The power loss is not the same. I am not going to argue this any further because it is off topic of what this thread is about. No offense, but no matter what I say you still will not believe me that turbos are more effecient and sap less power than superchargers. If you feel that your point of view is correct then call Kenny Dutweiler and discuss it with him.
As far as the turbocharger heat arguement: A turbocharger has a turbine which powers the compressor using waste energy from the exhaust gases. When you ignite the air/fuel mixture in the cylinder, heat is produced (a/f mixture burns) which causes the gases to expand. These expanding gases exit the cylinder on the exhaust stroke and turn the turbine wheel in the turbocharger. Therefore turbos work off HEAT, which is the expanding of the combustion gases. Without ignition there is no HEAT therefore there is not expansion of the gases therefore there is no energy to turn the turbine in the turbocharger, nor power the engine.
As a matter of fact the internal combustion engine is classified as a type of a heat engine.
Please point out where I said a) a turbocharger takes more power than a supercharger to run or b) that an engine or turbo doesnt run off heat.
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12:50 AM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
Please point out where I said a) a turbocharger takes more power than a supercharger to run or b) that an engine or turbo doesnt run off heat.
First off, the Turbocharger heat arguement was not with you, it was with aaron88, thats why I started a new paragraph that said: "As far as the turbocharger heat arguement:"
As far as the first part of your question:
quote
Originally posted by PontiacMan: I have to disagree...
The turbo charged engine would also be making "more" than 300HP, but some of the power is lost by throwing a huge obstruction in the exhaust.
I acknowledge you did not come out and directly say a turbo saps more power than an SC, but within the context of the discussion it sounded like you were implying that a turbo saps more power than what I said it does. I apologize if I offended you and read what you said incorrectly. That was not my intent. The only point I was just trying to make is that a turbo, being a "restriction", does not sap as much power as some would believe.
Well now i'm a bit confused.......I was thinking of using a supercharger since cuz of the sheer fact that they have no lag time & are instant power. But have a parasistic problem.
But now i'm thinking maybe turbocharged cause its' not really parasistic......Well crap.....back to brainstorming.
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04:27 AM
Nov 2nd, 2004
cooguyfish Member
Posts: 2658 From: Hamilton, OH, USA Registered: Mar 2002
Originally posted by Shadow_Wolf: I'm not aware of any 2.8 in GM's lineup?!?! There is the new 3.5 and the up-coming 3.9, but neither one has a 7200rpm redline? The only current 2.8 I'm aware of is the 4cyl used in the Colorado/Canyon.
Thought i'd give this thread a bump since it was a rather interesting discussion. That, and i found out where i got the 2.8 info from.
Well now i'm a bit confused.......I was thinking of using a supercharger since cuz of the sheer fact that they have no lag time & are instant power. But have a parasistic problem.
But now i'm thinking maybe turbocharged cause its' not really parasistic......Well crap.....back to brainstorming.
either way you go you won't be disappointed.. trust me I knew about the SC power drops and that didn't bother me. Good write up btw Ryan, there'll always be a debate on which is better. I like them both its more power which is relatively cheap and easy and unless you're going to build a drag strip warrior who cares?
I'd like a sense of both worlds so maybe the next car I do will have a turbo.
FieroX compressor: 76% efficient. That means that 76% of the energy you put into it goes into compressing air and only 24% goes into non-adiabatic heating of the air.
Eaton M90: 55% (using FieroX's numbers) efficient. That means 55% of the energy from the pulley goes into compressing air and 45% goes into unnecessary heat.
So say you need to put 50HP into adiabatically compressing air in order to hit your boost/CFM goals... You'll have to put 66HP into the turbo to get it to do that, but you'll have to put 91 HP into the blower to get it to do that. Blowers have more parasitic loss because they are less efficient. Centrigufal SC's are a different beast.
Turbo is exhaust restriction...
"restriction" doesn't BEGIN to describe the effect that a turbo has on a car's exhaust. The difference in exhaust energy across the turbine is equivalent to the power to compress the air going into the engine, the waste heat of the compressor, the waste heat of the turbine, AND the parasitic loss of oil film smooth bearings (or in some cases ball bearings) spinning at or above 100,000 RPM. In any streetable turbo system, the exhaust back pressure will EXCEED boost pressure. Running 19 psi of boost? You've probably got 25 psi of back pressure.
Turbines are turned by pressure ratio. In the case of the internal combustion engine, the pressure increase is generated by adding heat to the working fluid, but the turbine itself is operated by pressure ratio.
------------------ Turn the key and feel the engine shake the whole car with its lope; Plant the gas pedal and feel in your chest neither a shriek nor a wail but a bellowing roar; Lift and be pushed into the harness by compression braking that only comes from the biggest cylinders while listening to music of pops and gurgles. Know that you are driving an American V8. There are finer engines made, but none of them are this cool.
Luck, Fate and Destiny are words used by those who lack the courage to define their own future
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09:11 PM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
In any streetable turbo system, the exhaust back pressure will EXCEED boost pressure. Running 19 psi of boost? You've probably got 25 psi of back pressure.
I can test that theory. I still have the O2 bung plug in my stock rear manifold I can take it out and hook a pressure gauge up and see what kind of pressure I have in the exhaust. Not that it will tell us how much power it is sapping from the engine because that is more difficult to measure.
I can test that theory. I still have the O2 bung plug in my stock rear manifold I can take it out and hook a pressure gauge up and see what kind of pressure I have in the exhaust. Not that it will tell us how much power it is sapping from the engine because that is more difficult to measure.
