[Cytoplasm0671]

Once I've added my performance downpipe, and a stage 2 BM3 tune, it seems I've approximated the HP/TQ of the M2 or M3. Are there other ways the M cars are more advanced (besides tech stuff)? Like, upgrades sway bars or better control arms?

If I was going to try and imitate the M3 what are the other components I'd upgrade?

[im_an_alien]

Get some ///M badges and put them all over the car, will really stand out. Most people won't even be able to tell it's not an M3

[Runner340]

Originally Posted by Cytoplasm0671

Once I've added my performance downpipe, and a stage 2 BM3 tune, it seems I've approximated the HP/TQ of the M2 or M3. Are there other ways the M cars are more advanced (besides tech stuff)? Like, upgrades sway bars or better control arms?

If I was going to try and imitate the M3 what are the other components I'd upgrade?

Nothing screams M3 like an emblem swap! A cool CSL wing is another great add-on too.

[Cytoplasm0671]

Ha well yeah but I am more curious about internals. Does the M3 have different/better things like sway bars and control arms, or does matching the HP basically result in a similar driving experience?

Naturally, all of the internals are different. Well, ok. But what are the big ones?

[toxik]

yeah all the bracing and suspension is beefier and completely different. F30s look completely different underneath the car from an F80.

[Runner340]

All joking aside. It's a different car and more than skin deep if compared it to a F30 340i. The F8x suspension components, chassis stiffeners, rear differential, engine, transmission, interior trim and gauges, most of the body panels etc, are all different. Car is more track focused and has wider stance for wider wheels and the wider fenders to support it. Considerably cheaper to sell your car and buy an M3 if that's what you are aiming to do.

[freakystyly]

Enjoy your car for what it is, or trade up. What are you after? Just appearance or exact 1:1?

I think you are greatly underestimating how different the cars really are.

That being said, you can still make the car your own with mods.. people with M cars still mod their cars too, it's a disease.

[toxik]

Originally Posted by freakystyly

Enjoy your car for what it is, or trade up. What are you after? Just appearance or exact 1:1?

I think you are greatly underestimating how different the cars really are.

That being said, you can still make the car your own with mods.. people with M cars still mod their cars too, it's a disease.

i agree in trading up if you’re really after an M3, G80s are quite readily available these days and F80 values really tanked in the last year. they’re fairly attainable to anyone that can afford a 340i.

[Cytoplasm0671]

Thanks for the responses. The goal isn't to have an M3 but to make the few major improvements on my 340i which will have the biggest impact. After the engine it seems like those are sway bars and control arms.

[Jvac]

Originally Posted by Cytoplasm0671

Thanks for the responses. The goal isn't to have an M3 but to make the few major improvements on my 340i which will have the biggest impact. After the engine it seems like those are sway bars and control arms.

Better suspension components-shocks, springs, increase negative front camber, better tires to put the power down to the road. Lsd in the rear. By doing these along with your power mods, and avoiding all the stiffening braces, you will have a pretty close approximation to an m3 with better on-road manners. At leat mechanically. Appearance is a different story. Like others said, the m3 is track-focused, so the ride isn't great for daily driving.

[Cytoplasm0671]

Originally Posted by Jvac

Better suspension components-shocks, springs, increase negative front camber, better tires to put the power down to the road. Lsd in the rear. By doing these along with your power mods, and avoiding all the stiffening braces, you will have a pretty close approximation to an m3 with better on-road manners. At leat mechanically. Appearance is a different story. Like others said, the m3 is track-focused, so the ride isn't great for daily driving.

Excellent advice, thanks.

Why avoid stiffening braces? A lot suggest replacing the front sway bar to reduce body roll.

[Jvac]

Originally Posted by Cytoplasm0671

Excellent advice, thanks.

Why avoid stiffening braces? A lot suggest replacing the front sway bar to reduce body roll.

