[95opal]

Originally Posted by WildWill to continue on the original subject.... what's interesting to me is the fact that today I ran with a 2002 GT that was almost stock (except for exhaust) and the only thing on my 95 is flowmasters and a shifter and I stayed right with him in first and second (he beat me pretty good after that tho). so that makes me wonder about the actual power rating of the 5.0. Were the 99-04 GT's much heavier than the 94-95's? I've heard that the our gen. mustang is extremely heavy compared to others???

5.0=Torque>4.6

[Goblin]

4.6s make the same torque, just not like a 5.0 does. The Sn95s and New Edge arent far apart in weight.

[Bullitt95]

Originally Posted by WildWill to continue on the original subject.... what's interesting to me is the fact that today I ran with a 2002 GT that was almost stock (except for exhaust) and the only thing on my 95 is flowmasters and a shifter and I stayed right with him in first and second (he beat me pretty good after that tho). so that makes me wonder about the actual power rating of the 5.0. Were the 99-04 GT's much heavier than the 94-95's? I've heard that the our gen. mustang is extremely heavy compared to others???

The '94-'98 SN95 is about 100lb heavier than both the Fox body and the '99-'04 New Edge, but is about 120lb lighter than the '05+ S197.
As far as the power rating of the 5.0 goes, stock SN95 T5's are putting down about 190-195rwhp and 255-260rwtq. With a drivetrain loss of 13%, that comes to 220-225hp and 295-300lbft at the flywheel. The factory ratings of 215hp and 285lbft were clearly slightly conservative.
The '99-'04 4.6 PI engine was factory rated at 260hp and 302lbft but again that's slightly conservative. In reality, they put down about 230-235rwhp and 275-280rwtq which translates into 265-270hp and 315-320lbft at the flywheel.
The '94-'95 5.0 and the '99-'04 4.6 produce similar torque up to 3500rpm and it's only above 3500rpm that the 4.6 starts to walk away. The 5.0 lays down and dies by 5000rpm while the 4.6 still pulls well up to 5500rpm. That probably explains your subjective impression Wildwill.

[Goblin]

Heres my problem. How can you be absolutely sure your losing 13% through the drivetrain? Unless you measure the power of the engine under brake specific, and then re-measure at the tires, you dont actually know how much your losing. 13% is just another number people through out there to make the math work in their favor. This is why i dislike chassis dynos.

I know people will argue and say... "Well, 12-14% is a general rule, and most have been proven to lose that amount." Well, wheres the proof? Just because people say this, and say that... and its all general, that doesnt mean its right! Ive seen stock 5.0s on the dyno, and even with accessories, ive seen numbers as high as 250bhp, and 315-20lb-ft of torque. Plug in your 13% rule, and see if the math works out.

[WildWill]

thanks for the explanation bullitt95.... that lays it out perfectly for me.

Goblin... those approximate numbers are what have been tested. if you pulled a motor and threw it on an engine dyno, you would get the specific horsepower at the flywheel, but then you put that engine back into the car, and it (on average) will loose 12-15% of it's dyno'd power at the wheels (through a manual tranny... an automatic looses more power). this horsepower is lost due to uncontrollable factors such as friction and heat loss. energy cannot be created or destroyed, and all horsepower is is kinetic energy. it is almost impossible to transfer any kind of energy with 100% efficiency. at the very least, small amounts are lost to heat, friction, and sound. the reason an automatic looses more power is because there are more moving parts inside it (creating more friction etc..).

[Bullitt95]

Originally Posted by Goblin Heres my problem. How can you be absolutely sure your losing 13% through the drivetrain? Unless you measure the power of the engine under brake specific, and then re-measure at the tires, you dont actually know how much your losing. 13% is just another number people through out there to make the math work in their favor. This is why i dislike chassis dynos.

Like them or not, it's rwhp and rwtq that gets your car down the 1/4 mile so the chassis dyno is a more practical and accessible tool. I can't see many people ripping their engines out of the car to run them on an engine dyno, so does the flywheel HP and TQ really matter except for bar-room bragging rights?

Originally Posted by Goblin Ive seen stock 5.0s on the dyno, and even with accessories, ive seen numbers as high as 250bhp, and 315-20lb-ft of torque.

I don't think so. I did read one article in Hotrod magazine about a '93 5.0 build-up where the engine dynoed 251hp and 305lbft in "stock" form on a Superflow, but it actually had Kooks long tube headers/performance exhaust/electric water pump attached to it so it wasn't really stock. Those dyno numbers were also standard correction which is 4% higher than SAE, so the SAE corrected numbers would have been 241hp and 293lbft.

