[Peter Morrin]

Seeing that I stirred the pot....

I think the l brackets could also be built in carbon to save weight. It would likely require the steel pieces to use as a model, but I don't think it would be a biggie. Since these are not life-critical if they break, I am more willing to play DIY with exotic materials which are difficult to design from standard engineering principals. The F1 guys make all their control arms out of CF, but they have a few more tools and grey matter at their disposal.

Thank you for clarifying the interference point on the strut towers. This explains why Biginboca slotted the tops of the towers and used the Dinan camber plates. I understand reservations about cutting into the tops of the strut towers but suspect it can be done with impunity. The towers could also be reinforeced from the outside with CF/epoxy strips over their tops to prevent "punch out" if it was a concern.

Has there been any discussion of gaining extra camber by extending the control arm? I have not seen one on the aftermarket so I am wondering if this introduces other problems. I did a back of envelope calc and it looks like 10mm (3/8") could produce about 1 degree of camber. Biginboca has followed a more traditional and factory approach to camber. Becaurs my car is an xi, I don't have the same number of options. Relying on OEM parts and engineering is definitely preferred, but the xi was likely never thought of as a performance vehicle by the design group.

[Biginboca]

Originally Posted by 335i54n

you could lighten the flange to save some weight

https://www.wholesalepartsexpress.co...250-b250e-246/

https://www.fcpeuro.com/products/por...160500#fitment

Good suggestion! I currently have the F80 front hubs which are like 1lb lighter due to some material removal. The F80 rear flanges are also lighter but I couldn’t verify if they work with the e9x wheel bearings and spindles. They are like 1/2lb lighter than e9x hubs though.

[Biginboca]

Originally Posted by Peter Morrin

Seeing that I stirred the pot....

I think the l brackets could also be built in carbon to save weight. It would likely require the steel pieces to use as a model, but I don't think it would be a biggie. Since these are not life-critical if they break, I am more willing to play DIY with exotic materials which are difficult to design from standard engineering principals. The F1 guys make all their control arms out of CF, but they have a few more tools and grey matter at their disposal.

Thank you for clarifying the interference point on the strut towers. This explains why Biginboca slotted the tops of the towers and used the Dinan camber plates. I understand reservations about cutting into the tops of the strut towers but suspect it can be done with impunity. The towers could also be reinforeced from the outside with CF/epoxy strips over their tops to prevent "punch out" if it was a concern.

Has there been any discussion of gaining extra camber by extending the control arm? I have not seen one on the aftermarket so I am wondering if this introduces other problems. I did a back of envelope calc and it looks like 10mm (3/8") could produce about 1 degree of camber. Biginboca has followed a more traditional and factory approach to camber. Becaurs my car is an xi, I don't have the same number of options. Relying on OEM parts and engineering is definitely preferred, but the xi was likely never thought of as a performance vehicle by the design group.

So there are adjustable arms (SPL) that would allow more camber, and also E9XM3 arms gain camber. A third option is I noticed the F80 front LCA attached to the F80 spindles I purchased were longer than E9XM3 arms. So they would give more camber than the E9XM3 arms, but one other consideration is that due to using the same thrust arm it looked to me like they might start moving the wheel forward in the wheel well.

I measured the F80 LCA at about 20mm longer than the E9XM3 LCA:

[rothwem]

Originally Posted by Peter Morrin

Seeing that I stirred the pot....

I think the l brackets could also be built in carbon to save weight. It would likely require the steel pieces to use as a model, but I don't think it would be a biggie. Since these are not life-critical if they break, I am more willing to play DIY with exotic materials which are difficult to design from standard engineering principals. The F1 guys make all their control arms out of CF, but they have a few more tools and grey matter at their disposal.

Thank you for clarifying the interference point on the strut towers. This explains why Biginboca slotted the tops of the towers and used the Dinan camber plates. I understand reservations about cutting into the tops of the strut towers but suspect it can be done with impunity. The towers could also be reinforeced from the outside with CF/epoxy strips over their tops to prevent "punch out" if it was a concern.

