hp gain

[COramprat]

I think you have your logic a little wrong. How much air goes in and out of your engine does effect how much power it makes. Because an engine is basically a massive air pump, the more air that is moves, the more power it will make, in theory. The cats restrict air flow, thus dampening your motor's ability to produce power. However something liek the tranny and the sound energy it gives off eats up power as it goes from your motor to the ground.

OK....I understand airflow into the engine will "make" HP because that is the function of a supercharger but the flow out is after it has already been "pumped". All you are doing by removing restrictions is freeing up the HP that was used to force it past the cats.

 

[jstreet0204]

its not all accessories, its all accessories now, but when the 260 was claimed it wasn't. also back then they could use some super slick lubricants, very cold inlet temps etc.

They started using net hp in 1971

 

[COramprat]

We've just ruined 04gtboy's thread. Wait till he comes back to see all of this.

 

[twogts4us]

OK....I understand airflow into the engine will "make" HP because that is the function of a supercharger but the flow out is after it has already been "pumped". All you are doing by removing restrictions is freeing up the HP that was used to force it past the cats.

With that logic, there is absolutely no gains to be had with any exhaust mods - so, are you saying that all these guys with full exhaust including long tubes are doing so just for looks and/or sound? And that the only way to make power is to get more air in...doesn't matter how it gets out? Hell, why run exhaust manifolds or headers at all?
Man, where do you get your logic? Your earlier post stating "You will not "gain" flywheel HP meaning you will still be at 260 but you will free up some that is lost to the wheels" ???? crapola

 

[ponysarepretty]

OK....I understand airflow into the engine will "make" HP because that is the function of a supercharger but the flow out is after it has already been "pumped". All you are doing by removing restrictions is freeing up the HP that was used to force it past the cats.

No energy is "used" to push it out the cats, the cats just limit the amount of air that can be pumped out and therefre the amoutn that can be sucked in, and even if there is, the gain is all in the motor, if there was a separate pump that pumped out the smog (like the old smog pumps), yes it would be parasitic, but removing cats improves FWHP which then makes it to the RWHP.

 

[ponysarepretty]

They started using net hp in 1971

Quite aware of that, but they have tweaked it from time to time. There have been new standards instituted, one was just insituted, which caused a lot of ratings (like toyota) to go down and some otehrs to go up (like GM), it is now a lot stricter as to the accessories and stuff.

 

[ponysarepretty]

With that logic, there is absolutely no gains to be had with any exhaust mods - so, are you saying that all these guys with full exhaust including long tubes are doing so just for looks and/or sound? And that the only way to make power is to get more air in...doesn't matter how it gets out? Hell, why run exhaust manifolds or headers at all?
Man, where do you get your logic? Your earlier post stating "You will not "gain" flywheel HP meaning you will still be at 260 but you will free up some that is lost to the wheels" ???? crapola

he is thinking alone the lines of driveshaft and drivetrain loss i think. Like if you have lighter wheels, you will probably make more power at the wheels.

 

[COramprat]

With that logic, there is absolutely no gains to be had with any exhaust mods - so, are you saying that all these guys with full exhaust including long tubes are doing so just for looks and/or sound? And that the only way to make power is to get more air in...doesn't matter how it gets out? Hell, why run exhaust manifolds or headers at all?
Man, where do you get your logic? Your earlier post stating "You will not "gain" flywheel HP meaning you will still be at 260 but you will free up some that is lost to the wheels" ???? crapola

First...how about being civil and avoid the confrontational tone...Thanks

I'm not saying that there are no benefits to full exhuast. What I'm saying is you free up what is lost in a restrictive system. So what happens is you have a less restrictive exhaust which allows more FWHP which in turn is able to flow through the unrestricted pipes to make RWHP which in turn adds more FWHP to flow thru the unrestricted system...like a never ending cycle until infinity?

All accessories zap HP...the water pump, alternator, power steering...all require HP to turns these items. Same as a stock catted system. The air is restricted and requires HP to push it out. But remove these restrictions, or in the case of the accessories underdive them, and you free up some of the HP required to drive them. See what I'm getting at? I'm just trying to get some info and started this for the sake of discussion.

 

[COramprat]

he is thinking alone the lines of driveshaft and drivetrain loss i think. Like if you have lighter wheels, you will probably make more power at the wheels.

...at the wheels may have been better.

 

[03ghoststang]

their is a huge difference in adding a mod that increases both your WHP and at the fly, over a mod that reduces the powertrain loss to deliver more WHP with out adding FWHP but eventually they do like gears dont really add power but multiply torque to get that car moving easily

 

[COramprat]

their is a huge difference in adding a mod that increases both your WHP and at the fly, over a mod that reduces the powertrain loss to deliver more WHP with out adding FWHP but eventually they do like gears dont really add power but multiply torque to get that car moving easily

So where does a full exhuast fall in the equation...

Say you have a built engine on an engine dyno. It lays down 400HP with the dyno headers. THEN you take the same engine and add long tubes thru an X and a free flowing catback. Are you going to add to that 400?

 

[comporange04GT]

First...how about being civil and avoid the confrontational tone...Thanks

I'm not saying that there are no benefits to full exhuast. What I'm saying is you free up what is lost in a restrictive system. So what happens is you have a less restrictive exhaust which allows more FWHP which in turn is able to flow through the unrestricted pipes to make RWHP which in turn adds more FWHP to flow thru the unrestricted system...like a never ending cycle until infinity?

All accessories zap HP...the water pump, alternator, power steering...all require HP to turns these items. Same as a stock catted system. The air is restricted and requires HP to push it out. But remove these restrictions, or in the case of the accessories underdive them, and you free up some of the HP required to drive them. See what I'm getting at? I'm just trying to get some info and started this for the sake of discussion.

