the beefy build

[Redd]

Originally Posted by omgzirra_exe

i can confirm 3.45 is amazing on DCT helps with the low end ompff you'll want sometimes. something to look out for. doesn't need a TCU tuning.

Completely agree on the 3.45. Really wakes up the car. 1st and 2nd gears are frantic now! Plus I daily the car and don't really feel that rpms are too high when cruising.

I'd like to put in a vote for the os giken lsd, if for no other reason than how long long lasting and quiet they are.

[roastbeef]

i don't feel a huge need for more power. i've tracked alongside cars with more power and they don't pull away as quickly as i had expected. i have trouble keeping up in the corners, so that is where i'm focusing efforts. ring and pinion ratio is also playing a role in this- i just don't feel the need at the moment.
obviously, there are a lot of changes coming to the car, and it is going to be a lot lighter. if i do decide to change ratio, its going to be later after i become accustomed to the car's new state.

i was sort of torn between the drexler gt4 lite and the OS Giken. i read through florian's lsd shootout thread a few times in the past couple of weeks. i know dogbone is happy with his osg, and OG Shark likes his drexler. pricing is close. function is close. sort of a coin toss, so i went with the drexler because driftflo seemed to like it more.

[roastbeef]

one of the things i'm most excited about is the aeromotions wing. their website isn't great at explaining construction and design. i don't expect them to divulge trade secrets, but i've been having conversations via email and i'm getting more and more excited.
basically, they use 6061 aluminum extrusion and carbon fiber. no tubes, no fiberglass, no styrofoam. one of the unique features is a very thin trailing edge on a relatively "plain" looking airfoil, but wind tunnel testing has proven the design. legitimate, full scale, 180mph wind tunnel testing.
i first questioned them on how the wings work. it basically has internal sensors and accelerometers to track G forces and read data from the CANBUS. its self contained, but allows settings and tunes. i have the ability to manually activate the drag reduction system, air braking, and set the angle of the wing to be static if required for specific rules.
even in the drag reduction setting, it produces downforce. there is just no getting around that- there is an airfoil present on the car and air is flowing around it. if there is a malfunction, it defaults to a specific angle of attack.

another thing i questioned them on was the lack of a gurney flap. most wings have them, and theirs do not. below is their copied and pasted response so i don't butcher the interpretation trying to put it into my own words;

"Basically, they [gurney flaps] help reduce turbulence when the low pressure and high pressure meet at the trailing edge. They can also help at high AoA (Angle of Attack) when the air detaches (can't follow the surface contour). They're often needed most when the trailing edges are thick, inconsistent, etc. or when the airfoils have avery aggressive 2d shape that means the surface is a "cliff" on the underside. You can of course run them on our wings, but we do two things that make them less necessary; we have a nice and thin trailing edge (because we don't add glass and we have that beefy spar) and we use a sort of proprietary Concave Pressure Recovery system that means the 2D shape at high AoA can keep the air better detached. The Airfoil is designed to create max downforce at 14.2º in clean air so that underside is never perpendicular enough to the rear surface of the car (usually)."

incredible stuff.

one of the things i'm kinda waiting on depending on budget, is a kmp steering wheel like what slicer sells. bottom two buttons would be MDM and horn activation. top right would manually actuate the air brake to allow for the left hand to rotate and slap the downshift paddle on the left side, and the top left button would be for DRS since the right hand would be doing the upshifts. also kinda depends on how easy it is for me to get in and out of the car with my long clumsy legs.

[DrFerry]

Sub'd.. Photos of goodies?

[roastbeef]

Originally Posted by DrFerry

Sub'd.. Photos of goodies?

I'm waiting on a ton of parts, but there will be thorough documentation. I don't have anything to really document yet.

[derbo]

This is going to get good. Speedholes!

[rhyary]

sub

[omgzirra_exe]

Originally Posted by Redd

Completely agree on the 3.45. Really wakes up the car. 1st and 2nd gears are frantic now! Plus I daily the car and don't really feel that rpms are too high when cruising.

