Why so much false advertising.

[ONE92]

I would just like some answers about how manufacturers are able to post a dyno result, that can never be backed when we the buyers go and Dyno. I would think this goes under false advertising. I have noticed a lot of exhaust systems do this, and intakes. I have been told that the limiting factor in the exhaust system is in the pipes, why then does Remus say 10bhp gain by just adding there muffler. I was also told that an intake without a ecu tune actually makes the ecu show an error and you lose horsepower. Any advice on this subject would be greatly appreciated. I am a total noob and am a bit concerned that Remus ripped me off and that I might get ripped off some more.

[FStop7]

It's been this way for 40 years or more, for all types of cars. For all products in general, really. People who sell you things often overstate what it is to make it more attractive. That's why people always say caveat emptor - "Let the buyer beware"

[Brianrg]

Great explanation.

[askiles]

Also, aftermarket performance parts mfg.'s don't say YOU will gain that much HP/TQ, they said that when they put it on their car and dynoed it, that is what they got.

-Andy

[ONE92]

Originally Posted by PencilGeek

Auto manufacturers don't commit fraud. The differences you are referencing occur because of different dyno types, and different dyno testing methods. Auto manufactures test their motors on a motor dyno using steady-state testing. A motor dyno measures the torque at the crankshart. Steady-state testing means they hold the RPM steady for 5 seconds while the dyno measures the torque. This is BY FAR the most accurate way to measure results.

When you measure your dyno results, you don't take the motor out of your car and place it on a dyno, and you don't use steady-state testing. Instead, you most likely place the car on a chassis dyno which measures acceleration at the wheels, and basically guesses what the horsepower must be. You're not really measuring much of anything -- you're inferring it based on acceleration. (Some roller dyno's do actually measure torque, but I'm intentionally over simplifying things here.) When you measure torque at the wheels, you're also incurring about 12-15% drivetrane loss, and about another 10% of losses caused by your heavy wheels and tires. So in the end, you get about 25% loss from the crankshaft to the ground when you try to measure horsepower with the motor still in the car.

Thank you very much for your explanation and keeping it simple.

[URBAN LEGEND]

You can keep it even more simple by leaving the car stock. This way you have nothing to worry about.

[niterider]

Also take in consideration that every car will respond differently to mods. Some engines respond better to mods then other, its been like this forever.

[URBAN LEGEND]

Originally Posted by PencilGeek

The guy was curious why home-grown dyno results don't match factory results. How on earth does "keeping the car stock" answer that question, or explain the disparity?

Simple. By leaving the car stock you have nothing to worry about (false advertising). But what do I know.

[m34jlp]

also keep in mind alot of companies say you gain x amount of power, but this doesn't necessarily mean peak power...you could be gaining 10hp at 3000rpm and 0 at 8000

[Kadarin]

It's been like this for decades. I remember back in the 5.0 Mustang days, if you believed advertised horsepower numbers, it was theoretically possible to double the horsepower of the engine via bolt-on mods alone. If, of course, you believed the advertised numbers.