Will RPM/Speed relationships change with modding?

BMW135pls · 02-25-2015, 11:48 PM

Got a theoretical question. Say your stock car will do x mph in y gear while held at z RPM. If you mod and tune the engine to get a couple hundred more hp or tq out of it, can you expect to see the car do higher speeds at the same RPM in a specific gear? Or will the extra power mainly be used for going from one speed to another more quickly? I'm new to modding cars, so I don't really know what I should expect to see.

Silenus · 02-25-2015, 11:55 PM

The extra power will not change the speed of the vehicle at a certain RPM and gear. Modifying the cars gear ratios will do this (different differential, or transmission).

BMW135pls · 02-26-2015, 12:04 AM

Quote:

Originally Posted by Silenus

The extra power will not change the speed of the vehicle at a certain RPM and gear. Modifying the cars gear ratios will do this (different differential, or transmission).

Thought that might be it. Thanks!

elzorro4 · 02-26-2015, 08:34 AM

Quote:

Originally Posted by BMW135pls

Got a theoretical question. Say your stock car will do x mph in y gear while held at z RPM. If you mod and tune the engine to get a couple hundred more hp or tq out of it, can you expect to see the car do higher speeds at the same RPM in a specific gear? Or will the extra power mainly be used for going from one speed to another more quickly? I'm new to modding cars, so I don't really know what I should expect to see.

Its like being in a bike on gear y at z rpm and expecting to go quicker because you went to the gym 6 months... you will be able to achieve that rpm quicker but at a given gear/rpm the speed will be the same.

Vigilante375 · 02-26-2015, 09:03 AM

Quote:

Originally Posted by BMW135pls

Got a theoretical question. Say your stock car will do x mph in y gear while held at z RPM. If you mod and tune the engine to get a couple hundred more hp or tq out of it, can you expect to see the car do higher speeds at the same RPM in a specific gear? Or will the extra power mainly be used for going from one speed to another more quickly? I'm new to modding cars, so I don't really know what I should expect to see.

That only things that will effect your speedo/tech is swapping tires or changing the rear diff to a different ratio. Even then, you can get adjust the ECU to display the correct readings.

Doing mods to add power like a tune, exhaust, intake, cam(s), FI (forced induction), etc. will NOT affect what the speedo/tach.

02-25-2015, 11:48 PM	#1
BMW135pls First Lieutenant 90 Rep 341 Posts Drives: Bucket of screws and sadness Join Date: Jul 2014 Location: NJ, USA iTrader: (0)	Will RPM/Speed relationships change with modding? Got a theoretical question. Say your stock car will do x mph in y gear while held at z RPM. If you mod and tune the engine to get a couple hundred more hp or tq out of it, can you expect to see the car do higher speeds at the same RPM in a specific gear? Or will the extra power mainly be used for going from one speed to another more quickly? I'm new to modding cars, so I don't really know what I should expect to see. __________________ Model: '08 135i N54 6AT Coupe ///M Sport - E85 + 93 = E30 Mods: AA DPs + Gen I - BMS JB4 (Race + Map 2) + DCI + OCC - Cobb CP - ///M RSFB + Front Control Arms - Koni Yellow - Swift Spec R - Vorshlag camber plates - MPSS 225/255 - x-ph Angel Eyes 160w
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02-25-2015, 11:55 PM	#2
Silenus Second Lieutenant 98 Rep 233 Posts Drives: 2017 M3 Join Date: Apr 2014 Location: Bay Area, CA iTrader: (0)	The extra power will not change the speed of the vehicle at a certain RPM and gear. Modifying the cars gear ratios will do this (different differential, or transmission).
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