new ** MRZ Performance UDP and Lightweight Crank Pulleys for the 2.2/2.4 NA Ecotec's
09-14-2008, 10:51 PM
#101
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I ordered the Lightweight version mostly because I'm concerned about the electric assist power steering on our cars. I don't want any C.E.L. either and that could happen with the underdrive version since your changing the diameter of a crucial engine part affecting the entire electrical system.
09-14-2008, 11:06 PM
#102
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I ordered the Lightweight version mostly because I'm concerned about the electric assist power steering on our cars. I don't want any C.E.L. either and that could happen with the underdrive version since your changing the diameter of a crucial engine part affecting the entire electrical system.
09-15-2008, 12:53 AM
#103
ill post anything out of the ordinary, everything from anything, if it rattles, if it makes a weird sound, if it chakes the engine alot, anything, ill post it all, this is a honest review, hell if the ghost in the trunk leaves my car ill post it too...i know you guys remember the ghost in the trunk
Last edited by Jn2; 09-15-2008 at 02:43 PM.
09-17-2008, 09:15 PM
#105
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ill post anything out of the ordinary, everything from anything, if it rattles, if it makes a weird sound, if it chakes the engine alot, anything, ill post it all, this is a honest review, hell if the ghost in the trunk leaves my car ill post it too...i know you guys remember the ghost in the trunk
I'll post my review in here as well after I take the car for a test drive.
My Pulley just arrived in the mail today. It will be installed this friday
Yours should have made it through customs by now, Hopefully
09-17-2008, 09:29 PM
#107
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all the way at the bottom of the damn country...i have someone home 24/7 
if it arrives, i will be alerted by text message
09-18-2008, 04:25 AM
#109
couple questions guys. Now, I'm 95% sure this is the case, but when using a light weight crank pulley, im gaining whp, but not bhp, correct? it just frees up some hp that was lost in the drivetrain?
and whats the difference between the 2.2 lightweight crank pulley and the 2.0 lightweight crank pulley?
and whats the difference between the 2.2 lightweight crank pulley and the 2.0 lightweight crank pulley?
09-18-2008, 08:41 AM
#110
and whats the difference between the 2.2 lightweight crank pulley and the 2.0 lightweight crank pulley?
09-18-2008, 10:37 AM
#111
If you change something on the engine and you get more whp, its because youve got more bhp. The only way to put more power to the wheels but NOT gain Bhp is to reduce drivetrain power loss, that is to make it easier to spin the transmission, final drive and axles/wheels. So switchin to some super efficient lightwieght super lube for your trans would show more hp on a chassis dyno, but you arent actually making anymore hp, a pulley however, if it shows hp gain on a chassis dyno, it will also show gain on an engine dyno. Key point, if it goes in or attaches to the engine to the engine, it can make or lose you horsepower. If it goes in or attaches to the trans it merely USES more or less horsepower
I am gonna say the 2.2 is a 5 rib belt and the 2.0 is a 6 rib belt
09-18-2008, 11:08 AM
#112
So how much of an increase in REVs are we talking with an underdrive. I don't feel like spending 200 dollars to gain a thousandth of a second in the 1/4. I mean, do you think a extra tenth or half a tenth extra in the quarter is possible with this.
09-18-2008, 12:10 PM
#113
If they are both 6 rib I have no idea what the difference could be, I mean **** the number of ribs IS the difference
An underdrive pulley isnt gonna get you a tenth in the 1/4, and it isnt gonna increase your rev limit. What it does is reduce alternator/AC drive speed, if youre spinning the pulleys slower, it requires less power.
09-18-2008, 12:26 PM
#114
im pretty positive, based on the common knowledge i have and what you were just telling me that a lightweight pulley will NOT make more bhp. The engine will continue making the same power, but less of it will be used to spin the crank pulley, meaning less drivetrain loss (via power lost through the accessory belt).
