Yet another car question from a guy who know's nothing about cars

For any discussions at all relating to the movies

Re: Yet another car question from a guy who know's nothing about cars

Postby Mr. Know it all » Wed Jul 28, 1999 12:30 pm

In Reply to: Re: Yet another car question from a guy who know's nothing about cars posted by AN on July 27, 1999 at 21:30:55:


once again I must explain myself. Lets get one thing straight: Turbocharging utilizes exhaust gases. Thus using NO horsepower from the Engine because it is taking energy from these gases as they exit the manifold.

Supercharging is generaly known as a "blower" or crankshaft driven component. From the cranshaft runs a belt like shown in the Mad Max films. OKay?

I cannot help but say you are completely wrong on thinking that Turbos rob engine HP to run. That is why they run on exhaust gases, which is not connected to the CRANKSHAFT like a supercharger or blower. If you still do not beleive me then go here: http://www.activeautowerke.com/faq1turbovssuper.html

: I probably would not bother responding, but the tag-line of Mr. Know-it-all was too tempting.

: CORRECTIONS

: 1) A turbocharger IS a supercharger. A supercharger is a device to pressurize the intake air. BELT-DRIVEN (I know or no CRANKSHAFT-DRIVEN) superchargers are called superchargers, exhaust-driven supercharger are also known as turbochargers.

: 2) The heat that is shed by an intercooler is does not come from the exhaust gas, it comes from the heat of compression (the heat that makes your bicycle pump get warm, or a shop air compressor heat up) that is why many supercharged motors also have intercoolers

: 3) I am not aware of any air/fuel mixtures running thru intercoolers, on all new cars, they will be running fuel injection (usually port) and no air fuel mixture will be passed so close to the turbo or thru pressurized tubes

: 4) While a turbocharger is an efficient way to boost the specific output of a vehicle (diesels are a good example) it is not correct to say they use no power. IE where do you think the power to compress a stream of gas from atmospheric to 1or 2 bar come from? The engine is supplying the motive force to produce the compression,granted, some of that is normally "wasted" is in the exhaust anyway, but it is not "free". The car must labor against the turbine, similar to a restrictive exhaust.

: 5) One benefit in a supercharged engine is the lack of "turbo lag" in a supercharged engine, as the "blower" is already at max speed, whereas a turboed car may requier several seconds to build boost (old Porsche 911 were notorious for that)

: 6)Lastly, properly maintained turbocharged and supercharged engines are not incredibly trouble-prone. I have friends with both with +100K miles with no problems, earlier turbos were prone due to oil "coking"( burning) if shut down after a long ride with no time to cool, modern cars use thermo-siphon oil or water-cooling to address this

: 7) If the writer of the original post is asking the best way to get more power out or a car, I agree that Suping of Turbing a car is dumb because you will need to lower the compresssion, requireing a engine rebuild--if you are going to that length, the normal route of high compression, and better heads will give you better bang-for-buck.
Mr. Know it all
 
Posts: 23
Joined: Thu Jul 22, 1999 4:14 pm

Re: Yet another car question from a guy who know's nothing about cars

Postby andre N » Wed Jul 28, 1999 1:25 pm

In Reply to: Re: Yet another car question from a guy who know's nothing about cars posted by Mr. Know it All on July 28, 1999 at 20:30:35:


I do not know what your experience or expertise is, but your "proof" is a link to the FAQ page of a car accesory provider, hardly a "expert witness". In fact they state that turbos have most effect down low in the RPM range, when it is generally accepted that it is Supercharging, not turbocharging that gives you the best "off idle"or low response, and that turbocharging is know for its "high-rpm" prowess Nevertheless, I agree in principle that a turbo is a efficient method of improving performance, and that it able to utilize a significant percentage of otherwise wasted energy that goes out a cars exhaust. But like so many other things it is not totally free. Picture this, you have the turbo motor on the test stand, running against a brake dynamometer at max HP or max torque.

You measure the speed of the turbo, and decide that you will get an electric motor to run the turbo (thru proper gearing) to provide the same amount of intake air , and just run straight pipes. Well your intake won't know the difference, but you will see a decrease in exhaust backpressure which WILL equate to greater HP, for the same reason that lower restriction exhaust is used in higher performance cars. Another way to look at it is that some outside energy (electricity) would be required to turn that turbo if the exhaust didn;t--the exhaust needs to be pressurize to deliver the power to turn the turbine,and a stream of presurize gas requies power. Now, that being said, I would agree that the parasitic drag of a turbo is less significantly less than that of a superC especially in light-throttle conditions.

