E8x e9x suspension / track duty / etc

May 25, 2018
29
#1
Road racing is a wholly different animal than drag. Even time attack, while closer, is not the same thing. Imagine running an N54 in a 2 hour road race. Impossible to consider at the moment. It's not a turbo problem. The N54 world revolves around the turbo as the center of its solar system. I'm not addressing you specifically, @berns of course, just jumping off the distinction you well pointed out.

There are only so many S-engined E92s to go around. S54 M3s are climbing in cost, while availability diminishes (we saw this with the E30 M3 in the late nineties). The E36 is about to go the way of the E30 dodo bird. So in the long haul - unarguable - none of these are market level solutions. One-offs ... sure people can go swap all they want.

The first issue with road racing is reliability. This comes in two primary issues: 1) Heat is the killer. a) The N54 cooling system is not old school - this idea of throwing hardware at the cooling system is 20 year old thinking with little understanding of how the N54 cooling system works - with electromechanical cooling, tables with non Ve targets, and likely adaptive and predictive algorithms to control temps. Oil coolers are even more foolishness to that - if one can't tame the cooling system (primary job is cooling), trying to tame it by cooling oil (which cooling is an oiling system SECONDARY function) is fruitless in such a pursuit. That is, fruitless without addressing the core controls. Some programming is needed because the cooling logic for the N54 is in software and controlled at multiple points. b) Furthermore, the E90 likely has some packaging problems in road racing trim. That old saying, "10 lbs of shit packed in a 3 lb bag". The packaging is a long conversation, exacerbated by oversized FMIC installs, piping, a very imperfect engine intake air routing design for this application, etc. c) the head is designed to support characteristics BMW thought necessary to bring its customer base into the turbo world. But the 165 cfm head is horrible for road racing - causing the need for higher turbo pressures than we want (and more heat). Maybe with the N53 head one can get 500 whp on pump gas under 20psi? Heat is the monster to tame. 2) Turbos that are motorsport grade are the next issue (they exist but the market has not existed for the N54 - this is a cart/horse problem). @[email protected] was looking at the Garrett GTX 550 small frame turbos, for example, but Garrett has been dog slow in releasing the IWG versions. Other possible solutions may exist - but not much proven out so immature as a solution space in twin mode.

Second the E9x suspension, particularly in the rear, has not seen the kind of development necessary to put the kind of power down the N54 can deliver - consider momentary power exiting the apex is likely 2x what the typical NA BMW HPDE car makes. No one has seriously addressed the rear suspension for this application. And 98% of the "old school" BMW road race people have no clue about anything past an S54 - that's about 2006. Two fundamental issues - the E90 suspension is revolutionary design (not evolutionary) from the prior BMW designs. Next, managing 500whp or 600 ft lbs, not to mention nearly instantaneous torque off an apex is beyond foreign to any BMW road racing specialist - they fairly well haven't dealt with this.

The good news is lots of development continues on the N54 platform. There is work underway on all three of these fronts - cooling, turbos, and suspension - for road racing application. Other work being performed, such as with advancements in fueling support that allow higher horsepower DI native, will also contribute to a potentially reliable road racing setup. Too early to say if this all comes to fruition. But then again, I wouldn't count it out just yet :). Anyway above is my conjecture ... it's also part of what brought me to this platform from the old school BMW world: kind of feel like a foreigner in what should be my father's land lol.

BTW great discussions on this thread - thanks @martymil and @Hydra Performance for all the back and forth. I gave up on the idea of just repeatedly pressing like button on all the thread posts.

Filippo
I had some guys (that track their 335is) try to tell me off on Facebook a few months back because I said this platform is not ideal for tracking. It's just not. Honestly. BMW did not put a lot of "track ready" development into this car compared to the E9x M3 and it totally shows. It doesn't even have LSD from the factory.

My S2000 and Evo were great track ready cars with platforms that emphasized being used on track. This is a platform you have to Frankenstein into being tracked.
 

Hydra Performance

Corporal
Platinum Vendor
Jan 31, 2017
181
#2
At the end of the day the 135/335 chassis is woefully insufficient for high-performance driving as-is, and this becomes more apparent as torque is increased (even with just basic bolt-ons + tune). The stock damping is a joke, and the subframe bushing & toe arm bushing lateral stiffness leave much to be desired. Keep in mind these cars were designed for run-flat tires, which explains some of the compromises BMW had to make.
 
Aug 11, 2017
1,666
Virginia
#3
While I agree, @Hydra Performance, I also think we are asking a lot of these cars. Simple bolt-ons, as you say, yield 100whp. Comparatively, what would one do to add that to, say, an S54 or S65? And that's even gross - we could be unfair (but accurate to the issue) and say, what do you need to do to an S54 or S65 to get 80ft-lbs more torque at 3,000rpm? But even more so the rate of power change (versus power levels) is what the suspension is actually having to manage - and I don't even know what that difference is, compared to an NA motor except to say it is likely significant (as I've heard - that rate of change can be tuned so aggressively as to bend stock rods with factory turbos. Try that with an NA tune). Stock dampening has never been that great, either, IMHO ... compared to the average pedestrian anything else street car the m-sport suspension is pretty decent. But not when things get dialed up.