09-18-2008, 12:32 PM
#115
im pretty positive, based on the common knowledge i have and what you were just telling me that a lightweight pulley will NOT make more bhp. The engine will continue making the same power, but less of it will be used to spin the crank pulley, meaning less drivetrain loss (via power lost through the accessory belt).
09-18-2008, 12:44 PM
#116
im pretty positive, based on the common knowledge i have and what you were just telling me that a lightweight pulley will NOT make more bhp. The engine will continue making the same power, but less of it will be used to spin the crank pulley, meaning less drivetrain loss (via power lost through the accessory belt).
Heres how you can tell if you increase BHP or just whp. If the part would show gains on an engine with just the engine(no trans/axles/wheels/brakes/hubs) then you increased BHP, if it wouldnt matter on an engine dyno, its a whp increase. A crank pulley most certainly will alter BHP as measured on an engine dyno.
09-18-2008, 02:00 PM
#118
not at all dude....
horsepower is created through combustion chamber pressures pushing on the piston. mods like a smaller SC pulley make the SC force more air into the chamber, thus more, fuel, thus more pressure. adjusting ignition timing can add more pressure. lowering IAT2s can allow you to run more timing and yields denser air for more cylinder pressure. These all create brake horsepower by adjusting conditions inside the cumbustion chamber. Now, Im pretty positive that any mods that DO NOT alter combustion chamber pressures do not make horsepower. Those mods would include: neutral balance shafts, lightweight crank pulley, underdrive pulley, lighter rims, lightweight crankshaft....basically removing any rotating weight. No mod that removes rotating weight will create BHP, however, less horsepower will be lost trying to spin those heavy objects, leaving more of your BHP available to reach the wheels, which is then WHP. So effectively, a 200BHP car that pulls 160WHP, that then gets neutral balance shafts, lightweight underdrive crank pulley, lightweight rims, and a lightweight crankshaft can then be a 200BHP car that has 180WHP, because none of those mods would affect the cylinder pressures.
in your example by the way, the crank pulley is considered part of a drivetrain. its not the drivetrain that powers your wheels, but the drivetrain that powers your alternator, air conditioning, etc
horsepower is created through combustion chamber pressures pushing on the piston. mods like a smaller SC pulley make the SC force more air into the chamber, thus more, fuel, thus more pressure. adjusting ignition timing can add more pressure. lowering IAT2s can allow you to run more timing and yields denser air for more cylinder pressure. These all create brake horsepower by adjusting conditions inside the cumbustion chamber. Now, Im pretty positive that any mods that DO NOT alter combustion chamber pressures do not make horsepower. Those mods would include: neutral balance shafts, lightweight crank pulley, underdrive pulley, lighter rims, lightweight crankshaft....basically removing any rotating weight. No mod that removes rotating weight will create BHP, however, less horsepower will be lost trying to spin those heavy objects, leaving more of your BHP available to reach the wheels, which is then WHP. So effectively, a 200BHP car that pulls 160WHP, that then gets neutral balance shafts, lightweight underdrive crank pulley, lightweight rims, and a lightweight crankshaft can then be a 200BHP car that has 180WHP, because none of those mods would affect the cylinder pressures.
in your example by the way, the crank pulley is considered part of a drivetrain. its not the drivetrain that powers your wheels, but the drivetrain that powers your alternator, air conditioning, etc
09-18-2008, 02:04 PM
#119
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not at all dude....
horsepower is created through combustion chamber pressures pushing on the piston. mods like a smaller SC pulley make the SC force more air into the chamber, thus more, fuel, thus more pressure. adjusting ignition timing can add more pressure. lowering IAT2s can allow you to run more timing and yields denser air for more cylinder pressure. These all create brake horsepower by adjusting conditions inside the cumbustion chamber. Now, Im pretty positive that any mods that DO NOT alter combustion chamber pressures do not make horsepower. Those mods would include: neutral balance shafts, lightweight crank pulley, underdrive pulley, lighter rims, lightweight crankshaft....basically removing any rotating weight. No mod that removes rotating weight will create BHP, however, less horsepower will be lost trying to spin those heavy objects, leaving more of your BHP available to reach the wheels, which is then WHP. So effectively, a 200BHP car that pulls 160WHP, that then gets neutral balance shafts, lightweight underdrive crank pulley, lightweight rims, and a lightweight crankshaft can then be a 200BHP car that has 180WHP, because none of those mods would affect the cylinder pressures.