I'd like to put in a vote for the os giken lsd, if for no other reason than how long long lasting and quiet they are.

speaking again from personal preference, but being able to take Off Ramp in 3rd vs 2nd at buttonwillow is pretty nice. i do want to upgrade to a OSG soon.

im excited for what roastbeef has for us def one of my inspiration for my car.

as well as DRLane and dogbone

[berns]

Running full carbon doors without a full cage isn't smart.

Premium build list but seems like your safety EQ is taking a back seat. Just a shitty harness bar with fixed back seats, carbon doors, no interior, aero... A sub 3000lb E92 is going to be FAST. You should at least run a proper rear half cage. Surprised you're not going with Pinnacle. He uses T45. Strong and light -- 45 lbs. But again, I'd have a cage if I was running carbon doors.

[roastbeef]

Originally Posted by berns

Running full carbon doors without a full cage isn't smart.

Premium build list but seems like your safety EQ is taking a back seat. Just a shitty harness bar with fixed back seats, carbon doors, no interior, aero... A sub 3000lb E92 is going to be FAST. You should at least run a proper rear half cage. Surprised you're not going with Pinnacle. He uses T45. Strong and light -- 45 lbs. But again, I'd have a cage if I was running carbon doors.

possibly. lets discuss it.

i'm not confident a 1/2 cage is going to do any more for me than a harness bar. the brey krause harness bar has been tested to NHTSA standards. can the same be said for the pinnacle 1/2 cage (i couldn't find any info on it)? could the same be said for any 1/2 cage?

secondary to that, i've seen the braces within the doors and they aren't that great. i'm not sure what they are going to do for me in anything other than a mild side impact. the schirmer doors also have these "rails", but in carbon fiber. not sure what the strength delta is, but i have no data, and i highly doubt they are tested.

there was some discussion about this in the chit chat thread. there were some pretty bad incidents where the doors were just about untouched. would the same safety precautions be mentioned if i bought a shelby cobra with thin fiberglass doors to track? maybe my risk tolerance is a little higher, but i don't see a huge safety lapse here.

i'm not saying no to a cage, just not yet. obviously, a cage is safer than no cage. what i'm questioning is how much less safe carbon doors over oem.

[Shmelgy]

Schroth belts here as well.

6 point for both seats, with the narrower Hans version for driver's seat

[roastbeef]

i'm eyeballing these.
https://www.sparcousa.com/product/6-pt-3-steel-pd

[SYT_Shadow]

I would not change the final drive.

I curse the day I put a 3.62 in my E90. Acceleration traces show... zero discernible difference. If I could go back, I would keep it stock and run the OEM GTS software.

Absolutely never again. The OEM ratios were great. This isn't a piece of shit GT4 with the longest gearing known to mankind, the DCT/6MT M3 is well geared stock.

[Richbot]

I think a 4.10 is about perfect for the 6MT, especially if you've got a lighter aggressive aero car that starts to make some gains in low-speed. There are a LOT of 50mph corners in the US where 2nd is too much and 3rd is boggy. That plus a ~25" tall rear tire *chef's kiss*.

Here's a picture of Road America with a 4.10 and a short tire:

4th-5th-4th-3rd-4th-5th-3rd-4th-3rd-4th-5th-3rd-4th-3rd repeat

With 3.85 and the stock rear tire height:

4th-5th-4th?3rd?-4th-3rd-4th-5th-2ndWHEELSPIN3rd-4th-3rd-4th-4th-5th-3rd-4th-3rdbooooggggg just pit this sucks heh

Funny enough, BMW Motorsport agrees with that assessment, heh

3rd gear is a lot shorter on the DCT , so just running a 295/30-18 would do most of the work, for basically free

This is a rad build from a person who has the right mindset. A rad *first* build. Nobody starts out with the boring ol' cage on their first track build on a platform. But I've seen oh about a hundred peoples' second cars get the cage first. So, if this is your practice kid, then go for it, heh. Nobody likes to do that because it's unsexy and costs bucketloads of money, and a bad crash means you not only write off a production tub but also a bespoke crash structure that probably can't be re-used. It's a huge commitment for a low probability event, so I understand why people don't do it. But that's how it's done, if you have any inkling you might start to get nervous about safety later on, do it now, get to the choppa, get down. I would estimate at least...100lb of titanium hardware's worth, or 500 step-bits, lol.
The E9x isn't strong in the footwells and fender/tire crush zones like modern cars and an offset hit on the front end will wreck your legs and feet. But again, relatively low PK on that. The nightmare #1 dig-in and end-over-end flip off at 100mph, and #2 a brake failure, are the major ones. I think a quality roll structure in the back half can address #1 to some extent (that's why you'll see OEM's do this on a street-homologated production car), but it doesn't do much for #2 except give you a good place to mount your harness to perform optimally in the event of a brake failure.

