Lose HP with bigger brakes???

[95blackGsTurbo]

Was watching t.v. today and even after putting a full cat back on a 2003 Acura RSX-S they still were showing a loss of 12 hp with a big brake kit. Even though the rotors wiegh less its more rotating mass. Rims and everything weighed the same too. Anyone on here run into that problem???

 

[jtmcinder]

While I haven't had this problem (sorry about the thread-jack), this is a good lesson for those thinking of putting mondo wheels on their cars, even if they weight less than stock.

Hey, search engine, look here! 18" wheels, 19" wheels, 20" wheels, etc.

- Jtoby

ps. 10 hp is a very big deal to a Honda, tee hee

 

[my97mitsGSX]

horsepower isn't a big deal with honda's, its torque.. something of which they lack a lot of!

 

[PaulPDX]

Are you *sure* the HP loss is attributed to the brakes and not the catback?

Believe it or not... aftermarket exhausts don't always make power all by themselves.

Even if it's because of the brakes... who puts bigger brakes on to make more power? point is to stop quicker so one can late brake and beat the other car to the apex.

 

[ckozlgod]

Ya theres no way a brake upgrade affected your HP level to that extent.

It's definately the exhaust. I have several friends who have lost HP after their "upgrade"

 

[PieTSI]

Maybe the brakes were not adjusted right somehow and the pads were dragging on the rotors, causing the loss of hp?

 

[KRAZYKOREAN]

Originally posted by 95bLaCkGsTuRbO
Was watching t.v. today and even after putting a full cat back on a 2003 Acura RSX-S they still were showing a loss of 12 hp with a big brake kit. Even though the rotors wiegh less its more rotating mass. Rims and everything weighed the same too. Anyone on here run into that problem???

wtf loosing horsepower from the brakes there ####ing retarded quit watching that show...

 

[Ballin' GS]

Originally posted by KRAZYKOREAN
wtf loosing horsepower from the brakes there ####ing retarded quit watching that show...

I think he means on the dyno. I.E. heavier rotating mass... not the actual motor losing hp.

 

[95blackGsTurbo]

Ok, This is what i saw, cause i watched them dyno the car 8 times, stock was like 190, with big brake kit and the rotors wiegh LESS but are bigger they loss 17hp. Put on a Mugen cat back, ran it again, only lost 12hp. They showed it on the dyno and all. they said because they are larger in diameter its harded to spin even though its lighter, then they put the stock ones back on and they were +5 from stock. Obviously they do affect it.

 

[Defiant]

Originally posted by 95bLaCkGsTuRbO
after putting a full cat back on a 2003 Acura RSX-S they still were showing a loss of 12 hp with a big brake kit.

Jesus, a 50% loss of power. That must really suck donkey balls.

 

[Velo7825]

Its called the Moment of Inertia, because the rotor is bigger around say 13" compared to 10" the instant center of gravity for the rotating mass is farther away from the spin center. The farther away from the spin center the instant center of gravity is the more Inertia the rotating mass will create. Inertia is just like weight on the car the more you have the harder it is to move it. So if your spinning the wheel it will actually weight more then it did when the wheel is not moving. Thought the wheel will always have the same Mass its weight at any given moment can be affected by lots of things.

Its like a bullet, you throw it at someone and they point and laugh. fire it at upwards of 1500 ft/s and it will go right through them. the faster an object moves (spinning is moving) the more Inertia it will create or "Force Weight" it will have.

So yes if you put big rims and big brakes on a car it will dyno with less hp because the extra inertia the rims and rotors are making take more hp to move them.

go to www.howstuffworks.com they got lots of visual aids.

 

[igs]

Please stop the madness. Unless that car was originally making over 10,000 hp there is no way heavier rotors, or wheels, will make it lose 12 hp on the dyno. Well, there is a way, if the new rotors weighed about 300 lbs more.

 

[PaulPDX]

Originally posted by igs
Please stop the madness. Unless that car was originally making over 10,000 hp there is no way heavier rotors, or wheels, will make it lose 12 hp on the dyno. Well, there is a way, if the new rotors weighed about 300 lbs more.

Yourself.

http://hyperphysics.phy-astr.gsu.edu/hbase/mi2.html

I = m r^2.

It doesn't have to weight 300lbs static. In this case size matters (r).

This is why big wheels are detrimental to performance.

 

[Todd TCE]

I'd tend to fault the wheels more than the rotors. Yes, the MOI is changed with the rotors too but man it's pretty small change unless you went from some stock 10.5 x .75 to 13 x 1.375 monsters. I've got some rotors upwards of 19lbs each, but who would put those on a Honda? ahh, never mind...

 

[95blackGsTurbo]

Originally posted by igs
Please stop the madness. Unless that car was originally making over 10,000 hp there is no way heavier rotors, or wheels, will make it lose 12 hp on the dyno. Well, there is a way, if the new rotors weighed about 300 lbs more.