horsepower is created through combustion chamber pressures pushing on the piston. mods like a smaller SC pulley make the SC force more air into the chamber, thus more, fuel, thus more pressure. adjusting ignition timing can add more pressure. lowering IAT2s can allow you to run more timing and yields denser air for more cylinder pressure. These all create brake horsepower by adjusting conditions inside the cumbustion chamber. Now, Im pretty positive that any mods that DO NOT alter combustion chamber pressures do not make horsepower. Those mods would include: neutral balance shafts, lightweight crank pulley, underdrive pulley, lighter rims, lightweight crankshaft....basically removing any rotating weight. No mod that removes rotating weight will create BHP, however, less horsepower will be lost trying to spin those heavy objects, leaving more of your BHP available to reach the wheels, which is then WHP. So effectively, a 200BHP car that pulls 160WHP, that then gets neutral balance shafts, lightweight underdrive crank pulley, lightweight rims, and a lightweight crankshaft can then be a 200BHP car that has 180WHP, because none of those mods would affect the cylinder pressures.
09-18-2008, 02:13 PM
#120
what hes saying makes sense, but i dont think hes taking into account that the crank pulley along with all of the other accessory pullies are adding drag on the system, robbing horsepower. BHP is the same, the above is just stealing some of it, so getting a light weight crank pulley would limit the amount stolen its stolen HP that causes BHP at the crank to become WHP
09-18-2008, 03:24 PM
#121
Well if you wanna get really technical, engine pressure directly correlate to torque production, (IMEP is the engines theoretical peak pressure, this is affected only by mechanical design, BMEP is the engine "brake" pressure or likely average functioning pressure taking into account pumping losses and friction these are key and relate directly to "bolt on" mods) higher effective pressures create more torque, being able to deliver this torque is horsepower, if you reduce engine friction, reciprocatin or rotating mass you alter how quickly the engine can deliver torque.(how quicky torque is delivered is essentially the definition of horsepower ) Lets forget that for now though even though its the key point.
Your getting heavily involved with semantics here, that being "creating" horsepower, versus "freeing" horsepower. This is one issue. The second is you are intermingling the whole bhp and whp deal in their with the "freed" versus "produced" power.
The drivetrain of the car is the transaxle, wheel axle shafts, hubs, rotors, brakes and wheels/tires. All of these things can only REDUCE how much of the power the engine produces is put to the ground. They cant increase it, so if youve got 200bhp there is no way youve got 215whp, we agree on this right?
The engine of the car, as pertains to horsepower ratings given by Chevrolet and every other manufacturer based on the new SAE standards is a fully dressed engine, that is the complete air intake system as found in the car, the airbox, filter everything, the complete exhaust system as found in the car that is manifold cat, muffler, tip, all of it, and ALL accesories and drive systems, that is the serp belt, crank pulley, AC, alternator, power steering, water pump , everything mechanically attached to and driven by engine. Its in this "fully dressed" state that our hp numbers come from , my '08 LS is 148hp based on this test, an SS/TC is 260hp.
When we run my LS on the chassis dyno at Tune time, maybe it pust down 133hp to the wheels, it still makes 148hp at the crank, but only 133 of it makes it to the wheels. Well lets say that we now take my LS and put stupid light wheels, low friction hubs, lightweight axles, smaller brakes and super lube in the trans, and we run it on the TuneTime dyno again....whats gonna happen, well its highly likely that it will now register more power on that dyno, lets 138hp, but if we take the engine and retest it like GM did its STILL gonna make 148hp just like stock, even though my car now puts more to the ground. So did we make more power??? Yes, we made my car have more power to the wheels. Is the engine putting out anymore power??? No. theres just less of it being used up spinning the wheels.
