Performance mods 101
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Joined: Jun 2008
Posts: 59
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From: San Diego CA
Performance mods 101
Excuse my ignorance. Perhaps there are others reading this also wondering about some of the things I am and they can benefit from these questions as well. I'm looking for a little enlightenment on performance mods. The basic approaches with my questions are below. If I have some of the basic concepts wrong, I'd very much appreciate some education.
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased
. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased
). Repeat until satisfied.
My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil coooler?
NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow?
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure?
Tuning-
Are you altering the air/fuel ratio?
Advance timing?
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased
. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased). Repeat until satisfied.My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil coooler?
NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow?
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure?
Tuning-
Are you altering the air/fuel ratio?
Advance timing?
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
Drifting
Joined: Oct 2006
Posts: 1,569
Likes: 4
From: Phoenix AZ
St. Jude Donor '09-'10-'11
Excuse my ignorance. Perhaps there are others reading this also wondering about some of the things I am and they can benefit from these questions as well. I'm looking for a little enlightenment on performance mods. The basic approaches with my questions are below. If I have some of the basic concepts wrong, I'd very much appreciate some education.
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased). Repeat until satisfied.
My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil coooler?
****
The heat to which you allude is a product of both engine and supercharger, but within the confines of your query in relation to F/I, the heat which is spoken of is due to the drive mechanism/impellers of the supercharger which can easily run 30K to 40K+ rpms--far more than the engine rpms--this ratio between engine R's and S/C R's is governed by the size of the pulleys on the Crank and S/C. In order to offset this heat generated by the S/C, an intercooler is used either with water or air or both--to cool the supercharger. The radiator is only tangentially associated with the supercharger. Oil cooler has to do with either engine oil, transmission oil, or power steering oil--the Z51 package on the C6 has them all. Meth injection has nothing to do with cooling the supercharger, but rather the AIR CHARGE which enters the engine--misted meth is injected into the air stream to cool the air because colder air is more dense than hot air and helps the prospect of high temperatures in the engine during combustion.
NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow?
****
Colder air is more dense=more air=more fuel=more power
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions.
****
The use of headers does not impose ANY emissions problems--It is the job of the Catalytic converters to burn any unused fuel coming through the exhaust so it does not enter the atmosphere whether it's in California or Siberia.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this.
****
This is a subject to be dealt with all by itself because the Cam is the "brain" of the internal combustion engine.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure?
****
Yes.
Tuning-
Are you altering the air/fuel ratio?
Advance timing?
****
Perhaps both. Each engine is different in its own skin. Some engines like more fuel (richer), some like less fuel (leaner), But the theoretical basis of Air/Fuel ratio is approximately 13 to 1, give or take. The object of Tuning is to take into account many factors including, but not limited to, A/F ratio, ignition timing (advance/retard), operating temperature, density of air/ambient temperature (atmosphere at the location of tuning), intended use of the engine, emissions, and on and on. Think of it like tuning a guitar. You can pick it up and play it, but it doesn't sound good (work good) until the strings are tuned to the proper key and also tuned to each other. Then beautiful music projects. In the internal combustion engine, the music can also be beautiful and have beautiful results but not until all the various parts have been synchronized and orchestrated to work well together.
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased
. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased). Repeat until satisfied.My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil coooler?
****
The heat to which you allude is a product of both engine and supercharger, but within the confines of your query in relation to F/I, the heat which is spoken of is due to the drive mechanism/impellers of the supercharger which can easily run 30K to 40K+ rpms--far more than the engine rpms--this ratio between engine R's and S/C R's is governed by the size of the pulleys on the Crank and S/C. In order to offset this heat generated by the S/C, an intercooler is used either with water or air or both--to cool the supercharger. The radiator is only tangentially associated with the supercharger. Oil cooler has to do with either engine oil, transmission oil, or power steering oil--the Z51 package on the C6 has them all. Meth injection has nothing to do with cooling the supercharger, but rather the AIR CHARGE which enters the engine--misted meth is injected into the air stream to cool the air because colder air is more dense than hot air and helps the prospect of high temperatures in the engine during combustion.
NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow?
****
Colder air is more dense=more air=more fuel=more power
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions.
****
The use of headers does not impose ANY emissions problems--It is the job of the Catalytic converters to burn any unused fuel coming through the exhaust so it does not enter the atmosphere whether it's in California or Siberia.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this.
****
This is a subject to be dealt with all by itself because the Cam is the "brain" of the internal combustion engine.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure?
****
Yes.
Tuning-
Are you altering the air/fuel ratio?
Advance timing?
****
Perhaps both. Each engine is different in its own skin. Some engines like more fuel (richer), some like less fuel (leaner), But the theoretical basis of Air/Fuel ratio is approximately 13 to 1, give or take. The object of Tuning is to take into account many factors including, but not limited to, A/F ratio, ignition timing (advance/retard), operating temperature, density of air/ambient temperature (atmosphere at the location of tuning), intended use of the engine, emissions, and on and on. Think of it like tuning a guitar. You can pick it up and play it, but it doesn't sound good (work good) until the strings are tuned to the proper key and also tuned to each other. Then beautiful music projects. In the internal combustion engine, the music can also be beautiful and have beautiful results but not until all the various parts have been synchronized and orchestrated to work well together.