Actually the pressure differential will give you very close and accepted figures...by using the gas laws you can ascertain loss which directly can be linked to power, still need to know true manifold psi again taking a psi differential on the cold side, this will also tell us a lot...
Will I agree with what you said about backpressure always exceeding intake pressure on street apps, however the goal is always to get into crossover later in the power band and get closer to a 1:1ratio...more importantly CLOSER and LATER!! The reason I laugh when a said company claims their "turbo cams" are proven for 3800s2...more like, you were lucky!?!?
------------------ 3800 II v6 intercooled turbo...CWP!
[This message has been edited by nocutt (edited 11-03-2004).]
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01:17 AM
Will Member
Posts: 14278 From: Where you least expect me Registered: Jun 2000
I can test that theory. I still have the O2 bung plug in my stock rear manifold I can take it out and hook a pressure gauge up and see what kind of pressure I have in the exhaust. Not that it will tell us how much power it is sapping from the engine because that is more difficult to measure.
I'd be very interested in seeing that data. Back pressure will be higher than your boost... how much higher will be tough to figure out ahead of time.
my assumption is that the backpressure to boost pressure ratio will change with rpm
might be nice to also have a pressure guage after the turbo to get pressure drop across the turbine..
reduce presure after the turbine should improve theo whole equation - less heat buildup, faster spooling less pressure between the combustion chamber and turbing required to generate the same boost pressure.
If you are putting in an SBC, it is pretty easy to get N/A with a Demon carb or an Edelbrock carb to 300 hp. The question was 300 hp?
There are any number of reliable, N/A streetable muscle cars with 300 hp.
Why mess around with all the complications of a boost system when you can put out streetable power with the old reliable?
As for the arguement that you can't get a smooth street runner with N/A, I just don't buy it. I drove a very smooth running 300 hp Olds in 1964. Hmm......
Why mess around with all the complications of a boost system when you can put out streetable power with the old reliable?
Arn
its not an issue of 300hp its an issue of NA tuning an engine or boosting an engine
if you drop a stock 300hp engine in there then want to increase its power 50% which way is best - in my experience it depends on the application and the personal prefferance of the driver
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10:59 AM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
If you are putting in an SBC, it is pretty easy to get N/A with a Demon carb or an Edelbrock carb to 300 hp. The question was 300 hp?
There are any number of reliable, N/A streetable muscle cars with 300 hp.
Why mess around with all the complications of a boost system when you can put out streetable power with the old reliable?
As for the arguement that you can't get a smooth street runner with N/A, I just don't buy it. I drove a very smooth running 300 hp Olds in 1964. Hmm......
Arn
This discussion was not about the SBC. I will agree that getting 300hp naturally asperated out of a SBC is much easier than getting 300hp N/A out of a V6. However this brings up another arguement that the SBC is going to cost a ton more money just to install in a Fiero, but again that is a different debate. Your 300hp 1964 olds ran on leaded gas and undoubtedly had higher compression than what most engines have today because today's gas is lower octane. Besides that 1964 HP measuring standards were in GROSS numbers and by today's NET HP standards your 300hp olds probably only produces closer to 240hp. Still don't buy it? Try this analogy:
Most of the cars during the 60's only ran 14's in the 1/4 mile with a 3200-3600lb total vehicle weight. Granted the tire technology wasn't as good as it is today but lets say that with today's tire technology those same cars would probably run high 13's. Well today's 300hp camaro that also weighs about 3400lbs runs low 13's all day long and with the right driver they are quite capable of high 12's in the 1/4. So you cannot just pick up a book with 1960's power figures and directly compare them to today's engines because the measuring system and other variables are vastly different.
This discussion was not about the SBC. I will agree that getting 300hp naturally asperated out of a SBC is much easier than getting 300hp N/A out of a V6. However this brings up another arguement that the SBC is going to cost a ton more money just to install in a Fiero, but again that is a different debate. Your 300hp 1964 olds ran on leaded gas and undoubtedly had higher compression than what most engines have today because today's gas is lower octane. Besides that 1964 HP measuring standards were in GROSS numbers and by today's NET HP standards your 300hp olds probably only produces closer to 240hp. Still don't buy it? Try this analogy:
Most of the cars during the 60's only ran 14's in the 1/4 mile with a 3200-3600lb total vehicle weight. Granted the tire technology wasn't as good as it is today but lets say that with today's tire technology those same cars would probably run high 13's. Well today's 300hp camaro that also weighs about 3400lbs runs low 13's all day long and with the right driver they are quite capable of high 12's in the 1/4. So you cannot just pick up a book with 1960's power figures and directly compare them to today's engines because the measuring system and other variables are vastly different.
See how hard it is to get 4 years of schooling and years of experience within one thread.
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03:40 PM
Nov 4th, 2004
Will Member
Posts: 14278 From: Where you least expect me Registered: Jun 2000
An easy driving 300 HP SBC is not that hard to build. But what about a 500 HP SBC? That's going to be a lot less civilized. A 3800 can make 500 with a more boost and a few mods, but it's going to be a LOT more civilized and get a LOT better gas mileage, especially if the SBC in consideration has a Demon carb on it. Also, the 500 HP turbo 3800 with make more torque across a broader band than the 500 HP 350 or even 383.
------------------ Turn the key and feel the engine shake the whole car with its lope; Plant the gas pedal and feel in your chest neither a shriek nor a wail but a bellowing roar; Lift and be pushed into the harness by compression braking that only comes from the biggest cylinders while listening to music of pops and gurgles. Know that you are driving an American V8. There are finer engines made, but none of them are this cool.
Luck, Fate and Destiny are words used by those who lack the courage to define their own future