Okay pretend the car is stock again, and weve got 133hp at the wheels, Now lets put on that super light pulley. And we go back to TT, lets say the pulley is awesome and we now get 140hp to the wheels. You say all we did was reduce drag/loss whatever and the car is not really more powerful, well if we take the engine out and retest at GM it will make more than the 148hp it originally did. Why? because we modified the engine and it now puts more power into the drivetrain and more reaches the ground.
I know youre going to say we didnt "create" horsepower, we only freed it by changing the pulley. Well if thats how you wanna look at then I guess its your perogative, but based on that are you gonna then say that exhaust mods dont add power they really just free it? because they dont have the engine MAKE more pressure, they just allow it to breathe more easily and make the pressure it can, same with the intake, the intake doesnt "create" pressure, it just reduces pumping losses and enhances cylinder fill which allow it to make the pressure its designed to...... By your definition only nitrous, blowers, turbos, pistons and combustion chamber size affect power creation, because only these things actually set the maximum potential pressures possibly created.
Ignition timing and mods wouldnt count because they can only adjust pressures within the engines design specs, they cant add pressure beyond what is physically dictated by induction type, and static compression ratio.
Cooling mods wouldnt make power because they dont affect ideal pressure of the engine
Same goes for cams, they cant increase pressure, only tune how much fresh air comes in, how much exhaust goes out and how much static and dynamic compression is allowed to bleed off.
Same for tuning, etc, etc, etc,......very few things actually directly set maximum pressure limits, and anything isnt involved in setting maximum possible pressures doesn "make" horsepower by your definition
Again if its part of the engine it can affect bhp.
Your getting heavily involved with semantics here, that being "creating" horsepower, versus "freeing" horsepower. This is one issue. The second is you are intermingling the whole bhp and whp deal in their with the "freed" versus "produced" power.
The drivetrain of the car is the transaxle, wheel axle shafts, hubs, rotors, brakes and wheels/tires. All of these things can only REDUCE how much of the power the engine produces is put to the ground. They cant increase it, so if youve got 200bhp there is no way youve got 215whp, we agree on this right?
The engine of the car, as pertains to horsepower ratings given by Chevrolet and every other manufacturer based on the new SAE standards is a fully dressed engine, that is the complete air intake system as found in the car, the airbox, filter everything, the complete exhaust system as found in the car that is manifold cat, muffler, tip, all of it, and ALL accesories and drive systems, that is the serp belt, crank pulley, AC, alternator, power steering, water pump , everything mechanically attached to and driven by engine. Its in this "fully dressed" state that our hp numbers come from , my '08 LS is 148hp based on this test, an SS/TC is 260hp.
When we run my LS on the chassis dyno at Tune time, maybe it pust down 133hp to the wheels, it still makes 148hp at the crank, but only 133 of it makes it to the wheels. Well lets say that we now take my LS and put stupid light wheels, low friction hubs, lightweight axles, smaller brakes and super lube in the trans, and we run it on the TuneTime dyno again....whats gonna happen, well its highly likely that it will now register more power on that dyno, lets 138hp, but if we take the engine and retest it like GM did its STILL gonna make 148hp just like stock, even though my car now puts more to the ground. So did we make more power??? Yes, we made my car have more power to the wheels. Is the engine putting out anymore power??? No. theres just less of it being used up spinning the wheels.
Okay pretend the car is stock again, and weve got 133hp at the wheels, Now lets put on that super light pulley. And we go back to TT, lets say the pulley is awesome and we now get 140hp to the wheels. You say all we did was reduce drag/loss whatever and the car is not really more powerful, well if we take the engine out and retest at GM it will make more than the 148hp it originally did. Why? because we modified the engine and it now puts more power into the drivetrain and more reaches the ground.
I know youre going to say we didnt "create" horsepower, we only freed it by changing the pulley. Well if thats how you wanna look at then I guess its your perogative, but based on that are you gonna then say that exhaust mods dont add power they really just free it? because they dont have the engine MAKE more pressure, they just allow it to breathe more easily and make the pressure it can, same with the intake, the intake doesnt "create" pressure, it just reduces pumping losses and enhances cylinder fill which allow it to make the pressure its designed to...... By your definition only nitrous, blowers, turbos, pistons and combustion chamber size affect power creation, because only these things actually set the maximum potential pressures possibly created.
Ignition timing and mods wouldnt count because they can only adjust pressures within the engines design specs, they cant add pressure beyond what is physically dictated by induction type, and static compression ratio.
Cooling mods wouldnt make power because they dont affect ideal pressure of the engine
Same goes for cams, they cant increase pressure, only tune how much fresh air comes in, how much exhaust goes out and how much static and dynamic compression is allowed to bleed off.
Same for tuning, etc, etc, etc,......very few things actually directly set maximum pressure limits, and anything isnt involved in setting maximum possible pressures doesn "make" horsepower by your definition
Again if its part of the engine it can affect bhp.
Last edited by Maven; 09-18-2008 at 08:39 PM.
09-19-2008, 01:37 AM
#124
Well if you wanna get really technical, engine pressure directly correlate to torque production, (IMEP is the engines theoretical peak pressure, this is affected only by mechanical design, BMEP is the engine "brake" pressure or likely average functioning pressure taking into account pumping losses and friction these are key and relate directly to "bolt on" mods) higher effective pressures create more torque, being able to deliver this torque is horsepower, if you reduce engine friction, reciprocatin or rotating mass you alter how quickly the engine can deliver torque.(how quicky torque is delivered is essentially the definition of horsepower ) Lets forget that for now though even though its the key point.
Your getting heavily involved with semantics here, that being "creating" horsepower, versus "freeing" horsepower. This is one issue. The second is you are intermingling the whole bhp and whp deal in their with the "freed" versus "produced" power.
The drivetrain of the car is the transaxle, wheel axle shafts, hubs, rotors, brakes and wheels/tires. All of these things can only REDUCE how much of the power the engine produces is put to the ground. They cant increase it, so if youve got 200bhp there is no way youve got 215whp, we agree on this right?
The engine of the car, as pertains to horsepower ratings given by Chevrolet and every other manufacturer based on the new SAE standards is a fully dressed engine, that is the complete air intake system as found in the car, the airbox, filter everything, the complete exhaust system as found in the car that is manifold cat, muffler, tip, all of it, and ALL accesories and drive systems, that is the serp belt, crank pulley, AC, alternator, power steering, water pump , everything mechanically attached to and driven by engine. Its in this "fully dressed" state that our hp numbers come from , my '08 LS is 148hp based on this test, an SS/TC is 260hp.
When we run my LS on the chassis dyno at Tune time, maybe it pust down 133hp to the wheels, it still makes 148hp at the crank, but only 133 of it makes it to the wheels. Well lets say that we now take my LS and put stupid light wheels, low friction hubs, lightweight axles, smaller brakes and super lube in the trans, and we run it on the TuneTime dyno again....whats gonna happen, well its highly likely that it will now register more power on that dyno, lets 138hp, but if we take the engine and retest it like GM did its STILL gonna make 148hp just like stock, even though my car now puts more to the ground. So did we make more power??? Yes, we made my car have more power to the wheels. Is the engine putting out anymore power??? No. theres just less of it being used up spinning the wheels.