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
There are NO downsides to Tuning--considering that "tuning" in the vernacular is meant to imply "tuning correctly" (See last paragraph).
Last edited by YLOFEVR; Oct 20, 2009 at 06:44 PM. Reason: clarity
Drifting
Joined: Oct 2006
Posts: 1,569
Likes: 4
From: Phoenix AZ
St. Jude Donor '09-'10-'11
For clarity
My comments on the OP post are embedded **** in the quote section for the most part. What can I say, I'm a gearhead, not a geek.
Last edited by YLOFEVR; Oct 20, 2009 at 06:46 PM. Reason: clarity
Advanced
Joined: May 2008
Posts: 94
Likes: 1
From: Omaha NE
Excuse my ignorance. Perhaps there are others reading this also wondering about some of the things I am and they can benefit from these questions as well. I'm looking for a little enlightenment on performance mods. The basic approaches with my questions are below. If I have some of the basic concepts wrong, I'd very much appreciate some education.
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased). Repeat until satisfied.
My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil cooler? Heat is greater through out the components, the S/C creates heat when compressing air, the intake temps are also from the hot air and the cylinders are from the extra power being produced. Methanol although a band-aid to me will cool all of this back down before it gets to the combustion chamber. Problem is if you tune it for Meth and then there is a problem with the pump or you run out you will have big problems.NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power Actually increases air flow and leans out the mixture making more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow? Both are possible, but often the longer tubing and increased bends in a CAI are hurting the flow.
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions. Headers and collectors will affect the scavenging of the gasses so yes this is true. You have to have a system that scavenges though and over sizing will not always do this, the port shape will also play a part in this.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this. A cam can have more lift for better flow characteristics and altered overlap specs for different applications. More overlap will help N/A at times but hurt forced induction motors by letting the compressed air out before the valves close all the way.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure? Yes raises the overall compression, but you need to consider and know valve clearances and actual compression uniformity. CNC head work will give consistency, but hand porting work may flow a little better at times.
Tuning-
Are you altering the air/fuel ratio?
Advance timing? Yes to all
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
I remember the basics of the 4 stroke engine. Piston drops down, intake valve opens, fuel is drawn in. Piston starts back up, valve closes, compresses fuel, spark occurs at (or near?) the peak of travel. Fuel explodes, piston is driven back down, and driver is pleased
. When it starts coming back up, the exhaust valve opens, expended fuel is forced out (Al Gore is not pleased). Repeat until satisfied.My basic, and shallow, perhaps even incorrect, understanding of the various performance mods are as follows (with some questions):
Super or turbo charging-
------------------------
Instead of going in at ambient pressure, you compress the air/fuel mixture and force it into the intake valve. You get more of it in there since it's already compressed. I assume you'll have whatever pressure at the top of the stroke that you previously had, plus the additional from the boost. Mucho stress on pistons, push rods, valve springs, etc. can be a problem at high horsepower levels. Heat is mentioned as a big problem. Is this heat in the engine, the supercharger itself, or both? Why does methanol injection help? Would a better radiator help? Oil cooler? Heat is greater through out the components, the S/C creates heat when compressing air, the intake temps are also from the hot air and the cylinders are from the extra power being produced. Methanol although a band-aid to me will cool all of this back down before it gets to the combustion chamber. Problem is if you tune it for Meth and then there is a problem with the pump or you run out you will have big problems.NA mods
----------
Porting intake, throttle body-
Reduces intake impedance by. Less impedance to fuel intake = more fuel. More fuel = more power Actually increases air flow and leans out the mixture making more power
Cold air intake-
Is there some benefit to actual lower temp air at the input, or is this just reduced impedance to the air flow? Both are possible, but often the longer tubing and increased bends in a CAI are hurting the flow.
Headers/exhaust-
Reduce impedance to outgoing gases = less energy expended by the piston when pushing out the gases. Don't lose as much momentum. More power. May have trouble meeting strict (i.e. Calif.) emissions standards? Doesn't seem like any downside from this, other than perhaps emissions. Headers and collectors will affect the scavenging of the gasses so yes this is true. You have to have a system that scavenges though and over sizing will not always do this, the port shape will also play a part in this.
Cam-
Longer duration on intake (or exhaust) valves? More fuel? Timing altered? Not sure what's being done with this. A cam can have more lift for better flow characteristics and altered overlap specs for different applications. More overlap will help N/A at times but hurt forced induction motors by letting the compressed air out before the valves close all the way.
Porting heads-
Improved flow of fuel in/out? I've heard of milling the heads as well. Does this just decrease the amount of space the air/fuel mix is compressed into increasing the pressure? Yes raises the overall compression, but you need to consider and know valve clearances and actual compression uniformity. CNC head work will give consistency, but hand porting work may flow a little better at times.
Tuning-
Are you altering the air/fuel ratio?
Advance timing? Yes to all
How do these affect power? What are the downsides to tuning? Carbon buildup? Emissions test fails? Are air fuel ratio and timing programmable as a function of RPM?