@EthanolTurbo very true ... the E92 M3 is first an M car: no regular BMWs have gotten LSDs, and brakes (which work for HPDE with pads and fluid), and a normally aspirated V8 not with turbo power - it's likely an easier starting point for someone doing basic day sessions at the track. Also true that the N54 is not (currently) a platform to track without significant work - and even then, most everyone I know has had fair to mid success ... so there is more work to be done.

I'm optimistic. One of the things I appreciate about Spoolstreet is the collection of people that seem to be working various issues. I'm cautiously optimistic about where things are going, though I agree with both perspectives above.

Filippo
 
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Jan 29, 2018
99
#4
"no regular BMWs have gotten LSDs, and brakes (which work for HPDE with pads and fluid)"

ive owned a few.. the e12 was my favorite, albeit i had to add vented rears.

I would argue that most of the previous 3er's need quite a bit of help to be "race" ready. sub frames, CA's, Rtab pockets, etc... Given the e9x m3 stuff bolts up i dont see these cars being much more crippled then the previous generations...and those seem to do fine out there. I really dont think this chassis is as handicapped as you guys are making it out to be. Sure it doesnt stack up to OTHER MANUFACTURER's but in terms of a 3er.... ehhh it could be worse. At-least the shock towers dont split on these lol
 

Hydra Performance

Corporal
Platinum Vendor
Jan 31, 2017
181
#5
@fmorelli,
When you TT or Supercharge a 350Z or 370Z, the chassis doesn't turn into dogpoo all of a sudden. Sure traction goes out the window, but the car doesn't "oscillate" in yaw @ WOT in the higher gears (I am NOT referring to wheelspin here), or pogo all over the place at the slightest surface undulation...

@JimboFresh206,

Not saying our chassis are no good, far from it. All I'm saying is that the STOCK chassis/suspension is ill-suited to extra power, and that these cars are probably more luxury-oriented/less driver-focused than previous BMW sports sedans. Fortunately, its nothing that the subtitution of a few choice //M and aftermarket parts can't fix. And at least we have a torsionally-rigid chassis to begin with, which is more than can be said about earlier models with splitting subframe mounts and shock towers etc...
 
Jan 29, 2018
99
#6
"All I'm saying is that the STOCK chassis/suspension is ill-suited to extra power"

gotcha! yeah would agree, but hey its kinda fun driving a pool noodle of death sometimes :)

this thread is great lol

@fmorelli
Kinda off topic, but i know your z4 uses an e46 rear end. Just thought id share this if you have'nt seen it. I believe they can also make it to suit 210mm big case stuff aswell.

http://uniball.fi/cgi-bin/webio2kauppa?Merkkikohtaiset-osat/BMW/BMW-E46-cromo-taka-apurunko-E36-188-perälle&naytasivu=1150&id=0&saitti=rallycorsa

@Hydra Performance

for the 1er but i would assume a 3er too.

http://uniball.fi/cgi-bin/webio2kau...on-arms&naytasivu=1241&id=0&saitti=rallycorsa

just wanna see people go fast
 
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Aug 11, 2017
1,666
Virginia
#7
@fmorelli,
When you TT or Supercharge a 350Z or 370Z, the chassis doesn't turn into dogpoo all of a sudden. Sure traction goes out the window, but the car doesn't "oscillate" in yaw @ WOT in the higher gears (I am NOT referring to wheelspin here), or pogo all over the place at the slightest surface undulation...
I cut my teeth racing Nissans for a decade, so I've got a soft spot in my heart for the Z's (we ran the single turbo cars, amongst others).

But that said, the above comment is depressing!

Filippo
 

berns

Specialist
Jan 15, 2018
72
#8
While I agree, @Hydra Performance, I also think we are asking a lot of these cars. Simple bolt-ons, as you say, yield 100whp. Comparatively, what would one do to add that to, say, an S54 or S65? And that's even gross - we could be unfair (but accurate to the issue) and say, what do you need to do to an S54 or S65 to get 80ft-lbs more torque at 3,000rpm? But even more so the rate of power change (versus power levels) is what the suspension is actually having to manage - and I don't even know what that difference is, compared to an NA motor except to say it is likely significant (as I've heard - that rate of change can be tuned so aggressively as to bend stock rods with factory turbos. Try that with an NA tune). Stock dampening has never been that great, either, IMHO ... compared to the average pedestrian anything else street car the m-sport suspension is pretty decent. But not when things get dialed up.

