Kit Vexed Posted July 7, 2009 Report Share Posted July 7, 2009 i was watching some tuner show where they were upgrading a car's front brakes (the car was fwd) and then dyno'd the car and LOST hp to the ground. for the life of them they couldn't figure why? then one of the techs on the show was saying it was because they had put a big brake kit on the car and the larger rotors robbed horsepower because of the increased weight/mass of the overall rotating assembly of the wheel - meaning it took more power to move them. is this true? any of you guys that went with bigger rotors notice a difference? like do you think you have to get on the pedal a little more to move from stops? anybody dyno their car and lose hp after a bbk? i ask cause i got bigger wheels for my t-5r (18X8 225/35/18) and each wheel with the tire on was actually 9 lbs heavier than my stock wheel with the tire on was, and i totally noticed the difference in how much throttle i gave it to make it move from stops. i dont want to make the rotation of the front wheels even HEAVIER with bigger rotors too! anyone buy larger rotors that were the same weight or lighter than stock? if so, what kind? how much? etc. i can't afford diff calipers, i was thinking the kit with just the brackets for bigger rotors? thanks guys Link to comment Share on other sites More sharing options...
Chilled man Posted July 7, 2009 Report Share Posted July 7, 2009 yes I did but then I went to a super light rim and acutally cut rotation mass. if you want to a BBK and light weigth you will have spend $$$$ to get alumin hat 2 peice rotors. Link to comment Share on other sites More sharing options...
AverageVolvo Posted July 7, 2009 Report Share Posted July 7, 2009 I Went with 17lb 17in rims and the Porsche Bbk, I had 17 titans with the BBK on before. The car basically handles the same even though new rims weigh at least 7 lbs less. You lose a little straight off the line acceleration(with heavier Brakes) but it balances out in handling and braking. Depends what your overall goal is. Link to comment Share on other sites More sharing options...
Che'_Moderator Posted July 7, 2009 Report Share Posted July 7, 2009 Anytime you add weight, especially rotating weight, you will loose some performance. Id stop watching whatever show could not figure this out without the help of a tech. Link to comment Share on other sites More sharing options...
Kit Vexed Posted July 7, 2009 Author Report Share Posted July 7, 2009 well, i love the look of the wheels i'd gotten, and without question the handling is much better; so there's no turning back there.. so should i assume bbk's ARE, for the most part, power robbing? guess i'll stick with stock diameter rotors and just upgrade to slotted. get decent pads, SS lines and call it a day! Link to comment Share on other sites More sharing options...
HtownTurboBrick Posted July 7, 2009 Report Share Posted July 7, 2009 If you make the power the power the necessitates BBK's then you're not really going to worry about the power you're losing by putting them on. If you're stock and just want the BBK's for show, then yea maybe you should consider if you need them or not. But for a show to not be able to figure out where the horsepower went then they fail. Bigger rims lose power too, the more rotational mass the harder it will be to put the power down. Link to comment Share on other sites More sharing options...
randomdude Posted July 7, 2009 Report Share Posted July 7, 2009 first off, whoever was on that show shouldnt be let near a car or dyno if they couldnt figure that out, lol. i mean seriously, extra rotational mass, ddeeeeerrrr. and i would think you would loose more TQ than HP. Link to comment Share on other sites More sharing options...
turbotuner Posted July 7, 2009 Report Share Posted July 7, 2009 HP is simply a function of TQ. So if you lose TQ, you lose HP at the same RPM. Link to comment Share on other sites More sharing options...
Kit Vexed Posted July 7, 2009 Author Report Share Posted July 7, 2009 i think the show may have been Tuner Transformation? the car was an Integra (which is a low torque car to begin with, lol). i had titans, which were pretty darn light, but they were also 17" and only 205's. they looked great from the side, but ridiculous from the rear cause they were soo thin. 205's are narrow for an 850. one of the reasons i posted this thread is because not a lot of people think about how larger rotors can affect acceleration and power. when you go on iPd, EST, or any of the sites, it's not like they're saying, "you'll stop on a dime @ the cost of a few hp to the ground" or go into the physics of rotational mass. it may sound silly but some ppl just dont think about it. some of us try just about ANYTHING to squeeze a few extra horses out of our cars (ive read some crazy things ppl will do), so modified or not, i would rather not lose the hp just to stop a few feet sooner; i'll just brake earlier! for me personally, the porsche kit would be overkill, but it does look good.. i dont race or drive super crazy, i just want to up the feel and function of the stock set-up and wondered which way would be best to not rob hp since there ARE times i do drive wack. Link to comment Share on other sites More sharing options...
HtownTurboBrick Posted July 7, 2009 Report Share Posted July 7, 2009 Sticky tires, you can have the baddest ass brakes in the world, but if you have cheapy rubber that has no grip then yea, it sucks to be you in a "need to stop now" situation. With good rubber and pads you'll out brake a 850 with BBK's with shitty rubber. Link to comment Share on other sites More sharing options...
AverageVolvo Posted July 7, 2009 Report Share Posted July 7, 2009 Sticky tires, you can have the baddest ass brakes in the world, but if you have cheapy rubber that has no grip then yea, it sucks to be you in a "need to stop now" situation. With good rubber and pads you'll out brake a 850 with BBK's with shitty rubber. After a few 90-60mph dives stock brakes start to fade(hills etc..), so it depends on your driving style. In the city you will notice the additional rotational mass of the bbk and only slight benefit of brakes, On the highway the addt weight is not noticed and the brakes are Vastly superior, SO again it comes down to the overall picture. Link to comment Share on other sites More sharing options...
HtownTurboBrick Posted July 7, 2009 Report Share Posted July 7, 2009 But that begs the question, wtf are you doing on the freeway that you're experiencing brake fade? BBK is a performance mod, for racing. If you need BBK's because you're experiencing brake fade in your daily commute, you've got bigger problems at hand, like avoiding getting sent to the slammer for driving like a douche everywhere. Not saying that refering to you, but anyone in that particular situation needs to chill the hell out, because stock brakes, with good pads and sticky rubber, good brake fluid and maye stainless steel lines will be more then adequate to stop in emergency situations. If someone is using the freeway as a personal road course and get brake fade at freeway speeds theres a major problem like killing innocent people. Link to comment Share on other sites More sharing options...
AverageVolvo Posted July 7, 2009 Report Share Posted July 7, 2009 100% agreed Not needed for DD unless your a douche. But the BBK is noticeable even with spirited downhill driving. : ) That and frequent late trip up too San Francisco I5 All I am saying is there is a reason Volvo Uses larger Calipers and rotors on the R Line, I myself am running a stage 3 tune with 5 speed. I have more Hp than a Stock s60R so the brakes seemed pertinent. The 302mm setup is a great mid-point on improved braking and minimal rotational mass. Link to comment Share on other sites More sharing options...
Che'_Moderator Posted July 7, 2009 Report Share Posted July 7, 2009 i would rather not lose the hp just to stop a few feet sooner; i'll just brake earlier! i think u should just ask the person who cuts you off to let you know earlier so you have time to brake thats what i think Link to comment Share on other sites More sharing options...
JCviggen Posted July 7, 2009 Report Share Posted July 7, 2009 Big brakes are the best mod I ever did. And 2-piece rotors can be lighter than stock rotors (especially if you own a P2 R) Link to comment Share on other sites More sharing options...
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