First law of thermo--there is no free lunch

Second law--if there was a free lunch , you couldn't eat it.
andre N
 
Posts: 224
Joined: Tue Jun 29, 1999 4:09 am

Re: Yet another car question from a guy who know's nothing about cars

Postby Mr. Know it all » Thu Jul 29, 1999 5:08 am

In Reply to: Re: Yet another car question from a guy who know's nothing about cars posted by AN on July 28, 1999 at 21:25:56:


Heres a what you need to do: Check out an Indy car site, I don't have time to look it up now. But they should talk a lot about Turbos. That will clear up some of you "fuzz".

: I do not know what your experience or expertise is, but your "proof" is a link to the FAQ page of a car accesory provider, hardly a "expert witness". In fact they state that turbos have most effect down low in the RPM range, when it is generally accepted that it is Supercharging, not turbocharging that gives you the best "off idle"or low response, and that turbocharging is know for its "high-rpm" prowess Nevertheless, I agree in principle that a turbo is a efficient method of improving performance, and that it able to utilize a significant percentage of otherwise wasted energy that goes out a cars exhaust. But like so many other things it is not totally free. Picture this, you have the turbo motor on the test stand, running against a brake dynamometer at max HP or max torque.

: You measure the speed of the turbo, and decide that you will get an electric motor to run the turbo (thru proper gearing) to provide the same amount of intake air , and just run straight pipes. Well your intake won't know the difference, but you will see a decrease in exhaust backpressure which WILL equate to greater HP, for the same reason that lower restriction exhaust is used in higher performance cars. Another way to look at it is that some outside energy (electricity) would be required to turn that turbo if the exhaust didn;t--the exhaust needs to be pressurize to deliver the power to turn the turbine,and a stream of presurize gas requies power. Now, that being said, I would agree that the parasitic drag of a turbo is less significantly less than that of a superC especially in light-throttle conditions.

: First law of thermo--there is no free lunch

: Second law--if there was a free lunch , you couldn't eat it.
Mr. Know it all
 
Posts: 23
Joined: Thu Jul 22, 1999 4:14 pm

Re: Yet another car question from a guy who know's nothing about cars

Postby andre N » Thu Jul 29, 1999 9:40 am

In Reply to: Re: Yet another car question from a guy who know's nothing about cars posted by Mr. Know it All on July 29, 1999 at 13:08:38:


This is going on too long. I'm done. If you can't understand the point that work needs to be done to compress air, and that the energy comes from somewhere, then I'm wasting my time, your time and the message boards bandwidth. Plus this is a MM site and we are both way off the subject of a movie we really respect.

If you still want to debate this, post a site of some real merit, but remember, if you read my last post you will note that we are probably in more agreement than you think............. A turbo DOES utilize wasted some of the energyo--no doubt! And a turbo at part throttle, low throttle is spinning more slowly than at full whereas a supe is spinning regardless of the power required. My point is , were you to supply an engine with pressurized air in the same volume and PSI as the turbo supplies BUT WITHOUT the additional backpressure that a turbo causes, more HP would be created due to lower exhaust restriction.
andre N
 
Posts: 224
Joined: Tue Jun 29, 1999 4:09 am

Re: Yet another car question from a guy who know's nothing about cars

Postby Mr. Know it all » Fri Jul 30, 1999 1:01 am

In Reply to: Re: Yet another car question from a guy who know's nothing about cars posted by AN on July 29, 1999 at 17:40:55:


YOU STARTED IT!

Once again I was trying to convey some intelligence by answering a simple question by the original post, but no, you couldn't leave it alone. Next time maybe keep your pipe hole shut.

And one more thing, a turbo does not require engine HP.

: This is going on too long. I'm done. If you can't understand the point that work needs to be done to compress air, and that the energy comes from somewhere, then I'm wasting my time, your time and the message boards bandwidth. Plus this is a MM site and we are both way off the subject of a movie we really respect.

: If you still want to debate this, post a site of some real merit, but remember, if you read my last post you will note that we are probably in more agreement than you think............. A turbo DOES utilize wasted some of the energyo--no doubt! And a turbo at part throttle, low throttle is spinning more slowly than at full whereas a supe is spinning regardless of the power required. My point is , were you to supply an engine with pressurized air in the same volume and PSI as the turbo supplies BUT WITHOUT the additional backpressure that a turbo causes, more HP would be created due to lower exhaust restriction.
Mr. Know it all
 
Posts: 23
Joined: Thu Jul 22, 1999 4:14 pm

Previous

Return to General Movie Discussion

Who is online

Users browsing this forum: No registered users and 2 guests


cron