RomRaider

I've installed my M50B25 Intake Cam as exhaust and can provide the first logs

At the moment, it's timed the same as stock M52B28 exhaust cam.

old vs new: (Both Volume and mass)

I think this gives a good example why it is important to adjust for temperature. Just looking at the mass one could overestimate the effect of the cam shaft.

Here is the chart I used to set the vanos@5200:


Overall, the longer duration of the camshaft lets the engine breath a little better in the mids and highs. For 100€ not a bad investment.

I will investigate the Valve overlap (not sure if this correct technical term) and its effects. I'd like to have a more gradient transition between 5200 and 5400.
Not sure if I should retard or advance the cam tho.

When looking at the second graph you only picked up up airflow and never lost any! Cheap upgrade with great results =)
I run the same ex cam on mine. I have it ca. 1 mm open at TDC but never messed with it since.

Ps: do you know why the first graph is showing the curve with ex cam sometimes losing compared to stock ex cam?
I know for mass-based curves airmass and load are mathematically linked.
Please help me understand

Your message actually sent me down quite the rabbit hole, there was an issue in my approach.

Until now, I just applied a rolling window after I grouped and averaged out load and maf at a given rpm. The issue is that in 2 different logs, of course the data points are not distributed the same.
Also, the rolling window pushes the curve to the right, which makes the performance look worse.

My new approach is:
- Find data points where the Throttle is fully opened or very close to fully opened
- Round the RPM Value to full a bin width value. For example: 1657 becomes with a bin width of 50 1650. 1720 beomces 1700 and so on.
- group by the now rounded rpm and take the average with in a bin

New Diagram using the new approach:


Unfortunately, this also makes the new cam look a bit worse

What do you think about this approach to get Data to be easily comparable:

It compensates for IAT to a reference Temp of 20°C.
Would be great if we would log pressure also, to normalize this to 1013mBar. The outside Airpressure can make multiple percent influence.

I tried it out in the attached example:

What do you think?

We could also calculate Volumetric-Efficiency and plot it over RPM. I guess thats the main thing we actually care about =D get those holes filled as much as possible

Do you know how much opening at tdc you have on the ex cam?

For comparison purposes, it really makes sense to normalize the airmass (Not just convert it to a volume like I do)
Going forward, I will implement it in my script.
I agree, logging pressure would be ideal, but I think for now we can do without it.

The bigger issue I face at the moment is dealing with the noisy data of multiple runs.
In my opinion, comparing single WOT runs with each other is not that meaningful. If you overlay those runs, you will see the data is actually quite noisy. (At least in my case )
Therefore, I think it is better to make multiple runs and then craft a diagram with averaged data.

VE-Charts are also a good idea!

No not yet, I will measure it before I will adjust it

Yeah thats great!

So far i just logged all the time and did a couple of pulls, then in excel i put everything in a point diagram and filtered for tps=WOT.
Its a bit messy to look at and therefore no real use to compare after mods where we want to see exactly where it gained or lost (a single line curve).

For airpressure i think i have a cheap solution already here:

BMP 280 can provide temp and also pressure data.
I can print Airpressure to the Oled and write it down to accomodate in the calculation also.

I use an Arduino right now to pass through the RS-232 WBO2 Signal from the AEM to RR-Logger with a RR plugin. I think it could be possible to set up a second Arduino and Plugin to Pass the Pressure Data aswell.

Looks good! A seperate sensor is the best way to go.
I like to do things as cheap as possible, so for the mean time I will likely get the pressure from my phone or weather report and treat it as constant for the drive.

Thats a great idea!
My BMP 280 has a good track record but is no comparison to certified pressure sensing equipment

I found a resource where i can look up past weather data and can see the pressure curve for every day
You ll propably find something similar!


...the BMP 280 could be used to measure possible Ram-Air effects when feeding the Airbox from a fog-light-hole or similar opening...

Small Update: I finally got a wideband o2 sensor and was able to fine tune fueling.

The car accelerates now from 100kph to 200kph in 16.1s before my tuning efforts it was around 19.7s if I recall correctly. Of course measured with GPS:

I wanted to have the HP/Torque measured at the end of the season but it did not work out. I assume power is around 210hp - 220hp

Ideally, I'd like to get down to 15.9x seconds. Judging by posts on facebook groups that what "good" m52b28 can achieve

Wow alot of information here mate great work

I to am doing a M50B25NV and M54B30 cam swap on my car

You wouldnt have the tune available at all would you?? Just so i can get my car moving etc

Sorry, I did not visit the forum for some time.

I think my tune would be even worse than the stock tune. Get a Wideband O2 sensor and start tuning - there is no shortcut here. Your car will move just fine with the stock tune

The car was able to put down 228 PS @ 6000rpm and 290 nm @ 4600 rpm (at the flywheel) corrected via EWG on a dyno.

Thank you for following through with the measurements. Were you able to measure before/after the changes you made to fuel maps?

Also are you happy with the result? I have the exact same mods and engine + a long tube header (supersprint design) & resonated trackpipe and exhaust (similar to Active Autowerke). I have yet to do any measurements though. From what i've seen on forums these mods are supposed to bring the power out to about 240hp, 228hp seems a bit far off