[Goblin]

Originally Posted by WildWill thanks for the explanation bullitt95.... that lays it out perfectly for me. Goblin... those approximate numbers are what have been tested. if you pulled a motor and threw it on an engine dyno, you would get the specific horsepower at the flywheel, but then you put that engine back into the car, and it (on average) will loose 12-15% of it's dyno'd power at the wheels (through a manual tranny... an automatic looses more power). this horsepower is lost due to uncontrollable factors such as friction and heat loss. energy cannot be created or destroyed, and all horsepower is is kinetic energy. it is almost impossible to transfer any kind of energy with 100% efficiency. at the very least, small amounts are lost to heat, friction, and sound. the reason an automatic looses more power is because there are more moving parts inside it (creating more friction etc..).

Thats nothing i dont already know, and have heard people preach about.

Originally Posted by Bullitt95 Like them or not, it's rwhp and rwtq that gets your car down the 1/4 mile so the chassis dyno is a more practical and accessible tool. I can't see many people ripping their engines out of the car to run them on an engine dyno, so does the flywheel HP and TQ really matter except for bar-room bragging rights? I don't think so. I did read one article in Hotrod magazine about a '93 5.0 build-up where the engine dynoed 251hp and 305lbft in "stock" form on a Superflow, but it actually had Kooks long tube headers/performance exhaust/electric water pump attached to it so it wasn't really stock. Those dyno numbers were also standard correction which is 4% higher than SAE, so the SAE corrected numbers would have been 241hp and 293lbft.

Like it or not eh? So, let me see if i understand you correctly... the wheels and tires actually produce their own Torque and HP?

The engine is what produces torque, and is the only form of power the car has. So yes, BHP (Brake Horsepower or Flywheel Power) matters MOST, because thats the true power the engine is making, and thats the ONLY power that drives the car down the street or track. Chassis dynos are flawed, and inaccurate. Anyone who tells you they arent, is fooled into thinking there actually a good tool to measure power with. A chassis dyno measures torque/force at the wheels, and then has a series of functions and equations to modify the number, based on a percentage (thats preset by the way) of how much SHOULD be lost. The dyno doesnt actually know how much power is being lost, so its made to guess.

An engine dyno works with the basic Torque and HP formula, which gives you the most accurate numbers. How can a chassis dyno give you an accurate measurement of the cars HP and TQ if its not measuring the power at brake specifc? Oh yeah, it has to guess with a preset percentage value. Because most chassis dynos follow the same rule, or close to it... you'll see the majority of 5.0Ls in stock form putting down the same numbers, or close to the same numbers. I can modify the function tables and formulas on a chassis dyno to actually produce the stock numbers the car is rated at. So if i can do that... whats to say the pre-determined 12 or 13% in-efficeincy loss is correct?

You dont think stock 5.0Ls can produce 240-250bhp with accessories and stock exhaust? Okay, thats your choice not to believe it. I believe it, because ive seen it, and two of mine have done it.

[94pacecarSVT]

how come i get pulled off the line by 4.6ers but then by time i grab third im walkin off on em like theres no tomorrow?

[Bullitt95]

Originally Posted by Goblin So, let me see if i understand you correctly... the wheels and tires actually produce their own Torque and HP?

Come on Goblin, don't insult my intelligence by making ridiculous statements like that. I know very well that it's the engine that produces HP/TQ, but it's the amount of HP/TQ that reaches the driven wheels that determines how fast a car will go.
It doesn't matter at the end of the day whether the engine makes 215hp with a drivetrain loss of 25hp, or 250hp with a drivetrain loss of 60hp. If the same 190hp is reaching the driven wheels, the car is going to accelerate at the same rate regardless of whether the engine produces 215hp or 250hp.

[WildWill]

Goblin... if you wanna get that specific... it's the individual firing motion of each cylinder that produces horsepower and torque... i guarantee there is some power lost by the time you are measuring it at the flywheel. a dyno is a tool that measures the amount of work that a machine can do... whether its turning at the flywheel or at the rear tires, it doesn't make a difference. what your saying is irrelevant. horsepower is horsepower.

[Goblin]

Originally Posted by Bullitt95 Come on Goblin, don't insult my intelligence by making ridiculous statements like that. I know very well that it's the engine that produces HP/TQ, but it's the amount of HP/TQ that reaches the driven wheels that determines how fast a car will go. It doesn't matter at the end of the day whether the engine makes 215hp with a drivetrain loss of 25hp, or 250hp with a drivetrain loss of 60hp. If the same 190hp is reaching the driven wheels, the car is going to accelerate at the same rate regardless of whether the engine produces 215hp or 250hp.

Im sorry if i insulted you, that wasnt my intent at all.

Originally Posted by WildWill Goblin... if you wanna get that specific... it's the individual firing motion of each cylinder that produces horsepower and torque... i guarantee there is some power lost by the time you are measuring it at the flywheel. a dyno is a tool that measures the amount of work that a machine can do... whether its turning at the flywheel or at the rear tires, it doesn't make a difference. what your saying is irrelevant. horsepower is horsepower.

Irrelevant huh? You dont know much about dynos do you. . . A dyno doesnt measure how much work a machine can do, it measures how much torque it produces under a brake. HP is a mathematical function of torque, and the dyno calculates how much work (HP) the engine is doing at any given rpm, with the value of measured torque. Horsepower is not something you can measure from rotational force. If you wanna get that specific.

[Bullitt95]

Originally Posted by Goblin Im sorry if i insulted you, that wasnt my intent at all.

No worries. I'm

Originally Posted by Goblin Irrelevant huh? You dont know much about dynos do you. . . A dyno doesnt measure how much work a machine can do, it measures how much torque it produces under a brake. HP is a mathematical function of torque, and the dyno calculates how much work (HP) the engine is doing at any given rpm, with the value of measured torque. Horsepower is not something you can measure from rotational force. If you wanna get that specific.

Both the engine and chassis dynos basically work on the same principle i.e. they measure torque and the HP numbers are extrapolated from the TQ numbers and rpm:

HP = TQ (lbft) x rpm/5252

While it would be nice to measure the flywheel HP after every mod on an engine dyno, it's not practical to remove the engine from the vehicle each time. You only see the engine dyno used to test performance parts in magazine tech articles.
The chassis dyno will also give you HP/TQ numbers that are more applicable in the real world because it's RWHP/RWTQ that determines how fast your car will go. If you're going to test performance parts or do dyno tuning on a chassis dyno, it's important to use the same dyno each time so that you can make a fair comparison.

[Goblin]

I guess its just me. Im used to getting combos dynoed before they actually end up between the strut towers. I understand that the power at the wheels is what is motivating the car. Its difficult for me to put it in terms that makes it easier to understand. Its like i said earlier, i know that 13-15% is a generalization for most manual transmission cars, but i almost never go by that, because you never know what your losing unless you measure the power at flywheel. I really hope this isnt coming off as an opinion..

[WildWill]

Originally Posted by Goblin I really hope this isnt coming off as an opinion..

yup it sure is. if you took physics in high school, you would understand why i brought up "work." your right, i don't know jack about dynos because i've never used one... but the measurement of torque is all relative to work... torque is a force that is generally related to a turning motion, and if an object moves (in any way shape or form) work is being done upon it. please do not insult my intelligence.

[Goblin]

Actually, i did take physics in highschool.. and i DO understand why you brought up "work." Im not insulting your intelligence when you just admitted you dont know jack about dyno's. That was the only comment i made that would have insulted you. If you feel insulted, im sorry.

Your absolutely right, work is all relative to torque and driven motion of movement, whether its in rotation or displacement of an object. But, the way a dynomameter works is based on a function of a mathematical formula. Im sure you know that already. A dyno measures force/torque and rpm, and thats it. It doesnt actually measure work (or horsepower.. same thing) of an object, or wheel, or crank. It gets a work value based on the linear fuction of the formula the software is based on. This is all i was trying to point out to you, sorry if i insulted you.

[Bullitt95]

Originally Posted by Goblin I guess its just me. Im used to getting combos dynoed before they actually end up between the strut towers. I understand that the power at the wheels is what is motivating the car. Its difficult for me to put it in terms that makes it easier to understand. Its like i said earlier, i know that 13-15% is a generalization for most manual transmission cars, but i almost never go by that, because you never know what your losing unless you measure the power at flywheel. I really hope this isnt coming off as an opinion..

What you're saying is correct. Figures like 13-15% come about because the stock rwhp numbers that people are getting on their cars are compared to the manufacturers' advertised flywheel hp rating. As we all know, the actual flywheel hp that each engine produces in stock form can vary quite a bit from the manufacturers' rating, so that real world dynoed rwhp to rated flywheel hp comparison is flawed. The drivetrain loss % is, at best, an estimate so the flywheel hp will also be only an estimate if it is calculated from the measured rwhp. That is why I'd rather stick to what I can easily measure, which is rwhp.