I was literally recommended some 2pc rotors yesterday, i wondered if they even made any....well they will now i guess
K24Z7 - Crew Member #373
14' Honda Civic Si Coupe
GodSpeed 2-Way MonoMax Coilovers
MakspeedTurbo Kit - Comp 6062BB
Action Clutch - Stage 3
Hawk Performance Brakes
Progress Sway Bar
GearX - 1-4th w/RSX Final Drive
there are for bbk applications, we have been recommending it for forum members that wants more power & faster acceleration... we finally was able to package a set up for oem size applications !
for those we been buying parts with me knows how much faster a car can become by shave rotating mass
here is a DBA ROTORS testing results on light weight rotors...
All performance fanatics talk about reducing un-sprung weight. Yes, a rotating disc does have a certain amount of rotating inertia or a flywheel effect which requires power to accelerate and to decelerate. It takes approximately 18 lbf-ft of torque to get those 21lbs disc spinning up to 80mph and back down to 0mph when braking. The lighter 19lbs disc requires ONLY 15.1 lbf-ft which is a little better than 10% saving in energy required to accelerate and decelerate the same vehicle.
By thinking smarter DBA has developed opportunities to reduce weight without reducing performance by using higher quality disc rotor materials like DBA’s performance range or by replacing stock rotors with two piece designs such as DBA’s 5000 series discs which reduce weight from the mounting bell while maintaining the optimal weight on the braking band.
Last edited by team3d; 06-23-2017 at 11:02 AM.
Rotor TypeWeight (lbs)
Stock Front Cast Rotor~17.75 lb
Baer Front 2-Piece Rotor~15.80 lb
weight shaved for the front rotors, 1.95lbs each side
Stock Rear Cast Rotor~14.45 lb
Baer Rear 2-Piece Rotor~11.75 lb
weight shaved for the rear rotors 2.70lbs each corner
Mitsubishi Evolution before and after installing a set of lightweight rotors.
Emery at STM Tuned claimed the Evolution pulled 327 HP and 313 TQ and then jacked the car up while still on the dyno, replaced the rotors with Baer 2-piece rotors, and performed another dyno pull to the tune of 339 HP and 319 TQ. That’s a gain of over 10 horsepower to the ground.
results for the light weight rotor gain a max of 12whp & additional 6lbs of torque, if you look at the dyno chart, the gains is through out the whole power band.
and yes, brake makes power too....
Last edited by team3d; 06-23-2017 at 08:35 PM.
By shaving a grand total of 9.3lbs the Evo was able to make an extra 12WHP so based on those calculations if you drop the 29lbs stock wheels for lightweight 15lbs wheels you'd shave 56lbs all around than you'd make an extra 72WHP lol.
in your case, your stock is 23lbs 17" si wheels with 17x8 et35 rpf1 15.6lbs, that gives you a weight reduction of 7.4lb each corner, a total of 14.8lbs rotational weight reduction.
reduce inertia technically is not gaining horsepower, the power gain you see are the drive-train loss power that is recovered due to less energy use.
the rule of thumb for fwd drivetrain loss is 20%, so a 200hp car will be 160whp on a chassis dyno, that 40hp drivetrain loss can be recover some from light weight wheels, tires, rotors, clutch, axles...
if you can recover 20%, that is a good 8whp gain without adding any load into your engine.
Last edited by team3d; 06-24-2017 at 12:55 AM.
Okay you win so by dropping 28lbs unsprung (ie. 29lbs-15lbs) on the drive wheels of a FWD car you'll gain 36WHP lol. The Evo example clearly states a horsepower gain you yourself claim a 8WHP gain if you recover 20% of the loss (not sure where you came up with these numbers but whatever). Oh and also your saying power gain and loss is different with AWD versus FWD so that post is irrelevant to our cars to begin with.
Shut up and take my money Andy lol. No seriously I'm interested.
2014 Civic Si Sedan
^I think these kids need a little pow-wow to work out their differences lol
Interesting concept again, looking at rotational energy, back to the discussion of lightweight pulleys! The Evo also makes more HP and TQ than the Si, I mean were talking about a difference of over 100 HP and TQ difference, so maybe the amount of lightweight reduction, in various areas of course, will yield different results.
For example, the Si 2012 was 200HP, theoretically, 200HP is the max amount of HP that the motor can function at with absolutely no restrictions, so if the 20% was applied in the loss/restrictions, then only 40HP is left to make up...however, to what extend and how close you can come to the original 200HP is subjective.
For the Evo, the max HP that dyno made was right around 320, so, adding 20% would bring the max HP for the Evo (at crank) is up to 384HP (320 X .20 = 64, 64 + 320 = 384), so you have now 64 HP to make up, versus 40HP on the Si, (37.5% more), you have a much larger window to make up that HP/TQ than the Si.
If we look at the claim of 10HP gain with the new rotors, you have to take that from the 64HP, which is a gain of 15% (10/64 = 15.62%), or you could use the language of "recover" versus "gain", The light weight rotors "recovered" 10HP that was originally lost.
So, now you use the 15% as a basis for measure for what could be on the loss of the 40HP that the Si goes through, which takes the theoretical gain to 6HP (40 X .15), so with the lightweight rotors, you could anticipate a "recovered" 6HP from the original loss
Everything is always going to be proportionate to the original HP and TQ numbers of each engine at crank. Hope this makes sense.
Last edited by turkeyfeast123; 06-24-2017 at 11:41 AM. Reason: sentence structure