Update number 3.... Theres been a lot going on.....
Winter Upgrades
Easiest way to start this one is to look at the dyno graph for the current engine set up.
I have always stayed with the M50 manifold as the torque curve on this engine set up is brilliant in my opinion, the area under the graph is great for track work, however as with everything I always wonder is there something better? What could be improved? I would love peak power to be later in the RPM range, if peak power was at 7000rpm that would be amazing, I don't have any interest in the M54 manifold as all the back to back testing I did the M50 made a better mid range and smoother power curve. But I have taken interested in what some people have been doing outside of the UK with the N54/N55 inlet manifolds...
The dyno graphs I have seen from these look really promising, and by design the runner lengths are much shorter than the M50 manifold, runner length is important due to the frequency of the pulses which occur in the inlet manifold when the rushing inward air hits the back of the inlet valve as it closes, this causes a pressure wave inside the inlet valve, this means that different length runners are more efficient at different rpms and why a lot of manufacturers now use adjustable length runners in their manifold such as DISA valve in the original bmw manifold.
Anyway.. What am i doing?
Bought myself a N55 and a N54 manifold
N54 top - No opening for the ECU, better design on the inside, same design internally for all cylinders, metal thread inserts in the manifold for the throttle body. Has a vac line take off near the throttle body but will likely relocate this.
N55 bottom - Large opening for the ECU - Plastic holes for the throttle bold mounting
Both manfiolds take the same throttle body dimensions, the design of the ports are the same, both use a oring push fit air temp sensor in the top of the manifold.
Both manifolds are not designed for port injection and are very short!
prototype one
I have had my spare m54 head on the work bench to take measurements from and work out injector spacing to work with my Bosch injectors and a m54 dead head fuel rail, slightly different to my current return system but easy changes to make
CAD design for prototype 1
Took some measurements of the runner lengths with this prototype and compared with M50, looked at clearance between the fuel rail areas and the vanos unit and made some changes to the design
CAD version 2 (Realistically there are about 10 different CAD versions and many hours of work gone into the CAD file)
Bench mock up
Once I was happy with the prototype in the bench I had to give it a proper test in the car to check the position of the manifold in the engine bay.
Out with the M50 manifold
Assembled with the N54 manifold
Test fit in the engine bay
Also designed it to use the M54 inlet gasket
Will point out at this stage it is still a prototype and I have been experiencing with how I am going to reinforce areas with pressed in metal inserts for the production one... Will be coming back with that soon. At the moment the whole idea is looking promising, I spent the weekend working out the pipework pre throttle body, everyone else I've seen do this ideas goes to a open cone filter in the engine bay and I really don't want to do that, focusing on using the OEM airbox with the same diameter from the throttle body to the airbox. Will post more about this when it's all finalised
While in the engine bay I thought a bit of servicing wouldn't go a miss, at Snetterton with old oil and warm temps the engine was sounding a little more tappy than normal when the engine oil was hot so decided to strip down some of the head
Pulled out the cams, lifters and cam trays, split all the lifters open, gave them a good clean, checked the functionality of the one way valves and reassembled. What a saturday afternoon that was!
Back together it goes, freshly built lifters and the whole top end checked over
Service, fresh brake fluid, I have removed the proportioning valve and happy to just let the Mk60E5 handle all the biasing of the braking as it does such as good job at it I have removed these extra lines and gone back to the OEM metal brake line.
Fresh filter and some new oil.
Checked over all the wheel bearings, front right starting to grumble so swapped it for a spare, was a good chance to check over all the Mk60 changes I made at the beginning of the year and everything looks spot on after 8 months of abuse, no issues with the heat. Looks exactly the same as when it was fitted, just a little dirtier from the brake dust. Will be making a few minor adjustments to this design and getting a handful of "prototype" sets made up should anyone be interested in a set let me know.
That just about brings me up to date as of October 2025...
Will be pushing on with manufacturing the inlet adapters, pipe work and braces for this project and then the plan is to head to the dyno at the start of 2026 and produce some of my own data to compare...