It's no secret that the M50 manifold used on the 92-95 E36 cars flows considerably more air than the manifolds on the S52 or M52 engines but what is a secret is installing it correctly to make gains in both horsepower and torque. There are many kits out there and not all of them do a seamless job adapting the M50 to a newer M52 or S52. Turner offers a seamless adapter kit that allows the M50 to be bolted right up to the S52 with everything in the stock location. There is no need to re-route hoses and wires like other adapter kits.
This kit allows full function to the factory components including the PCV cyclone/oil separator valve. There are no vacuum leaks and no check engine lights. The best part is there is no fab work or anything that needs to be done so the installation of this kit is completely reversible.
With the introduction of the 1996 model year came the OBDII emissions compliant engine. Among the many changes the OBDII engines received was a more restrictive air intake manifold. Where the older M50/S50 engines continued to make power up in the higher RPMs, the newer M52/S52 ran out of breath, limiting high-end horsepower, but boosting low-end torque. Converting the OBDII cars to the 1995 and earlier OBDI manifold is a popular modification to remove this high-rpm restriction.
As you can see to the right, the M50 manifold is roughly 40% larger than the original equipment manifold that comes on 94-99 cars. This picture does a good job at illustrating how much more air is gained through the intake into the motor by replacing your manifold with an M50.
To best maximize the horsepower gains of this modification, I would reccommend using the M50 manifold with bigger cams, HFM, injectors, and software. We have found this combination of upgrades and software to yield the best results for producing top-end power. Note: using the M50 manifold shifts the power band higher in the RPM range. This is GREAT for track cars but not well-suited for street cars where the OBDII manifold works best to produce torque at lower RPM. (Note: This modification sacrifices low end torque for mid to high end horsepower. This modification does not drastically drop torque but will be noticeable in many street cars where driving at low RPM is common.) In my opinion this modification combined with many of the other engine modifications mentioned in this blog, is a great addition. Schrick Cams tend to balance the dip in low end torque.
Sourcing an M50 manifold is not as hard as many people think it is. I got mine from a local junk yard and spent an hour cleaning it up and it was as good as new for $75. Whether or not you buy a new manifold or find a used one, this modification is a must on any S52 car. You will feel the difference the very first time you get in the car and press the gas pedal. I found that the mid-range to high range horsepower changed significantly. It also gives the car a slighly deeper sound when at wide open throttle.
Next entry I will talk about the Active Autowerkes track pipe and race exhaust setup which really complements the M50 manifold and other engine modifications done to this E36 M3.
You can find the Turner Motorsport M50 Adapter Kit here: