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M8 Competition 1000HP Build

M8 Competition 1000HP Build

Posted on August 25, 2025 By rehan.rafique No Comments on M8 Competition 1000HP Build

BIMMERPOST

Hi Folks,

I wanted to post some info on my 1000HP build, because when I embarked on this journey, I didn’t find much info on S63 builds (so hopefully this will answer some questions that some of you have if you’re considering pushing the limits a tad bit). Many folks with M8s and M5s seem to do moderate tunes and mods, and the ones that do major builds just go crazy all out for drag times. I just wanted to build a reliable and stable weekend car that was a 9-second car without too much drama. So this is my brief story and a few step-by-step methods I took to achieve this power and the mods I made. Also, several members on the forums messaged me and asked me about the build and dyno numbers, so I put this together to give you all some info, especially about the Pure 900 Turbos and their Spool/Lag (which you can see from Dyno Chart 1 showing the bright blue line when I had the stock engine internals running the stock turbos).

Please be advised, my idea was not to make a 1000+ whp car. I just wanted to make an 850-900 whp car that I could daily drive. I didn’t care about drag times or creating a dyno numbers car. I also wanted to be done with the whole build in less than 2 months and not be stuck super complex build that would have my car in a shop for 6 months to an year.

Disclaimer – Any serious mods you make will void your warranty, and if you don’t do it right or follow the correct steps or use a competent shop, it will result in your car being screwed up. So I am just warning you.

These were my goals to make my 1000HP 9 Sec Everyday Car:

Step 1 – Reduce 50-100 lbs of weight from the car

Step 2 – Improve Intake, Cooling & Misc Engine Mods

Step 3 – Improve Exhaust Flow

Step 4 – Get the S63 TU4 Engine Fully Built and Install New Turbos

Step 5 – Get ZF Transmission 8HP76 Fully Built to Withstand 1200 WHP and 1200WTRQ

Step 6 – Update Suspension & Tires

Step 7 – Update Brakes

Step 8 – Find a really good tuner or three for BM3 and for Trans Tune and Street Test

Step 1 – Reduce 50-100 lbs from the car

I managed to reduce a total of 80 lbs by eliminating my factory primary and secondary cats, and installing a high-flow cat and replacing some exhaust parts with titanium bits. Being in California and the fact that I didn’t want my car to sound like a rice rocket, it was important to have high-flow 200-cell primary cats installed. I hate the raw smell of catless exhausts and the annoying pops and bangs the car makes when you have straight pipes. Plus, your car smells like a gas station when you pull up, and that’s just not something I am willing to have on my weekend drive

Step 2 – Improve Intake & Misc Engine Mods

I took out the factory inlet pipes and installed the Dinan pipes. They actually have the largest intake channels and flow more air than any inlet pipe out there. It’s just that they have really shitty fitment and you get a lot of annoying error codes with intake leaks. So I created some custom gaskets and did my own smoke tests to make sure no air leaked and got these fitted. I also didn’t want to get rid of my stock air box. I felt the stock airbox coupled with a CarBahn high-flow filter and Dinan inlets would flow more or less the same or better air as the Eventuri’s. I also replaced the stock air inlet intake channels behind the front grill (which actually point up) with Ram air units. The Ram air units coupled with the high-flow filters and the Dinan air inlets actually produced 4 more whp and 6 wtq than the Eventuri setup. So I kept this config rather than going with an Eventuri intake.

Then I dumped my coolant overflow reservoir tank that BMW replaced under warranty and installed the RK billet tank. This thing is built like a beast and is a solid component. Even with BMW replacing the original tank with a newer tank, I didn’t feel comfortable pushing the car with it. So I went with the billet tank.

Changed spark plugs to new NGKs Part No 97506S8KT gapped at 0.22

Changed OEM ignition coils to upgraded CarBahn units

Changed factory intercoolers to CSF intercoolers

Changed factory oil cooler to CSF oil cooler

Installed CarBahn front-mounted heat exchanger

Step 3 – Improve Exhaust

Removed my factory primary and secondary catalytic converters and straight-piped the secondaries and installed 200-cell heat-shielded primary catalytic converters

Step 4 – Get the Engine Built and Install New Turbos

Took the car to CarBahn and they rebuilt my engine with their Stage 2 package. I opted to keep the compression at stock. Bought a pair of Hybrid Pure 900 turbos from Pure Turbo and installed them

Step 5 – Get ZF Transmission 8HP76 Fully Built to Withstand 1200 WHP & 1200 WTRQ

This part was essential, and I learned a ton along the way about the ZF 8HP76 trannies during the build. I got my whole tranny pulled out and got it rebuilt for Stage 2 with a billet torque converter, and the transfer case fully upgraded as well.

Step 6 – Update Suspension & Tires

Installed CarBahn monoball kit

Installed CarBahn toe link kit

Installed CarBahn high-performance coil-over suspension kit

Dropped the car by 1.2 inches

Front Tires – Michelin Pilot Sport 4S 285/35 ZR 20 (using stock rims) and 10mm spacers

Rear Tires – Michelin Pilot Sport 4S 295/35 ZR 20 (using stock rims) and 10mm spacers

Step 7 – Update Brakes (PENDING)

I was part of the CCB group buy, got the product, looks great but haven’t had time to install and test them. I am still on my OEM steel rotors and Isweep 2000 pads. I will update later once I have the new brakes installed.

Step 8 – Find a really good tuner or three for BM3 and for Trans Tune and Street Test

Oh boy, I spent a lot of time going through tuners and dealing with map revisions, dyno sessions and over 300 hours of street testing. The lesson I learned was always go with the quiet humble guy who knows their shit and is super thorough and technical. Never fall for these big-name tuners. And don’t even think that doing a simple xHP tune will suffice when you’re pushing serious power. You need a reliable tranny tuner as well.

Here are my dyno charts taken on two super hot days when ambient air was 91-93F at 102 ft above sea level.

Dyno used was a Mustang dyno with a 18% drivetrain loss for AWD readings.

(1). 100 Octane = With the stock engine internals with BM3 running just the CarBahn front Core and Secondary Cat Delet with 100 Octane I was making 732 WHP and 690WTRQ at Max. [Fuel Pumps and Injectors are Stock]

(2). 100 Octane = With built engine, Pure 900 Turbos, CFS Intercoolers, and 200 Cell Primary Cats I was making 766/758 WHP and 819WTRQ at Max. [Fuel Pumps and Injectors are Stock]
I got some sort of power limiter, Nanny system kicking in at 755-770 WHP here when tuning, that’s why I was getting capped with 100 octane at 766WHP. I think I know what’s going on here and will work on this in August. It was never a big deal since I mostly run E40 and only switch to 100 octane in winter to avoid moisture with cold weather and Ethanol.

(3). E40 = With built engine, Pure 900 Turbos, CFS Intercoolers, and 200 Cell Primary Cats I was making 850 WHP and 787WTRQ at Max. [Fuel Pumps and Injectors are Stock]

*** The Dyno Fan failed on this day and the car was super heat soaked after 12 runs of dyno in getting this map perfected. Ideally with a fully working dyno Fan and a not So Heat soaked car the numbers should be close to 890WHP and 840WTRQ.

I am going to go back to the dyno one of these days and get updated numbers after a few more tweaks. Another reason I am stopping at these 850-890 WHP numbers is to avoid my stock Injectors and pumps from overloading. At a later date if I get bored and feel like pushing the car a bit more I will be updating my injectors, but for now I am very happy with the way the car drives. I have put a total of 1500 miles on the mods and the car is super reliable and is a real beast. I achieved what I wanted which was 1000HP on the crank, and 850WHP x 18% correction on the mustang dyno – 1003 HP on a 92-93 degree day with a broken Dyno fan. On a cool day this is probably 1100HP.

Total build time 5 weeks, and a special thanks to the CarBahn San Jose guys who were just super awesome.

I have not dragged this yet and my best street 1/4 was 9.81 at 147MPH, with a 0-60 in 2.66 being my best. I feel like there’s more wiggle room to improve. The top end on this car is insane, and it pulls like a freight train with afterburners.

So this is plenty good for me, and plenty fast for now

Hope this info helps you all.

Cheers.





Last edited by cham; 07-27-2025 at 09:59 PM..


Reason: Forgot some engine pics

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