Black & Tan 332iT

[Bry5on]

No worries. The same general concept applies, correct? Datalog and make iterative changes to the appropriate maps. I purchased a HTE tune so should be able to adjust part throttle response from there if i’m on the right track.

Mike

Kinda - you really need an engine dyno to get the cam angles correct with custom cams unfortunately. There’s really no replacement for that. More thorough than what I’ve been doing for sure.

[nuc1]

Realistically pretty unlikely. Either an engine dyno and a lot of time, or I’d need to daily that setup and iterate for several months. Sorry!

No worries. The same general concept applies, correct? Datalog and make iterative changes to the appropriate maps. I purchased a HTE tune so should be able to adjust part throttle response from there if i’m on the right track.

Mike

[heinzboehmer]

Pulling what I wrote in from the sister e46f thread:


So instead of just projecting the upper and lower control arms to a point and assuming that’s roughly where the IC is, I’m projecting those arms to a point, and using that point to define a line that extends outward to define the IC (and in turn, roll center). Very hard to describe in words, I can show you with a model open some time.

Worth noting that jacking is still an issue with the suspension design due to that lower control arm angle, and with the added fore/aft angle I’d been ignoring, jacking looks like it’s even worse. So the butt isn’t lying but it’s not from the roll center itself, just the placement of the members.

Aah I see. Think I got it, but down to peek at your models sometime.

[Bry5on]

Thank you! Instant buy. There's also a guy building a cybertruck vehicle of sorts (channel Project66). He did a phenomenal video talking about building optimal suspension setups, but I feel what's optimal depends on your weight distribution and where your CG is. Another great guy talks about building suspension but leaves the details out - still a great watch (channel XF Motorsports). He's absolutely unhinged and lets his dreams steer his engineering. Very cool stuff

Definitely will be pulling up some of those channels, thanks!

[Bry5on]

What changed in the way you were calculating roll center?

Pulling what I wrote in from the sister e46f thread:

The instant center is basically an imaginary point that defines the roll center when combined with the tire location and track width. It is an important part of handling characteristics. In previous posts I’d estimated the instant center location as the virtual point that the upper and lower control arms make, this was an error as I hadn’t considered the true angle of the upper and lower control arms when looking up/down on the car. As a result, the instant center is significantly farther outboard, which means the roll center is much lower and more reasonably placed than I had originally thought. I’ll have to redo the roll center calculation and update my suspension geometry/roll calculator. I’m disappointed in myself for missing this!

So instead of just projecting the upper and lower control arms to a point and assuming that’s roughly where the IC is, I’m projecting those arms to a point, and using that point to define a line that extends outward to define the IC (and in turn, roll center). Very hard to describe in words, I can show you with a model open some time.

Worth noting that jacking is still an issue with the suspension design due to that lower control arm angle, and with the added fore/aft angle I’d been ignoring, jacking looks like it’s even worse. So the butt isn’t lying but it’s not from the roll center itself, just the placement of the members.