Has there been any discussion of gaining extra camber by extending the control arm? I have not seen one on the aftermarket so I am wondering if this introduces other problems. I did a back of envelope calc and it looks like 10mm (3/8") could produce about 1 degree of camber. Biginboca has followed a more traditional and factory approach to camber. Becaurs my car is an xi, I don't have the same number of options. Relying on OEM parts and engineering is definitely preferred, but the xi was likely never thought of as a performance vehicle by the design group.

Don't you start to run into diminishing returns though with regards to camber? I don't even think the time attack guys are running much more than 3.5° of negative camber, I've read that you start running into straight-line traction issues.

Also, I don't want to pour cold water on your idea about the extended control arm (I love actual engineering/fab discussions on car forums), but I wonder at what point you're going to run out of range on the plunge joint for your xi.

[Biginboca]

Originally Posted by rothwem

Don't you start to run into diminishing returns though with regards to camber? I don't even think the time attack guys are running much more than 3.5° of negative camber, I've read that you start running into straight-line traction issues.

Also, I don't want to pour cold water on your idea about the extended control arm (I love actual engineering/fab discussions on car forums), but I wonder at what point you're going to run out of range on the plunge joint for your xi.

I don’t think he’s looking to run -3.5, I suspect he’s wanting more camber than the -0.5 stock for a better performer on the street. I also would think pulling the strut top mount inwards with some slots will get him what he’s looking for. (-1.5 to -2.0 I suspect, which is perfectly fine for tire wear and enhanced street performance.)

You make a good point about pushing the spindle outwards lowering the spline engagement on the front half shafts. With pulling the top mount inwards you can probably gain a little freedom to extend the LCA but based on the geometry in my head I would say you can only lengthen the LCA by an amount roughly 1/3 of what you pull the top mount inwards… so not much room to lengthen the LCA really on a Xdrive.

[Peter Morrin]

Good points everyone. I am going to slot the tops of the shock towers and see what that yields. Next step would be the Dinan camber plates. Last step would be experimenting with a longer control arm making sure there was still adequate engagement of the splines in the half shafts. For a dual purpose care I would need to be careful.

I have a question about the Manzo???? adjustable toe arms that you used at one time, but I believe you have now removed. Was there a reason you did not like them? There would certainly be lighter versions as I believe the Manzo are a steel barrel. I will likely need to get adjustable toe arms as I may not be able to raise the back with the ST rear adjusters to get to M Sport height.

Thanks,

Peter

[Biginboca]

Originally Posted by Peter Morrin

Good points everyone. I am going to slot the tops of the shock towers and see what that yields. Next step would be the Dinan camber plates. Last step would be experimenting with a longer control arm making sure there was still adequate engagement of the splines in the half shafts. For a dual purpose care I would need to be careful.

I have a question about the Manzo???? adjustable toe arms that you used at one time, but I believe you have now removed. Was there a reason you did not like them? There would certainly be lighter versions as I believe the Manzo are a steel barrel. I will likely need to get adjustable toe arms as I may not be able to raise the back with the ST rear adjusters to get to M Sport height.

Thanks,

Peter

Hey Peter,

The Manzo were good! I had no issues with them I just wanted to upgrade to a full uniball set up. They are heavy for sure I was surprised when I took them off and compared the weight to the aluminum SPL toe arms I replaced them with.

But I would definitely recommend the Manzo arms.

[Peter Morrin]

This is really more of an issue for the xi cars, but I will ask this group as I think it has some of the best suspension knowledge for our cars.

Has anyone seen, or experimented with, raising the shock tower tops to elevate the bearing point of the strut bearing/camber plate? On my xi, it should be possible to raise the top of the strut towers 1-1.5 inches, increasing travel and reducing the risk of crashing the bump stops. My only question is why BMW would not have done this from the outset. What are we missing?

I saw this done on a VW Golf modified for pro-rally duty, so the concept has been tried before. It would likely contravene the more restrictive racing class rules if that is a concern.

Thoughts?