Obviously there is a way cause they ran it with the stock rotors back on it and the results were 12hp higher, so they put the new rotors back on and he lost the 12hp again. the dyno doesnt lie.

 

[bigfoot]

I saw that one too. Thats an informative show, unlike most of those drama queen ricer shows.

 

[igs]

Originally posted by PaulPDX
Yourself.

http://hyperphysics.phy-astr.gsu.edu/hbase/mi2.html

I = m r^2.

It doesn't have to weight 300lbs static. In this case size matters (r).

This is why big wheels are detrimental to performance.

WTF???

Why don't you calculate for me that 12 hp loss, genius.

 

[eclipse420a2nr]

alright, i was skimmin through these threads and most of u are all confused. i've seen that show too. its filmed here in toronto. its actually quite easy to understand, common sense. they actually even explained it in the show. and it is a good show. they slapped on bigger breaks that wieghed 1.3 or 1.2lbs less. they dynoed it and lost 12hp. the reason is because even though they wieghs less since the diameter of the breaks are larger there is more wieght farther from the centre of the break and therefore since there is more wieght further from the centre, there is more resistance from the wieght of the break when it is spinning. and that is why there is a loss in hp. end of story. btw, there has been anotehr episode after that one where they gained the power back though intake alone. the next new show plays on tuesday. just thought id tell all of you incase ur wondering when it plays.

 

[ShyBoyRico]

I had my FMIC and AFC2 installed the same time I got my Baer track kit, so I could not really tell a difference. But the 13'' rotors are pretty heavy(1-piece) so i'm sure it cost me HP wise.

 

[Todd TCE]

Once agian it comes down to trade offs huh?
I'd be a bit shocked at 12hp, but maybe a couple.

Here's the kicker; do you get back the 'performance' you desire/need from brakes to make up for the loss?

Granted I can supply a very small, compact 11.75 kit for the drag racers which is lighter in overall weight than stock. It has rotors only slightly larger in diameter. They can also be light weight too if they are the .81 Ultralites.
But do you want it if you run open track days? Probably not.

 

[greathuskie]

my AEM rotors weigh like 16 lbs (estimated weight based on gym comparison...)

 

[igs]

Originally posted by eclipse420a2nr
alright, i was skimmin through these threads and most of u are all confused. i've seen that show too. its filmed here in toronto. its actually quite easy to understand, common sense. they actually even explained it in the show. and it is a good show. they slapped on bigger breaks that wieghed 1.3 or 1.2lbs less. they dynoed it and lost 12hp. the reason is because even though they wieghs less since the diameter of the breaks are larger there is more wieght farther from the centre of the break and therefore since there is more wieght further from the centre, there is more resistance from the wieght of the break when it is spinning. and that is why there is a loss in hp. end of story. btw, there has been anotehr episode after that one where they gained the power back though intake alone. the next new show plays on tuesday. just thought id tell all of you incase ur wondering when it plays.

You are completely wrong. Stop the madness. If you don't know what you are talking about DON'T POST. Just because you heard it on some ricer TV show does NOT mean it's true. Even if you put on heavier wheels you will not lose that kind of hp. End of discussion. Until you do the calculation yourself stop posting BS.

 

[Todd TCE]

Yup, my HD Road Race ones (13x1.10) come in at nearly 20 each. Lighter ones can be had for those who are a bit less serious....

 

[Orange_dsm]

Originally posted by igs
You are completely wrong. Stop the madness. If you don't know what you are talking about DON'T POST. Just because you heard it on some ricer TV show does NOT mean it's true. Even if you put on heavier wheels you will not lose that kind of hp. End of discussion. Until you do the calculation yourself stop posting BS.

You won't loose HP, but you will lose perfomace i.e. acceration times, etc. Although the losses will probably be small enough you wouldn't notice them.

 

[Velo7825]

Originally posted by igs
You are completely wrong. Stop the madness. If you don't know what you are talking about DON'T POST. Just because you heard it on some ricer TV show does NOT mean it's true. Even if you put on heavier wheels you will not lose that kind of hp. End of discussion. Until you do the calculation yourself stop posting BS.

"you are completely wrong". WHY? becasue you says so. and no i don't want to sit down for 2 hours working out calculations for you becasue you can't grasp the concept. if you read my post or the other ones that say the same thing then there is your answer. Besides i would have to have the car itself in my possesion to weigh and measure everything to actually show the 12hp loss. But why they already did on the show. Oh and that would be 6hp per rotor. Which does seem like a bit much but then again if it was 2hp overall would we still be wrong?

I've had 3 years of Engineering School and its a basic concept. If you want more info on why then there are lots of resourses on the internet.

I think what you learn from this kind of test is that there is always comprimises between maximum speed and handling. Like Todd said there are lots of options for either the road racer or the drag guys.