fe1rx adds full aero

[fe1rx]

I have been to one of the smaller local tracks (Shannonville) and had the opportunity to meet up with BabyBimmerGuy and to give him a ride. Fun day, but also an opportunity to test out a couple of things:

PowerFlex Exhaust Hangers

My switch to PowerFlex exhaust hangers wasn’t really done to fix a problem – they just seemed like a good idea to stiffen up the mounting and to reduce the required sway space. Which reminds me of the observation that if the only tool you own is a hammer, every problem looks like a nail. I am not saying that cast polyurethane doesn’t have its uses, but maybe we shouldn’t be so eager to use it to solve every problem.

My second thoughts started once I had them in my hand though, because I recalled that urethane’s stiffness is strongly temperature dependent. I realized that the stiffness I measured at room temperature would not apply at elevated temperature. And the hangers might actually be softer than OE in operation.

The PowerFlex hangers are narrower than OE, so to restrict lateral play, I made up a set of Delrin clips – I copied that idea from Vibrant, but adapted it to our 10 mm hanger rods,

https://vibrantperformance.com/catal...7f7d11128f1738

Of course, I didn’t give the thermal properties of Delrin any thought at the time.

So how did that work out? I melted a couple of the Delrin clips and two of the three PowerFlex hangers failed after a track day.









So I have reverted back to the OE hangers, which were never really a problem to begin with.

PowerFlex USA very kindly gave me a refund after listening to my story.

Both urethane and Delrin won’t work above about 300°F so in retrospect I am not surprised that the did not work as intended.

Despite the heat shields on my axle-back piping, the LH inner CV joint boot is still distorting due to the heat. I think a dedicated cooling duct blowing cold air onto the boot will be needed if I want to eliminate this problem.

Not all was bad on the temperature front though. My current baffle arrangement successfully kept both the differential and transmission below my 250°F maximum target. I had planned to log temperatures at this event but it was primarily a fun day and my right seat remained occupied all day, interfering with the installation of the temperature logger. Accordingly, I don’t know how hot they actually got, just that they did not exceed 250F.





Prior to this event I replaced my hinged “landing gear doors” with a hingeless design that relies on bending rather than a spring-loaded hinge. Being made of 7075T6 like the rest of the diffuser, they will bend as far as required without taking a permanent set. They worked well and survived a brief agricultural excursion.





I have now added an additional pair of strakes in the forward part of the diffuser. The main reason for this mod was to stiffen up the diffuser skin in the forward section, but it should also aid in conditioning the flow into the aft part.



I now consider the diffuser configuration to be frozen, so I will proceed with downforce measurements of this configuration at a variety of wing angles.

[BMWWorld]

Great thread, & even greater job on your part. Keep it up👌🏽

[tracer bullet]

I love the progress, and the learnings. I'm an engineer at a medical device manufacturer and know well how the good ideas turn up sometimes to not be so good or to even have the opposite effect (i.e. the hangers). I'm not trying to talk about myself just saying that I love the updates and the writing style.

Agricultural excursion, LOL.

[rac]

Originally Posted by fe1rx

That assumes I have a method of logging voltage data. Solving that would not be too much a problem, but the endoscopes were a dirt cheap solution. To be really useful you would want to simultaneously log speed data.

My current data logger is an AiM Solo DL, which does not accept any additional data channels beside those that come from the CAN bus. Too bad the existing ride height (headlight leveling) sensors aren't accessible on the CAN bus.

Shock pots and a AiM Dash Logger are definitely on my wish list. Mostly because without being able to look at shock velocity histograms, shock tuning is a bit of a black art, but it would be cool to be able to plot average ride height against speed using the Race Studio software.

The rotary headlight leveling style ride height potentiometers are certainly an ecomomical way to go vs. linear potentiometers.

Its a shame there seems to be such a huge price uplift between built data loggers and the actual hardware. I wouldn't mind trying a diy data logger build, they seem fairly straight forward.

[imported_mega]

there are ways to add data to canbus, racecapture analog X comes to mind

[fe1rx]

Originally Posted by imported_mega

there are ways to add data to canbus, racecapture analog X comes to mind

That is an interesting idea. I want to get the data into AiM Race Studio to be able to use its suspension analysis tools (e.g. shock speed histograms) and to tie that to the rest of the lap data. In theory a sustom protocol could be written to provide all the functionality of the AiM BMW protocol (BMW PT6) plus shock positions, using a Solo DL as the data logger. The AiM rep is looking into whether BMW PT6 is open source or subject to some NDA. If open source the task might be manageable, but otherwise, probably not. This science project is definitely outside my area of exerience though.