Peter

[Biginboca]

Originally Posted by Peter Morrin

This is really more of an issue for the xi cars, but I will ask this group as I think it has some of the best suspension knowledge for our cars.

Has anyone seen, or experimented with, raising the shock tower tops to elevate the bearing point of the strut bearing/camber plate? On my xi, it should be possible to raise the top of the strut towers 1-1.5 inches, increasing travel and reducing the risk of crashing the bump stops. My only question is why BMW would not have done this from the outset. What are we missing?

I saw this done on a VW Golf modified for pro-rally duty, so the concept has been tried before. It would likely contravene the more restrictive racing class rules if that is a concern.

Thoughts?

Peter

I can’t speak much into that, probably Tambohamilton can weigh in.

My thoughts are that BMW added xdrive onto what was likely designed as a rwd chassis in the beginning. So the way they incorporated the necessary driveline angle to keep the front half shaft joints in a happy operating range was to keep the front higher. Like the front differential requires a certain amount of clearance under the car and then to keep the correct driveline angles to the hubs they needed to raise the front.

When you raise or lower a car with halfshafts you are going to affect the longevity of the joints. The less angle on them the longer they last. So consider if what you are suggesting would change the driveline angles.

In my mind I picture what you are suggesting would be using a taller top hat for the spring? Or are you suggesting a different strut mount from a non Xdrive?

[Torgus]

Halfshafts can go bad quick if they are at angels they don't like.

Also, I swear this is the busiest thread on the forum!

[Peter Morrin]

I believe Biginboca is correct that the xi is an "adaptation" of the RWD platform and as such, the engineers were constrained by what they could do. A revised shock tower would not get past the bean counters even if it is the correct solution.

Good comments about the half shafts. I will set the car at xi height and verify the half-shaft inclination. I will then lower the car to M-Sport height and see the difference. If I were to raise the bearing point of the strut bearing, I might have to get a longer shock body (probably from a RWD) to bring the half-shafts back into a suitable range.

My thought on raising the strut bearing is to build a stepped disc from carbon fibre that would move the bearing surface of the xi strut bearing up 1-1.5". I will make the determination of height considering this half shaft discussion.

Thanks, Peter

[Tambohamilton]

Yeah, it's surely possible to do the chassis work. Driveshafts will be the limitation, but depending on angle perhaps adding track/negative camber would help there.

Personally I think you're getting into silliness there though. Why does the car need to be low? I guarantee you that if you had an xi height car with sorted suspension, you wouldn't be able to take advantage of any performance gain lowering it an inch or 2 might possibly give you. Keep it simple, and enjoy the car for what it is!

Edit; Says the guy who's changed and/or modified almost every suspension component on his car.....

[Biginboca]

Originally Posted by Tambohamilton

Yeah, it's surely possible to do the chassis work. Driveshafts will be the limitation, but depending on angle perhaps adding track/negative camber would help there.

Personally I think you're getting into silliness there though. Why does the car need to be low? I guarantee you that if you had an xi height car with sorted suspension, you wouldn't be able to take advantage of any performance gain lowering it an inch or 2 might possibly give you. Keep it simple, and enjoy the car for what it is!

Edit; Says the guy who's changed and/or modified almost every suspension component on his car.....

I get the impression he wants to raise the front ride height and use a longer travel shock, so as to enjoy more comfort and less bottoming out on the bump stops.

[Tambohamilton]

Originally Posted by Biginboca

I get the impression he wants to raise the front ride height and use a longer travel shock, so as to enjoy more comfort and less bottoming out.

I think he wants to lower the front ride height but maintain the current bump travel... We'll see

[Peter Morrin]

Well you both are partially correct. My primary objective is to set the ride height for optimum handling. Secondary objectives are dealing with lots of snow in the winter and, if possible, looks (height and rake).

I have connected with a track instructor who drives a 328 xi and has provided his basic recommendations that I am following as a guide; (http://dreamingin302ci.blogspot.com/...ve-handle.html).

Most of his recommendations mirror what Biginboca has recommended. When I spoke with him, he did comment on the limited suspension travel of the xi, even at stock ride height. His opinion was that the lowest setting to maintain an ideal camber curve was M-sport height which is probably around 1" (25 mm) lower than the way it came from the factory.