So by reducing the back pressure on the motor by changing to a less restrictive exhaust you reduce the pumping losses of the system. The motor does not have to work as hard to pump the exhaust gases down the new exhaust system therefore the difference in power that it takes to pump exhaust gases down the old system verses the new system can be transferred through the transmission through the rear axle and to the pavement via the wheels and tires. This will be shown as an increase in both rear wheel horse power and fly wheel horse power it just depends on where you want to reference your measurement.

 

[COramprat]

So by reducing the back pressure on the motor by changing to a less restrictive exhaust you reduce the pumping losses of the system. The motor does not have to work as hard to pump the exhaust gases down the new exhaust system therefore the difference in power that it takes to pump exhaust gases down the old system verses the new system can be transferred through the transmission through the rear axle and to the pavement via the wheels and tires. This will be shown as an increase in both rear wheel horse power and fly wheel horse power it just depends on where you want to reference your measurement.

I agree until the last sentence...I don't see how it would ADD to the HP you have. See my engine dyno analogy above...

 

[comporange04GT]

I agree until the last sentence...I don't see how it would ADD to the HP you have. See my engine dyno analogy above...

I am not sure if this answers your question or not.

The components of the drive train (transmission, rear end etc.) all have there own inherent inertia so it takes energy to move them. For example your motor makes 100 horse power at the crank and the drive train requires 20 horse power just to turn everything. The power seen at the wheels will be 80 horsepower. Now lets say you change the exhaust out and reduce pumping loses so you are seeing 110 horsepower at the crank the drive train still requires the same 20 horsepower to rotate (this is not exactly true since the amount of friction in the system is a direct function of the force you put into it but at this level of power the difference would be negligible) so you will see 90 horsepower at the wheels.

 

[03ghoststang]

So where does a full exhuast fall in the equation...

Say you have a built engine on an engine dyno. It lays down 400HP with the dyno headers. THEN you take the same engine and add long tubes thru an X and a free flowing catback. Are you going to add to that 400?

ok i get you but you already have the free flowing exhaust on it now do it in another way. Let's say that the engine on a dyno laid down 400HP with a Full exhaust setup like the mustangs have it now with stock manifolds 4 cats on the midpipe and a restrictive catback, and swap it to LT's and a o/r midpipe and less restrictive catback. The exhaust is now flowing more freely now wouldn't that give you power gains

 

[big T]

1) Factory hp is 260

2) Zero hp gains from the exhaust

I hope u r joking cause I picked up 18rwhp and 19...rwtq with my exhaust.

 

[COramprat]

I am not sure if this answers your question or not.

The components of the drive train (transmission, rear end etc.) all have there own inherent inertia so it takes energy to move them. For example your motor makes 100 horse power at the crank and the drive train requires 20 horse power just to turn everything. The power seen at the wheels will be 80 horsepower. Now lets say you change the exhaust out and reduce pumping loses so you are seeing 110 horsepower at the crank the drive train still requires the same 20 horsepower to rotate (this is not exactly true since the amount of friction in the system is a direct function of the force you put into it but at this level of power the difference would be negligible) so you will see 90 horsepower at the wheels.

Understand the power gains/losses with the drivetrain...but setting that aside...

I'm looking at supposed gains at the FW with the exhaust.

 

[COramprat]

ok i get you but you already have the free flowing exhaust on it now do it in another way. Let's say that the engine on a dyno laid down 400HP with a Full exhaust setup like the mustangs have it now with stock manifolds 4 cats on the midpipe and a restrictive catback, and swap it to LT's and a o/r midpipe and less restrictive catback. The exhaust is now flowing more freely now wouldn't that give you power gains

But not above what the motor is already putting out unrestricted. If you have a motor dyno'd at 400 HP with the stock set-up then move to a more free flowing exhaust then yes you would gain but not more than you already had meaning without the stock exhuast your motor would dyno at 420 unrestricted for example.

 

[comporange04GT]

If you lay it out as a closed cell diagram you only have a finite amount of energy going into the system (the fuel) so anything you do to reduce losses while converting the potential energy into kinetic energy is going to show up at the fly wheel. Losses come from things such as accessories as mentioned by someone earlier (AC compressor, power steering pump, water pump, etc.), thermal losses for example to the radiator, frictional losses, and pumping losses. So if you reduce any or a combination of these things you will have more of the kinetic energy show up at the crank since the amount of energy that goes into the system has to come out. What goes in must = what goes out or you will violate the laws of thermal dynamics.

 

[COramprat]

If you lay it out as a closed cell diagram you only have a finite amount of energy going into the system (the fuel) so anything you do to reduce losses while converting the potential energy into kinetic energy is going to show up at the fly wheel. Losses come from things such as accessories as mentioned by someone earlier (AC compressor, power steering pump, water pump, etc.), thermal losses for example to the radiator, frictional losses, and pumping losses. So if you reduce any or a combination of these things you will have more of the potential energy from the fuel converted into kinetic energy.

Understood...but you are only freeing up what is already there. The engine, unrestricted, lays down a certain HP. Each accessory drains that power. You find ways to drive those accessories more effieciently but not more than what the engine put out unrestricted. You will not add power, just free up what was lost.

I know what you are saying that this will still be measured at the flywheel and the gains will be there...I guess is boils down to whether the 260 rating is an unrestricted HP or if it was with accessories and exhaust. Given that then yes you would add to the totla output HP of the engine. But if that is unrestricted numbers, and that is what I based my early reply on, then you wouldn't add to that 260...just get closer to it.