[imported_mega]

I use a racecapture pro MK2 because of all the proprietary stuff, it can mix all kinds of data sources together.

I thpught you could add custom addtional can data into AIM if it's present on the network, never messed with it though

[lowside67]

Originally Posted by imported_mega

I use a racecapture pro MK2 because of all the proprietary stuff, it can mix all kinds of data sources together.

I thpught you could add custom addtional can data into AIM if it's present on the network, never messed with it though

Originally Posted by fe1rx

That is an interesting idea. I want to get the data into AiM Race Studio to be able to use its suspension analysis tools (e.g. shock speed histograms) and to tie that to the rest of the lap data. In theory a sustom protocol could be written to provide all the functionality of the AiM BMW protocol (BMW PT6) plus shock positions, using a Solo DL as the data logger. The AiM rep is looking into whether BMW PT6 is open source or subject to some NDA. If open source the task might be manageable, but otherwise, probably not. This science project is definitely outside my area of exerience though.

If the goal is to add the data to the logger only, you could also skip going to CAN and just add AIM sensors directly into the logger. That is what I am doing on my sports racer - I have the CAN connection ECU providing everything engine and then have manually added sensors for oil pressure, temperature, brake pressure x2, which is all integrated nicely on my dash/data for after the event.

If the goal is to add a really large number of sensors, most of the AIM hardware supports adding additional channels via the expansion module - you can add an unlimited number of these which allow for 4x more sensors per module.

-Mark

[imported_mega]

this will be the next sensor I add, probably just two to start out, I doubt it works with AIM though

https://wiki.autosportlabs.com/TireX

[amg6975]

Originally Posted by fe1rx

That is an interesting idea. I want to get the data into AiM Race Studio to be able to use its suspension analysis tools (e.g. shock speed histograms) and to tie that to the rest of the lap data. In theory a sustom protocol could be written to provide all the functionality of the AiM BMW protocol (BMW PT6) plus shock positions, using a Solo DL as the data logger. The AiM rep is looking into whether BMW PT6 is open source or subject to some NDA. If open source the task might be manageable, but otherwise, probably not. This science project is definitely outside my area of exerience though.

This would be fairly trivial. I spent a lot of last winter reverse engineering the PT-CAN so I know where almost anything you'd want to data log is, and certainly don't have an NDA with BMW. It wouldn't be rocket surgery to make a PT-CAN pass-through with added channels for some ADC data. You could simply add more data into the car's PT-CAN and the other modules would ignore it but it would be safer to buffer it to keep the PT-CAN safe.

If there was actually a market for this I'd be willing to prototype up a handful of units. I'd be surprised if there wasn't an off the shelf system that could do this though.

[imported_mega]

Originally Posted by amg6975

This would be fairly trivial. I spent a lot of last winter reverse engineering the PT-CAN so I know where almost anything you'd want to data log is, and certainly don't have an NDA with BMW. It wouldn't be rocket surgery to make a PT-CAN pass-through with added channels for some ADC data. You could simply add more data into the car's PT-CAN and the other modules would ignore it but it would be safer to buffer it to keep the PT-CAN safe.

If there was actually a market for this I'd be willing to prototype up a handful of units. I'd be surprised if there wasn't an off the shelf system that could do this though.

I would be interested depending on cost, they hide important engine values like IAT and ignition on the other network, it would be useful for on track engine warnings on my dashboard.

I know there is a similar project for e46, the engine swap threads have some info on it, on bimmerfest they use it to get all of the gauges to work

[amg6975]

Originally Posted by imported_mega

I would be interested depending on cost, they hide important engine values like IAT and ignition on the other network, it would be useful for on track engine warnings on my dashboard.

I know there is a similar project for e46, the engine swap threads have some info on it, on bimmerfest they use it to get all of the gauges to work

Well, a lot of engine parameters aren't broadcast because they aren't used by any other modules so there's no point taking up bandwidth on the CAN bus. You need to send a request to the ECU for the specific parameter you're looking for, and it'll broadcast the current value. This is really where my digging has come up short. I know where IAT is, but none of the others... I was much more focused on driver parameters like individual wheel speed, brake pressures, RPM, Speed, steering angle, etc etc.

[imported_mega]

Originally Posted by amg6975

Well, a lot of engine parameters aren't broadcast because they aren't used by any other modules so there's no point taking up bandwidth on the CAN bus. You need to send a request to the ECU for the specific parameter you're looking for, and it'll broadcast the current value. This is really where my digging has come up short. I know where IAT is, but none of the others... I was much more focused on driver parameters like individual wheel speed, brake pressures, RPM, Speed, steering angle, etc etc.

ohh those are known, I have not looked for wheelspeed it, I really need to add it though.

I already log all of this via canbus, I belive all are signed little endian values

[imported_mega]

more data, I will try getting my wheelspeed working

http://www.loopybunny.co.uk/CarPC/k_can.html

[amg6975]

Originally Posted by imported_mega

more data, I will try getting my wheelspeed working

http://www.loopybunny.co.uk/CarPC/k_can.html

I have everything figured out. Wheel Speeds:

[imported_mega]

yeah I saw that on the site, I just need to translate it into racecapture lingo, the formula format is different.

I dont see a way to get ignition, iat, boost off the ptcan network

[amg6975]

Originally Posted by imported_mega

yeah I saw that on the site, I just need to translate it into racecapture lingo, the formula format is different.

I dont see a way to get ignition, iat, boost off the ptcan network

Like I said, you need to send a request to the DME to get those values, they aren't broadcast.

Also, the TPS you have is DME commanded throttle, not the actual throttle pedal position. Actual pedal position is only available as a request.

[imported_mega]

I do it now with a odb2 adapter that feeds my data logger, not the fastest or best solution

[Nugget]

Originally Posted by Nugget

I saw someone in another forum using boot struts from a mercedes for the same purpose.
Unfortunately that forum is down right now so I can't grab the details.

https://performanceforums.com/forums...93#post7145093

Following up on this option for suspension travel.
Not sure how you would integrate it into the Aim though.

[lowside67]

Originally Posted by Nugget

https://performanceforums.com/forums...93#post7145093

Following up on this option for suspension travel.
Not sure how you would integrate it into the Aim though.

For each sensor, you will need to cut off the wiring at the end of the Mercedes sensor, buy an AIM sensor plugs (Binder 712 or Binder 719 depending on which data logger you have, both in 4 pin) and solder it on. Then you'll need to provide it 5V and confirm the voltage it provides at each end of the range (reported on that forum at ~0.8-4.2V). Once you have that, you can add a custom sensor to your AIM logger profile which incorporates these values.

-Mark

[fe1rx]

Originally Posted by lowside67

For each sensor, you will need to cut off the wiring at the end of the Mercedes sensor, buy an AIM sensor plugs (Binder 712 or Binder 719 depending on which data logger you have, both in 4 pin) and solder it on. Then you'll need to provide it 5V and confirm the voltage it provides at each end of the range (reported on that forum at ~0.8-4.2V). Once you have that, you can add a custom sensor to your AIM logger profile which incorporates these values.

-Mark

Getting data into AiM dash loggers is really easy. The logger provides the 5V source, and takes care of calibration, including non-linear calibration (as might be needed for a rotary position sensor). Unfortunately the Solo DL loggers don't accept additional inputs, unless they can be located on the CAN bus, and accessed by a custom protocol. I have had no luck with getting details of the BMW PT6 protocol from AiM, despite some prodding, so I suspect the details are considered to be proprietary. I think that means my next logger will not be a Solo II DL, but one of their dash loggers.

With regard to rotary sensors, AiM pointed me at the 2004-06 Cadillac Escalade ride height sensor. Various other GM models with continuously variable real time magnetorheological damping appear to use essentially the same sensor with differing brackets by application and widely varying pricing. The cheapest variant I found (Dorman branded) was only about $32 USD each at Rock Auto, making it very hard to beat, price-wise.

The mating connector (Standard Motor Products S1663) is also available at Rock Auto.

Motec repackages and uses a GM sensor also. They indicate that it is "contactless", i.e. a Hall effect sensor mimicking a potentiometer. Likely this is better with respect to signal-to-noise ratio than a true potentiometer.

https://www.motec.com.au/ac-sn-position/sn-position-rp/

I am also investigating the Mercedes linear pots. I suspect they will be a bit pricey though. Also, a lift gate normally works in a 0.1 Hz environment, whereas the GM sensor is intended for the suspension environment so it may be a better choice.

[amg6975]

Originally Posted by fe1rx

Getting data into AiM dash loggers is really easy. The logger provides the 5V source, and takes care of calibration, including non-linear calibration (as might be needed for a rotary position sensor). Unfortunately the Solo DL loggers don't accept additional inputs, unless they can be located on the CAN bus, and accessed by a custom protocol. I have had no luck with getting details of the BMW PT6 protocol from AiM, despite some prodding, so I suspect the details are considered to be proprietary. I think that means my next logger will not be a Solo II DL, but one of their dash loggers.

You can get I/O type expanders for the AiM ecosystem that I think should work with the SOLO II DL: https://www.aimtechnologies.com/aim-channel-expansion/

If you need to find channels on the PT6 that you want to data log, PM me... I probably know where they are.