I bought the car with ST-X (same as KV-1) coilovers set very low. I really like the spring rates and dampening of this system, but both rear shocks are blown. General deterioration of other suspension components is forcing a complete re-build. I plan to keep the ST-X springs and front struts, but replace the rear shocks with Koni Yellows.

I am targeting a front static camber of 2 degrees, rear of 1.5 degrees, reduced compliance and striction, increased chassis stiffness, and hopefully no increase in NVH.

I will replace the front thrust arm bearing with a proflex polyurethane bushing, replace the control arm with OEM xi arms, replace the ball joints with OEM, and replace the strut bearings with OEM xi units. I was initially planning on simply slotting the tops of the strut towers, when I started thinking about other options for the top of the struts.

In the rear I will replace the shocks (Koni Yellow), top shock mounts (Monroe), lower shock mounts (oem), upper control arms (TRW M3) and toe arms (Manzo adjustable).

I run 225/40-17 DWS 06 on 17x8 Moda rims (10.3 kg)with 20mm spacer in rear in summer. In winter I will likely run 205/55-16 Hakka 5 on 16x7 OEM rims (not yet purchased). I will consider a 17" summer track set-up if one comes up for a good price.

Ride height set to MSport specifications, aligne vehicle to above camber settings. Toe and caster settings (front caster adjustable with Proflex bushing) to be set to recommendations here.

Over time I hope to follow some of the weight reduction, chassis stiffening, and power adders listed in this build thread.

Get some track time to improve the nut behind the wheel and appreciate all of the above.

Peter

[Biginboca]

Originally Posted by Peter Morrin

I have connected with a track instructor who drives a 328 xi and has provided his basic recommendations that I am following as a guide; (http://dreamingin302ci.blogspot.com/...ve-handle.html).

That was a good read!

[Peter Morrin]

What is the collective opinion of exhaust modifications to the NA engine? More horsepower?, more torque?, change in power band?, more noise? I think we can break it down into 3 areas; headers/exhuast manifolds/cats; resonator; rear muffler.

There is a long thread on removing the rear muffler and leaving the rest of the OEM system in place. Some people simply chopped off the muffler, others extended the piping to a proper exit location. Most of this was done to make the exhaust louder. Results were mixed.

Three of the more common after-market header systems I have seen are; Supersprint, AA, and Roundel Werk. The Supersprint are lovely, but outrageous, the AA seem a little rough from the pictures, and the Roundel Werk look pretty good for $650 USD.

My intent is to move to the 3 stage manifold first and then look at the exhaust. I already have the BMW performance muffler and like the sound, but doubt there is much performance difference between rear mufflers (or none at all). I don't currently have any special tune, but understand that this is also important.

What is the collective wisdom of this group?

Peter

[Tambohamilton]

Loud exhausts often stimulate the butt-dyno. Only go by dyno proven results...and even those aren't bulletproof.

[Biginboca]

Originally Posted by Peter Morrin

What is the collective opinion of exhaust modifications to the NA engine? More horsepower?, more torque?, change in power band?, more noise? I think we can break it down into 3 areas; headers/exhuast manifolds/cats; resonator; rear muffler.

There is a long thread on removing the rear muffler and leaving the rest of the OEM system in place. Some people simply chopped off the muffler, others extended the piping to a proper exit location. Most of this was done to make the exhaust louder. Results were mixed.

Three of the more common after-market header systems I have seen are; Supersprint, AA, and Roundel Werk. The Supersprint are lovely, but outrageous, the AA seem a little rough from the pictures, and the Roundel Werk look pretty good for $650 USD.

My intent is to move to the 3 stage manifold first and then look at the exhaust. I already have the BMW performance muffler and like the sound, but doubt there is much performance difference between rear mufflers (or none at all). I don't currently have any special tune, but understand that this is also important.

What is the collective wisdom of this group?

