressive BOOM! regardless of the initial temperature of the mixture. You need to go farther back into your education for the equation here - The Smokey Bear fire triangle - fuel/oxygen/ignition source!

The amount of power available in a 4-cycle engine is a function of how much properly mixed gasoline and oxygen in introduced into the combustion chamber and of the peak pressure reached in the combustion chamber. Of course there are a myriad of operational parameters that pertain but those are the basic thermodynamic parameters. Supercharges, tuned intake and exhaust manifolds, fuel injection, camshaft timing, ignition improvements are all items we play with to optimize those two goals. The colder the charge we can introduce into the combustion chamber, the more energy we can extract because there is more potential energy in the temperature difference between the incoming charge and the peak combustion temperature. And it is temperature difference between stages of the thermodynamic cycle that yields the power.

Heat isn't a catalyst, it is a form of energy. A catalyst is a substance that increases the rate of a chemical reaction by reducing the activation energy, but which is left unchanged by the reaction. Platinum metal in a catalytic converter is a catalyst for the combustion of hydrocarbons in air.

Last edited by willys36@aol.com; 10-31-2004 at 07:54 PM.
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  #49 (permalink)  
Old 10-31-2004, 07:55 PM
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Does that mean I get to keep the blower? Maybe add a chiler for a little extra boom??
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  #50 (permalink)  
Old 11-01-2004, 08:20 AM
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Willysocrates has spoken. I have listened.

Pro70,
I want to go for a ride when your done with that beast. I dare you to try and scare me.

Larry
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  #51 (permalink)  
Old 11-01-2004, 11:37 AM
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Quote:
Originally posted by coldknock
Willysocrates has spoken. I have listened.

Pro70,
I dare you to try and scare me.

Larry
Lemme' see what I can do.
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  #52 (permalink)  
Old 11-01-2004, 07:15 PM
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I always thought superchargers were better than turbos, because if the turbo quits, than you can't go anywhere. But if the supercharger quits, you can still drive the car? it just won't run as good.
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  #53 (permalink)  
Old 11-01-2004, 07:39 PM
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It the other way round really.

If a supercharger belt breaks the engine won't be able to spin the rotors with vacuum. You're dead in the water unless you have a spare belt in the trunk. Which is always a good idea.

If its a centrifugal supercharger the engine may still run but it will have a large obstruction in the intake tract. You can yank the uppipe off of it and keep on rolling.

Same for turbos unless the shaft is siezed, then it stops up the exhaust pretty good but you can keep on cruising.

Larry
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  #54 (permalink)  
Old 12-03-2004, 03:17 PM
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Quote:
Originally posted by coldknock
It the other way round really.

If a supercharger belt breaks the engine won't be able to spin the rotors with vacuum. You're dead in the water unless you have a spare belt in the trunk. Which is always a good idea.

If its a centrifugal supercharger the engine may still run but it will have a large obstruction in the intake tract. You can yank the uppipe off of it and keep on rolling.

Same for turbos unless the shaft is siezed, then it stops up the exhaust pretty good but you can keep on cruising.

Larry
First off, this is my first post here. I've been lurking for a while and figured I'd join in.

I'm not sure about the other types of superchargers, but I know my roots blower will still run with no belt. When I needed a blower belt I drove it around to different parts stores till I found one that fit. Of course it ran like crap with no power, but it still ran.

Now for my 2 cents here on the the turbo vs SC debate...

I'll take the middle of the road on this subject. I've owned them both (turbo 4 cyl and SC 4 cyl.) and like them both in their own respects. I like the boost advantage turbos have and the way a turbo pulls when it spools up. On the same token, I like the instant throttle response and tire melting wheelspin of a supercharger.

My latest little project is a unique setup. It's a FWD truck with a transverse 4 cylinder that I installed a B&M supercharger on. At a time when it seems everyone is putting turbos on their fuel injected 4 cylinders, I thought I'd be different and put a B&M roots blower on mine with a good old carb.

Dare to be different.

Tom
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  #55 (permalink)  
Old 07-07-2005, 08:24 AM
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Well heres my two cents, a turbo is a supercharger and so is a roots style blower. The question is a little askew technically but I understand the meaning.

I did scroll through a couple of posts regarding heat but didnt read em from the beginning so I could be way off here but, it is well established that heated gases will flow at much higher velocities then cooler gases. If the discussion was over hot gas turning the turbo faster, I'd agree with that. I'd also agree that the longer you can contain that heat in the exhaust system, the better the flow hence the effect and benefits of ceramic coated headers.

I also think each one has its place and the mission of the car will dictate which one. If you are going around corners at maximum performance, I would think the turbo would give you a lower center and better cornering. My blower, injector hat and associated pulleys and belts probably weighs in excess of 100 lbs. I wouldnt want that weight up in the air that high if I also wanted to turn a corner.
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  #56 (permalink)  
Old 07-07-2005, 08:37 AM
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Wow, I cant believe this old rag got drug up again. There is alot of good info if you can get around all the lover crap. Glad that guy is gone.
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Old 07-07-2005, 08:41 AM
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Oh, is this an old one? lol nevermind. I thought this must of went on last night and this morning lol.
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  #58 (permalink)  
Old 07-08-2005, 02:16 PM
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Quote:
Originally Posted by willys36@aol.com
End of story!

While nice..."End of story!" would much better be summed up with this...





This car used to be powered by nitrous and a roots blower....it ran 8s...replacing the blower and bottle with this hair dryer brought him to low 7s...almost breaking into the 6s.

Then there is this one...



This car ran an 8.35 @ 168mph with 1.35 60's beating the LT-1 world record of 8.96...a supercharged LT-1 might I add.


The numbers speak for themselves


Turbo will outdo a blower anyday...Its the technilogical revolution, as much as the older guys like their belt driven power adders, they just cant keep up with turbo technology...their not just for imports anymore.
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  #59 (permalink)  
Old 07-08-2005, 03:17 PM
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I too believe a turbo will out perform a SC in the 1/4. The potential for boost is higher with a turbo. But, like I said I still like them both in there own respects.

Having ran both on the street I will say the SC was more fun than the turbo. Sure, a roots tire melting wheel spin is not beneficial in the 1/4 but on the street it sure is fun.

That and there is something to be said for the musical sound (to me) of a roots blower. To this day when I hear a roots blower that is in tune with a deep exhaust rumbling it gives me shivers. I can't say the same for a turbo.

Just my 2 cents.
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  #60 (permalink)  
Old 07-08-2005, 04:51 PM
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Interesting (and occasionally heated) thread!

My "grocery-getter" is a 98 Grand Prix GTP (Supercharged 3.8 V/6) and I just love it! It has the power of a V8 (240 HP), with the fuel economy of a 6-cyl. Actually, this (midsize?) car gets better mileage than my old carbuereted (85 HP) Ford Tempo beater!

It's really cool watching the (electonic) boost guage going up a fairly steep hill ... most of the time the transmission doesn't even have to downshift!

I really haven't driven may turboed cars to do a really fair comparison ... an 89 Ford Probe 2.2 is the only one that I recall, and it wasn't all that impressive.

So anyway ... my vote is just like the old T-shirts used to say...
"I'd rather be blown"

Don
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