Okay pretend the car is stock again, and weve got 133hp at the wheels, Now lets put on that super light pulley. And we go back to TT, lets say the pulley is awesome and we now get 140hp to the wheels. You say all we did was reduce drag/loss whatever and the car is not really more powerful, well if we take the engine out and retest at GM it will make more than the 148hp it originally did. Why? because we modified the engine and it now puts more power into the drivetrain and more reaches the ground.
I know youre going to say we didnt "create" horsepower, we only freed it by changing the pulley. Well if thats how you wanna look at then I guess its your perogative, but based on that are you gonna then say that exhaust mods dont add power they really just free it? because they dont have the engine MAKE more pressure, they just allow it to breathe more easily and make the pressure it can, same with the intake, the intake doesnt "create" pressure, it just reduces pumping losses and enhances cylinder fill which allow it to make the pressure its designed to...... By your definition only nitrous, blowers, turbos, pistons and combustion chamber size affect power creation, because only these things actually set the maximum potential pressures possibly created.
Ignition timing and mods wouldnt count because they can only adjust pressures within the engines design specs, they cant add pressure beyond what is physically dictated by induction type, and static compression ratio.
Cooling mods wouldnt make power because they dont affect ideal pressure of the engine
Same goes for cams, they cant increase pressure, only tune how much fresh air comes in, how much exhaust goes out and how much static and dynamic compression is allowed to bleed off.
Same for tuning, etc, etc, etc,......very few things actually directly set maximum pressure limits, and anything isnt involved in setting maximum possible pressures doesn "make" horsepower by your definition
Again if its part of the engine it can affect bhp.
Your getting heavily involved with semantics here, that being "creating" horsepower, versus "freeing" horsepower. This is one issue. The second is you are intermingling the whole bhp and whp deal in their with the "freed" versus "produced" power.
The drivetrain of the car is the transaxle, wheel axle shafts, hubs, rotors, brakes and wheels/tires. All of these things can only REDUCE how much of the power the engine produces is put to the ground. They cant increase it, so if youve got 200bhp there is no way youve got 215whp, we agree on this right?
The engine of the car, as pertains to horsepower ratings given by Chevrolet and every other manufacturer based on the new SAE standards is a fully dressed engine, that is the complete air intake system as found in the car, the airbox, filter everything, the complete exhaust system as found in the car that is manifold cat, muffler, tip, all of it, and ALL accesories and drive systems, that is the serp belt, crank pulley, AC, alternator, power steering, water pump , everything mechanically attached to and driven by engine. Its in this "fully dressed" state that our hp numbers come from , my '08 LS is 148hp based on this test, an SS/TC is 260hp.
When we run my LS on the chassis dyno at Tune time, maybe it pust down 133hp to the wheels, it still makes 148hp at the crank, but only 133 of it makes it to the wheels. Well lets say that we now take my LS and put stupid light wheels, low friction hubs, lightweight axles, smaller brakes and super lube in the trans, and we run it on the TuneTime dyno again....whats gonna happen, well its highly likely that it will now register more power on that dyno, lets 138hp, but if we take the engine and retest it like GM did its STILL gonna make 148hp just like stock, even though my car now puts more to the ground. So did we make more power??? Yes, we made my car have more power to the wheels. Is the engine putting out anymore power??? No. theres just less of it being used up spinning the wheels.
Okay pretend the car is stock again, and weve got 133hp at the wheels, Now lets put on that super light pulley. And we go back to TT, lets say the pulley is awesome and we now get 140hp to the wheels. You say all we did was reduce drag/loss whatever and the car is not really more powerful, well if we take the engine out and retest at GM it will make more than the 148hp it originally did. Why? because we modified the engine and it now puts more power into the drivetrain and more reaches the ground.
I know youre going to say we didnt "create" horsepower, we only freed it by changing the pulley. Well if thats how you wanna look at then I guess its your perogative, but based on that are you gonna then say that exhaust mods dont add power they really just free it? because they dont have the engine MAKE more pressure, they just allow it to breathe more easily and make the pressure it can, same with the intake, the intake doesnt "create" pressure, it just reduces pumping losses and enhances cylinder fill which allow it to make the pressure its designed to...... By your definition only nitrous, blowers, turbos, pistons and combustion chamber size affect power creation, because only these things actually set the maximum potential pressures possibly created.