@EthanolTurbo very true ... the E92 M3 is first an M car: no regular BMWs have gotten LSDs, and brakes (which work for HPDE with pads and fluid), and a normally aspirated V8 not with turbo power - it's likely an easier starting point for someone doing basic day sessions at the track. Also true that the N54 is not (currently) a platform to track without significant work - and even then, most everyone I know has had fair to mid success ... so there is more work to be done.

I'm optimistic. One of the things I appreciate about Spoolstreet is the collection of people that seem to be working various issues. I'm cautiously optimistic about where things are going, though I agree with both perspectives above.

Filippo
I've got to say, being as embedded into the racing community as I am here in Southern California, and even more so with the BMW crowd, there is no extra work I've had to do to my N54 powered car that my S54 friends haven't. The S54 has cooling issues as well. Friends are doing hood vents, big radiators, trying different fan combinations and fluids. Heat is the enemy. I will say that the N54 has way more going on in the DME, and finding and hunting down these factory protective codes and algorithms is a pain in the ass. I'm curious how much better everything might be with a standalone setup like AEM Infinity or Syvecs.

At the end of the day, NA is the way to go for a reliable track car that can turn laps. End of story. Turbos work and have been used throughout history, but full motorsport race car builds are different than your HPD and Time Attack local car.

In any event, I'm going to keep pushing with the E82. I felt all the awful mush of the factory chassis when it was stock, but I'd hand anyone the keys to my car for a lap and you'll see it handles the power and torque with ease, and has immense grip.
 
Jan 24, 2018
481
SC
#9
Anyone have thoughts on the best toe arms for dual duty cars? I have spherical arms on now, but rear started stepping out hard again so thinking they have probably worn out.

Something with a bearing or hard rubber bushing?
 
Jan 29, 2018
99
#11
Shpericals are a PITA on a dual use car, given that most of them are unsealed, and your (supposed) to clean and lube them.

M3 arms are great, for that type of use. Totally agree @martymil
 
Jan 24, 2018
481
SC
#12
Shpericals are a PITA on a dual use car, given that most of them are unsealed, and your (supposed) to clean and lube them.

M3 arms are great, for that type of use. Totally agree @martymil
Can't use M3 toe arms on nonM rear. Already did aluminium RSFBs and not willing to change the rear at this point. Have M3 everything else including camber link and damper. Toe arm is the bitch.
 
Jan 29, 2018
99
#13
Can't use M3 toe arms on nonM rear. Already did aluminium RSFBs and not willing to change the rear at this point. Have M3 everything else including camber link and damper. Toe arm is the bitch.
Well if your not willing to do that, then get something with more of a solid bushing and not a spherical. Strongflex makes poly toe arm bushings for the stock non m link. You could also look into oem balljoints that are the same size. That was one of my favorite upgrades to.my e46s rear (OEM balljoints instead of the normal rubber on the RTA)
 

Hydra Performance

Corporal
Platinum Vendor
Jan 31, 2017
181
#15
Unfortunately, M3 toe arms won't fit without an M3 subframe, they're approx 40mm too short. I am running Bimmerworld toe arms on my car with additional dust boots on each end to seal out all the dust and grime. Solid bushings add a lot of "stiction" in the suspension, (and even sphericals do to a lesser extent) compared to a rubber bushing which operates in torsion, not what you want at all if grip is what you're after. The added friction increases hysteresis in the system and ultimately reduces tire to road contact and thus grip.
 
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Jan 29, 2018
99
#16
Definitely! To clarify by more solid im talking about poly or a solid core rubber bushing at the most.
The stuff I referenced was all poly, 80a iirc.

For ex. Poly on the inboard side and an OEM balljoint where it meets the hub/knuckle. Or a sealed ball joint on both like the m3 arm.



I wish there was ots spherical stuff that's sealed (a pipedream for a street car) did you just use generic boots? @Hydra Performance I have a decent source of tie rod boots and stuff for my other cars. Here in the pnw our main issue is moisture attacking the the joints/hardened surface. So I've been down this road a few times in the past.
 
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Hydra Performance

Corporal
Platinum Vendor
Jan 31, 2017
181
#17
Poly bushings (for moving joints) are also a no-no in my book... A Solid-core, or stiffer rubber bushing preloaded in torsion (like the M3 FLCA bushing for instance) is great though if that option is present.

Yes I just used generic spherical boots (sized accordingly) similar to those below. A bit of WD40 or silicone grease combined with zip ties at eah end should be enough to repel most moisture, no?
1547278048197.png



PS - Funny how this thread ended up going from being a turbo discussion to one about suspension , and bushings in particular. Sorry OP! :D
 
Jan 29, 2018
99
#18
Marine grease :)

but yeah I can understand the issue given the lack of zirks to keep them lubed/operating in that regard. Poly does nasty things when it can't move..

Lots of E36/46 people with poly rtabs seem to get along fine, but if it's dry/sticky I can see your point about it reducing grip etc... Not to mention when they eat themselves lol
 

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