Stiffening braces are great for improving performance on a track car, not so great for drive ability on a street car unless you have great smooth roads in your area. The stiffer chassis will make the ride harsher over bumps and cracks unless the suspension is improved in some way to compensate. They're also one more labor step before and after any maintenance work is done in their area as you often have to remove and replace them to access other components under the car or in the engine bay. This is different from sway bars, suspension components which limit body roll during cornering but don't affect ride comfort. Replacing or upgrading the sway bars is costly though, as it requires lowering the front and rear subframes to gain access. You'd be better off doing things in stages though, maybe replacing shocks and springs first, then seeing how the car feels. If it still isn't up to your demands then look at matching a front and/ or rear sway bar with your new shocks and springs.
This is what I've done. I argue that a 335/340 with key improvements such as these is 80% of an m3 at 50% of the purchase and maintenance costs and more liveable as a daily driver. If it's made to be a track car, or money is no object, then sure get the m car. But hop over to the m forums and see what those owners are saying and doing first. Lots of suspension modding, griping about ride quality etc, just like us, but with a bigger budget.

[HeartbreakerF80]

Originally Posted by Cytoplasm0671

Thanks for the responses. The goal isn't to have an M3 but to make the few major improvements on my 340i which will have the biggest impact. After the engine it seems like those are sway bars and control arms.

Way more than that. The M3 literally only shares the doors and trunk with with the F30. Under the hood, the DCT alone is night and day from the ZF8.
I can tell by your responses you’re not going to take no for an answer so do whatever makes you happy but also just buy an M3

[Runner340]

Check out this review. Gives you a seat of pants comparison of a modified engine RWD 340i and a stock F80 M3 with comp pkg.

https://www.youtube.com/watch?v=7qjomnz6-eM

[a5m]

Originally Posted by HeartbreakerF80

Way more than that. The M3 literally only shares the doors and trunk with with the F30. Under the hood, the DCT alone is night and day from the ZF8.
I can tell by your responses you’re not going to take no for an answer so do whatever makes you happy but also just buy an M3

Yea in their mind their 340i is already an M3 minus sway bars.

[Cytoplasm0671]

Maybe for others that's the case, but your statement is not true for me

[Djphonics]

What is the goal for your car? What's the end game?

As others have pointed it, there are few components that are shared. Hp/tq figures don't make a 340 into an m3. The m3s powertrain is completely different. Ignoring the fact they are different motors (not just different internals), cooling is a huge upgrade in the m3.

[IcewaterPete]

Do you have access to a real M3 so you can baseline feel and then reassess once you make mods?

[Cytoplasm0671]

I do not. But the previous comment before yours was quite helpful, as was watching that YouTube video above showing this M3 owner bemoaning the lack of comfort in his track focused car.

My goals: maintaining my 340i as a comfortable daily driver, while also helping to smooth out some of the vague steering and body roll that the car comes with, namely via the installation of upper and lower control arms, as well as the installation of a firmer front sway bar, and then rear sways if that doesn't solve the issue. On the topic of sway bars I've seen 340i owners basically say that Less is More, so increasing the front sway bar by just 2mm is probably ideal.

I understand that sway bar DIY is a total pain in the butt, but that only excites me more to do it myself.

My goal is really just to have a fantastic drivers car to tool around town with, so my stage 2 tune with downpipe and steering mods above should help make that happen.

[johnung]

Originally Posted by Cytoplasm0671

I do not. But the previous comment before yours was quite helpful, as was watching that YouTube video above showing this M3 owner bemoaning the lack of comfort in his track focused car.

My goals: maintaining my 340i as a comfortable daily driver, while also helping to smooth out some of the vague steering and body roll that the car comes with, namely via the installation of upper and lower control arms, as well as the installation of a firmer front sway bar, and then rear sways if that doesn't solve the issue. On the topic of sway bars I've seen 340i owners basically say that Less is More, so increasing the front sway bar by just 2mm is probably ideal.

I understand that sway bar DIY is a total pain in the butt, but that only excites me more to do it myself.

My goal is really just to have a fantastic drivers car to tool around town with, so my stage 2 tune with downpipe and steering mods above should help make that happen.

I totally understand what you are saying. I’ve spent the past five years modding my F30 335i XDrive (same chassis as 340i) with the exact same goals/priorities that you expressed. I didn’t want to create a stiff track car. I wanted a daily driver that maintained a comfortable ride while being a really fun performance street car. My car is driven comfortably on family road trips and it’s an absolute blast to step on it when lights turn green or when I find challenging curves. Engine, suspension, brakes and wheels/tires have all been upgraded with those priorities in mind.

I can provide recommendations/options. What are you starting with? RWD or XDrive? Standard struts & shocks or does your car have the Adaptive Suspension/EDC front struts & rear shocks? See photo. Do you have grey or blue brake calipers? Which tire brand, model and size(s) do you have? Do you have access to E85 at your local gas stations? Your VIN would be helpful.

