[2007 to 2016 M6 Cab]

Originally Posted by tony@tony-t.com

Speedracerlo,

I have a 2014 M6 with no mods. I love that sound and can give you some tips on how to replicate it consistently.

First it is important to understand where the pop is coming from. It's un burnt fuel reacting with fresh oxygen and partially igniting from heat of the exhaust system. As the fuel air mixture ignites it heats up, expands and causes the BRAP we love so much. The un burnt fuel gets into the exhaust because the engine management system continues to inject fuel through the system to cool the turbine after it heats up from hard acceleration.

Here's a few tips on how to get the system to BRAP:

• Let the engine warm up. If the turbines are not hot, fuel won't be used to cool them. If the exhaust tips are not hot, they won't ignite the fuel as it runs through the system.
• Use sport or sport plus engine settings. Both settings keep the turbines spinning faster so they will spool up faster. The turbines will also run hotter because exhaust will be running through them more consistently.
• Roll on full throttle at a low RPM. Starting at a lower rpm gives the turbine a longer time spool up and generate heat.
• Don't loose traction. Using 2nd gear helps here.
• Short Shift. This is the most important tip. Short shifting (about 5,700 RPM from second to third) at full throttle causes the engine to retard the ignition for a brief moment to allow for a smoother shift. During that time fuel continues to flow into the exhaust, unburnt. Shifting near redline doesn't have the same effect because the system knows that there is significantly less torque at that RPM and shifting will be significantly smoother, therefore the amount of ignition retarding if any won't send enough unburnt fuel through the system. Peak torque is at ~6,000 RPM so that's your target.
• In third use slightly higher RPM's. Above 3rd, gear spacing gets closer so ignition retarding doesn't have to compensate for a large RPM shift. I find letting revs climb and abruptly removing throttle will sometime cause a brap.
• First gear is very difficult to brap. There is not enough traction to apply full throttle at low RPM's which allow the turbine to spool up and generate heat. From 2,500 RPM to 3,200 RPM the engine begins to generate an additional 125 ft/lbs of torque with an additional surge above 5,000 RPM. Both torque surges, especially the earlier one, typically cause a loss of traction in 1st gear. The more traction control gets involved, the less chance you will have at creating a brap.

Hope this helps.

If your engine is already at operating temp, you can get the exhaust to brap while in neutral. Use sport plus. Do one short rev to pre spool the turbine. Just before getting back to idle, give a full throttle rev and abruptly remove throttle at 5,500 RPM ish (perhaps higher.) Use a higher RPM than you use for short shifting. You need the turbine to spool up and generate heat. When you pull back on the throttle, the engine will send fuel through the exhaust to cool the turbines. If the engine isn't hot this is a waste of time and if it is cold it won't even rev. NOTE: don't make the same mistake I made. Always check to make sure you are in neutral first. I pulled into a parking spot, engaged the safety brake and to satisfy a friends request attempted the rev but forgot I was still in first. Oops.

Wow! Thanks for the detail!

Can't wait till I can try this!!!