Anyway, regardless of what you decide to do for crash structure, take a look at right-side nets, can be beneficial even on a "full-containmnet" seat and relatively low-impact, and even a half-cage gives you somewhere to stick it to. Sounds like you'll have the dash out at least once so you could do your forward mounting point then

[omgzirra_exe]

Originally Posted by roastbeef

possibly. lets discuss it.

i'm not confident a 1/2 cage is going to do any more for me than a harness bar. the brey krause harness bar has been tested to NHTSA standards. can the same be said for the pinnacle 1/2 cage (i couldn't find any info on it)? could the same be said for any 1/2 cage?

secondary to that, i've seen the braces within the doors and they aren't that great. i'm not sure what they are going to do for me in anything other than a mild side impact. the schirmer doors also have these "rails", but in carbon fiber. not sure what the strength delta is, but i have no data, and i highly doubt they are tested.

there was some discussion about this in the chit chat thread. there were some pretty bad incidents where the doors were just about untouched. would the same safety precautions be mentioned if i bought a shelby cobra with thin fiberglass doors to track? maybe my risk tolerance is a little higher, but i don't see a huge safety lapse here.

i'm not saying no to a cage, just not yet. obviously, a cage is safer than no cage. what i'm questioning is how much less safe carbon doors over oem.

i was going to say, there are some cars out there with fiberglass doors and barely any internal structure. Although a part of me does believe he should have a full cage for the unknown. the other part of me thinks he'll be fine since it's just HPDE / Time attack stuff with no W2W..

Originally Posted by SYT_Shadow

I would not change the final drive.

I curse the day I put a 3.62 in my E90. Acceleration traces show... zero discernible difference. If I could go back, I would keep it stock and run the OEM GTS software.

Absolutely never again. The OEM ratios were great. This isn't a piece of shit GT4 with the longest gearing known to mankind, the DCT/6MT M3 is well geared stock.

main reason why i got rid of my 3.62 right there. 3.45 was a good medium for me. in my experience, since I didn't have to downshift as much.

inb4 this becomes the chit chat thread... lmao

[DrFerry]

I have 3:45 in mine - with the DCT - and it's been an okay mod IMO (for the street). I didn't go with a 3:62 due to the chance of over-rev on downshifts if the DCT ECU wasn't re-flashed. I think the stock DCT Diff ratio is a 3:15 so it was quite a decent change to go to the 3:45 given the 7 speed DCT box ratios. Just sayin'..
.

[roastbeef]

Big box of metal showed up today!

[Jive]

Love this build and will be looking forward to seeing it come together!

I gotta say I am a bit envious of the people that can front the time and energy (and money of course) to put something like this together and actually use it at the TRACK where it is meant to be used (who cares about canyons?) on a regular basis. Perhaps one day when the kids are much older and hate having me puttering around... but today nor tomorrow is not that day.

In the mean time, I'll live vicariously through you and dogbone. I would probably go the same exact route for a build - lightweight, focus on mechanical grip, squeezing every last ounce out of a NA engine.

[roastbeef]

You guys ever see carbon fiber fuel service lid covers?

[DRLane]

Originally Posted by roastbeef

You guys ever see carbon fiber fuel service lid covers?

Beautiful! I assume nominal weight savings over aluminum?

[roastbeef]

I'll have a weight figure to share after the titanium nuts come in.

[DRLane]

Originally Posted by roastbeef

I'll have a weight figure to share after the titanium nuts come in.

Now I'm curious how much Mrs RB truly knows about this build.