What mods have you already done?

Note: Not sure where you heard that a 2mm front sway bar increase would be a good idea. After all of that work, you would be extremely disappointed in the weak results. Most sway bar comments on F3x platforms aren’t very useful because people are so inexperienced with sway bars, and with understanding how all the suspension components interact. Sway bar labor can be costly so people are more likely to throw heavy springs on a car to control body roll, which can really harsh the ride. I’ve been upgrading sway bars on my various cars for many years. It’s a valuable component that’s often ignored on F3x’s.

[Cytoplasm0671]

I can provide recommendations/options. What are you starting with? RWD or XDrive? Standard struts & shocks or does your car have the Adaptive Suspension/EDC front struts & rear shocks? See photo. Do you have grey or blue brake calipers? Which tire brand, model and size(s) do you have? Do you have access to E85 at your local gas stations? Your VIN would be helpful. What mods have you already done?

The car is RWD, has Adaptive Suspension (confirmed), has the big blue caliper brakes, is lowered on Dinan springs and has a Dinan exhaust. The tires are PS4S 245/40/18 and I do have access to E85.

Labor history (Date/Mileage/Description):
9/7/22 41k Cabin and engine air filters
9/26/22 41k 0w30 BMW oil change
10/5/22 Added coolant (was low)
10/11/22 42k New plugs
10/25/22 42k Tested brake fluid (1%). Added Hawk 5.0 Street brakes, Zimmerman rotors, new OEM coolant cap, and washer fluid reservoir.
11/20/22 43k 1.25L of OEM 75W85 G1 Hypoid oil for differential, 1L of Pentosin MTF LT5 oil for transmission.
12/29/22 43k Bootmod3 stage 1 91 octane tune, Bimmercode mods
3/21/23 44k Active Autowerke catted downpipe

As per your question on sway bars, I have seen reports of people who went overboard with thickness and later had to swap out lighter bars, so that's where the Less is More principle comes from. Do you have a suggestion for front (or even rear) sway bars that maintain overall comfort but still improve body roll?

[johnung]

Originally Posted by Cytoplasm0671

The car is RWD, has Adaptive Suspension (confirmed), has the big blue caliper brakes, is lowered on Dinan springs and has a Dinan exhaust. The tires are PS4S 245/40/18 and I do have access to E85.

Labor history (Date/Mileage/Description):
9/7/22 41k Cabin and engine air filters
9/26/22 41k 0w30 BMW oil change
10/5/22 Added coolant (was low)
10/11/22 42k New plugs
10/25/22 42k Tested brake fluid (1%). Added Hawk 5.0 Street brakes, Zimmerman rotors, new OEM coolant cap, and washer fluid reservoir.
11/20/22 43k 1.25L of OEM 75W85 G1 Hypoid oil for differential, 1L of Pentosin MTF LT5 oil for transmission.
12/29/22 43k Bootmod3 stage 1 91 octane tune, Bimmercode mods
3/21/23 44k Active Autowerke catted downpipe

As per your question on sway bars, I have seen reports of people who went overboard with thickness and later had to swap out lighter bars, so that's where the Less is More principle comes from. Do you have a suggestion for front (or even rear) sway bars that maintain overall comfort but still improve body roll?

You made some smart mod choices towards your goals. I’ve got a few more questions, some immediate suggestions and some other recommendations that are more expensive, but worth budgeting for.

IMO I wouldn’t focus on sway bars next. You have some other highly impactful mods that you could do first that are reasonably priced/easy to install including:
Weichers Front Strut Brace
MST Intake or aFe Free Flow Airfilter
xHP Automatic Transmission Tune

Then install VAC Monoball Front Upper Control Arms, followed by an M Performace LSD. An LSD is a major differentiator between an M3 & a 340i RWD.

Once you have done those, it will give you a better idea about how much body roll you still have, and which sway bars may be the solution.

I also listed some other potential mods to do later. The biggest is lightweight Forged wheels. Reduced rotating inertial mass provides huge improvements. Many details below.

Hope this helps!

Note: Please be cautious about reading the same opinion multiple times. The natural assumption is that if you see something a lot, then it must be correct. Sometimes it’s just a bunch of ill informed people repeating the same incorrect opinion.

FRONT STRUT TOWER BRACE
Inexpensive and easy to install yourself, this reduces chassis flex when entering curves so it feels like steering is quicker, more responsive.

(Note: Whoever told you that reducing chassis flex was a bad thing was confusing components like this, with replacing bushings designed to impede NVH from the cabin with more solid race materials. Two different issues.)

I’ve investigated in detail most strut brace designs on the market and this is the best one for several reasons.

https://www.kiesmotorsports.com/prod...&_v=1.0?aff=22

STRUT BRACE INSTALLATION
(Fits F3x 335i/340i, etc)
https://youtu.be/eP9Jyr2v93s

INTAKE/AIR FILTER
Have you considered installing an Intake for more turbo spool sound and a small performance bump from the free flow airfilter?

I recommend the MST Intake. Link below. It’s an excellent design. Don’t get sucked into those open/closed/cold air/hot air intake design arguments. They are mostly slick marketing mixed with misinformation.

MST INTAKE
https://www.kiesmotorsports.com/prod...7&_ss=r?aff=22

MST INTAKE INSTALLATION
https://youtu.be/tXQvORtzx4w
FYI- They experimented in this video with placing a microphone under the hood. It’s a neat idea, but I would have also included video recorded inside the cabin while driving like they usually do. Don’t be alarmed at the loud strange sound from under the hood in the video. It actually sounds really good from inside and outside the car.

AFE PRO DRY PERFORMANCE AIRFILTER
If you intend to hold off on an intake it’s a good idea to upgrade the stock airfilter to a free flow aFe Pro Dry airfilter. See photo for part number. It’s washable, reusable and doesn’t require oiling like most performance airfilters.

STAINLESS STEEL BRAKE LINES
Next time that you replace brake fluid, which should be done every two years for safety, replace stock rubber brake hoses with stainless steel lines. See photo. This reduces stock brake pedal mush and provides a firmer pedal feel.

XHP AUTOMATIC TRANSMISSION TUNE
This provides a huge improvement in how the extra engine power is put to the asphalt. It’s a no brainer. Just purchase the xHP license and xHP Map Pack. It flash installs just like Bootmod3. I recommend trying their Stage2 first, then their Stage3.
It’s awesome. Whenever I want to drive aggressively I just hit the button from Comfort to Sport mode, and flick the gear selector to the left to engage Sport transmission mode.

LSD- LIMITED SLIP DIFFERENTIAL
M Performance LSD Part# 33108659989
Link below. An absolutely huge difference between the 340i and the M3 is that the M3 has an LSD. An LSD removes the rear wheel slippage that you feel and often don’t feel until it’s gone. The moment one rear wheel slips, the LSD transfers that slipping wheel’s power to the other rear wheel. It’s a monster difference in traction from standing starts and when entering turns. Instead of spinning the car powers out of those situations.

Dealer installation is about $650. This is one of the few jobs that I recommend taking to a BMW dealer. Removing drive shafts on an F3x requires two special tools. Independent shops often don’t have the tools or experience. I know guys who took theirs to independent shops to try to save a couple hundred bucks and it turned into a nightmare where the shop mechanic buggered up the LSD trying to rig his own tools to work.

https://www.getbmwparts.com/oem-part...w2LWdhcw%3D%3D

VAC MONOBALL FRONT CONTROL ARMS
It sounds like you have read my posts on this subject. Removes the vague F3x steering feel and makes it much more precise.

Monoball bushings are NOT a commodity apples to apples product like can be price shopped. Designs differ. I’m convinced that VAC has the best design and USA manufactured product. This isn’t some Chinese made thing with multiple brand labels slapped on it. VACs are unique. Designed, engineered and manufactured at VAC in Philadelphia.

I recommend upgrading the Upper Control Arms first (link below) if you don’t have the immediate budget. Then do the Lower Arms later if you want. It’s very simple to install, probably 1-2 shop hours to do one pair and 2-3 shop hours to do both pairs at the same time.

VAC F3X RWD FRONT CONTROL ARMS
(XDrive models use a different part#)
https://www.kiesmotorsports.com/prod...&_v=1.0?aff=22

BRAKE ROTORS
I understand that your rotors are new. At some point when they need to be changed, upgrade to full floating full crossdrilled rotors. BMW installs them on M2/M3/M4 because they are the best for street performance and the best in rain.
I installed front StopTech full floating full crossdrilled on my car 3-4 years ago. Now their price is too high for me to recommend them. Right now I would choose Paragon 370x30 full floating rotors. They save 3lbs per front wheel in rotating inertial mass which is huge! Link below.