Ignition timing and mods wouldnt count because they can only adjust pressures within the engines design specs, they cant add pressure beyond what is physically dictated by induction type, and static compression ratio.
Cooling mods wouldnt make power because they dont affect ideal pressure of the engine
Same goes for cams, they cant increase pressure, only tune how much fresh air comes in, how much exhaust goes out and how much static and dynamic compression is allowed to bleed off.
Same for tuning, etc, etc, etc,......very few things actually directly set maximum pressure limits, and anything isnt involved in setting maximum possible pressures doesn "make" horsepower by your definition
Again if its part of the engine it can affect bhp.
heres where your wrong though. your exhaust is not using horsepower...it is limiting horsepower. Getting a bigger exhaust would increase scavenging and flow rates, yielding higher volumetric efficiency, yielding more actual pressure (hp) in the cylinders.
ignition mods also change cylinder pressures, creating horsepower.
cooling mods make a denser charge, and allow more timing, creating more pressure,
cams increase airflow, meaning more pressure in the cylinder.
a underdrive pulley however does NOT create more pressure in the cylinders...
One thing I think you are confused about is when i say cylinder pressure, im not referring to air pressure, like the 14.7 PSIa in each cylinder....i am referring to combustion cylinder pressures, the 100's of PSI that push the pistons down during the power stroke.
09-19-2008, 09:39 AM
#125
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heres where your wrong though. your exhaust is not using horsepower...it is limiting horsepower. Getting a bigger exhaust would increase scavenging and flow rates, yielding higher volumetric efficiency, yielding more actual pressure (hp) in the cylinders.
ignition mods also change cylinder pressures, creating horsepower.
cooling mods make a denser charge, and allow more timing, creating more pressure,
cams increase airflow, meaning more pressure in the cylinder.
a underdrive pulley however does NOT create more pressure in the cylinders...
One thing I think you are confused about is when i say cylinder pressure, im not referring to air pressure, like the 14.7 PSIa in each cylinder....i am referring to combustion cylinder pressures, the 100's of PSI that push the pistons down during the power stroke.
heres where your wrong though. your exhaust is not using horsepower...it is limiting horsepower. Getting a bigger exhaust would increase scavenging and flow rates, yielding higher volumetric efficiency, yielding more actual pressure (hp) in the cylinders.
ignition mods also change cylinder pressures, creating horsepower.
cooling mods make a denser charge, and allow more timing, creating more pressure,
cams increase airflow, meaning more pressure in the cylinder.
a underdrive pulley however does NOT create more pressure in the cylinders...
One thing I think you are confused about is when i say cylinder pressure, im not referring to air pressure, like the 14.7 PSIa in each cylinder....i am referring to combustion cylinder pressures, the 100's of PSI that push the pistons down during the power stroke.
The same goes for a forced induction engine, with the exception that raising boost levels will raise IMEP or potential power, but at any given boost level everything that applies to an NA engine applies to boost, you simply can not make more power than hte engine would if it could operate under ideal conditions, so EVERY mod you make is merely in an attempt to reduce the amount of power lost through imperfect cylinder fill, pumping, friction, power wasted spinning heavy parts, etc.
And to use your words "...is not using horsepower...it is limiting horsepower." Heavy parts, whether it be a pulley, a rod, the crank, pistons, heavy springs are not "using" horsepower, they are limiting it. Hopefully one last example:
Take an LNF, it makes 260bhp. Now bolt on a 10lb crank pulley, a 30lb flywheel, 100lb crank, 5lb rods, 2lb pistons, and much heavier valve springs.
None of those things changed combustion pressures correct?
Will this engine now produce less bhp on an engine dyno?