Peter

My opinion is, go with the Condor Speed Shop headers if you can. They are priced like the AA but made in the US where I believe AA is sourcing from Asia likely they exact same factory and header as Roundel Work. The Condor looks like the one to get currently.

Pairing headers with Performance Exhaust is known to be obnoxiously loud. I have never heard that pairing. You need to research it. It’s possible those same people would consider my exhaust obnoxiously loud also lol

I’m really happy with my set up. On several track days I’ve had people come up to me after and say I had the best sounding car there. This is on days where other cars were e92m3’s with loud exhaust, GT3’s, Camaros, Corvettes, and Mustangs. So I can guarantee you mine sounds good at minimum. Also my set up is pretty much a straight pipe but my muffler has an anti drone hemholtz chamber tuned to reduce the noise from 2000-3500 rpms. So it’s pretty quiet at those rpms but is loud when you wind it out. My exhaust is: AA Headers to Supersprint Secondary Cat Delete to OEM Resonator to AA Gen 2 Muffler.

From everything I’ve read the performance exhaust sounds good until you start pairing it with other exhaust mods and then it’s gets too rowdy.

[Peter Morrin]

I know this can be a delicate area, but are you now running now catalytic converters in your system? I don't think many of us can do that. Where are the OEM cats and any idea if the car can meet emissions with one set (possibly a freer flowing variety)? Do the cats attenuate the sound?

Is the resonator effectively an open box that mixes the exhaust streams?
My reading of exhaust theory suggest that the exhaust pulses are nulled in the resonator and exhaust scavenging is no longer a design factor. I presume this is why BMW went to a single pipe beyond the resonator.

Can you discuss the rear muffler and how it was tuned to mitigate drone in the mid-band. I would want to minimise interior cabin noise in the highway cruising band of 50-80 MPH if possible.

How heavy are the OEM exhaust components. Is this a place where weight can be saved without going to extremes like titanium or Carbon Fibre?

Peter

[tylerhart_21]

To answer your first question the oem cats are in the headers and right after the exhaust has a bend (I think they call it section a). So in total you have four cats or two sets of cats. If you want more free flowing cats I have only seen the afe headers with sport cats. But for 2 grand I wouldn't buy them personal.

With the resonator I would keep it, since it resonates the sound of the exhaust similar to what you were saying. Changing the resonator could change the tone of the car but not in a huge way. An example would be vibrant and their resonators known to have a lower tone to them. The biggest sound/tone change would be in the headers.

I don't have the right knowledge to speak about the AA muffler. But from what I have hear and with other research. They use an pipe that caps at the end. This causes the exhaust pulses to collide and reduce the drone in that certain rpm. But to reduce sound while cruising you would need something to reduce drone and noise around the 2-3 range. The only recommendation I can give the Eisenmann sport muffler, good tone and not to loud. (Gives the car more character, good for daily driving)

The biggest places your can save weight within the exhaust system is the headers and the muffler. How much you could save not sure about that. Some people would say go to a single after the headers, but in my opinion that's a lot of work (if you are doing yourself) and or money if you get a shop to do it.

[Peter Morrin]

I was coming home late last night when I could wind the car up a bit, and the reality is that on the street, our RPM band is 2000-3300 (at least with my xi-6 speed final drive). An enthusiastic on ramp from second might go to 5500, but the car is screaming at 6500. This is the top of the power band for the base engine and going beyond that produces less power.

Biginboca has done a number of things to move the power band up (higher final drive, N54 intake, catless headers, ?????).

My question for Alphonse; what is your typical RPM range on the track?

Do you feel your modifications have compromised performance for daily driver that typically would not rev beyond 3500?

My guess is that the ideal header/exhaust system for a car biased toward spirited daily duties might have a different design than what is available on the market. This is because the designs on the market are likely biased to a much higher rev range. Similarly, if we are looking at header designs for an E46 M3 (last factory campaigned 6 cylinder), they are also likely biased toward a higher RPM range.

Has anyone heard of header designs or theory that would favour mid-range torque over maximum high range horsepower?

I am also curious what the current thinking is for the 330d. This would be in Tambohamilton's purvey.

Peter