PARAGON FULL FLOATING 370x30 ROTORS (it’s very important to special order them with full crossdrilled rings and anti-rust coating. Standard slotted are for tracking and don’t provide the advantages of full crossdrilled on the street. See photo.

https://paragonbrakes.com/2-piece-ro...mance-m-sport/

LIGHTER FORGED WHEELS
Provide huge reduction in rotational inertial mass. I have ordered the new APEX VS-5RS 18x8.5” which at 17.2lbs each are the lightest, strongest wheels that I’ve found. It will save close to 10lbs per corner that will improve acceleration, handling and even gas mileage. Could cut 0-60 by 0.5 seconds. Allows me to run optimal square setup with 255/40-18 MPS4S tires. Link below for more details.

REAR DIFFERENTIAL BRACE
It would be worth investigating a rear brace that reduces rear diff movement. I’ve read that they can be helpful especially with RWD. Don’t know enough to actually recommend it.

QUESTIONS:
When you installed your Dinan springs did you trim your stock bump stops or install the Dinan bump stops? If you did, did you happen to take stock vs Dinan comparison photos? Did you note which BMW part number was on the Dinan bump stop?

How would you describe any difference that you felt between stock and after the Dinan springs were installed? Did the ride feel any more stiff, or more harsh especially on rough roads? Did body roll seem the same? Was there any improvement?

SWAY BARS
From realoem website, it appears that your car has a stock Front 25mm sway bar and a stock Rear 13mm sway bar.

Most people don’t understand that the functions of suspension springs and sway bars are different, but they do overlap in terms of controlling body roll. Unless the road is perfectly straight with a surface as smooth as glass, springs (and dampers) are always working to handle imperfections and not transmit them to the cabin. As a car enters a curve and forces try to make the body roll, the springs push back.

The problem with trying to control body roll by installing stiffer and stiffer springs, is that often springs are installed that are much stiffer than required to do the springs main job. A car can be driving straight down a road and hit a bump or a rough patch. Springs that are too stiff will feel harsh, even teeth rattling.

Note: Dinan website claims that your front springs are +25% stiffer and rear springs are +34% stiffer. I’ve emailed them asking for actual spring rate numbers so I can compare to other setups. I’ve seen some about +10% vs stock and others over +50%. I’ve seen springs included in coilover sets with spring rates all over the place.

The main function of sway bars is to prevent/lessen body roll. They act as a lever so that when the chassis enters a curve and tries to roll to one side, that force is transmitted to the other side to try to keep the chassis flat. So when driving on a straight road and encountering normal bumps, etc the sway bar is doing nothing.

So the ideal suspension setup is to have springs (and dampers) sized to provide a comfortable ride over bumps, rough patches and potholes, along with front and rear sway bars sized to lessen body roll in curves.

Note: Yes, I know that suspension components and forces are more complex than I’m making it sound, but the goal here isn’t to take a deep suspension dive, but instead to provide enough conceptual information to make appropriate mod choices. FaRKle! has posted a lot of great stuff about suspensions.

HOLLOW VS SOLID SWAY BARS
I would never install a hollow bar on my car. When they fail, they suddenly snap. Years ago I lost a friend who was killed just driving down the highway when a front suspension piece snapped and sent his car sideways into a concrete barrier. Do NOT believe marketing nonsense about hollow bars being stronger. They are much cheaper to make so they are more profitable. Also having multiple adjustment holes is not a feature that 99% of people would use. Just install sway bars at the hole closest to the end.

I would suggest first doing the Front Strut Brace and the VAC monoball Upper (and possibly Lower) Control Arms. See how the overall ride and body roll is before doing sway bars.

FRONT SWAY BAR
Since the stock front bar is 25mm, the H&R solid Front 28mm solid steel sway bar for F30 6-cylinder RWD (part# 70878-2) is the most logical choice.

REAR SWAY BAR
The stock rear sway bar is 13mm. I already know from experience that the H&R 20mm bar is too heavy for the F3x chassis. On high speed curves it tends to crest too much lift in one of the rear wheels, reducing its tread patch on the asphalt.

But there are several solid rear bar choices in the range needed: 15mm BMW bar, 16mm Eibach bar and 17mm KC Design bar. See photos.